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1
Dudas, Sarah E., Brian A. Grantham, Anthony R. Kirincich, Bruce A. Menge, Jane Lubchenco, and John A. Barth. "Current reversals as determinants of intertidal recruitment on the central Oregon coast." ICES Journal of Marine Science 66, no. 2 (December 2, 2008): 396–407. http://dx.doi.org/10.1093/icesjms/fsn179.
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Abstract Dudas, S. E., Grantham, B. A., Kirincich, A. R., Menge, B. A., Lubchenco, J., and Barth, J. A. 2009. Current reversals as determinants of intertidal recruitment on the central Oregon coast. – ICES Journal of Marine Science, 66: 396–407. The influence of current reversals on intertidal invertebrate recruitment was investigated using two seasons of nearshore physical and intertidal biological observations along the central Oregon coast, an intermittent upwelling system. In 1998, upwelling periods were punctuated by infrequent wind reversals and widespread increases in nearshore temperature, whereas 1999 was characterized by frequent, shorter wind reversals. In 1998, barnacle recruitment was best at the site experiencing more frequent reversals of the predominantly equatorward currents, higher poleward velocities, and coincident temperature increases. In 1999, barnacle recruitment peaked at the site with greater poleward current velocities, and maximum mussel recruitment at the site with consistent deep (10 m) onshore currents. Barnacle recruitment generally increased with onshore surface currents and temperature; mussel recruitment showed variable, weaker correlations. The data indicate that substantial decreases or complete reversals of upwelling-driven alongshore currents may be important for barnacle recruitment, but topographically driven differences in the response of currents to wind changes may generate local recruitment differences. This suggests that even relatively straight coastlines may have enhanced recruitment zones attributable to the variable local oceanography. Further, the interannual differences observed in current reversals and recruitment patterns highlight the potential importance of upwelling variation for onshore communities.
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Wiafe, George, Hawa B. Yaqub, Martin A. Mensah, and Christopher L. J. Frid. "Impact of climate change on long-term zooplankton biomass in the upwelling region of the Gulf of Guinea." ICES Journal of Marine Science 65, no. 3 (March 14, 2008): 318–24. http://dx.doi.org/10.1093/icesjms/fsn042.
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Abstract Wiafe, G., Yaqub, H. B., Mensah, M. A., and Frid, C. L. J. 2008. Impact of climate change on long-term zooplankton biomass in the upwelling region of the Gulf of Guinea. – ICES Journal of Marine Science, 65: 318–324. We investigated long-term changes in coastal zooplankton in the upwelling region in the Gulf of Guinea, 1969–1992, in relation to climatic and biotic factors. We considered the role of hydrographic and climatic factors, i.e. sea surface temperature (SST), salinity, sea level pressure, windfield, and Southern Oscillation Index (SOI), in the long-term variation of zooplankton in a multiple regression analysis, along with the abundance of Sardinella. Annual variation in zooplankton biomass was cyclical, with the annual peak occurring during the major upwelling season, July–September. Over the 24-year period, there was a downward trend in zooplankton biomass (equivalent to 6.33 ml per 1000 m3 per year). The decomposed trend in SST during the major upwelling revealed gradual warming of surface waters. This trend was believed to be the main influence on the abundance of the large copepod Calanoides carinatus (sensitive to temperatures above 23°C), which appears in the coastal waters only during the major upwelling season. The warming trend associated with global climate change could affect zooplankton community structure, especially during the major upwelling season. Global warming coupled with “top–down” (predation) control by Sardinella might be responsible for the long-term decline in zooplankton biomass in the upwelling region of the Gulf of Guinea.
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Scheel, D., and C. Johnson. "Sea-surface temperatures predict targeted visual surveys of octopus abundance." Marine and Freshwater Research 72, no. 9 (2021): 1321. http://dx.doi.org/10.1071/mf20318.
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In upwelling systems around the world, octopus abundance is forecast by marine productivity linked to upwelling strength, often indicated by sea-surface temperatures. Climate change may disrupt populations of marine animals that are linked to such temperature-dependent events. We analysed the relationship of the abundance of giant Pacific octopuses (Enteroctopus dofleini) to Gulf of Alaska and Washington State water temperatures. Abundance was measured in targeted visual surveys in Prince William Sound, Alaska, over the period 1995–2016 and from REEF.org diver surveys in Washington State from 2003 to 2019. Octopus counts from both survey programs had significant negative correlations with water temperatures over the previous 2.5–4 years. Water temperature accounted for from 0.41 to 0.71 of the variance (R2) in octopus abundance in eastern Gulf of Alaska waters located in ocean currents up-stream of the survey areas, and up to 0.81 of the variance in Washington State waters. These negative correlations provide a possible predictive index for octopus abundance as measured by targeted visual surveys. These methods may be useful tools in management of octopuses and indicate impacts of climate change on North Pacific coastal marine ecosystems.
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Noblezada, Mary Mar P., and Wilfredo L. Campos. "Spatial distribution of chaetognaths off the northern Bicol Shelf, Philippines (Pacific coast)." ICES Journal of Marine Science 65, no. 3 (March 17, 2008): 484–94. http://dx.doi.org/10.1093/icesjms/fsn027.
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Abstract Noblezada, M. M. P., and Campos, W. L. 2008. Spatial distribution of chaetognaths off the northern Bicol Shelf, Philippines (Pacific coast). – ICES Journal of Marine Science, 65: 484–494. The composition, abundance, and distribution of chaetognaths off the northern Bicol Shelf, Philippines (Pacific coast), from 31 stations along transects perpendicular to the coast were analysed. Samples were collected in April, 2001. In all, 26 species belonging to 14 genera were identified. Flaccisagitta enflata was the most abundant and frequently captured species at all stations, and constituted 41.9% of the total specimens. Most of the smallest diversity values were observed from areas affected by upwelling, although the greatest densities were observed at stations located within the upwelling zones. The occurrence of mesopelagic and bathypelagic species (Decipisagitta decipiens, Caecosagitta macrocephala, and Eukrohnia fowleri), in samples collected from upper water layers, could be explained by vertical transport caused by upwelling.
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Jackson, Thomas, Heather A. Bouman, Shubha Sathyendranath, and Emmanuel Devred. "Regional-scale changes in diatom distribution in the Humboldt upwelling system as revealed by remote sensing: implications for fisheries." ICES Journal of Marine Science 68, no. 4 (December 22, 2010): 729–36. http://dx.doi.org/10.1093/icesjms/fsq181.
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Abstract Jackson, T., Bouman, H. A., Sathyendranath, S., and Devred, E. 2011. Regional-scale changes in diatom distribution in the Humboldt upwelling system as revealed by remote sensing: implications for fisheries. – ICES Journal of Marine Science, 68: 729–736. A diatom-detection algorithm was parametrized for the Humboldt upwelling system using local cruise data that were first validated, then used to create monthly composites of diatom distribution from 0 to 40°S and 90 to 70°W for both normal and El Niño conditions. There was a 50% reduction in the areal extent of diatom-dominated waters during the peak of the 1997 El Niño. The extent of the coastward contraction in the diatom-dominated area varied along the South American coastline. These regional shifts in phyto- and zooplankton communities would have increased food stress on local anchovy (Engraulis ringens) populations and could have contributed to diminished larval survival and landings the following year. A region of strong upwelling over the wide Peruvian continental shelf around 15°S was the only area that maintained a strong diatom population throughout the El Niño; the area may require special protection from fishing pressure in years following an El Niño event.
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de Lecea, Ander M., Rachel Cooper, and Albertus J. Smit. "Identifying the drivers of the pelagic ecosystem of an oligotrophic bight (KwaZulu–Natal, South Africa) using stable isotopes (δ13C, δ15N) and C : N ratio analysis." Marine and Freshwater Research 67, no. 11 (2016): 1750. http://dx.doi.org/10.1071/mf15256.
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The international literature highlights the importance of understanding the role and fate of terrestrial organic matter (OM) in the marine system, yet little is known about this on the oligotrophic east coast of South Africa. Within the Bight, three important processes make OM biologically available: (1) a topographically induced upwelling cell (north), (2) a Cyclonic Eddy (south), and (3) riverine input. We hypothesise that: (i) these OM sources differ substantially in their isotope ratios, and (ii) zooplankton at the inshore region has an isotope signature linked to localised fluvial fluxes. Particulate OM samples were collected at five locations along the Bight and in three main estuaries during austral summer and winter seasons in 2010 and subjected to isotopic and mixing model analysis. Riverine input played an important role in this ecosystem inshore during the wet season. Only marine OM played a role as a biological driver offshore and at all sites during the dry season. Although there were indications that the upwelling cell did occur, it was not confirmed as active in either season. The current study provides valuable insights into the Bight's biological functioning and principle insights into the fate of terrestrial organic carbon on the east coast of southern Africa.
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Shannon, Lynne J., Marta Coll, Dawit Yemane, Didier Jouffre, Sergio Neira, Arnaud Bertrand, Erich Diaz, and Yunne-Jai Shin. "Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends." ICES Journal of Marine Science 67, no. 4 (December 24, 2009): 807–32. http://dx.doi.org/10.1093/icesjms/fsp270.
