Dissertations / Theses on the topic 'Caddisflies'

Larval, pupal and adult samples of Culoptila cantha, from a large riffle of the Brazos River in north-central Texas from January, 1995 to March, 1997, indicated a predominately trivoltine cycle during both years; the over-wintering generation spanned 6-7 months and warm-season generations spanned 2-3 months. Eggs, larvae of all instars, larval cases, case reconstruction progression and behavior, pupae, and adults are described.

Caddisflies (Trichoptera) were collected from over 500 different locations throughout the Interior Highlands (Ozark, Ouachita, Arbuckle, and Wichita Mountains) between March 1990 and March 1994. I systematically sampled representative lotic and lentic habitats in 131 natural watersheds that comprise the 17 different physiographic subregions of this area. From my examination of approximately 60,000 specimens, surveys of regional museum collections, and review of literature records, I document 229 species distributed in 16 families and 58 genera. Included in this total are 27 endemic species and 15 new regional records. Descriptions are provided for a species new to science (Cheumatopsyche robisoni), four larvae (Helicopsyche limnella, H. piroa, Marilia species A, Polycentropus crassicornis) and a female (Helicopsyche piroa). Hydropsyche reiseni Denning, previously known only from the Arbuckle Mountains, is reduced in synonymy with H. arinale Ross. Further, I provide illustrated family, generic, and selected species-level keys that reflect this regional biodiversity.

The life history and case-making behaviors of Phylloicus ornatus from two springfed first order streams in the Edwards Plateau Bioregion of Texas were studied from January 1998 to November 1999. Field larval, pupal and adult samples and laboratory rearings indicated a multivoltine cycle. First instars differ from late instars in number of labral setae and in having a unique spur-like claw on each lateral hump. Larval development was asynchronous with second through fifth instars and pupae present most months. First instars were present April through July, October and November. Case making of first instar and case reconstruction of later instars extracted from their cases was documented by videophotography.

Thesis (M.S.) University of Missouri-Columbia, 2005.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 10, 2006) Includes bibliographical references.

Physical disturbance in the form of storm events has been implicated as a major determinant of community structure in streams. But there has been limited study of this effect on individual taxa within the communities. Such work is needed because of untested assumptions regarding the behavior of bioindicator species in these systems. Development of intricate indices of insect tolerances to organic pollution have become commonplace in environmental monitoring. However, research on the effects of natural disturbance on biological water quality assessment is lacking. Hydropsychid caddisflies are relatively intolerant to organic pollution and the United States Environmental Protection Agency has outlined the use of these organisms and others as an indication of clean water. If a species is recorded as absent from samples when it is present but hidden, this false negative would bias the water quality assessment. I tested hypotheses regarding the behavior of hydropsychid caddisflies facing increased discharge, and the effect of stream size on the magnitude of this phenomenon.Three sites along the West Fork of the White River, Indiana USA were studied during nine storms between 2001 and 2004. Stratified sampling from the upper 15 cm of substrate prior to and just after a storm, and again following reestablishment of normal flow, revealed alterations of hydropsychid distributions. During storms all but one species sought refuge in the hyporheic zone at depths dependent upon storm intensity. The possibility that poor water quality resulting from increased discharge caused the hydropsychid behavior was refuted by chemical analysis. Family level biotic index (FBI) data demonstrated that increased discharge results in a reduction of stream FBI values. These results indicate that high intensity storm events influence biological monitoring and should be factored into sampling protocol.
Department of Biology

Through the use of natural history records, published literature, and personal sampling (2011-2016) a total of 454 caddisfly species represented by 24 families and 93 genera were documented from the south-central United States. Two Hydroptilidae species were collected during the 2011-2016 collection efforts that are new to the region: Hydroptilia scheringi and Mayatrichia tuscaloosa. Eightteen species are endemic and 30 are considered species of concern by either federal or state agencies. The majority of each of these groups is Hydroptilidae, or microcaddisflies. Trichoptera community structure, by minimum number of species, was analysed in conjunction with large-scale geographical factors to determine which factor illustrated caddisfly community structure across the region. Physiographic provinces compared to other geographic factors analyzed best-represented caddisfly communities with a minimum of 10 or more species. Statistically, Hydrologic Unit Code 4 (HUC 4) was the most significant geographical factor but low number of samples representing this variable rendered it less representative of caddisfly community structure for the study area.

