Gotowa bibliografia na temat „Macroalgal forest”

Macroalgae are invaluable constituents of marine forest environments and important sources of material for human needs. However, they are currently at risk of severe decline due to global warming and negative anthropogenic factors. Restoration efforts focus on beds where macroalgae previously existed, as well as the creation of new marine forests. Some artificial seaweed reefs (ASRs) have succeeded but others have failed; the contributions of ASRs to marine forest formation have been not fully determined. Here, we review ASRs, the benefits of macroalgal forests, threats to macroalgae, restoration, and marine forest formation to explore the current status of ASRs. The published literature indicates that ASRs have played critical roles in marine forest formation; notably, they support the establishment of submerged aquatic vegetation beds that allow ocean macroalgal afforestation. ASRs have evolved in terms of complexity and the materials used; they can sustainably mitigate marine deforestation. However, continuous reviews of ASR performance are essential, and performance improvements are always possible.

Temperate rocky reefs and kelp forest ecosystems have been severely affected by overfishing, pollution and habitat destruction, and climate change is a major driver of kelp decline in many regions. Although necessary for management, ecological interactions between kelp and fish remain largely unknown in the north-east Atlantic. In the present study, underwater visual censuses (UVC) and univariate and multivariate multiple regression models were used to analyse the spatiotemporal variations in the abundance and habitat use of the rocky reef fish and macroalgae assemblages of Galicia (north-west Spain). The underwater seascape was dominated by large rocks and kelp forests of Laminaria hyperborea, L. ochroleuca and Saccorhiza polyschides. Fish assemblages were ruled by gadids, labrids and sparids. The most frequent fish species were Labrus bergylta (counted in 90% of UVC) and Pollachius pollachius (in 100% of UVC), whereas the most abundant were Boops boops (mean±s.d., 556.4±39.7 individuals ha–1) and L. bergylta (432.10±440.05 individuals ha–1). Fish and macroalgal assemblages showed different spatial preferences and responded strongly to seasonality, wave exposure and depth. To a lesser degree, fish and macroalgal assemblages showed preferences for habitat structure. Moreover, because the findings of the present study indicate that L. bergylta is a good indicator species of the health of rocky reef and kelp forests ecosystems, monitoring of this fish can be helpful for management and conservation actions.

Large-scale finfish farms are increasingly located in dispersive hard-bottom environments where Laminaria hyperborea forests dominate; however, the interactions between farm effluents and kelp forests are poorly understood. Effects of 2 levels of salmonid fish-farming effluents (high and low) on L. hyperborea epiphytic communities were studied by sampling canopy plants from 12 sites in 2 high-energy dispersive environments. Specifically, we assessed if farm effluents stimulated fast-growing epiphytic algae and faunal species on L. hyperborea stipes—as this can impact the kelp forest community composition—and/or an increased lamina epiphytic growth, which could negatively impact the kelp itself. We found that bryozoan biomass on the stipes was significantly higher at high-effluent farm sites compared to low-effluent farm and reference sites, resulting in a significantly different epiphytic community. Macroalgal biomass also increased with increasing effluent levels, including opportunistic Ectocarpus spp., resulting in a less heterogeneous macroalgae community at high-effluent farm sites. This habitat heterogeneity was further reduced by the high bryozoan biomass at the high-effluent sites. Such changes in the epiphyte community could have implications for the faunal community that relies on the epiphytes for food and refuge. On the kelp lamina, no clear response to farm effluents was found.

A mangrove forest can harbour several macroalgal assemblages growing on pneumatophores, roots, stems and other hard substrates. These algae belong to various genera, most typically Bostrychia, and form a community called the Bostrychietum. This study describes the fauna associated with the Bostrychietum and the effect of emersion time on the community. Seasonal samples were collected from pneumatophores on an island in Araçá Bay in 2012, in two areas, one on the border of the island and one inland. Each pneumatophore was considered a sample. The border samples, with a shorter emersion time, contained a richer algal flora associated with pneumatophores, and fauna with species of varied dietary habits. The inland samples, with a longer emersion time, contained only two algal genera and fauna species comprised mostly of omnivorous amphipods and desiccation-resistant detritivorous species. Macrofauna diversity and richness varied over time and were lower in spring. Therefore, the emersion time of the Bostrychietum and the period of the year affect the community structure, for both the macroalgae and the associated fauna.

Macroalgal and urchin barren communities are alternately stable and persist in the Aleutians due to sea otter presence and absence. In the early 1990s a rapid otter population decline released urchins from predation and caused a shift to the urchin-dominated state. Despite increases in urchin abundance, otter numbers continued to decline. Although debated, prey quality changes have been implicated in current otter population status. This study examined otter prey abundance, size, biomass, and potential energy density in remnant kelp forest and urchin-dominated communities to determine if alternate stable states affect prey quality. Findings suggest that although urchin barrens provide more abundant urchin prey, individual urchins are smaller and provide lower biomass and potential energy density compared to kelp forests. Shifts to urchin barrens do affect prey quality but changes are likely compensated by increased prey densities and are insufficient in explaining current otter population status in the Aleutians.

The shallow benthos along the western Antarctic Peninsula supports brown macroalgal forests with dense amphipod assemblages, commonly including Gondogeneia antarctica (Amsler et al. 2014). Gondogeneia antarctica and most other amphipods are chemically deterred from consuming the macroalgae (Amsler et al. 2014). They primarily consume diatoms, other microalgae, filamentous macroalgae and a few undefended macroalgal species, including Palmaria decipiens (Aumack et al. 2017). Although unpalatable when alive, G. antarctica and other amphipods will consume the chemically defended brown algae Himantothallus grandifolius and Desmarestia anceps within a few weeks of death (Amsler et al. 2014).

