The PLFA profiling method was adopted and used to determine changes in microbial community structure and abundance along natural and human-induced environmental gradients. The presented studies were based on field sampling campaigns combined with targeted laboratory experiments. According to the aims of particular studies, microbial PLFA fingerprinting was combined with the auxiliary below- and aboveground ecosystem characteristics to identify the drivers of microbial responses to environmental changes or with 13C-labelling and metagenomics to obtain more complex information about running processes and involved microorganisms.

The Nordic Seas region marks a transitional zone between the temperate North Atlantic Ocean and the polar Arctic Ocean. The influence of contrasting fluxes of organic matter on benthic community structure and function within the deep waters of the region were investigated. Samples of the macrofaunal community were collated throughout the region employing a standardised method. In the summer of 2002, during the RRS James Clark Ross 75 cruise, replicated samples were obtained with the SMBA multiple corer and the USNEL boxcorer from four stations located at similar sampling depths along a latitudinal transect at the Norwegian Sea continental margin. Additional replicated samples were obtained with a megacorer at six stations located along two bathymetric transects across the Norwegian Sea continental margin in the summer of 2005 during the RRS James Clark Ross 127 cruise. Contrasting fluxes of organic matter influenced benthic community structure, functional ecology and bioturbation potential. Species known to adopt the feeding strategy of the sub-surface storage of organic matter occurred in areas characterised by a seasonal input of organic matter. Species richness and diversity was highest at the Svalbard Margin, located within the marginal ice zone. Bathymetric patterns of macrofaunal biomass were comparable with previously reported global patterns. However, bathymetric patterns of macrofaunal abundance were higher than global patterns. The previously reported rapid subduction of organic matter by the sipunculan Nephasoma sp. and associated deep burrow networks on the Voring Plateau was linked to the species Nephasoma lilljeborgi. It is proposed that N. lilljeborgi is an ecosystem engineer.

Master of Science / Department of Biology / Keith B. Gido / Fishways are a common tool for mitigating the effects of habitat fragmentation on fish communities, but their utility in low-gradient, sand-bed rivers of the Great Plains is not well studied. The Lincoln Street Fishway on the Arkansas River became operational in 2015 and was built specifically to pass small-bodied threatened fishes. We used a combination of surveys up-and downstream of the barrier and tagging experiments to test the ability of fishes to move into and through the fishway. Differences in fish community structure up- and downstream of the dam were more pronounced prior to the construction and operation of the fishway. In particular, Emerald Shiner Notropis atherinoides was absent from collections upstream of the dam before fishway construction, but commonly collected upstream in 2015 and 2016 surveys. Surveys within the fishway structure revealed 29 species, or 74% of the total species captured during our study were using the fishway. To further quantify fishway passage, we used a VIE experiment to assess if fish marked downstream of the fishway moved into or upstream of the fishway. Although we did not recapture marked fish upstream of the fishway, some marked individuals moved into the fishway. Finally, we conducted a PIT tag experiment to evaluate short distance movements within the fishway for three species of small-bodied minnow and were able to document upstream movement across a gradient of flows through the fishway. Results from our study illustrate the potential for fishways to mitigate the effects of habitat fragmentation on small-bodied fishes in sand-bed rivers.