Food habits, net-spinning activity, energetics, and mercury accumulation in Hydrospsyche morosa were examined over a one year period on the South River in central Virginia. Feeding nets were observed as early as April and were widespread by May. Nets were virtually absent from late November through March. Gut content analysis revealed seasonal patterns in the consumption of various food items. From April through October, when feeding nets were widespread, detritus formed the bulk of the diet in terms of both numbers of particles and volume occupied. From November through March however, the algal component dominated in terms of numbers of particles although the detritus component still occupied a greater volume. Ivlev's preference index was employed and indicated that the seasonal differences in the relative amount of the three food types were not simply a matter of changing seston concentrations, but rather suggested a shift from a filter-feeding mode of feeding in the summer months to grazing on diatoms in the winter. H. morosa was bivoltine on the South River. The estimate of secondary production for the summer cohort was 3,246 mg AFDW/m²/yr, while the estimate for the winter cohort was 2,145 mg AFDW/m²/yr. The secondary production also was estimated for each season based on food habits to determine the impact of the observed seasonal switch in feeding habits on production and egestion rates. During the summer, the detritus component contributed most to production averaging about 50 percent. Animal and algal material contributed 30 and 20 percent, respectively. During the winter, algal material contributed most to the production, averaging just over 62 percent. Detritus also contributed during the winter averaging over 30 percent. Monthly rates of production and egestion were between 3 and 3.5 times faster during the summer. The concentrations of total mercury in seston, periphyton, and in the body tissue of H. morosa were analyzed each month. Mercury concentrations were between four and six times higher in the seston than in the periphyton. The concentration of mercury in the body tissue of H. morasa ranged from 0.14 ppm in March to over 1.20 ppm in July. Differences in Mercury concentration in the insects between seasons were significant. Regression analysis revealed a significant relationship between Hg concentration in the insects and the relative amount of detritus found in the guts.
Master of Science

Caddisflies (Insecta, Trichoptera) is one of the most important group of benthic components in temperate freshwater ecosystems. They are sensitive to changes of physical and chemical parameters in water bodies, so often used to assess the ecological status of the water body. The main objective of this work was to investigate the caddisfly fauna, diversity, species distribution and rarity in Lithuania, to evaluate the influence of environmental factors on the distribution and abundance of caddisflies in different habitats of Lithuanian rivers. The results obtained supplement the knowledge of the fauna, diversity and distribution of caddisflies and other benthic invertebrate animals of Lithuanian rivers. The determined patterns of caddisfly distribution and abundance are important in optimizing biodiversity conservation measures. The results are important for improvement of methods for biotic assessment of ecological status of Lithuanian rivers. For the first time 22 new species of caddisfly were discovered and the checklist of Lithuanian caddisfly was updated. The relation between Lithuanian caddisfly distribution and abundance was determined. Seasonal flight periods for caddisfly adults and the factors influenting the flight dynamics were estimated. The environmental factors influencing the distribution and abundance of caddisfly taxa (families, genera, species) in Lithuanian rivers were detected. The significance of caddisflies in the communities of benthic invertebrates of... [to full text]
Apsiuvos (Insecta, Trichoptera) yra vienas svarbiausių vidutinio klimato gėlavandenių ekosistemų bentoso komponentų. Būdamos jautrios vandens telkinių fizinių ir cheminių parametrų pokyčiams, dažnai naudojamos vandens telkinių ekologinės būklės bioindikacijai. Gauti darbo rezultatai papildo žinias apie apsiuvų ir kitų bentoso bestuburių fauną, įvairovę, paplitimą ir gausumą Lietuvos upėse. Nustatyti apsiuvų paplitimo ir gausumo dėsningumai yra svarbūs optimizuojant bioįvairovės apsaugos priemones. Darbo rezultatai svarbūs tobulinant Lietuvos upių ekologinės būklės biotinio vertinimo metodus. Pirmą kartą buvo rastos 22 naujos apsiuvų rūšys ir atnaujintas Lietuvos apsiuvų faunos sąrašas. Nustatyta priklausomybė tarp Lietuvos apsiuvų paplitimo ir gausumo. Nustatyti apsiuvų suaugėlių sezoninio skraidymo tipai ir veiksniai kurie turi įtakos skraidymo dinamikai. Išaiškinti aplinkos veiksniai, kurie daro įtaką apsiuvų taksonų (šeimų, genčių, rūšių) paplitimui ir gausumui Lietuvos upėse. Įvertinta apsiuvų reikšmė skirtingų Lietuvos upių bentoso bestuburių bendrijų sudėtyje. Patikslintos apsiuvų taksonų bioindikacinės ypatybės Lietuvos sąlygomis ir pateiktos tekančių vandenų ekologinės būklės vertinimo rekomendacijos.