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Abstract Shannon, L. J., Coll, M., Yemane, D., Jouffre, D., Neira, S., Bertrand, A., Diaz, E., and Shin, Y-J. 2010. Comparing data-based indicators across upwelling and comparable systems for communicating ecosystem states and trends. – ICES Journal of Marine Science, 67: 807–832. A suite of ecological indicators was selected for communicating, in a comparable way, how fishing affects the state of several upwelling ecosystems and others in which small pelagic fish play key ecological roles. Detailed background and understanding of system-specific processes and changes is needed for proper interpretation of results. In particular, environmental forcing is important in driving dynamics in upwelling systems; fishing impacts cannot be understood without understanding the corresponding dynamics of the environment. The Saharan Coastal (Morocco) and southern Benguela, both having experienced upsurges in low-trophic-level species, differed from other ecosystems when considering indicator trends. The ecosystem off Portugal emerged as showing reduced signs of fishing impacts in recent years, although the change may also be reflecting climate change favouring recruitment and abundance of demersal stocks. The indicator suite confirmed general understanding that the Mediterranean ecosystems have been notably degraded for several decades. Results and conclusions from this descriptive synthesis are compared with other comparisons of more complex, model-derived indicators. Even in upwelling and comparable systems, the simple data-based indicators are useful in synthesizing information on the status of an ecosystem, in particular on the ecosystem effects of fishing, to provide an ecological diagnosis at the ecosystem level, to be used in decision-making. Indicators of recent ecosystem state and trends over time are needed to assess the effects of fishing, but more indicators measuring biodiversity attributes and environmental change would complement the suite, providing fuller assessment of the status of upwelling and comparable ecosystems.
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Litz, Marisa N. C., Robert L. Emmett, Paul J. Bentley, Andrew M. Claiborne, and Caren Barceló. "Biotic and abiotic factors influencing forage fish and pelagic nekton community in the Columbia River plume (USA) throughout the upwelling season 1999–2009." ICES Journal of Marine Science 71, no. 1 (June 19, 2013): 5–18. http://dx.doi.org/10.1093/icesjms/fst082.
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Abstract Litz, M. N. C., Emmett, R. L., Bentley, P. J., Claiborne, A. M., and Barceló, C. Biotic and abiotic factors influencing forage fish and pelagic nekton community in the Columbia River plume (USA) throughout the upwelling season 1999–2009. – ICES Journal of Marine Science, 71: . Large river plumes modify coastal environments and can impact production across multiple trophic levels. From 1999 to 2009, the assemblages of forage fish, predator fish, and other pelagic nekton were monitored in coastal waters associated with the Columbia River plume. Surveys were conducted at night to target vertically migrating species, and community structure evaluated to better understand ecological interactions. Distinct inshore and offshore communities were identified during spring and summer that were correlated with ocean temperature, salinity, plume volume, and upwelling intensity. Resident euryhaline forage fish species, such as smelts, anchovy, herring, market squid, juvenile salmon, and spiny dogfish, showed a high affinity for inshore habitat and the lower salinity plume during spring. Highly migratory species, such as sardine, piscivorous hake, sharks, and mackerels, were associated with warmer, saltier waters offshore, during strong upwelling periods in summer. Overall, our study of pelagic nekton revealed that temporal dynamics in abundance and community composition were associated with seasonal abiotic phenomenon, but not interannual, large-scale oceanographic processes. Forage fish assemblages differed seasonally and spatially from the assemblages of major piscivorous predators. This finding suggests a potential role of the plume as refuge for forage fish from predation by piscivorous fish in the northern California Current.
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Boch, Charles A., Steven Y. Litvin, Fiorenza Micheli, Giulio De Leo, Emil A. Aalto, Christopher Lovera, C. Brock Woodson, Stephen Monismith, and James P. Barry. "Effects of current and future coastal upwelling conditions on the fertilization success of the red abalone (Haliotis rufescens)." ICES Journal of Marine Science 74, no. 4 (March 30, 2017): 1125–34. http://dx.doi.org/10.1093/icesjms/fsx017.
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Acidification, deoxygenation, and warming are escalating changes in coastal waters throughout the world ocean, with potentially severe consequences for marine life and ocean-based economies. To examine the influence of these oceanographic changes on a key biological process, we measured the effects of current and expected future conditions in the California Current Large Marine Ecosystem on the fertilization success of the red abalone (Haliotis rufescens). Laboratory experiments were used to assess abalone fertilization success during simultaneous exposure to various levels of seawater pH (gradient from 7.95 to 7.2), dissolved oxygen (DO) (∼60 and 180 µm.kg SW) and temperature (9, 13, and 18 °C). Fertilization success declined continuously with decreasing pH but dropped precipitously below a threshold near pH 7.55 in cool (9 °C—upwelling) to average (13 °C) seawater temperatures. Variation in DO had a negligible effect on fertilization. In contrast, warmer waters (18 °C) often associated with El Niño Southern Oscillation conditions in central California acted antagonistically with decreasing pH, largely reducing the strong negative influence below the pH threshold. Experimental approaches that examine the interactive effects of multiple environmental drivers and also strive to characterize the functional response of organisms along gradients in environmental change are becoming increasingly important in advancing our understanding of the real-world consequences of changing ocean conditions.
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Higgason, Kelley D., and Maria Brown. "Local solutions to manage the effects of global climate change on a marine ecosystem: a process guide for marine resource managers." ICES Journal of Marine Science 66, no. 7 (May 14, 2009): 1640–46. http://dx.doi.org/10.1093/icesjms/fsp133.
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Abstract Higgason, K. D., and Brown, M. 2009. Local solutions to manage the effects of global climate change on a marine ecosystem: a process guide for marine resource managers. – ICES Journal of Marine Science, 66: 1640–1646. The marine environment plays an important role in controlling the amount of CO2 that remains within the earth’s atmosphere, but it has not received as much attention as the terrestrial environment regarding climate-change effects, mitigation programmes, and action plans. Potential physical effects of climate change within the marine environment, including ocean acidification, changes in winds that drive upwelling and ocean circulation patterns, increasing global sea surface temperatures, and sea level rise, can result in dramatic changes within marine and coastal ecosystems. Often, marine resource managers feel overwhelmed by the magnitude of this issue and are therefore uncertain how to begin to take action. It may seem that they do not have the time, funding, or staff to take on a challenge as large as climate change, and fail to act as a result. Using NOAA’s Gulf of the Farallones National Marine Sanctuary as a case study, this paper outlines the need to act now and presents an easy-to-use process guide, providing managers options to incorporate effectively the influences of climate change into management strategies, as well as mitigate these influences through community outreach and a reduction in workplace emissions.
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Gertseva, Vladlena, Sean E. Matson, and Jason Cope. "Spatial growth variability in marine fish: example from Northeast Pacific groundfish." ICES Journal of Marine Science 74, no. 6 (February 17, 2017): 1602–13. http://dx.doi.org/10.1093/icesjms/fsx016.
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Abstract Marine fish populations exist in a complex environment, with oceanographic and fisheries factors affecting their dynamics. It has been shown that life history characteristics of marine fish vary in space and time. We examined spatial variability in growth of eight groundfish species in the Northeast Pacific Ocean to identify shared spatial patterns and hypothesize about common mechanisms behind them. Growth parameters were estimated in different areas over the latitudinal range of the species, and several hypotheses were tested as to how these parameters vary along the US west coast. Clear differences in spatial growth variability emerged among the species examined. Shelf species exhibit the highest growth rate between Cape Blanco and Cape Mendocino, which may, in part, be attributed to area-specific upwelling patterns in the California Current ecosystem, when nutrient-rich deep water is brought to the surface south of Cape Blanco and is uniquely distributed throughout this area, providing favourable conditions for primary productivity. Slope species showed a cline in asymptotic size (L∞), with L∞ increasing from south to north. This cline, previously attributed to fishery removals, also fits a specific case of the widely described Bergmann’s rule, and we explore specific potential ecological mechanisms behind this relationship.
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Moloney, Coleen L., Astrid Jarre, Hugo Arancibia, Yves-Marie Bozec, Sergio Neira, Jean-Paul Roux, and Lynne J. Shannon. "Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models." ICES Journal of Marine Science 62, no. 3 (January 1, 2005): 493–502. http://dx.doi.org/10.1016/j.icesjms.2004.11.009.
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Abstract Large-scale, mass-balance trophic models have been developed for northern and southern regions of both the Benguela and Humboldt upwelling ecosystems. Four of these Ecopath models were compared and calibrated against one another. A common model structure was established, and a common basis was used to derive poorly known parameter values. The four resulting models represent ecosystems in which the main commercial fish species have been moderately to heavily fished: central-southern Chile (1992), northern-central Peru (1973–1981), South Africa (1980–1989), and Namibia (1995–2000). Quantitative ecosystem indicators derived from these models were compared. Indicators based on large flows (involving low trophic levels) or top predators were not well estimated, because of aggregation problems. Many of the indicators could be contrasted on the basis of differences between the Benguela and Humboldt systems, rather than on the basis of fishing impact. These include integrated values relating to total catches, and trophic levels of key species groups. Indicators based on integrated biomass, total production, and total consumption tended to capture differences between the model for Namibia (where fish populations were severely reduced) and the other models. We conclude that a suite of indicators is required to represent ecosystem state, and that interpretation requires relatively detailed understanding of the different ecosystems.
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Ostrowski, Marek, José C. B. da Silva, and Bomba Bazik-Sangolay. "The response of sound scatterers to El Niño- and La Niña-like oceanographic regimes in the southeastern Atlantic." ICES Journal of Marine Science 66, no. 6 (May 3, 2009): 1063–72. http://dx.doi.org/10.1093/icesjms/fsp102.
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Abstract Ostrowski, M., da Silva, J. C. B., and Bazik-Sangolay, B. 2009. The response of sound scatterers to El Niño- and La Niña-like oceanographic regimes in the southeastern Atlantic. – ICES Journal of Marine Science, 66: 1063–1072. Oceanographic conditions off Angola alternate seasonally between upwelling in the austral winter and El Niño-like intrusions and downwelling in summer. During winter in regions deeper than 30 m, the water column consists of a top layer of warm, tropical water overlying cold, nutrient-rich, and hypoxic South Atlantic Central Water (SACW). Closer inshore the water becomes well mixed. In the stratified region, acoustic backscatter at 38 kHz matches the oceanographic structure. It is strong in the top layer, but declines sharply in the SACW. During summer, the water column is continuously stratified, and the SACW is absent from the shelf. The backscatter reveals multiple thin layers extending across much of the shelf. The scattering layers are often perturbed by internal waves. The combined evidence from multiple acoustic surveys and the existing synthetic-aperture radar imagery suggests that tidal internal waves are a pervasive phenomenon in Angolan waters.