Gastropods play an important ecological role in kelp forests; however, this role is dependent on where exactly in such communities these animals are located. We assessed the spatial and temporal patterns in the utilisation of available reef and macroalgal substrates by three gastropods in a north-eastern New Zealand kelp (Ecklonia radiata (C. Agardh) J. Agardh, 1848) forest, focusing on predation as a factor influencing these patterns. Although kelp provided a large habitable surface area for gastropods, much of this area was under-utilised. During the day, gastropods on E. radiata were largely confined to the primary laminae. At night, gastropods on the reef migrated into the algal canopy where they occupied regions of the kelp that were not occupied during the day. Over a 36-day period, 93% of the gastropods tethered to the reef were consumed by predators, whereas none tethered in the algal canopy was consumed. We consider that night-time vertical migration and dispersion through the algal canopy may be primarily a response to predation by diurnally feeding fish and nocturnal benthic predators such as lobsters. Our research highlights the importance of considering diel changes in epifaunal distribution and abundance when assessing their ecological role.

Abstract This study aims to investigate the relative effects of urchin removal, non-urchin gastropod herbivores removal, and transplantation on macroalgal forest restoration using an additive manipulation design. A field experiment was conducted in subtidal urchin barren rocks in the eastern coast of South Korea from August 2017 to June 2020 with three experimental treatments: no urchins (NU), NU plus no herbivorous gastropods (NH), NH plus Ecklonia bicyclis transplant (NHT). Six months after experiment initiation, seaweed abundance rapidly increased in all three experimental treatments. The highest peak was found in the spring season of the first year (2018). The year-to-year variations became smaller throughout the survey period. The results of comparing NU and control site indicated that urchin removal had an exclusive effect on algal recovery while additional removal of herbivorous gastropods did not affect algal recovery quantitatively. With the successful establishment of E. bicyclis, the community assemblages of the three treatments became more distinct in the subsequent years, showing diverse dominance in NU, red algal dominance in NH, and dominance of E. bicyclis canopy and understory groups in NHT. This study provides evidence that urchin removal on its own from barren grounds can lead to rapid restoration of seaweed forest in subtidal habitats.

Synopsis Dense macroalgal forests on the Western Antarctic Peninsula serve important ecological roles both in terms of considerable biomass for primary production as well as in being ecosystem engineers. Their function within the Antarctic ecosystem has been described as a crucial member of a community-wide mutualism which benefits macroalgal species and dense assemblages of associated amphipod grazers. However, there is a cheater within the system that can feed on one of the most highly chemically defended macroalgal hosts. The amphipod Paradexamine fissicauda has been found to readily consume the finely branched red macroalga Plocamium cartilagineum. This amphipod grazer not only feeds on its host, but also appears to sequester its host’s chemical defenses for its own utilization. This review summarizes what we know about both of these exceptions to the community-wide mutualism.

Made available in DSpace on 2014-06-11T19:23:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-02Bitstream added on 2014-06-13T18:50:15Z : No. of bitstreams: 1 almeida_fvr_me_rcla.pdf: 5323757 bytes, checksum: 55eb2e9b9c051e2271a31350a6e1ee7e (MD5)
Vários estudos envolvendo flora e distribuição de comunidades de macroalgas lóticas já foram desenvolvidos na região noroeste do estado de São Paulo; entretanto, nunca foi realizada qualquer abordagem sobre macroalgas lóticas em fragmentos florestais remanescentes, aspecto mais relevante deste estudo. Foram testadas as seguintes hipóteses: (1) entre as regiões/biomas estudados no estado de São Paulo, o atual trabalho deve apresentar maior similaridade florística com Floresta Tropical, por ser mais próxima e composta também por Floresta Estacional Semidecidual; (2) características intrínsecas de cada corpo d’água devem exercer maior influência na riqueza e abundância das comunidades de macroalgas do que parâmetros mais gerais de cada fragmento, como forma, tamanho e matriz adjacente, e da ordem de grandeza do riacho e sua respectiva bacia de drenagem. Este trabalho teve como objetivo geral realizar o levantamento florístico e analisar a distribuição ecológica das comunidades de macroalgas lóticas de fragmentos florestais remanescentes de Floresta Estacional Semidecidual da região noroeste do estado de São Paulo (20o00’13”-21o37’14”S, 48o32’26”- 50o26’02”O). Foram amostrados 17 riachos pertencentes a 12 fragmentos, no intervalo de junho a agosto de 2007 e 2008, período mais favorável para a região (estação seca). Foram identificadas 16 espécies de macroalgas, pertencentes a 14 gêneros. A maioria das espécies (69%) foi encontrada em um único ponto. Cyanophyta e Chlorophyta foram os grupos predominantes (44 e 37,5%), seguidos por Rhodophyta (12,5%) e Heterokontophyta (6%). Phormidium retzii (Cyanophyta) foi a espécie mais frequente, ocorrendo em seis pontos de amostragem. Apenas duas espécies representaram novos registros para a região: Trichocoleus sociatus (Cyanophyta) e Vaucheria pseudogeminata (Heterokontophyta); a última representa...
Several studies involving the flora and distribution of lotic macroalgal communities have been carried out in the northwest region of São Paulo State, southeastern Brazil. However, the lotic macroalgae in remnant forest fragments have never been studied, the most relevant aspect of this study. The following hypotheses have been tested: 1) among the biomes/regions previously studied in São Paulo State, the flora of the northwest region is expected to reveal the highest floristic similarity with the Tropical Forest, since it is the nearest biome and also composed by semidecidual seasonal forest; 2) particular characteristics of each water body are expected to be more influential on the species richness and abundance of macroalgal communities than more general parameters of each forest fragment, such as surrounding matrix, stream order and position in the respective drainage basin. This study aimed at surveying the flora and describing the ecological distribution the of lotic macroalgal communities from remnant forest fragments composed of semidecidual seasonal forest in the northwest region of São Paulo State (20o00’13”-21o37’14”S, 48o32’26”-50o26’02”O). 17 streams were sampled in 12 forest fragments from June to August of 2007 and 2008 during the typical most favorable period in the region (dry season). 16 species have been surveyed, belonging to 14 genera. 69% of species were found in a single site. Cyanophyta and Chlorophyta were the predominant algal groups (44 amd 37.5%), followed by Rhodophyta (12.5%) and Heterokontophyta (6%). Phormidium retzii (Cyanophyta) was the most frequent species, occurring in six sampling sites. Only two species were new records for the region: Trichocoleus sociatus (Cyanophyta) and Vaucheria pseudogeminata (Heterokontophyta); the later represents the first report for Brazil. The regional flora was more similar (nine species in common, 56%)... (Complete abstract click electronic access below)