Apsiuvos (Insecta, Trichoptera) yra vienas svarbiausių vidutinio klimato gėlavandenių ekosistemų bentoso komponentų. Būdamos jautrios vandens telkinių fizinių ir cheminių parametrų pokyčiams, dažnai naudojamos vandens telkinių ekologinės būklės bioindikacijai. Gauti darbo rezultatai papildo žinias apie apsiuvų ir kitų bentoso bestuburių fauną, įvairovę, paplitimą ir gausumą Lietuvos upėse. Nustatyti apsiuvų paplitimo ir gausumo dėsningumai yra svarbūs optimizuojant bioįvairovės apsaugos priemones. Darbo rezultatai svarbūs tobulinant Lietuvos upių ekologinės būklės biotinio vertinimo metodus. Pirmą kartą buvo rastos 22 naujos apsiuvų rūšys ir atnaujintas Lietuvos apsiuvų faunos sąrašas. Nustatyta priklausomybė tarp Lietuvos apsiuvų paplitimo ir gausumo. Nustatyti apsiuvų suaugėlių sezoninio skraidymo tipai ir veiksniai kurie turi įtakos skraidymo dinamikai. Išaiškinti aplinkos veiksniai, kurie daro įtaką apsiuvų taksonų (šeimų, genčių, rūšių) paplitimui ir gausumui Lietuvos upėse. Įvertinta apsiuvų reikšmė skirtingų Lietuvos upių bentoso bestuburių bendrijų sudėtyje. Patikslintos apsiuvų taksonų bioindikacinės ypatybės Lietuvos sąlygomis ir pateiktos tekančių vandenų ekologinės būklės vertinimo rekomendacijos.
Caddisflies (Insecta, Trichoptera) is one of the most important group of benthic components in temperate freshwater ecosystems. They are sensitive to changes of physical and chemical parameters in water bodies, so often used to assess the ecological status of the water body. The main objective of this work was to investigate the caddisfly fauna, diversity, species distribution and rarity in Lithuania, to evaluate the influence of environmental factors on the distribution and abundance of caddisflies in different habitats of Lithuanian rivers. The results obtained supplement the knowledge of the fauna, diversity and distribution of caddisflies and other benthic invertebrate animals of Lithuanian rivers. The determined patterns of caddisfly distribution and abundance are important in optimizing biodiversity conservation measures. The results are important for improvement of methods for biotic assessment of ecological status of Lithuanian rivers. For the first time 22 new species of caddisfly were discovered and the checklist of Lithuanian caddisfly was updated. The relation between Lithuanian caddisfly distribution and abundance was determined. Seasonal flight periods for caddisfly adults and the factors influenting the flight dynamics were estimated. The environmental factors influencing the distribution and abundance of caddisfly taxa (families, genera, species) in Lithuanian rivers were detected. The significance of caddisflies in the communities of benthic invertebrates of... [to full text]