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Nelson, Walter G., and Cheryl A. Brown. "Use of probability-based sampling of water-quality indicators in supporting development of quality criteria." ICES Journal of Marine Science 65, no. 8 (September 25, 2008): 1421–27. http://dx.doi.org/10.1093/icesjms/fsn158.
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Abstract Nelson, W. G., and Brown, C. A. 2008. Use of probability-based sampling of water-quality indicators in supporting development of quality criteria. – ICES Journal of Marine Science, 65: 1421–1427. Intensive, site-based data are typically used to establish protective water-quality criteria, but may only exist for few systems in a region. We examine whether or not water-quality indicator data collected from large-scale, probability-based assessments can support the development of regional quality criteria. Because such indicators may be subject to high natural variation over short time-scales, a key question is whether survey values will be sufficiently similar to site-based sampling to merit use in extrapolating quality criteria spatially. Median values for dissolved inorganic nitrogen, phosphorus, and Chl a for dry-season data collected within Yaquina Bay (OR, USA) over a 7-year period were compared with dry-season datasets collected from two studies comprising 6 and 14 Oregon estuaries, respectively. A second, reduced dataset (August–September only) was compared with data from 38 estuaries within the same ecoregion. All comparisons were made for marine and riverine salinity zones. Medians for Yaquina Bay were higher than those from the comparison surveys. Stochastic variation of coastal upwelling during sampling appears to cause the contrasts. Further work is required to define upwelling-based adjustments for regional, probability-based survey data before they can be used in regulatory applications. However, even without adjustment, these data may help in determining the appropriate regional context for quality criteria.
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Kolding, Jeppe, Alida Bundy, Paul A. M. van Zwieten, and Michael J. Plank. "Fisheries, the inverted food pyramid." ICES Journal of Marine Science 73, no. 6 (December 14, 2015): 1697–713. http://dx.doi.org/10.1093/icesjms/fsv225.
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Abstract A global assessment of fishing patterns and fishing pressure from 110 different Ecopath models, representing marine ecosystems throughout the world and covering the period 1970–2007, show that human exploitation across trophic levels (TLs) is highly unbalanced and skewed towards low productive species at high TLs, which are around two TLs higher than the animal protein we get from terrestrial farming. Overall, exploitation levels from low trophic species were <15% of production, and only 18% of the total number of exploited groups and species were harvested >40% of their production. Generally, well-managed fisheries from temperate ecosystems were more selectively harvested at higher exploitation rates than tropical and upwelling (tropical and temperate) fisheries, resulting in potentially larger long-term changes to the ecosystem structure and functioning. The results indicate a very inefficient utilization of the food energy value of marine production. Rebuilding overfished components of the ecosystem and changing focus to balancing exploitation across a wider range of TLs, i.e. balanced harvesting, has the potential to significantly increase overall catches from global marine fisheries.
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Souto, Debora Dezidério, Douglas Villela de Oliveira Lessa, Ana Luiza Spadano Albuquerque, Abdelfettah Sifeddine, Bruno Jean Turcq, and Cátia Fernandes Barbosa. "Marine sediments from southeastern Brazilian continental shelf: A 1200year record of upwelling productivity." Palaeogeography, Palaeoclimatology, Palaeoecology 299, no. 1-2 (January 2011): 49–55. http://dx.doi.org/10.1016/j.palaeo.2010.10.032.
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Crosnier, L., M. Drévillon, S. Ramos Buarque, and F. Soulat. "Three ocean state indices implemented in the Mercator-Ocean operational suite." ICES Journal of Marine Science 65, no. 8 (July 30, 2008): 1504–7. http://dx.doi.org/10.1093/icesjms/fsn122.
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Abstract Crosnier, L., Drévillon, M., Ramos Buarque, S., and Soulat, F. 2008. Three ocean state indices implemented in the Mercator-Ocean operational suite. – ICES Journal of Marine Science, 65: 1504–1507. We present three indices for the state of the ocean, all computed using the Mercator-Ocean analyses and ocean forecast system: an upwelling index based on sea surface temperature (SST), the tropical cyclone heat potential, showing the thermal energy available in the ocean to enhance or decrease the power of cyclones, and the Indian Ocean dipole mode index based on SST. Such indices are updated on a weekly or monthly basis.
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Cooper, Helen L., Donald C. Potts, and Adina Paytan. "Effects of elevated pCO2 on the survival, growth, and moulting of the Pacific krill species, Euphausia pacifica." ICES Journal of Marine Science 74, no. 4 (March 7, 2016): 1005–12. http://dx.doi.org/10.1093/icesjms/fsw021.
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While ocean acidification (OA) is expected to have wide-ranging negative effects on marine species, organisms currently living in variable pH environments that expose them intermittently to pH values approaching those predicted for the future, may be better adapted to tolerate prolonged exposure to high pCO2 levels caused by OA. Seasonal upwelling brings low pH water to the surface along the Pacific Coast of North America. In Monterey Bay, California Euphausia pacifica, a key species supporting a diverse multi-trophic-level ecosystem, currently experiences broad pCO2 and pH ranges due to both diel vertical migrations and seasonal upwelling. We determined tolerances of E. pacifica to prolonged exposure to pH levels predicted for 2100 by maintaining adults at two pCO2 levels (380 and 1200 µatm) for 2 months. Rates of survival and moulting were the same at both pCO2 levels. High pCO2 slowed growth in all size classes. In additional experiments to determine pCO2 threshold levels above which E. pacifica is adversely affected, survival was not affected down to pH 6.96 (6050 µatm), but declined rapidly at pH 6.92 (7228 µatm) and lower, with 100% mortality within 10 d at pH 6.89.
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Otero, P., M. Ruiz-Villarreal, and Á. Peliz. "River plume fronts off NW Iberia from satellite observations and model data." ICES Journal of Marine Science 66, no. 9 (June 8, 2009): 1853–64. http://dx.doi.org/10.1093/icesjms/fsp156.
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Abstract Otero, P., Ruiz-Villarreal, M., and Peliz, Á. 2009. River plume fronts off NW Iberia from satellite observations and model data. – ICES Journal of Marine Science, 66: 1853–1864. River plume fronts off NW Iberia during autumn 2002 are examined based on the gradient of the mixed layer depth (MLD) in three-dimensional model data and on sea surface temperature gradients in Advanced Very High Resolution Radiometer (AVHRR) imagery. The method reveals new aspects of the dynamics of fronts in the area. The strong gradient of the MLD between the plume and the adjacent ocean serves as a physical indicator of the maximum extension of the river plume and takes into account its three-dimensional structure as well as its surface signal. Differences in the position of river plume fronts are associated with local upwelling/downwelling conditions and their relaxation. During expansions of the plume induced by upwelling in late autumn, the shallower plume waters become colder and the thermal gradient with offshore waters increases. The model simulation also illustrates the existence of instabilities at the plume front and cross-shore variations in plume width that could induce the appearance of thermal gradients which can be resolved with AVHRR. Our simulations also show regional differences in front location, structure, and probability north (Galicia) and south (north Portugal) on the shelf, where bathymetry differs in shape and depth.
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Crawford, Robert J. M., Les G. Underhill, Leshia Upfold, and Bruce M. Dyer. "An altered carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus)." ICES Journal of Marine Science 64, no. 3 (March 5, 2007): 570–76. http://dx.doi.org/10.1093/icesjms/fsm009.
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Abstract Crawford, R. J. M., Underhill, L. G., Upfold, L., and Dyer, B. M. 2007. An altered carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus). – ICES Journal of Marine Science, 64: 570–576. The carrying capacity of an ecosystem for a species is an input parameter that is required for some models that assess population viability. It may be changed by an altered structure or functioning of the ecosystem, e.g. as a consequence of changes brought about by fishing or environmental change. Hence, it cannot necessarily be assumed that the pristine level of abundance of a species reflects the present-day carrying capacity of the ecosystem for that species. Historical and modern information on abundance and density-dependent responses is used to investigate changes in the carrying capacity of the Benguela upwelling ecosystem for African penguins (Spheniscus demersus), a species categorized as vulnerable. The carrying capacity was estimated to decrease from 1.5–3.0 million adult birds in the 1920s to just 10–20% of this value from 1978 to 2006, as a result inter alia of increased competition for food with purse-seine fisheries and fur seals (Arctocephalus pusillus pusillus). From 1988/1989 to 2005/2006, the per capita recruitment of young penguins to a colony where nesting space was not limiting was inversely related to the size of that colony, suggestive of a density-dependent response perhaps related to food availability.
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Downey, Nicola J., Michael J. Roberts, and Dan Baird. "An investigation of the spawning behaviour of the chokka squid Loligo reynaudii and the potential effects of temperature using acoustic telemetry." ICES Journal of Marine Science 67, no. 2 (October 3, 2009): 231–43. http://dx.doi.org/10.1093/icesjms/fsp237.
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Abstract Downey, N. J., Roberts, M. J., and Baird, D. 2010. An investigation of the spawning behaviour of the chokka squid Loligo reynaudii and the potential effects of temperature using acoustic telemetry. – ICES Journal of Marine Science, 67: 231–243. Spawning aggregations of chokka squid are influenced by environmental conditions. Acoustic telemetry was used to monitor the behaviour of spawning squid in relation to environmental variability. During the November squid-fishery closed seasons of 2003–2006, hexagonal VR2 receiver arrays were moored on and around active spawning aggregations in Kromme Bay, South Africa. In all, 45 squid were tagged (V9P-6L-S256 transmitters) and released within these arrays. Three presence–absence behaviours were identified: (i) arrival on the spawning site at dawn and departure after dusk, (ii) continuous presence for a number of days, and (iii) presence interrupted by frequent but short periods of absence. Movement between spawning sites was both diurnal and nocturnal. Squid presence at the monitored sites increased after dawn and decreased towards and after dusk. Occasionally, a core aggregation of squid remained on the spawning sites at night. Temperature data at the sites indicated occasional upwelling, and although the role of temperature in the spawning process is not well understood, data suggest that it is linked to the continuation and or interruption of spawning after an aggregation has formed. The initial formation of spawning aggregations appears to be triggered by upwelling events.