All marine ecosystems in the Mediterranean Sea are highly threatened by anthropogenic stressors that can alter their structure and function, especially in rocky shores. Moreover, extreme climate events are becoming more frequent and intense in our times. To detect the potential impacts and the vulnerability of any ecosystem, the combination of experimental and observational studies in the field is vital. In addition, long-term monitoring programs carried out simultaneously on human-protected and human- impacted environments may be crucial to discern the nature of the impacts. Macroalgal beds dominate the shallow benthic Mediterranean habitats where they play a pivotal role. Among them, the canopy-forming Cystoseira sensu lato species represent the highest structural complexity level and provide unique habitats with ecological services comparable to terrestrial forests. Canopy-forming algae are in decline in many coastal areas where, among other impacts, overgrazing by herbivorous can lead to the loss of these diverse habitats shifting towards degraded sea urchin barren grounds. Conservation tools such as marine reserves or No-take zones (NTZs) have the potential to reduce some of the anthropogenic threats and to restore benthic habitats through trophic cascade effects caused by the major abundance of predator. Besides, active ecosystem restoration strategies may speed up the recovery of impacted ecosystems. Nevertheless, there is an important lack of continuous and long-term studies providing robust ecological data of the natural dynamic and vulnerability of macroalgal assemblages while integrating the role of marine conservation. In this dissertation, different methodological approaches were combined to explore the long-term dynamics of macroalgal communities and the role of different conservation strategies (NTZs and active restoration) in the Montgrí, Medes Islands, and Baix Ter (MIMBT) Natural Park (NW Mediterranean Sea). In the first two chapters, the analysis of long-term monitoring datasets provided essential information to understand how macroalgal assemblages and sea urchin populations respond to natural fluctuations and anthropogenic disturbances, mainly overfishing. In the third chapter, field monitoring and sampling were combined with genetic analyses to increase the ecological knowledge of the canopy-forming alga Treptacantha elegans as well as to describe their recent expansion. In the fourth and last chapter, active restoration actions as seeding experiments were conducted in aquaria and in the field to optimize restoration techniques to recover degraded shallow ecosystems. In addition, different restoration strategies were combined in the field inside and outside the Medes Islands NTZ to evaluate the role of marine protection on restoration activities. The results of this thesis showed that the abundance and structure of the main macroalgal assemblages in the MIMBT Natural Park were stable at large over the last fifteen years. Overall, any effect of marine protection was observed on the most representative species of this habitat but we found a higher abundance of canopy- forming algae inside the NTZ than in unprotected areas. Contrarily, sea urchin populations were deeply affected by a severe storm in 2008 which caused the almost depletion of its populations in all the studied areas. Although similar trajectories of sea urchin abundance have been observed over the years between both protection regimes due to the large stability of the sea urchin high-density state, clear differences in the recovery of sea urchin populations were found after the storm linked to marine protection. The sea urchin populations inside the NTZ recovered slowly than the populations outside the NTZ inside due to the higher predatory fish abundance inside the NTZ. In contrast to the global widespread decline of canopy-forming macroalgal assemblages across many regions during the last decades, Treptacantha elegans has increased their distributional range and has shown an extraordinary expansion along the Catalan northern coast over the last two decades. The results of this thesis contributed to explaining this geographical and depth range extension, which could be linked to some ecological attributes such as their relative fast-growing dynamics, early fertile maturity, and high turnover rate. Besides, the molecular analyses have shown that all the populations of T. elegans in the Catalan coast constitute a single genetic group that could be originated in the MIMBT Natural Park under the marine protection benefit. Given the fast and stable population dynamics of T. elegans, this species was selected as a potential species to actively restore degraded shallow rocky ecosystems (e.g., sea urchin barren grounds) turning them into productive marine forests. In this way, the effectiveness of active restoration actions combined with passive strategies such as marine protection (e.g., NTZs) was experimentally demonstrated. This thesis addressed marine vegetation changes in the shallow rocky shores of the MIMBT Natural Park integrating the macroalgal and sea urchin dynamics in front of natural and human-related impacts, and the role and effectiveness of Marine Protected Areas and restoration actions as conservation tools at lower trophic levels. Besides, since most of this thesis is based on long-term monitoring data, a valuable baseline of the algal community’s structure and functioning was provided here which could be vital to predict and detect ecological changes that could jeopardize the preservation of marine forests.
Els ecosistemes bentònics mediterranis es troben fortament amenaçats per pressions, tant a nivell local com global, que poden alterar la seva estructura i funcionament, especialment en els fons rocosos litorals. A més, els episodis climàtics extrems esdevenen cada vegada més freqüents i intensos. Per a detectar els possibles impactes sobre qualsevol ecosistema així com la seva vulnerabilitat, la combinació d’estudis observacionals i experimentals al camp és primordial. En aquest sentit, els estudis a llarg termini realitzats simultàniament en zones impactades i en zones protegides de l’acció humana, poden ser crucials per a identificar la naturalesa dels impactes. Al mar Mediterrani, les comunitats de macroalgues dominen els hàbitats bentònics soms, on tenen un paper primordial. D’entre elles, les algues de tipus arborescent del gènere Cystoseira representen el nivell més elevat de complexitat estructural i proporcionen hàbitats amb serveis comparables als boscos terrestres. Aquestes algues es troben en declivi en diverses zones costaneres. És aquí on, entre altres impactes, la sobrepastura dels herbívors pot portar a la pèrdua d’aquests hàbitats rics i diversos i la seva transició cap a fons degradats dominats pels eriçons. Les eines de conservació, així com ara les reserves marines o les àrees on està prohibida completament l’extracció (NTZs), tenen el potencial de reduir algunes de les amenaces derivades de l’acció humana i de restaurar els hàbitats bentònics gràcies als efectes dels depredadors a través de les cascades tròfiques. A més de la restauració passiva a través de la creació d’aquestes àrees protegides, la restauració activa dels ecosistemes impactats pot accelerar la seva recuperació. No obstant això, hi ha una manca important d’estudis continuats i a llarg termini que proporcionin dades ecològiques robustes sobre la dinàmica natural i la vulnerabilitat dels hàbitats de macroalgues i que alhora integrin el paper de les diferents eines de conservació marina. En aquesta tesi, s’han combinat diferents metodologies per explorar la dinàmica de les comunitats de macroalgues juntament amb el paper de diferents estratègies de conservació (NTZs i restauració activa) al Parc Natural del Montgrí, les Illes Medes i el Baix Ter (MIMBT), situat al Nord-oest del mar Mediterrani. En els primers dos capítols, les anàlisis de dades d’estudis a llarg termini han proporcionat informació essencial per millorar la nostra comprensió sobre com les comunitats de macroalgues i les poblacions d’eriçons responen a les fluctuacions naturals i a les pertorbacions d’origen antròpic, principalment, la sobrepesca. En el tercer capítol, mostrejos en el camp s’han combinat amb anàlisis genètics per augmentar el coneixement ecològic de l’alga arborescent Treptacantha elegans i per descriure la seva recent expansió. Al quart i últim capítol, s’han realitzat accions de restauració activa, com ara experiments de sembra en aquaris i al camp per optimitzar les tècniques de restauració dels ecosistemes poc profunds degradats. A més, s’han combinat diferents estratègies de restauració a camp, dins i fora de la NTZ de les Illes Medes, per avaluar el paper de la protecció en les activitats de restauració. Els resultats d’aquesta tesi mostren que la abundància i la composició de les principals comunitats algals del Parc Natural del MIMBT s’han mantingut estables al llarg dels darrers quinze anys. En general, no es va observar cap efecte de la protecció en les espècies d’algues més representatives, tot i que si que es van trobar abundàncies més elevades de l’alga T. elegans a dins de la NTZ que a les zones no protegides de l’acció humana. Al contrari, les poblacions d’eriçons es van veure profundament afectades per una forta tempesta l’any 2008, el que va provocar el declivi gairebé total d’aquestes poblacions a les zones estudiades. Tot i que s’havien observat trajectòries similars en l’abundància d’eriçons al llarg del temps, tant a dins com a fora de la NTZ, degut a la gran estabilitat de les poblacions d’eriçons quan les poblacions presenten elevades densitats, en aquesta tesi es van trobar clares diferències en la recuperació d’aquestes poblacions després de la tempesta que estarien vinculades a l’efecte de la protecció marina. Les poblacions d’eriçons a dins de la NTZ es van recuperar més lentament que les de les zones no protegides degut a la major abundància de peixos depredadors a dins de la NTZ. Davant de la davallada generalitzada de les macroalgues arborescents que s’ha pogut observar a moltes regions al llarg de les darreres dècades, l’alga Treptacantha elegans ha demostrat una extraordinària expansió a la costa nord catalana al llarg de les dues darreres dècades, augmentat considerablement la seva distribució. Els resultats d'aquesta tesi contribueixen a explicar aquesta expansió, tant en fondària com a nivell geogràfic, que podria estar relacionada amb alguns trets ecològics, com ara la seva dinàmica de creixement relativament ràpid, la maduresa reproductiva precoç i la seva elevada taxa de renovació poblacional. A més, les anàlisis moleculars mostren que totes les poblacions de T. elegans a la costa catalana constitueixen un únic grup genètic que podria tenir el seu origen al Parc Natural del MIMBT com a conseqüència de la protecció marina. Atesa la dinàmica ràpida i estable de les poblacions de T. elegans, es va seleccionar aquesta com a potencial espècie per restaurar activament els ecosistemes rocosos poc profunds degradats (els blancalls originats per la sobrepastura d’eriçons) convertint-los en productius boscos marins. Gràcies a això, també s’ha demostrat experimentalment l’èxit de combinar accions de restauració activa amb estratègies passives com la protecció marina (p.e. NTZs). Aquesta tesi aborda els canvis de vegetació marina als fons soms i rocosos del Parc Natural del MIMBT integrant la dinàmica de les macroalgues i els eriçons enfront dels impactes naturals i humans, i, el paper i l’eficàcia de les zones marines protegides i de les accions de restauració com a eines de conservació per als nivells tròfics més basals. A més, atès que la major part d’aquesta tesi es basa en dades d’estudis a llarg termini, aquesta tesi proporciona una valuosa referència de la dinàmica i de l’estat actual de les comunitats infralitorals dominades per algues, el que podria ser vital per predir i detectar canvis ecològics que puguin posar en perill la preservació dels boscos marins.