Rivers and their catchments are under mounting pressure from direct channel modification, intensification of land use, and from a legacy of decades of channelisation. Recent legislation, in the form of the EU Water Framework Directive, places a greater emphasis on the management of water bodies as holistic systems, and includes the explicit consideration of hydromorphological quality, which describes the hydrologic and geomorphic elements of river habitats. These are defined specifically as hydrological regime, river continuity and river morphology. This appreciates that sediment and flow regimes, along with the channel structure, provides the 'template' on which stream ecological structure and function is built. Invertebrate fauna contribute significantly to the biodiversity of rivers, and often form the basis of monitoring river health. However much of the fundamental ecological knowledge base on the response of invertebrates to hydromorphological change needed to make informed decisions and accurate predictions, is either lacking, inadequate or contradictory. This thesis addresses some of the key potential shortcomings in recent bio-assessment that others have alluded to, but which have rarely been explored in the context of direct channel manipulations. By using two case studies of, realignment in a natural upland catchment, and flood protection engineering in an urban stream, this study investigates the sensitivity of hydromorphological impact assessment methods that rely on biodiversity patterns of benthic riverfly (Ephemeroptera, Plecoptera and Trichoptera) larva. This work employed widely used biomonitoring indices of benthic riverfly larva abundance, species richness, alpha and beta diversity, and community composition, applied over a range of spatial scales, in combination with spatially contemporaneous physical habitat data, to describe and explain community changes in response to disturbance, and patterns of natural variation. The effects of restoration were investigated using a high degree of sample replication within channels and across the wider catchment, as well as contrasting spring and autumn seasons. To assess change in a small urban channel, approaches that explicitly consider spatial elements of community data, using spatial eigenvectors analysis, were applied to spatially detrend community data and directly investigate spatial patterns. Restoration of the Rottal Burn was found to be successful in restoring habitat diversity and geomorphic processes, and in turn increasing reach scale species richness and beta diversity through the gradual arrival of rare and specialist taxa into novel habitats. Catchment scale replication revealed high variation in diversity indices of modified and undisturbed streams, and a strong temporal pattern related to antecedent flow conditions. Channels with greater habitat heterogeneity were able to maintain high gamma diversity during times of high flow stress by providing a number of low flow refuges along their length. The urban Brox Burn had surprisingly high riverfly richness and diversity driven by small scale hydraulic heterogeneity, created by bed roughness resulting in a range of microhabitats. Riverfly community responses to direct channel dredging could not be detected by measurements of average richness and diversity, however distinct changes were seen in gamma diversity, the identity of community members and their arrangement among sample patches. Impacts of sediment pollution release due to engineering were short lived and apparently had little detrimental impact on biodiversity. Strong spatial patterns of community assembly on the stream bed were uncovered, relating to longitudinal, edge and patchy patterns. Significant habitat drivers of community composition were confounded by high amounts of spatial autocorrelation, especially hydraulic variables. Due to the strongly physical and spatial nature of hydromorphological disturbance, turnover of species between sample locations at a range of scales, and the spatial arrangement of habitats and communities is of more use for detecting these types of subtle changes compared to mean richness or diversity. These findings have implications for the targeting of resources for monitoring of restoration, or engineering disturbances, in order to be sensitive to hydromorphological change. Efforts should target the main area of natural variability within the system, either replicating sampling in time or space to distinguish effects of impact. Spatial patterns, measures of beta diversity and species identity can be better exploited to identify systems with functioning geomorphological processes. Channel typologies proved misleading, and quantification of habitat and selection of control sites using multiple pre-defined criteria should be carried out. Studies of restoration operations and engineering impacts provide considerable opportunities for advancing our knowledge of the mechanisms that drive community response under a range of conditions to improve impact detection.