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Emslie, Steven D. "Radiocarbon dates from abandoned penguin colonies in the Antarctic Peninsula region." Antarctic Science 13, no. 3 (September 2001): 289–95. http://dx.doi.org/10.1017/s0954102001000414.
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Sixty-three radiocarbon dates on organic remains from 21 abandoned colonies of chinstrap (Pygoscelis antarctica) and Adélie (P. adeliae) penguins on 12 islands in the Antarctic Peninsula region are evaluated for determining the occupation history of penguins in this region. This record also provides a means for assessing sea-level change, glacial advances and retreats, and population responses by penguins to these events. All conventional dates were corrected for the marine-carbon reservoir effect by applying a ΔR = 700±50 BP and marine calibration curves. The 63 calibrated dates give 2σ ranges (95% confidence intervals) from modern to 5990 yr BP. These dates indicate progressively older occupations from north to south along the Antarctic Peninsula. No sites older than approximately 540 BP occur in the northern peninsula, either because they have not yet been found or older sites have been destroyed by solifluction and glacial scouring. Three dates from one locality near Rothera Point, Adelaide Island, also were calibrated with a ΔR = 750 ± 50 and 800 ± 50 BP. No difference was found between calibrated dates using these two other ΔR values, indicating that local corrections for variation in upwelling intensity may not be necessary.
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Solari, A. P., M. T. G. Santamaría, M. F. Borges, A. M. P. Santos, H. Mendes, E. Balguerías, J. A. Díaz Cordero, J. J. Castro, and C. Bas. "On the dynamics of Sardina pilchardus: orbits of stability and environmental forcing." ICES Journal of Marine Science 67, no. 8 (August 17, 2010): 1565–73. http://dx.doi.org/10.1093/icesjms/fsq107.
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Abstract Solari, A. P., Santamaría, M. T. G., Borges, M. F., Santos, A. M. P., Mendes, H., Balguerías, E., Díaz Cordero, J. A., Castro, J. J., and Bas, C. 2010. On the dynamics of Sardina pilchardus: orbits of stability and environmental forcing. – ICES Journal of Marine Science, 67: 1565–1573. The dynamics of Sardina pilchardus in Iberian upwelling are examined. Spawning-stock biomass (SSB), recruitment (R), and production (R/SSB) data for the years 1978–2006 are analysed in relation to the upwelling index (UPW) and sea surface temperature (SST). The population oscillates in two relatively stable orbits (identified by multiresolution decomposition of the recruitment series) because the external forcing (UPW and SST) are the inverse of each other and the synchrony is lost between the two external variables, R and R/SSB as they shift towards steep, negative (depensatory) trends. Such mechanics may have induced recruitment failures and significant decreases in abundance of Iberian sardine. The relationships are assumed to validate a complex and dynamic continuum (multiple orbits of stability) and an alternative variable-carrying-capacity population model. Radial systems with two orbits of stability are proposed for the R/SSB and S/SSB (where S is the stock size) relationships. Results are discussed in relation to classical and alternative SR models to address stock rehabilitation and fishing mortality issues as the population shifts towards low recruitment and abundance, and critical factors to consider in developing exploitation strategies for systems with multiple orbits of stability are discussed.
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Villablanca, Roberto, Guillermo Luna-Jorquera, Victor H. Marín, Stefan Garthe, and Alejandro Simeone. "How does a generalist seabird species use its marine habitat? The case of the kelp gull in a coastal upwelling area of the Humboldt Current." ICES Journal of Marine Science 64, no. 7 (August 17, 2007): 1348–55. http://dx.doi.org/10.1093/icesjms/fsm120.
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AbstractVillablanca, R., Luna-Jorquera, G., Marín, V. H., Garthe, S., and Simeone, A. 2007. How does a generalist seabird species use its marine habitat? The case of the kelp gull in a coastal upwelling area of the Humboldt Current. – ICES Journal of Marine Science, 64: 1348–1355. The distribution of kelp gulls (Larus dominicanus) was studied by ship-based transect counts in the SE Pacific Ocean off Chile, South America. Some 96–98% of the kelp gulls were in a band less than 20 km from the coast, mainly near the breeding colony on Pájaros Island and the City of Coquimbo. Abundance did not change significantly among years, but was influenced significantly by distance to land. Principal component analysis yielded two components that jointly explain 53% of the standardized variance. The first (explaining 36% of the variance) includes distance to the nearest coast and water depth, the second (17%) associates with the presence of fishing vessels. The results suggest that the stability of the summer distribution of kelp gulls is generated by the large and semi-permanent offer of food at fish markets and city sewage works, as well as the location of the breeding colonies. Further analysis on other temporal scales (seasonal, decadal) associated with reproductive or non-reproductive changes within the population and/or ENSO cycles will be necessary to confirm the multiscale stability of the pattern described.
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Currie, David R., Shirley J. Sorokin, and Tim M. Ward. "Infaunal macroinvertebrate assemblages of the eastern Great Australian Bight: effectiveness of a marine protected area in representing the region's benthic biodiversity." Marine and Freshwater Research 60, no. 5 (2009): 459. http://dx.doi.org/10.1071/mf08239.
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Marine reserves are used widely throughout the world to conserve biodiversity, but in many instances uncertainties exist over how well these areas represent biodiversity at a regional scale (i.e. 100–1000 km). In the present study, infaunal assemblages were examined in the eastern Great Australian Bight (GAB) to evaluate the efficacy of the Benthic Protection Zone of the GAB Marine Park in representing regional biodiversity. Distributional patterns in infauna were further examined in relation to epifaunal species composition and environmental conditions to investigate structural forcing. Grab samples of infauna were collected from the same 65 sites sampled in an earlier survey of epifauna. In total, 240 taxa belonging to 11 phyla were collected. Most taxa were uncommon, with 96% representing less than 2% of the total number of individuals collected and 39% occurring at only one site. Unlike the epifauna, the infauna of the eastern GAB does not appear to be particularly diverse. Sessile filter feeders dominated the infaunal communities of the inner shelf, whereas motile, deposit-feeding organisms dominated the shelf break. As was the case with the epifauna, the highest numbers of taxa and individuals were recorded near the head of the bight and in inner-shelf waters off the western Eyre Peninsula, where productivity is enhanced by upwelling. Cluster analysis identified three community groupings, which were strongly correlated with depth. All three communities and 72% (172) of the 240 taxa collected were represented within the Benthic Protection Zone of the GAB Marine Park, confirming findings from the epifaunal survey that this protected area is well placed to represent the benthic biodiversity of the eastern GAB.
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Drinkwater, Kenneth F., Franz J. Mueter, and Sei-Ichi Saitoh. "Shifting boundaries of water, ice, flora, fauna, people, and institutions in the Arctic and Subarctic." ICES Journal of Marine Science 75, no. 7 (December 1, 2018): 2293–98. http://dx.doi.org/10.1093/icesjms/fsy179.
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Abstract An international Open Science Meeting entitled Moving in, out, and across the Subarctic and Arctic marine ecosystems: shifting boundaries of water, ice, flora, fauna, people, and institutions, took place 11–15 June 2017 in Tromsø, Norway. Organized by the Ecosystem Studies of Subarctic and Arctic Seas programme and cosponsored by the International Council for the Exploration of the Sea and the North Pacific Marine Science Organization, the primary aim of the meeting was to examine past, present, and future ecosystem responses to climate variability and ocean acidification (OA) and their effect on fishing communities, the fishing industry and fisheries management in the northern Pacific and Atlantic oceans and the Arctic. This symposium issue contains several papers from the meeting covering topics from climate and OA, ecosystem responses to environmental change, and fisheries management including: a synthesis of the ecosystem responses to the AMO-linked cold period of the 1970s and 1980s;a novel approach to understand responses to OA in northern climes using natural carbonate chemistry gradients, such as CO2 vents, methane cold seeps, and upwelling area;the possibility that warm temperatures are allowing two generations of Calanus finmarchicus per year to be produced;a new hypothesis suggesting that in areas where sea ice disappears there could be an increase of fish species with swim bladders;results from laboratory experiments on the effects of temperature and food on Arctic and boreal fish larvae;the application of ecosystem-based management in northern regions; anda description of the United States National Oceanic and Atmospheric Administration approach to marine conservation and how it affects fish populations and fisheries.
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Williams, James R., and Russell C. Babcock. "Comparison of multiple techniques to evaluate reproductive variability in a marine bivalve: application to the scallop Pecten novaezelandiae." Marine and Freshwater Research 55, no. 5 (2004): 457. http://dx.doi.org/10.1071/mf03200.
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Reproduction and spawning of the scallop Pecten novaezelandiae were monitored at four sites in the Hauraki Gulf, New Zealand, from July 2000 to July 2001. A visual grading system based on the macroscopic appearance of the gonad was developed and tested, and changes in visual grade, quantitative histology, and standardised gonad mass were used to describe seasonal and spatial patterns in gametogenesis and spawning. Visual grade was significantly correlated with histological and gonad mass data (r 2 = 0.74–0.87) and validated as an accurate method for measuring reproduction in P. novaezelandiae. Visual grading facilitates rapid assessment of reproductive condition and can be conducted non-destructively, thus providing a tool allowing long-term studies of individual spawning behavior in relation to environmental signals. Scallops exhibited episodic spawning, with spawning events detected in spring, summer, autumn, and even early winter. Gonad recovery and subsequent gamete development and maturation were apparent between spawnings. Within-season variability in gonad size and condition could be the result of multiple (serial) spawnings during a season. The timing of spawning varied among populations, probably reflecting differences in environmental conditions that influenced reproduction. However, the largest spawning events occurred at all sites in early summer (December/January), coincident with wind-driven upwelling conditions.