Macroalgal forests represent some of the most productive and biodiverse habitats on Earth. In the Mediterranean Sea, species of the genus Cystoseira sensu lato dominate the well-preserved subtidal rocky habitats where they form complex macroalgal communities. However, since the end of the twentieth century, they have suffered important and widespread regressions across the Mediterranean Sea, mainly due to habitat destruction, changes in water quality and overgrazing by sea urchins. As a result, they are often replaced by simpler and less productive communities. The return to pre-disturbed conditions does not necessarily imply the natural recovery of Cystoseira s.l. stands, being active restoration the only feasible alternative to assist the recovery of these populations. Nowadays, climate change, especially gradual warming and acute marine heatwaves (MHWs), represents a global threat for macroalgal forests. In this context, while no studies have reported evidence of warming impacts for Cystoseira s.l. forests, taking into account that Cystoseira s.l. populations have been historically impacted and the expected climate change scenarios for the Mediterranean Sea, it is of paramount importance to know how climate change can affect these species. The results of this thesis show the potential effects of warming on populations of shallow Cystoseira s.l. species, pointing out the relevance of local environmental factors and processes ultimately defining the response of these populations to global trends of climate change. Moreover, we also offer new and promising tools to locally restore these habitats. Overall, our findings are relevant in order to inform local-scale management and conservation plans for safeguarding the persistence of these Mediterranean macroalgal forests
Els boscos de macroalgues representen un dels hàbitats més productius i diversos del planeta. A la Mar Mediterrània, les espècies del gènere Cystoseira sensu lato dominen els fons rocosos submareals de les àrees ben preservades, on formen comunitats d’elevada complexitat. Tanmateix, des de finals del segle XX, aquestes comunitats estan patint importants regressions arreu de la Mediterrània, principalment a causa de la destrucció de l’hàbitat, dels canvis en la qualitat de l’aigua i de la sobrepastura de garotes. En conseqüència, aquestes comunitats sovint són substituïdes per comunitats més simples i menys productives. En molts casos, el fet de revertir les condicions a nivells previs a la pertorbació, no necessàriament implica la recuperació natural dels boscos de Cystoseira s.l. i llavors, la restauració activa esdevé l’única alternativa factible per recuperar aquestes poblacions. Actualment, l’escalfament gradual i els episodis excepcionals de temperatura elevada, derivats del canvi climàtic, representen una amenaça global pels boscos de macroalgues. Encara que no hi ha evidències de l’impacte de l’escalfament en poblacions de Cystoseira s.l., si tenim en compte les pertorbacions que històricament han patit aquestes poblacions així com els escenaris climàtics que es preveuen per a la Mediterrània, és prioritari determinar com el canvi climàtic pot afectar aquestes especies. Els resultats d’aquesta tesi mostren els efectes potencials de l’escalfament en les poblacions d’espècies superficials de Cystoseria s.l., i assenyalen la rellevància dels factors i processos locals, els quals poden definir la resposta d’aquestes poblacions a les tendències globals de canvi climàtic. D’altra banda, es proporcionen noves eines esperançadores per tal restaurar localment aquests hàbitats amb èxit. En general, els nostres resultats són rellevants i aplicables a futurs plans de gestió i conservació a escala local per garantir la persistència d’aquests boscos de macroalgues de la Mediterrània
Programa de Doctorat en Medi Ambient