The systematics of the trichopteran families Conoesucidae, Helicophidae, Calocidae and Antipodoeciidae was investigated, with particular emphasis on immature stages (larvae and pupae). Study of Antipodoeciidae was limited to its inclusion in phylogenetic analysis, due to lack of material. Collecting was carried out throughout Tasmania to establish the species to be included in these families and their distribution. Immatures were associated with adults by rearing for all the conoesucid species, 3 of the 6 helicophids and 2 of the 5 calocids known from Tasmania. Larvae and pupae are described and keys to species given. Two new species of Conoesucus are described. Univariate morphometric analysis of male genitalia of Lingora vesca and L. aurata showed that L. vesca is a variant of L. aurata, and is therefore synonymised with it. Electrophoretic data showed Conoesucus adiastolus sp. n. to be distinct from the morphologically similar C. brontensis. Morphometric analysis of wing venation enabled adults of Conoesucus brontensis, C. nepotulus and C. adiastolus to be separated, but with some overlap; measurement of male maxillary palps showed that males could be reliably identified by their structure. Species distribution within Tasmania falls into two categories: those restricted to the west, and those species which are widespread. The 12 western species are all endemics; of the ten widespread species, at least six are shared with the mainland. More detailed study of mainland species is required before detailed biogeographic hypotheses explaining the entire Australian distribution of these families can be proposed. Chromosomes were counted in all the species for which immatures were identified. Chromosome number varied between families: for Conoesucidae n=25, Calocidae (Caenota and Tamasia) n=22, Helicophidae (Alloecella) n=32-40. 4, Although the number for Alloecella could not be determined precisely, it is tRlughest so far recorded for Trichoptera. Chromosomes were too small and uniform for other characteristics to be studied with the method used. These results are discussed in relation to placement of the families within Trichoptera, and chromosome evolution in Trichoptera and the sister order Lepidoptera. Phylogenetic analysis based on larval and pupal characters (including case characters) was carried out for a) the 22 Tasmanian taxa studied in detail and b) the Tasmanian species plus Antipodoecia and species of Conoesucidae, Calocidae and Helicophidae from New Zealand and South America. Analysis of Tasmanian taxa resulted in groups generally in agreement with the existing classification. Monophyly was demonstrated for the Tasmanian Conoesucidae, Helicophidae (Alloecella) and the Calocidae studied. The genera Lingora, Nampa and Matasia were shown to constitute a monophyletic group, providing evidence in support of congeneric status, although this conflicts with some characters of adults. In analysis of all taxa, New Zealand species were grouped with Australian confamilials. Groups outside the Conoesucidae were not shown to be monophyletic and thus their status remains uncertain.