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Geist, S. J., A. Kunzmann, H. M. Verheye, A. Eggert, A. Schukat, and W. Ekau. "Distribution, feeding behaviour, and condition of Cape horse mackerel early life stages, Trachurus capensis, under different environmental conditions in the northern Benguela upwelling ecosystem." ICES Journal of Marine Science 72, no. 2 (June 5, 2014): 543–57. http://dx.doi.org/10.1093/icesjms/fsu087.
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Abstract Early life history (ELH) traits are key to understand variable recruitment success and hence the stock size of marine fish. One of the currently most puzzling ecosystems in this regard is the northern part of the Benguela Current upwelling system off Namibia. Here, populations of the formerly dominant pelagic species, sardine and anchovy, failed to recover during the last three decades after a dramatic decline. In contrast, Cape horse mackerel, Trachurus capensis, maintained a constant population size. Warming of the system and shoaling of hypoxic zones together with feedback loops within an altered foodweb are discussed to be responsible for this regime shift. In this study, we address the role of larval traits for the successful performance of the T. capensis population under the present environmental conditions with the focus on feeding ecology. We investigated seasonal variations of the geographical distribution, growth rate, feeding ecology, and nutritional condition of their ELH stages and examined relationships with water temperature, dissolved oxygen concentration, and micro-zooplankton composition. T. capensis' ELH stages showed a wide spatial and seasonal distribution, a preference for higher water temperatures (18–21°C) and presence over a wide range of dissolved oxygen concentrations (0.13–6.35 ml O2 l−1). Feeding success was high and mainly different groups of Copepoda were targeted, which were strongly size selected. The high dietary importance of micro-copepods during large parts of the larval phase indicates successful exploitation of this food source, which has increased in abundance during the last decade. It also explains observed best nutritional conditions at temperatures between 18 and 21°C, since these small copepods are commonly associated with warmer temperatures. Altogether, these traits enhance the species' probability to encounter suitable environments for the survival of their ELH stages, which is likely to lead to their high recruitment success in the northern Benguela ecosystem.
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Bahou, Laurent, Tidiani Koné, Valentin N'Douba, Kouassi J. N'Guessan, Essetchi P. Kouamélan, and Gooré B. Gouli. "Food composition and feeding habits of little tunny (Euthynnus alletteratus) in continental shelf waters of Côte d'Ivoire (West Africa)." ICES Journal of Marine Science 64, no. 5 (May 26, 2007): 1044–52. http://dx.doi.org/10.1093/icesjms/fsm065.
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Abstract Bahou, L., Koné, T., N'Douba, V., N'Guessan, K. J., Kouamélan, E. P., and Gouli, G. B. 2007. Food composition and feeding habits of little tunny (Euthynnus alletteratus) in continental shelf waters of Côte d'Ivoire (West Africa). – ICES Journal of Marine Science, 64: 1044–1052. The stomach contents of 170 little tunny, Euthynnus alletteratus, sampled between June 2003 and December 2004 were examined. Fish size ranged from 27 to 81 cm fork length, and all fish were caught in gillnets deployed over the continental shelf off Côte d'Ivoire (West Africa). The type and quantity of prey ingested changed seasonally. Outside the major upwelling period the diet was more varied. Overall, fish were the dominant prey of all sizes of little tunny, far exceeding crustaceans, of which shrimps and prawns were commonest but were not found in the stomachs of juveniles (<42 cm FL) or larger adults (≥53 cm FL). Little tunny are carnivorous fish that feed opportunistically. A relationship was found between the size of the prey and the size of the predator.
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Paluch, I. R., G. McFarquhar, D. H. Lenschow, and Y. Zhu. "Marine boundary layers associated with ocean upwelling over the eastern equatorial Pacific Ocean." Journal of Geophysical Research: Atmospheres 104, no. D24 (December 1, 1999): 30913–36. http://dx.doi.org/10.1029/1999jd900990.
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Chan, Kit Yu Karen, Daniel Grünbaum, Maj Arnberg, and Sam Dupont. "Impacts of ocean acidification on survival, growth, and swimming behaviours differ between larval urchins and brittlestars." ICES Journal of Marine Science 73, no. 3 (May 7, 2015): 951–61. http://dx.doi.org/10.1093/icesjms/fsv073.
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Abstract Ocean acidification (OA) is widely recognized as an increasing threat to marine ecosystems. Many marine invertebrates have dual-phase life cycles in which planktonic larvae connect and sustain otherwise disconnected benthic adult populations. Many planktonic larvae are particularly sensitive to environmental stresses including OA. Here, we compared the developmental dynamics, survivorship, and swimming behaviours of plutei of two ecologically important echinoderm species that naturally experience variability in ambient pH: the purple urchin Strongylocentrotus purpuratus and the infaunal brittlestar Amphiura filiformis. Sensitivity to decreased pH differed between these two species and between maternal lineages. Larvae of both species experienced increased mortality and reduced growth rate under low pH conditions. However, larval brittlestars appeared more sensitive and experienced over 80% mortality after 7-d exposure to pH 7.7. Larval urchins from one maternal lineage underwent highly synchronized budding (release of blastula-like particles) at low pH. Observed budding temporarily increased numerical density and reduced individual size, leading to differences in growth and mortality rates between the two half-sibling groups and another population. Swimming speeds of larval brittlestars were reduced in decreased pH. In contrast, acidification had either no effect or positive effect on swimming speeds of larval urchins. The observed differences between species may be a reflection of pre-exposure in their natural habitats: larval brittlestars experience a relatively stable in situ pH environment, whereas larval urchins are occasionally exposed to low pH in upwelling regions. Urchins may therefore exhibit short-term compensatory responses such as budding and increased swimming speed. Natural selection could act upon the significant variations we observed between maternal lineages, resulting in more resilient populations confronting chronic exposure to OA.
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Zwolinski, Juan P., Robert L. Emmett, and David A. Demer. "Predicting habitat to optimize sampling of Pacific sardine (Sardinops sagax)." ICES Journal of Marine Science 68, no. 5 (May 1, 2011): 867–79. http://dx.doi.org/10.1093/icesjms/fsr038.
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Abstract Zwolinski, J. P., Emmett, R. L., and Demer, D. A. 2011. Predicting habitat to optimize sampling of Pacific sardine (Sardinops sagax). – ICES Journal of Marine Science, 68: 867–879. More than 40 years after the collapse of the fishery for Pacific sardine, a renewed fishery has emerged off the west coasts of the United States and Canada. The daily egg production method (DEPM) and acoustic-trawl surveys are performed annually and, to minimize the uncertainties in the estimates, sampling effort needs to be allocated optimally. Here, based on a 12-year dataset including the presence/absence of sardine eggs and concomitant remotely sensed oceanographic variables, a probabilistic generalized additive model is developed to predict spatio-temporal distributions of habitat for the northern stock of Pacific sardine in the California Current. Significant relationships are identified between eggs and sea surface temperature, chlorophyll a concentration, and the gradient of sea surface altitude. The model accurately predicts the habitat and seasonal migration pattern of sardine, irrespective of spawning condition. The predictions of potential habitat are validated extensively by fishery landings and net-sample data from the northeast Pacific. The predicted habitat can be used to optimize the time and location of the DEPM, acoustic-trawl, and aerial surveys of sardine. The method developed and illustrated may be applicable too to studies of other stocks of sardine and other epipelagic fish in other eastern boundary, upwelling regions.
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Kelly, S., E. de Eyto, M. Dillane, R. Poole, G. Brett, and M. White. "Hydrographic maintenance of deep anoxia in a tidally influenced saline lagoon." Marine and Freshwater Research 69, no. 3 (2018): 432. http://dx.doi.org/10.1071/mf17199.
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Low dissolved oxygen concentrations are of increasing concern in aquatic ecosystems, particularly at the interface between freshwater and marine environments. Oxygen depletion occurs naturally in many perennially stratified systems and it remains to be seen how climate change will affect these habitats. This is due, in part, to a lack of high-resolution, long-term data describing interannual variability in dissolved oxygen concentrations within stratified basins. Physicochemical parameters for Lough Furnace, an ecologically important tidal lagoon, were assessed using daily measurements (2009–14) from an undulating CTD (conductivity, temperature and depth) profiler and observations of tidal exchange flow. Continuous vertical saline stratification existed, with anoxia (<0.1mgL–1) typically persisting below 6m. Tidal inflows were generally restricted, with deep-water renewal events by intrusions of denser spring tidal water occurring episodically (three times in 6 years), following prolonged periods of low freshwater input. Although wind forcing alone was not sufficient to generate basin-scale mixing, the conditions that led to deep-water renewals may also be conducive to wind-driven upwelling events in nearshore areas. These findings have wider application to larger-scale two-layered stratified systems with deep anoxia because the ability to forecast such dynamic events is important for assessing the ecological implications of dissolved oxygen depletion.
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Simmonds, E. John, Mariano Gutiérrez, Andres Chipollini, Francois Gerlotto, Mathieu Woillez, and Arnaud Bertrand. "Optimizing the design of acoustic surveys of Peruvian anchoveta." ICES Journal of Marine Science 66, no. 6 (April 30, 2009): 1341–48. http://dx.doi.org/10.1093/icesjms/fsp118.