Orientador: Ciro Cezar Zanini Branco
Banca: Rogério Antonio Krupek
Banca: Cleto Kaveski Peres
Resumo: Estudos anteriores sugerem que, aparentemente, existem padrões específicos para descrever a composição e a estrutura das comunidades de macroalgas em ambientes lóticos em função das características do bioma ao qual estão inseridos. Neste contexto, a presente dissertação objetivou avaliar, de forma comparativa, a composição, a estrutura das comunidades e a distribuição espacial das comunidades de macroalgas lóticas de duas unidades de conservação (UCs) com biomas distintos: Campos no Parque Estadual de Vila Velha (PVV) e Floresta Estacional Semidecidual no Parque Nacional do Iguaçu (PNI). Em adição, pretendeu-se comparar as comunidades de macroalgas nas quatro estações do ano, a fim de se verificar a possível existência de padrões temporais. As amostragens foram realizadas em 5 segmentos de riacho de 10 m de extensão, em cada UC, através da técnica da transeção, onde as variáveis abióticas (temperatura, oxigênio, pH, condutividade, turbidez, profundidade e velocidade da correnteza) foram mensuradas, assim como a presença e a abundância de cada espécie de macroalga. Estes parâmetros bióticos foram avaliados através da análise visual do leito do rio/riacho. As amostragens foram feitas uma vez a cada estação do ano. O estudo taxonômico registrou 37 macroalgas no total, sendo 16 táxons de ocorrência exclusiva no PVV, 18 táxons de ocorrência exclusiva no PNI e apenas 3 táxons com ocorrência em ambos os parques (Phormidium retzii, Hildenbrandia angolensis e Batrachospermum puiggarianum). O táxon com maior ocorrência no PVV foi o Zygogonium sp. (9 ocorrências), e no PNI o estágio "Chantransia" pygmaea foi o que ocorreu em maior número de pontos amostrados (15). Em relação aos tipos morfológicos, foram encontrados: filamentos livres (24%), filamentos gelatinosos (22%)... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Previous studies suggest that, apparently, there are specific standards to describe the structure and composition of macroalgae communities in lotic environments depending on the characteristics of the biome to which they belong. In this context, the present study aimed to evaluate, comparatively, the floristic composition, community structure and spatial distribution of lotic macroalgae communities from protected areas (PAs) with two distinct biomes, Grassland on Vila Velha State Park (VVP) and Semideciduous Seasonal Forest on the Iguazu National Park (INP). In addition, we intended to compare the macroalgal communities in the four seasons, to verify the possible existence of temporal patterns. The sampling sites were carried out from five segments of stream, 10 m length, in each PA, by means of the transect technique, where the environmental variables (temperature, oxygen, pH, conductivity, turbidity, depth and current velocity) were measured, as well the presence and abundance of each species of seaweed. These biotic parameters were evaluated using visual analysis of stream/river. The samplings were taken once every season. The taxonomic study recorded 37 macroalgae in total, with 16 taxa occurring exclusively in VVP, 18 taxa occurring exclusively in INP and only three taxa occurring in both parks (Phormidium retzii, Hildenbrand angolensis and Batrachospermum puiggarianum). The taxon with the highest frequency of occurrence in the VVP was Zygogonium sp. (9 sites), whereas in INP "Chantransia" pygmaea is what happened to a greater number of sampled sites (15). Respecting the morphological types were found: free filaments (24%), gelatinous filaments (22%), mats (19%), gelatinous colonies... (Complete abstract click electronic access below)
Mestre