Obszar Polski Środkowej, w szczególności w okolicach Łodzi, charakteryzuje się zwiększoną liczbą skoncentrowanych wypływów wód podziemnych. Wynika to ze specyficznej budowy geologicznej tego terenu i przebiegu strefy krawędziowej Wzniesień Łódzkich. Źródła uważane są często, za „naturalne laboratoria” o niezmiennych parametrach fizyczno-chemicznych, które zapewniają stabilne miejsce do życia określonej grupy organizmów. Gatunki zwierząt bezkręgowych zamieszkujące źródliska i wypływające z nich strumienie posiadają dostosowane do tych warunków cykle życiowe. Dotyczy to w szczególności aspektów związanych z odżywianiem i reprodukcją. Dlatego zbadanie szczególnych powiązań ekologicznych istniejących pomiędzy fauną bezkręgową i środowiskiem może sprzyjać lepszemu poznaniu funkcjonowania tych ekosystemów, określeniu aktualnego ich stanu, a także rozpoznaniu zagrożeń oraz planowaniu działań ochronnych podejmowanych w stosunku do obszarów źródliskowych. Celem pracy była charakterystyka źródlisk położonych w Polsce Środkowej i procesów je kształtujących oraz rola zespołów chruścików w funkcjonowaniu tych specyficznych ekosystemów. Badania prowadzono w ośmiu źródliskach położonych w okolicach Łodzi. Prace rozpoczęto jesienią 2011 roku i kontynuowano przez kolejne 4 lata z różnym natężeniem w zależności od rodzaju prowadzonych badań. W pierwszej kolejności dokonano inwentaryzacji wytypowanych źródlisk pod względem elementów biologicznych, takich jak chruściki i okrzemki oraz abiotycznych, obejmujących rodzaj podłoża, a także podstawowe parametry fizyczno-chemiczne. Na tej podstawie przeprowadzono analizę, pozwalającą wyróżnić niektóre z badanych źródeł pod względem zarówno zamieszkujących je organizmów, jak i czynników środowiska. Na podstawie wyników pomiarów szerokości puszek głowowych larw chruścików, gatunków dominujących w źródliskach, określono przebieg cykli życiowych tych gatunków, a także preferencji przez poszczególne stadia larwalne różnych substratów. Prawidłowe funkcjonowanie źródlisk i początkowych odcinków strumieni wiąże się z przetwarzaniem materii allochtonicznej. W tym celu, w latach 2013 i 2014, przeprowadzono eksperymenty terenowe, w których zatopiono maty z liśćmi: A. glutinosa, A. pseudoplatanus, Q. robur oraz Q. rubra, w źródlisku Wolbórka oraz w strumieniu odpływowym, 150 metrów poniżej niszy źródliska. Bardziej szczegółowo zbadano preferencje pokarmowe dwóch dominujących gatunków detrytusożernych: P. nigricornis oraz C. villosa. Larwom dawano do wyboru kwadraty wycięte z liści A. glutinosa, A. pseudoplatanus, Q. robur oraz Q. rubra. Obserwacji poddano 55 larw P. nigricornis i 55 larw C. villosa. W oddzielnych, długotrwałych eksperymentach laboratoryjnych, oceniono aktywność pokarmową larw V stadium C. villosa. Doświadczenia te pozwoliły uzyskać informacje odnośnie synchronizacji cyklu życiowego, zróżnicowania czasu potrzebnego do zakończenia cyklu larwalnego oraz określenia masy i płci dorosłych C. villosa, w odniesieniu do czasu żerowania larw i rodzaju spożywanego pokarmu. W ocenie obserwowanych u C. villosa odchyleń od proporcji płci 1:1, wzięto pod uwagę znaczne różnice wielkości larw, które po przeobrażeniu staną się samcami (małe) i samicami (duże). W trakcie prowadzonych eksperymentów i obserwacji terenowych stwierdzono, że larwy te, przynajmniej częściowo zajmują inne obszary w źródlisku. Niezwykle interesujące okazały się zachowania kopulacyjne jak również strategia składania jaj przez samice C. villosa. W pracy analizowane są kompromisy ewolucyjne związane z późnym wylotem, długotrwałą kopulacją i przedłużonym okresem składania jaj obejmującym miesiące późno-jesienne, a nawet na zimowe. W wyniku przeprowadzonych badań uzyskane wyniki, pozwoliły na stwierdzenie, że: • trzy źródliska: Podwierzchowiec, Wardzyń i Mineralne mogą być traktowane jako odmienne pod względem stwierdzonej w nich fauny chruścików i mikroflory okrzemek, • dominujące w badanych źródliskach gatunki Trichoptera, P. nigricornis, C. villosa i S. personatum, mają zróżnicowane stadia rozwojowe, zależnie od źródła, w którym je łowiono, • poszukiwanie pożywienia lub też/i poszukiwanie odpowiednich materiałów do budowy domku, który często zbudowany jest z przewagą materii mineralnej lub organicznej, w zależności od stadium, w którym obecnie znajduje się larwa, prowadzi do wybiórczości mikrosiedliskowej określonych stadiów larwalnych, • dekompozycja liści A. glutinosa jest najszybsza w porównaniu z ubytkiem powierzchni liści A. pseudoplatanus, Q. robur i Q. rubra oraz, że ubytek powierzchni liści obcego gatunku Q. rubra zachodzi w podobnym lub nieco wolniejszym czasie, co liści rodzimego Q. robur, • liście Q. robur są pokarmem jedzonym przez larwy, nie tylko najmniej chętnie, ale także wpływającym na wydłużenie cyklu larwalnego oraz zmniejszenie masy imagines, • dysproporcje w ilości pobieranego przez Larwy C. villosa pokarmu oraz różnice w wielkości larw wpływają na zachowanie larw. Może to doprowadzać do „ucieczki” mniejszych larw , przyszłych samców,w dół źródliska, • różnice w masie dorosłych C. villosa, wynikają m.in. z różnych warunków termicznych i pokarmowych, w strumieniu odpływowym i w źródlisku. Wpływają one również na tempo metabolizmu larw, co w rezultacie przekłada się na masę imagines, • przynajmniej część larw i/lub poczwarek C. villosa przechodzi przez stan diapauzy. Zróżnicowanie czasu braku aktywności pokarmowej potwierdziło się, szczególnie wyraźnie, u larw przyszłych samic, które są zdolne „poczekać” do momentu, aż inne larwy uzupełnią zasoby energetyczne i „będą gotowe” do wylotu, aby przekształcenie w formę imaginalną odbyło się w podobnym czasie, • zwiększenie sukcesu reprodukcyjnego samic C. villosa może zależeć od liczby złożonych w różnym okresie złóż jajowych. Ostatnie złoże może zostać zdeponowane w połowie stycznia, • osobniki gatunków źródliskowych, podlegają kompromisy związane z optymalnym czasem wylotu i składaniem jaj. Co istotne, każda zmiana środowiska wywołana, czy to czynnikami naturalnymi, czy działalnością człowieka, niesie ze sobą ryzyko zaburzenia cyklu rozwojowego chruścików, co w konsekwencji może prowadzić do zaburzenia delikatnej równowagi ekosystemów źródliskowych.