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Abstract Simmonds, E.J., Gutiérrez, M., Chipollini, A., Gerlotto, F., Woillez, M., and Bertrand, A. 2009. Optimizing the design of acoustic surveys of Peruvian anchoveta. – ICES Journal of Marine Science, 66: 1341–1348. Acoustic surveys of stocks of small pelagic fish, in particular the Peruvian anchovy or anchoveta (Engraulis ringens), have been carried out off the coast of Peru since the late 1970s. In all, 51 of these have been carefully archived since 1983. The surveys provide a wealth of data on the distribution and abundance of pelagic fish in the most productive of the world's upwelling ecosystems. The data comprise integrated acoustic data at a resolution of 1 or 2 nautical miles along the cruise tracks, and trawl data, which include catch-by-species and catch-by-length information for anchoveta. Data since 1992 are sufficiently complete to allow a full re-evaluation of the surveys to determine their precision, taking account of the spatial variability of the catch and acoustic data. The methods used include bootstrap by trawl sample and transect segment, geostatistical simulation, and simulated surveys. The results reveal consistent spatial patterns of abundance with a more variable distribution of variance and a strong relationship between the local mean abundance and the variance. The temporal and spatial variabilities are considered in an evaluation of alternative survey designs, including pre-stratified and adaptive designs.
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Faraj, Abdelmalek, and Nicolas Bez. "Spatial considerations for the Dakhla stock of Octopus vulgaris: indicators, patterns, and fisheries interactions." ICES Journal of Marine Science 64, no. 9 (December 1, 2007): 1820–28. http://dx.doi.org/10.1093/icesjms/fsm160.
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Abstract Faraj, A., and Bez, N. 2007. Spatial considerations for the Dakhla stock of Octopus vulgaris: indicators, patterns, and fisheries interactions. – ICES Journal of Marine Science, 64: 1820–1828. The common octopus (Octopus vulgaris) is the target species of the cephalopod fishery that exploits two stocks, Dakhla and Cap Blanc, off southern Morocco (26°N 21°N), an area commonly referred to as the Saharan Bank. Octopusvulgaris is also one of the most abundant demersal species in this highly productive area, and plays a key role in the upwelling ecosystem. Spatial patterns of the main phases of the Octopus vulgaris life cycle of the Dakhla stock are described, using trawl surveys carried out twice a year from 1998 to 2003. Using geostatistics and spatial indicators, mature females and juveniles are analysed and mapped to characterize the main features of the spawning and recruitment phases. There are clear distinctions between the spatial patterns of the spawning and recruitment phases: juveniles are more coastal, less spatially dispersed, more anisotropically distributed, and more patchy. Our results suggest that the spatial pattern of the Octopus vulgaris Dakhla stock is different from that of the same species in other ecosystems such as the Mediterranean. GIS reveals that the spawning–stock biomass is globally more accessible to the industrial fleet than to the artisanal one, a finding contrary to contemporary thinking and with important resource management implications.
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Baumann, Hannes, R. J. D. Wells, Jay R. Rooker, Saijin Zhang, Zofia Baumann, Daniel J. Madigan, Heidi Dewar, Owyn E. Snodgrass, and Nicholas S. Fisher. "Combining otolith microstructure and trace elemental analyses to infer the arrival of juvenile Pacific bluefin tuna in the California current ecosystem." ICES Journal of Marine Science 72, no. 7 (April 14, 2015): 2128–38. http://dx.doi.org/10.1093/icesjms/fsv062.
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Abstract Juvenile Pacific bluefin tuna (PBT, Thunnus orientalis) are known to migrate from western Pacific spawning grounds to their eastern Pacific nursery and feeding grounds in the California Current Large Marine Ecosystem (CCLME), but the timing, durations, and fraction of the population that makes these migrations need to be better understood for improved management. To complement recent work focused on stable isotope and radiotracer approaches (“tracer toolbox”; Madigan et al., 2014) we explored the suitability of combining longitudinal analyses of otolith microstructure and trace elemental composition in age ∼1–2 PBT (n = 24, 66–76 cm curved fork length) for inferring the arrival of individuals in the CCLME. Element:Ca ratios in transverse otolith sections (9–12 rows, triplicate ablations from primordium to edge, ø50 μm) were quantified for eight elements: Li, Mg, Mn, Co, Cu, Zn, Sr, and Ba, which was followed by microstructure analysis to provide age estimates corresponding to each ablation spot. Age estimates from otoliths ranged from 328 to 498 d post-hatch. The combined elemental signatures of four elements (Ba, Mg, Co, Cu) showed a significant increase at the otolith edge in approximately half of the individuals (30–60 d before catch). Given the different oceanographic properties of oligotrophic open Pacific vs. high nutrient, upwelling CCLME waters, this signal is consistent with the entry of the fish into the CCLME, which was estimated to occur primarily in July after a transoceanic migration of ∼1.5–2.0 months. Our approach comprises a useful addition to the available tracer toolbox and can provide additional and complementary understanding of trans-Pacific migration patterns in PBT.
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Pielou, E. C. "Plankton, from the last ice age to the year 3007." ICES Journal of Marine Science 65, no. 3 (February 7, 2008): 296–301. http://dx.doi.org/10.1093/icesjms/fsn008.
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Abstract Pielou, E. C. 2008. Plankton, from the last ice age to the year 3007. – ICES Journal of Marine Science, 65: 296–301. Climate forcing of the environment and biota has been happening since time immemorial, human forcing only for the past 200 years or so. This paper considers, first, climatic changes over the past 30 000 years, as indicated by plankton and their effects on plankton. Only fossilizable plankton can be observed: principally foraminifera, radiolaria, and pteropods in the zooplankton, and their food, principally coccolithophores, diatoms, and dinoflagellate cysts, in the phytoplankton. The soft-bodied zooplankton species—especially copepods—that lived with them can only be inferred. Large, abrupt climate changes took place, aided by positive feedback. Second, this paper attempts to predict how human forcing in the form of anthropogenic climate change is likely to affect marine ecosystems in the future. Past predictions have underestimated the speed at which warming is actually happening: positive feedback has been unexpectedly strong. Thus, the melting of snow and ice, by reducing the earth's albedo, has increased the amount of solar energy absorbed. Also, warming of the surface (water and land) has caused outgassing of methane from buried clathrates (hydrates), and methane is a strong greenhouse gas. Currently, predictions emphasize one or the other of two contrasted alternatives: abrupt cooling caused by a shutdown of the thermohaline circulation (the “ocean conveyor”) or abrupt warming caused by copious outgassing of methane. Both arguments (the former from oceanographers and the latter from geophysicists) are equally persuasive, and I have chosen to explore the methane alternative, because I am familiar with an area (the Beaufort Sea and Mackenzie Delta) where outgassing has recently (2007) been detected and is happening now: in the Arctic Ocean and the Canadian Arctic Archipelago, where disappearance of the ice will affect currents, temperature, thermocline, salinity, upwelling, and nutrients, with consequent effects on the zooplankton.
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Robert, Marianne, Abdelmalek Faraj, Murdoch K. McAllister, and Etienne Rivot. "Bayesian state-space modelling of the De Lury depletion model: strengths and limitations of the method, and application to the Moroccan octopus fishery." ICES Journal of Marine Science 67, no. 6 (March 30, 2010): 1272–90. http://dx.doi.org/10.1093/icesjms/fsq020.
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Abstract Robert, M., Faraj, A., McAllister, M. K., and Rivot, E. 2010. Bayesian state-space modelling of the De Lury depletion model: strengths and limitations of the method, and application to the Moroccan octopus fishery. – ICES Journal of Marine Science, 67: 1272–1290. The strengths and limitations of a Bayesian state-space modelling framework are investigated for a De Lury depletion model that accommodates two recruitment pulses per year. The framework was applied to the Moroccan fishery for common octopus (Octopus vulgaris) between 1982 and 2002. To allow identifiability, natural mortality (M) and the recruitment rhythm were fixed, and the variance of both process and observation errors were assumed to be equal. A simulation–estimation (SE) approach was derived to test the performance of the method. If the data showed responses to harvest, the estimates of the most important figures, i.e. the initial abundance and the second recruitment pulse, were accurate, with relatively small bias. Results confirm that greater depletion yields smaller bias and uncertainty and that inferences are sensitive to the mis-specification of M. The 21 depletion series in the Moroccan dataset were jointly treated in a hierarchical model including random walk to capture the systematic fluctuations in estimates of catchability and initial abundance. The model provides estimates of the annual recruitment and monthly octopus population size. The recruitment estimates could be used to investigate the link between recruitment variability and the coastal North African upwelling regime to improve understanding of the dynamics and management of octopus stocks.
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Munday, Philip L., Sue-Ann Watson, Darren M. Parsons, Alicia King, Neill G. Barr, Ian M. Mcleod, Bridie J. M. Allan, and Steve M. J. Pether. "Effects of elevated CO2 on early life history development of the yellowtail kingfish, Seriola lalandi, a large pelagic fish." ICES Journal of Marine Science 73, no. 3 (November 20, 2015): 641–49. http://dx.doi.org/10.1093/icesjms/fsv210.
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Abstract An increasing number of studies have examined the effects of elevated carbon dioxide (CO2) and ocean acidification on marine fish, yet little is known about the effects on large pelagic fish. We tested the effects of elevated CO2 on the early life history development and behaviour of yellowtail kingfish, Seriola lalandi. Eggs and larvae were reared in current day control (450 µatm) and two elevated CO2 treatments for a total of 6 d, from 12 h post-fertilization until 3 d post-hatching (dph). Elevated CO2 treatments matched projections for the open ocean by the year 2100 under RCP 8.5 (880 µatm CO2) and a higher level (1700 µatm CO2) relevant to upwelling zones where pelagic fish often spawn. There was no effect of elevated CO2 on survival to hatching or 3 dph. Oil globule diameter decreased with an increasing CO2 level, indicating potential effects of elevated CO2 on energy utilization of newly hatched larvae, but other morphometric traits did not differ among treatments. Contrary to expectations, there were no effects of elevated CO2 on larval behaviour. Activity level, startle response, and phototaxis did not differ among treatments. Our results contrast with findings for reef fish, where a wide range of sensory and behavioural effects have been reported. We hypothesize that the absence of behavioural effects in 3 dph yellowtail kingfish is due to the early developmental state of newly hatched pelagic fish. Behavioural effects of high CO2 may not occur until larvae commence branchial acid–base regulation when the gills develop; however, further studies are required to test this hypothesis. Our results suggest that the early stages of kingfish development are tolerant to rising CO2 levels in the ocean.