Made available in DSpace on 2014-06-11T19:23:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-02Bitstream added on 2014-06-13T20:10:28Z : No. of bitstreams: 1 oliveira_rc_me_rcla.pdf: 588219 bytes, checksum: 1f0070b393c8b583e615e58edabb93b3 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Estudos anteriores sugerem que, aparentemente, existem padrões específicos para descrever a composição e a estrutura das comunidades de macroalgas em ambientes lóticos em função das características do bioma ao qual estão inseridos. Neste contexto, a presente dissertação objetivou avaliar, de forma comparativa, a composição, a estrutura das comunidades e a distribuição espacial das comunidades de macroalgas lóticas de duas unidades de conservação (UCs) com biomas distintos: Campos no Parque Estadual de Vila Velha (PVV) e Floresta Estacional Semidecidual no Parque Nacional do Iguaçu (PNI). Em adição, pretendeu-se comparar as comunidades de macroalgas nas quatro estações do ano, a fim de se verificar a possível existência de padrões temporais. As amostragens foram realizadas em 5 segmentos de riacho de 10 m de extensão, em cada UC, através da técnica da transeção, onde as variáveis abióticas (temperatura, oxigênio, pH, condutividade, turbidez, profundidade e velocidade da correnteza) foram mensuradas, assim como a presença e a abundância de cada espécie de macroalga. Estes parâmetros bióticos foram avaliados através da análise visual do leito do rio/riacho. As amostragens foram feitas uma vez a cada estação do ano. O estudo taxonômico registrou 37 macroalgas no total, sendo 16 táxons de ocorrência exclusiva no PVV, 18 táxons de ocorrência exclusiva no PNI e apenas 3 táxons com ocorrência em ambos os parques (Phormidium retzii, Hildenbrandia angolensis e Batrachospermum puiggarianum). O táxon com maior ocorrência no PVV foi o Zygogonium sp. (9 ocorrências), e no PNI o estágio “Chantransia” pygmaea foi o que ocorreu em maior número de pontos amostrados (15). Em relação aos tipos morfológicos, foram encontrados: filamentos livres (24%), filamentos gelatinosos (22%)...
Previous studies suggest that, apparently, there are specific standards to describe the structure and composition of macroalgae communities in lotic environments depending on the characteristics of the biome to which they belong. In this context, the present study aimed to evaluate, comparatively, the floristic composition, community structure and spatial distribution of lotic macroalgae communities from protected areas (PAs) with two distinct biomes, Grassland on Vila Velha State Park (VVP) and Semideciduous Seasonal Forest on the Iguazu National Park (INP). In addition, we intended to compare the macroalgal communities in the four seasons, to verify the possible existence of temporal patterns. The sampling sites were carried out from five segments of stream, 10 m length, in each PA, by means of the transect technique, where the environmental variables (temperature, oxygen, pH, conductivity, turbidity, depth and current velocity) were measured, as well the presence and abundance of each species of seaweed. These biotic parameters were evaluated using visual analysis of stream/river. The samplings were taken once every season. The taxonomic study recorded 37 macroalgae in total, with 16 taxa occurring exclusively in VVP, 18 taxa occurring exclusively in INP and only three taxa occurring in both parks (Phormidium retzii, Hildenbrand angolensis and Batrachospermum puiggarianum). The taxon with the highest frequency of occurrence in the VVP was Zygogonium sp. (9 sites), whereas in INP Chantransia pygmaea is what happened to a greater number of sampled sites (15). Respecting the morphological types were found: free filaments (24%), gelatinous filaments (22%), mats (19%), gelatinous colonies... (Complete abstract click electronic access below)

There is ongoing global concern over unwanted regime shifts in marine systems. Shifts from diverse and productive algal-dominated ecosystems to less productive urchin and coralline-dominated temperate reefs are becoming increasingly common. Kelp forests found along South Africa's south-west coast between Cape Point and Cape Agulhas occur in a region of biogeographical overlap. They are commonly referred to as transition zone kelp forests and are dynamic ecosystems that are particularly susceptible to grazing influence from species such as sea urchins. This study (1) explores the uniformity of these transition zone kelp forests along the western side of False Bay, with a focus on macroalgae and urchins, (2) identifies a threshold in urchin density above which algal abundance declines and (3) seeks to identify relationships between attached and drift algal abundance. Twenty replicate quadrats were sampled in six kelp forests along the western side of False Bay. Within each quadrat, urchins (Parechinus angulosus) and kelps (Ecklonia maxima) were counted, percentage covers of various understorey algal species were recorded and drift algae were collected. Although there was significant variability in algal and urchin cover across the six sites, kelps generally increased from north to south, while urchins did the opposite. Urchins were negatively correlated with algal communities, and a localised threshold of 1.43kg/m² (50 urchins/m²) was identified, above which attached kelp density failed to increase above 10/m² and percentage cover of understorey algae usually remained below 20%. Surprisingly, no relationship was discovered between abundance of drift kelp and attached kelp, understorey algae or urchin density. This result was likely distorted by the naturally turbulent conditions of South African waters. Results highlight the complexity of these cool-water environments. To better understand the role of urchins in this system, experimental research into the feeding behaviour and effect of P. angulosus on kelps and understorey seaweeds in the presence/absence of drift algae is advised.