This study was an investigation of lotic macroinvertebrate distribution in northeastern Oregon at two different spatial and biological scales. Examination of assemblages at a limited spatial scale revealed relationships with natural and disturbance gradients and led to questions about distribution of a population at broader spatial scales. In a 16 kilometer section of the North Fork John Day River, I examined the relationship of invertebrate assemblages to habitat and fine sediment deposition. This river section was subjected to sediment inputs resulting from several years of floodplain mine-tailing leveling, and erosion and tributary channel scouring following a forest fire. Invertebrate assemblages differed between habitat types. The proportion of sediment tolerant invertebrates, especially oligochaete worms, increased with higher amounts of deposited fine sediment, but total invertebrate abundance was not related to deposited sediment. The response of sediment tolerant invertebrates appeared to reflect cumulative impacts from multiple input points and downstream transport of sediment and cumulative and/or increasing impacts over the two years of sampling. In studying assemblages in the North Fork, I noticed an unusual abundance of the caddisfly, Lopidostoma pluviale (Milne). In a more spatially extensive examination of a population, I investigated distribution of this caddisfly in the Blue Mountain region of northeastern Oregon. L. pluviale was more common and/or abundant further downstream than would be expected for a shredding feeder based on the River Continuum Concept (Vannote, et al., 1980). Through gut content analyses, I demonstrated that this species is much more of a generalist feeder than its designation as a shredder would imply. Consequently, its distribution is not limited to headwaters where allochthonous food resources are abundant. I hypothesize that non-food environmental factors may be more important in determining the distribution of this species. Results of this research indicate that assemblage studies can reveal interesting relationships with environmental conditions. In addition, paying attention to unusual distributions of taxa in assemblage studies can lead to further studies that can improve our understanding of the biology and ecology of species.
Graduation date: 2004