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Tompkins, Paul, and Matthias Wolff. "Galápagos macroalgae: A review of the state of ecological knowledge." Revista de Biología Tropical 65, no. 1 (September 23, 2016): 375. http://dx.doi.org/10.15517/rbt.v65i1.18139.
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Previous work has highlighted the critical role of macroalgal productivity and dynamics in supporting and structuring marine food webs. Spatio-temporal variability in macroalgae can alter coastal ecosystems, a relationship particularly visible along upwelling-influenced coastlines. As a result of its equatorial location and nutrient rich, upwelling-influenced waters, the Galápagos Archipelago in the East Pacific, hosts a productive and biodiverse marine ecosystem. Reports and collections of macroalgae date back to the Beagle voyage, and since then, more than three hundred species have been reported. However, their ecology and functional role in the ecosystem is not well understood. According to various disparate and in part anecdotal sources of information, abundant and diverse communities exist in the Western regions of the archipelago, the North is essentially barren, and in the central/South abundance and distribution is variable and less well defined. Both oceanographic conditions and herbivore influence have been theorized to cause this pattern. Extensive changes in macroalgal productivity and community composition have occurred during strong ENSO events, and subsequent declines in marine iguana (an endemic and iconic grazer) populations have been linked to these changes. Iguanas are only one species of a diverse and abundant group of marine grazers in the system, highlighting the potentially important role of macroalgal productivity in the marine food web. This review represents a first compilation and discussion of the available literature and presents topics for future research.
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Beardsley, R. C., C. E. Dorman, C. A. Friehe, L. K. Rosenfeld, and C. D. Winant. "Local atmospheric forcing during the Coastal Ocean Dynamics Experiment: 1. A description of the marine boundary layer and atmospheric conditions over a northern California upwelling region." Journal of Geophysical Research 92, no. C2 (1987): 1467. http://dx.doi.org/10.1029/jc092ic02p01467.
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Shulzitski, Kathryn, Su Sponaugle, Martha Hauff, Kristen Walter, Evan K. D'Alessandro, and Robert K. Cowen. "Close encounters with eddies: oceanographic features increase growth of larval reef fishes during their journey to the reef." Biology Letters 11, no. 1 (January 2015): 20140746. http://dx.doi.org/10.1098/rsbl.2014.0746.
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Like most benthic marine organisms, coral reef fishes produce larvae that traverse open ocean waters before settling and metamorphosing into juveniles. Where larvae are transported and how they survive is a central question in marine and fisheries ecology. While there is increasing success in modelling potential larval trajectories, our knowledge of the physical and biological processes contributing to larval survivorship during dispersal remains relatively poor. Mesoscale eddies (MEs) are ubiquitous throughout the world's oceans and their propagation is often accompanied by upwelling and increased productivity. Enhanced production suggests that eddies may serve as important habitat for the larval stages of marine organisms, yet there is a lack of empirical data on the growth rates of larvae associated with these eddies. During three cruises in the Straits of Florida, we sampled larval fishes inside and outside five cyclonic MEs. Otolith microstructure analysis revealed that four of five species of reef fish examined had consistently faster growth inside these eddies. Because increased larval growth often leads to higher survivorship, larvae that encounter MEs during transit are more likely to contribute to reef populations. Successful dispersal in oligotrophic waters may rely on larval encounter with such oceanographic features.
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Figueroa, DF. "Environmental forcing on zooplankton distribution in the coastal waters of the Galápagos Islands: spatial and seasonal patterns in the copepod community structure." Marine Ecology Progress Series 661 (March 4, 2021): 49–69. http://dx.doi.org/10.3354/meps13617.
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The oceanographic setting of the Galápagos Archipelago results in a spatially diverse marine environment suitable for a variety of species with different climatic requirements. The goal of this study is to demonstrate that the community of zooplankton in the Galápagos is highly structured by regional differences in productivity patterns and advective sources. Results are mostly based on biodiversity patterns of the copepod community collected over the Galápagos shelf between 2004 and 2006. Two contrasting marine environments were observed: a nutrient-rich upwelling system with a shallow mixed layer and a diatom-dominated phytoplankton community in the west, and a non-upwelling system with a deeper mixed layer, lower surface nutrient concentrations, and a phytoplankton community dominated by small cells in the east. These conditions drive spatial structuring of zooplankton that varies seasonally, with 3 distinct copepod communities separated geographically in western, central, and southeastern regions. The western upwelling region has a high-abundance and low-diversity community, whereas the non-upwelling eastern region has a lower-abundance and higher-diversity community. The eastern community is further differentiated into central and southeastern regions, the former with tropical species advected from the north, the latter with temperate species advected from the south. During the warm season, when the equatorial front moves south, species typical of the central region spread southwest across the archipelago. This is the first taxonomically comprehensive list of copepod species for the Galápagos Islands. A total of 164 copepod species are identified, including 22 species previously unreported from the Eastern Tropical Pacific.
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Hardy, William, Aurélie Penaud, Fabienne Marret, Germain Bayon, Tania Marsset, and Laurence Droz. "Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyr." Biogeosciences 13, no. 16 (August 29, 2016): 4823–41. http://dx.doi.org/10.5194/bg-13-4823-2016.
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Abstract. A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our high-resolution dinocyst record indicates that significant temperature and moisture variations occurred across the glacial period, the last deglaciation and the Holocene. The use of specific dinocyst taxa, indicative of fluvial, upwelling and Benguela Current past environments for instance, provides insights into the main forcing mechanisms controlling palaeohydrological changes on orbital timescales. In particular, we are able, for the last 44 kyr, to correlate fluvial-sensitive taxa to monsoonal mechanisms related to precession minima–obliquity maxima combinations. While upwelling mechanisms appear as the main drivers for dinoflagellate productivity during MIS 2, dissolved nutrient-enriched Congo River inputs to the ocean also played a significant role in promoting dinoflagellate productivity between approximately 15.5 and 5 ka BP. Finally, this high-resolution dinocyst study permits us to precisely investigate the suborbital timing of the last glacial–interglacial termination, including an atypical warm and wet oceanic LGM signature, northern high-latitude abrupt climate change impacts in the equatorial eastern Atlantic, as well as a two-step decrease in moisture conditions during the Holocene at around 7–6 and 4–3.5 ka BP.
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Smith, Benjamin L., and Toby F. Bolton. "Consequences of natural variation in maternal investment and larval nutrition on larval growth of a marine polychaete." Marine and Freshwater Research 58, no. 11 (2007): 1002. http://dx.doi.org/10.1071/mf06103.
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Growth rates and planktonic development periods of marine invertebrate larvae have important consequences for the ecology of marine invertebrates. The growth and development of the larvae of a common southern Australian polychaete was examined to determine whether it was limited by natural concentrations of planktonic food, and whether naturally occurring variation in maternal investment in offspring influenced larval growth and development. Larvae that were provided concentrated diets of natural planktonic food were larger than larvae that were provided with food at ambient concentrations, but both experimental groups of larvae reached developmental stages immediately preceding settlement at the same time. Thus, larval growth was limited at natural concentrations of planktonic food but larval development rates were unaffected. These trends were also apparent in larvae fed with different concentrations of laboratory cultured food. Maternal investment in offspring (eggs) was higher on average for larger females than for smaller females. Larvae developing from smaller eggs were also smaller before settlement than larvae developing from larger eggs. Both maternal investment in offspring and the extent to which larval growth is food limited may vary spatially and seasonally along the southern coastline of Australia owing to the yearly occurrence of nutrient-rich oceanographic upwellings.
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Lavaniegos, B. E., O. Molina -González, and M. Murcia -Riaño. "ZOOPLANKTON FUNCTIONAL GROUPS FROM THE CALIFORNIA CURRENT AND CLIMATE VARIABILITY DURING 1997-2013." CICIMAR Oceánides 30, no. 1 (June 27, 2015): 45. http://dx.doi.org/10.37543/oceanides.v30i1.143.