Orientador: Orlando Necchi Junior
Banca: Carla Ferragut
Banca: Ciro Cesar Zanini Branco
Resumo: Vários estudos envolvendo flora e distribuição de comunidades de macroalgas lóticas já foram desenvolvidos na região noroeste do estado de São Paulo; entretanto, nunca foi realizada qualquer abordagem sobre macroalgas lóticas em fragmentos florestais remanescentes, aspecto mais relevante deste estudo. Foram testadas as seguintes hipóteses: (1) entre as regiões/biomas estudados no estado de São Paulo, o atual trabalho deve apresentar maior similaridade florística com Floresta Tropical, por ser mais próxima e composta também por Floresta Estacional Semidecidual; (2) características intrínsecas de cada corpo d'água devem exercer maior influência na riqueza e abundância das comunidades de macroalgas do que parâmetros mais gerais de cada fragmento, como forma, tamanho e matriz adjacente, e da ordem de grandeza do riacho e sua respectiva bacia de drenagem. Este trabalho teve como objetivo geral realizar o levantamento florístico e analisar a distribuição ecológica das comunidades de macroalgas lóticas de fragmentos florestais remanescentes de Floresta Estacional Semidecidual da região noroeste do estado de São Paulo (20o00'13"-21o37'14"S, 48o32'26"- 50o26'02"O). Foram amostrados 17 riachos pertencentes a 12 fragmentos, no intervalo de junho a agosto de 2007 e 2008, período mais favorável para a região (estação seca). Foram identificadas 16 espécies de macroalgas, pertencentes a 14 gêneros. A maioria das espécies (69%) foi encontrada em um único ponto. Cyanophyta e Chlorophyta foram os grupos predominantes (44 e 37,5%), seguidos por Rhodophyta (12,5%) e Heterokontophyta (6%). Phormidium retzii (Cyanophyta) foi a espécie mais frequente, ocorrendo em seis pontos de amostragem. Apenas duas espécies representaram novos registros para a região: Trichocoleus sociatus (Cyanophyta) e Vaucheria pseudogeminata (Heterokontophyta); a última representa... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Several studies involving the flora and distribution of lotic macroalgal communities have been carried out in the northwest region of São Paulo State, southeastern Brazil. However, the lotic macroalgae in remnant forest fragments have never been studied, the most relevant aspect of this study. The following hypotheses have been tested: 1) among the biomes/regions previously studied in São Paulo State, the flora of the northwest region is expected to reveal the highest floristic similarity with the Tropical Forest, since it is the nearest biome and also composed by semidecidual seasonal forest; 2) particular characteristics of each water body are expected to be more influential on the species richness and abundance of macroalgal communities than more general parameters of each forest fragment, such as surrounding matrix, stream order and position in the respective drainage basin. This study aimed at surveying the flora and describing the ecological distribution the of lotic macroalgal communities from remnant forest fragments composed of semidecidual seasonal forest in the northwest region of São Paulo State (20o00'13"-21o37'14"S, 48o32'26"-50o26'02"O). 17 streams were sampled in 12 forest fragments from June to August of 2007 and 2008 during the typical most favorable period in the region (dry season). 16 species have been surveyed, belonging to 14 genera. 69% of species were found in a single site. Cyanophyta and Chlorophyta were the predominant algal groups (44 amd 37.5%), followed by Rhodophyta (12.5%) and Heterokontophyta (6%). Phormidium retzii (Cyanophyta) was the most frequent species, occurring in six sampling sites. Only two species were new records for the region: Trichocoleus sociatus (Cyanophyta) and Vaucheria pseudogeminata (Heterokontophyta); the later represents the first report for Brazil. The regional flora was more similar (nine species in common, 56%)... (Complete abstract click electronic access below)
Mestre

Une perte des forêts marines de grandes algues brunes a été observée dans les récentes décennies, causant un changement des écosystèmes et une réduction de la biodiversité. Dans le cadre du projet MMMPA, ce travail de thèse vise à répondre à certaines importantes questions liées à la conservation et à la restauration des forêts d'algues, au rôle des Aires Marines Protégées (AMPs) et les poissons herbivores. Les résultats des expériences sur le terrain ont montré que les poissons herbivores indigènes, probablement Salpa Sarpa (saupes), peuvent être les herbivores les plus efficace des ceintures intertidales de Cystoseira. En effet, les saupes affectent fortement la croissance, la biomasse et la reproduction des forêts naturelles et limitent le succès de la restauration sur des substrats artificiels. Le rôle des poissons herbivores a probablement été négligé dans la régulation des communautés macroalgales Méditerranéennes. Une revue de la littérature existante a montré une amélioration de l'intérêt scientifique (articles publiés) sur les espèces formant les forêts marines, au cours des dernières décennies. Cependant, la plupart de la recherche scientifique n’est pas en relation avec les AMPs, probablement parce que les forêts marines ne sont pas toujours considérées pendant la création des AMPs et dans les plans de gestion. Les études sur les forêts marines étant concentrée dans les pays développés, elles ne sont pas réparties de manière homogène dans le monde
Loss of marine forests of large brown seaweeds has been observed in recent decades, causing a reduction of ecosystem biodiversity. In the framework of the MMMPA project, this PhD aimed to address some important topics related to the conservation and restoration of algal forests, the role of Marine Protected Areas (MPAs) and fish herbivory. Different approaches were used: macroalgae surveys, literature reviews, manipulative experiments, tank-based experiments and GIS habitat mapping. Results from field experiments showed that native herbivorous fish, likely Sarpa salpa (salemas), can be the most effective herbivore of intertidal Cystoseira belts both on natural and artificial substrates. Indeed, salemas strongly affected the growth, biomass and reproductive output of natural forests and limited restoration success on artificial substrates. Likely, the role of the herbivorous fish in structuring macroalgal communities has been overlooked in the Mediterranean Sea so far. A review of the existing literature showed that knowledge on marine forests forming species has improved in recent decades. However, most of the research is not in relation to MPAs, likely due to the fact that marine forests are not always included in MPAs planning and management plans. Studies on marine forests are not homogeneously distributed in the world, being concentrated in the developed countries. Interestingly, an increase of the scientific interest (published papers) was observed. Nowadays, marine forests are under continuous threats and especially sensitive to multiple impacts

Kelp forests dominate coastal environments in temperate and subpolar latitudes around the world and, much like terrestrial forests, create complex habitats that support diverse and productive food webs. Studies of the resilience and stability of habitat-forming ecosystem engineers such as kelp have typically focussed on the role of external factors such as disturbance. Here, I propose that the stability and resilience of these species are also strongly influenced by internal processes. Such that, changes to the environment caused by engineer species positively affect their own demography (e.g. growth, survivorship), resulting in intraspecific facilitation via an ‘environment-engineer’ feedback. Ecklonia radiata is the most widespread and abundant habitat-forming kelp in Australasia. Unfortunately, this species is threatened by increasing ocean temperatures, overgrazing, and pollution, and is consequently becoming increasingly patchy and sparse in many locations. Existing research has focussed on understanding how external stressors and disturbances influence the population dynamics of E. radiata, however internal drivers such as the environment-engineer feedback are potentially just as important but remain largely unaddressed. My core aims were to determine (i) how engineering of the local environment by E. radiata changes with patch size, and how this influences environment-engineer feedback on the species’ demography, and (ii) how the nature of the feedback influences stability and resilience of E. radiata in the face of increasing habitat fragmentation and degradation. Long-term field experiments confirmed that engineering of abiotic conditions within E. radiata habitats is patch size dependent (Chapter 2), and that reductions in patch size disrupt the recruitment of juvenile E. radiata (Chapter 3). These findings directed the construction of an artificial reef system spanning more than a hectare, and onto which over 500 adult E. radiata were transplanted. Using this unique experimental environment, I found that reductions to patch size and adult kelp density impair microscopic and macroscopic juvenile E. radiata due to a breakdown of ecosystem engineering by adult conspecifics, such that demographic collapse occurs in the absence of sufficient adult E. radiata (Chapter 4). Two key outcomes from these field studies were: (1) the provision of suitable habitat and amelioration of physical stressors via ecosystem engineering by adult E. radiata appears critical to juvenile conspecifics and; (2) formation and development of filamentous turf algae – which inhibit kelp recruitment – is a primary cause and effect of the demographic collapse of E. radiata populations. Ecklonia radiata and turf algae habitats exist as alternative stable states, with each state inhibiting the formation of the other. I developed an innovative laboratory experiment to improve understanding of how turf algae may disrupt the recruitment of E. radiata, and found that turf algae create highly modified chemical conditions in the benthic microenvironments with elevated concentrations of oxygen and pH relative to E. radiata assemblages (Chapter 5). Ultimately, this thesis presents results consistent with the hypothesis that positive environment-engineer feedback facilitates the demography of E. radiata. Moreover, the impaired ability of E. radiata to engineer change due to reductions in patch size cause a breakdown in this intraspecific facilitation, leading too reduced habitat stability and resilience. This work contributes to ecological theories of habitat resilience, facilitation, alternative stable states and ecosystem engineers, and provides insights for the future management, conservation and restoration of critically important kelp forest ecosystems.

In the frame of the European Water Framework Directive (WFD, 2000/60/EC), a macroalgae based index (CARLIT) was applied along the Sicilian coastal water bodies (WBs) in order to assess for the first time their ecological status and collect accurate information on the distribution and abundance of shallow-water communities, especially of those most sensitive. The ecological quality ratio values, sensu WFD, showed “high”/“good” levels in all WBs with lushy forests of Cystoseira amentacea except two with “moderate” level due to the presence of stress-tolerant species related to local factors.

It seems that all industrialised sectors grounded in natural biological raw materials go through the same cycle of commencing with low-value-added products. As scientific and technical knowledge develops, this opens the pathway towards higher value-added activities, which is taken by some part of the existing firms in the sector and also by other firms outside the original sector. There may be insights to be had for an industry like the macroalgae industry that is in the early phases of this development by looking at insights from an industry that is in later phases having gone through many cycles. This chapter aims to very briefly make some illustrations from the development in the forestry-based sector that might carry some insights for the emerging macroalgae sector.

Archaeologically, the use of marine kelps and seaweeds is poorly understood, yet California's islands are surrounded by extensive and highly productive kelp forests with nearshore habitats containing more than 100 edible species. Historical accounts from around the Pacific Rim demonstrate considerable use of seaweeds and seagrasses by native people, but there has been little discussion of seaweeds as a potential food source on California's islands. This chapter summarizes the biology, diversity, ecology, and productivity of marine macroalgae and marine angiosperms in the California Bight, supporting the likely consumption of seaweeds in the past. The potential use of plentiful and nutritious seaweeds by California Island peoples has major implications for the perceived marginality of the islands.

Abstract In this article, a local scale, fully nonlinear coupled fluid-structural interaction (FSI) sugar kelp model has been developed using a computational fluid dynamics (CFD) method. In this model, to be consistent with available experimental data, the sugar kelp is approximated as elongated rectangles with smoothed isosceles triangles at the ends and a single kelp model with one end fixed in a channel with constant current model is developed. Several different current speeds are simulated, and the resulting drag forces and calculated drag coefficients are validated by comparison with experimental data from the literature. In a previous study, a global scale model was developed using a computational structural dynamics (CSD) method to simulate macroalgae farming system and guide the system configuration design. In the global scale model, the hydrodynamic forces are calculated using Morison’s equation and the kinematics and dynamics of the sugar kelp are simplified and the group of kelps attached to the long line is modeled as a slender structure with the same length and an effective diameter such that the volumes are consistent with the real physical system. This simplified model matches the weight and buoyancy but adjusting the hydrodynamic properties when the general hydrodynamic coefficients are employed. Therefore, optimal hydrodynamic coefficients used in global scale model were determined to obtain the hydrodynamic force more accurately. The validated local scale model is then be applied to determine the hydrodynamic coefficients of the simplified sugar kelp model for global dynamic analysis.