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Zooplankton plays an important role in recycling matter and energy trough the pelagic ecosystem. The California Current is one of the large marine ecosystems with high productivity and bio-physical variability at multiple time scales. An interannual scale or longer periods requires data series sufficiently long to ensure reliable averages of zooplankton abundance in order to estimate their low frequency variability. Here, tendencies in physical and biological variables are presented for the period 1997-2013 with data obtained from IMECOCAL cruises in the Mexican sector of the California Current. The area was divided into four regions, two oceanic (off North and Central Baja California) and two neritic (Vizcaino bay and Gulf of Ulloa). Sea surface temperature (SST) and El Niño Oceanic Index (ONI) showed correlation in all areas, while extratropical indices (PDO and NPGO) exhibited different tendencies among the regions. The PDO had significant correlation with SST only in the central and Vizcaino bay regions. The NPGO was not correlated with temperature but presented significantly strong correlation with sea surface salinity in all regions, which has been attributed to changes in large-scale circulation of the north Pacific subtropical gyre. In spite of a significant influence of the El Niño Southern Oscillation (ENSO) in SST, the correlation between ONI and zooplankton abundance was limited to gelatinous herbivorous (tunicates) from the North region. Local influence was remarkable in Vizcaino bay where the tunicates showed a period of negative abundance anomalies (2000-2004) followed by increasing positive anomalies between 2005 and 2013 associated with positive upwelling index anomalies. Geometric mean abundance of salps (per oceanographic cruise) averaged in Vizcaino bay 33.3 ind m-3 during 2005-2013 compared to 1.4 ind m-3 in 2000-2004. Salps partially displaced crustacean herbivores since they compete for feeding particles; copepods decreased from 88.2 ind m-3 during 2000-2004 to 59.7 ind m-3 in 2005-2013; and euphausiids from 16.1 ind m-3 to 10.4 ind m-3. In the oceanic domain a period of saline stratification during 2002-2006 was associated with positive anomalies of all trophic groups (crustaceans, tunicates and carnivores). Alternation of particular taxa of tunicates and carnivores is discussed. The increase of gelatinous organisms associated to higher stratification in the oceanic region and enhanced upwellng in the coastal shelf appears to be in detriment of crustaceans, though the time-series are short to outline a more defined trend. That tendency is particularly disturbing in Vizcaino bay affecting the availability of food for fishes and other predators. Grupos funcionales de zooplancton de la corriente de California y variabilidad climática durante 1997-2013 El zooplancton juega un papel fundamental en el flujo de materia y energía en el ecosistema pelágico. La Corriente de California es uno de los grandes ecosistemas marinos con elevada productividad y amplia variabilidad físico-biológica a múltiples escalas temporales. A escala interanual y de mayor periodo es necesario contar con series de datos lo suficientemente extensas temporalmente que permitan calcular promedios robustos de la abundancia del zooplancton y poder estimar la variabilidad de baja frecuencia. En el presente estudio se muestran las tendencias en variables físicas y biológicas del periodo 1997-2013 de los datos obtenidos por los cruceros IMECOCAL en el sector mexicano de la Corriente de California. El área fue dividida en cuatro regiones, dos oceánicas (frente a Baja California, Norte y Central) y dos neríticas (Bahía Vizcaíno y Golfo de Ulloa). En todas las regiones la temperatura superficial del mar (TSM) estuvo correlacionada con El Niño Oceanic Index (ONI). Los índices extratropicales (PDO y NPGO) mostraron diferentes tendencias entre regiones. El PDO tuvo fuerte correlación con la TSM solo en la región central y en Bahía Vizcaíno. El NPGO no se correlacionó con la temperatura pero presentó correlación significativa con la salinidad superficial del mar en todas las regiones, lo cual ha sido atribuido a cambios en la circulación a gran escala del giro subtropical del Pacífico norte. A pesar de una influencia significativa del ENSO en la TSM, la correlación entre el ONI y la abundancia del zooplancton estuvo limitada a los herbívoros gelatinosos (tunicados) de la región Norte. La influencia local fue notable en Bahía Vizcaíno donde los tunicados mostraron un periodo de anomalías negativas (2000-2004) seguido por un periodo con anomalías positivas de creciente amplitud entre 2005 y 2013 asociadas con anomalías positivas del índice de surgencias. La abundancia expresada mediante medias geométricas de salpas (por crucero) mostró en Bahía Vizcaíno 33.3 ind m-3 durante 2005-2013 comparada con 1.4 ind m-3 en 2000-2004. Las salpas desplazaron parcialmente a los crustáceos herbívoros puesto que ambos compiten por las partículas de alimento; los copépodos disminuyeron de 88.2 ind m-3 durante 2000-2004 a 59.7 ind m-3 en 2005-2013; los eufáusidos disminuyeron de 16.1 ind m-3 a 10.4 ind m-3. En el dominio oceánico un periodo de estratificación salina durante 2002-2006 estuvo asociado con anomalías positivas de todos los grupos tróficos (crustáceos, tunicados y carnívoros). Se discute la alternancia de taxa particulares de tunicados y carnívoros. El incremento de organismos gelatinosos asociado a una mayor estratificación en la región oceánica y a la intensificación de las surgencias en la plataforma costera parece ir en detrimento de los crustáceos, aunque las series de tiempo son cortas para establecer una tendencia definida. Dicha tendencia es particularmente perturbadora en Bahía Vizcaíno al afectar la disponibilidad de alimento para peces y otros depredadores.
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Markel, Russell W., and Jonathan B. Shurin. "Contrasting effects of coastal upwelling on growth and recruitment of nearshore Pacific rockfishes (genus Sebastes)." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 6 (June 2020): 950–62. http://dx.doi.org/10.1139/cjfas-2019-0179.
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Knowledge of processes underlying recruitment is critical for understanding marine population dynamics and their response to ocean climate. We investigated the relationship between coastal upwelling and early life history of black rockfish (Sebastes melanops), a midwater aggregating species, and CQB rockfishes (a solitary benthic species complex including Sebastes caurinus, Sebastes maliger, and Sebastes auriculatus), between two oceanographically distinct years on the west coast of Vancouver Island, Canada. We analysed otolith microstructure to determine parturition and settlement dates, pelagic durations, and pre- and postsettlement growth rates. High CQB rockfish recruitment in 2005 was associated with prolonged downwelling and warm ocean temperatures, late parturition dates, fast presettlement growth, short pelagic durations, and small size-at-settlement. In contrast, high black rockfish recruitment in 2006 was associated with strong upwelling and cool ocean temperatures, slow presettlement growth, and protracted pelagic durations. Presettlement growth of both rockfish complexes increased with high sea surface temperature, but was unrelated to chlorophyll a concentration. Our results indicate that the same oceanographic conditions give rise to fast presettlement growth and short pelagic durations for both groups, but that different factors lead to strong recruitment in each.
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Larsen, T., L. T. Bach, R. Salvatteci, Y. V. Wang, N. Andersen, M. Ventura, and M. D. McCarthy. "Assessing the potential of amino acid δ<sup>13</sup>C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis." Biogeosciences Discussions 12, no. 2 (January 23, 2015): 1613–51. http://dx.doi.org/10.5194/bgd-12-1613-2015.
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Abstract. Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles, and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing biosynthetic origin of amino acid carbon skeletons, based on natural occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions; and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results underscore that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e. isoleucine, lysine, leucine and tyrosine), bacterial derived amino acids ranged from 10–15% in the sediment layers from the last 5000 years to 35% during the last glacial period. The larger bacterial fractions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to a substantially larger degree than suggested by changes in total organic nitrogen and carbon content. Taken together, these culturing and sediment studies suggest that δ13CAA patterns in sediments represent a novel proxy for understanding both primary production sources, as well as direct bacterial role in the ultimate preservation of sedimentary organic matter.
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Hofmann, G. E., T. G. Evans, M. W. Kelly, J. L. Padilla-Gamiño, C. A. Blanchette, L. Washburn, F. Chan, et al. "Exploring local adaptation and the ocean acidification seascape – studies in the California Current Large Marine Ecosystem." Biogeosciences 11, no. 4 (February 24, 2014): 1053–64. http://dx.doi.org/10.5194/bg-11-1053-2014.
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Abstract. The California Current Large Marine Ecosystem (CCLME), a temperate marine region dominated by episodic upwelling, is predicted to experience rapid environmental change in the future due to ocean acidification. The aragonite saturation state within the California Current System is predicted to decrease in the future with near-permanent undersaturation conditions expected by the year 2050. Thus, the CCLME is a critical region to study due to the rapid rate of environmental change that resident organisms will experience and because of the economic and societal value of this coastal region. Recent efforts by a research consortium – the Ocean Margin Ecosystems Group for Acidification Studies (OMEGAS) – has begun to characterize a portion of the CCLME; both describing the spatial mosaic of pH in coastal waters and examining the responses of key calcification-dependent benthic marine organisms to natural variation in pH and to changes in carbonate chemistry that are expected in the coming decades. In this review, we present the OMEGAS strategy of co-locating sensors and oceanographic observations with biological studies on benthic marine invertebrates, specifically measurements of functional traits such as calcification-related processes and genetic variation in populations that are locally adapted to conditions in a particular region of the coast. Highlighted in this contribution are (1) the OMEGAS sensor network that spans the west coast of the US from central Oregon to southern California, (2) initial findings of the carbonate chemistry amongst the OMEGAS study sites, and (3) an overview of the biological data that describes the acclimatization and the adaptation capacity of key benthic marine invertebrates within the CCLME.
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Hofmann, G. E., T. G. Evans, M. W. Kelly, J. L. Padilla-Gamiño, C. A. Blanchette, L. Washburn, F. Chan, et al. "Exploring local adaptation and the ocean acidification seascape – studies in the California Current Large Marine Ecosystem." Biogeosciences Discussions 10, no. 7 (July 16, 2013): 11825–56. http://dx.doi.org/10.5194/bgd-10-11825-2013.
Full textAbstract:
Abstract. The California Current Large Marine Ecosystem (CCLME), a temperate marine region dominated by episodic upwelling, is predicted to experience rapid environmental change in the future due to ocean acidification. Aragonite saturation state within the California Current System is predicted to decrease in the future, with near-permanent undersaturation conditions expected by the year 2050. Thus, the CCLME is a critical region to study due to the rapid rate of environmental change that resident organisms will experience and because of the economic and societal value of this coastal region. Recent efforts by a research consortium – the Ocean Margin Ecosystems Group for Acidification Studies (OMEGAS) – has begun to characterize a portion of the CCLME; both describing the mosaic of pH in coastal waters and examining the responses of key calcification-dependent benthic marine organisms to natural variation in pH and to changes in carbonate chemistry that are expected in the coming decades. In this review, we present the OMEGAS strategy of co-locating sensors and oceanographic observations with biological studies on benthic marine invertebrates, specifically measurements of functional traits such as calcification-related processes and genetic variation in populations that are locally adapted to conditions in a particular region of the coast. Highlighted in this contribution are (1) the OMEGAS sensor network that spans the west coast of the US from central Oregon to southern California, (2) initial findings of the carbonate chemistry amongst the OMEGAS study sites, (3) an overview of the biological data that describes the acclimatization and the adaptation capacity of key benthic marine invertebrates within the CCLME.