Made available in DSpace on 2014-06-11T19:22:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-04-28Bitstream added on 2014-06-13T20:49:35Z : No. of bitstreams: 1 goncalvessouza_t_me_sjrp.pdf: 528020 bytes, checksum: c517fa0c7acfebb2b1d0502c18e30b48 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A complexidade arquitetural de plantas é frequentemente reconhecida como um dos fatores que melhor prediz a distribuição de artrópodes sobre a vegetação. Basendose na hipótese da heterogeneidade ambiental plantas estruturalmente mais complexas possuem maior abundância e riqueza de artrópodes. Porém, não se sabe como a variação arquitetural e a distribuição espacial de grupos específicos, como as bromélias, afetam a riqueza e composição de espécies de aranhas. Neste trabalho nosso objetivo foi responder as seguintes questões: 1) espécies de bromélias com características arquiteturais similares possuem subconjuntos não-aleatórios da comunidade de aranhas bromelícolas? 2) a complexidade arquitetural das bromélias aumenta a abundância e a riqueza de espécies de aranhas? 3) espécies de bromélias com distribuição vertical mais ampla possuem maior riqueza de espécies de aranhas? Amostramos aranhas em 39 espécies de bromélias que apresentam diferenças de complexidade arquitetural e distribuição vertical em uma área de Mata Atlântica na região sudeste do Brasil. Usamos uma análise de equação estrutural para testar os efeitos da complexidade arquitetural e da distribuição vertical de bromélias sobre a abundância e riqueza de aranhas. Ao contrário do esperado, a arquitetura de bromélias não afetou a composição de espécies de aranhas. A complexidade arquitetural (i.e., número de folhas) e a distribuição vertical (amplitude de ocupação do estrato vertical por uma espécie de bromélia) correlacionaram-se positivamente com a abundância e a riqueza de aranhas. Nossos resultados corroboram a hipótese da heterogeneidade ambiental e sugerem que, além da estrutura da planta, a distribuição espacial das mesmas pode ser um forte determinante do aumento da diversidade de animais / Although bromeliads can be important in the organization of invertebrate communities in Neotropical forests, there are few studies supporting this assumption. Bromeliads possess a three-dimensional architecture and rosette grouped leaves that provide associated animals with a good place for foraging, reproduction and egg laying, as well as shelter against desiccation and natural enemies. In this work we collected spiders from an area of the Atlantic Forest, southeastern Brazil, through manual inspection in bromeliads, beating trays in herbaceous+shrubby vegetation and pitfall traps in the soil, to test if: (1) species subsets that make up the spider Neotropical forest community are compartmentalized in different habitat types (i.e., bromeliads, soil, vegetation) and amplify spider beta diversity, (2) bromeliads are important elements that structure spider communities and thus generate different patterns of abundance distributions and species composition. There were subsets of spider species compartmentalized into the three habitat types. The presence of bromeliads represented 41% of increase in total spider richness, and contributed mostly to explain the high beta diversity values among habitats. Pattern of abundance distribution of spider community differed among habitats. These results indicate that bromeliads are key elements in structuring spider community and highlight the importance of Bromeliaceae as biodiversity amplifiers in Neotropical ecosystems

As ascÃdias sÃo invertebrados marinhos bentÃnicos amplamente distribuÃdos nos oceanos, desde as zonas entremarÃs atà grandes profundidades. O curto perÃodo de vida larval confere Ãs ascÃdias uma dispersÃo natural restrita, o que implicaria ao grupo altas taxa de endemismo. Entretanto, em resposta ao rÃpido crescimento econÃmico das cidades costeiras, a construÃÃo de portos e outras facilidades marÃtimas tem favorecido a introduÃÃo de espÃcies exÃticas. Assim, com intuito de estabelecer uma base de dados para propostas de monitoramento, um estudo da fauna de ascÃdias do Cearà foi conduzido no Terminal PortuÃrio do PecÃm, bem como no mais antigo Porto do Mucuripe. Todos os espÃcimes coletados foram identificados ao menor nÃvel taxonÃmico possÃvel. Como resultado, das 38 espÃcies encontradas (31 e 30 para o Mucuripe e PecÃm, respectivamente), 16 constituem novos registro para o estado do Cearà e 2 (sublinhadas) previamente desconhecidas para a costa brasileira: Ascidia sydneiensis, Ascidia sp.1, Ascidia sp.2, Cnemidocarpa irene, Didemnum cineraceum, Didemnum perlucidum, Didemnum sp., Diplosoma sp., Distaplia bursata, Distaplia sp., Ecteinascidia cf. styeliodes, Eusysntyela sp., Lissoclinum sp., Polyandrocarpa anguinea, Polycarpa tumida e Styela canopus. De acordo com informaÃÃes de distribuiÃÃo geogrÃfica e ocorrÃncia restrita aos portos, 18 foram consideradas espÃcies introduzidas, 9 nativas e 7 criptogÃnicas. As assemblÃias apresentaram diferenÃas significativas entre portos (p=0,000), com S. canopus e M. exasperatus claramente dominantes, embora D. cineraceum e Distaplia sp. tambÃm possam ser consideradas espÃcies frequentes nos portos do PecÃm e Mucuripe, respectivamente. As anÃlises mostraram tambÃm diferenÃas significativas entre profundidades (p=0,000), sendo observada uma maior estratificaÃÃo vertical das assÃmblÃias nos pilares no porto do Mucuripe, o que indica a influÃncia de fatores como tempo de submersÃo dos pilares e turbidez. PorÃm, as diferenÃas entre faces nÃo foram significantes (p=0,866). Nos dois portos, os valores mÃximos de riqueza foram obtidos nas profundidades intermediÃrias (3-4m), mas voltando a reduzir ligeiramente na Ãltima profundidade estudada. As espÃcies coloniais foram as mais numerosas, mas a famÃlia Styelidae foi a mais importante em relaÃÃo Ãs espÃcies introduzidas. Contudo, a biota presente nos pilares de ambos os portos conta com uma grande participaÃÃo das ascÃdias, e portanto a continuidade de estudos à ainda necessÃria para detectar e, se possÃvel, evitar impactos ecolÃgicos e econÃmicos relacionados Ãs espÃcies invasoras / The ascidians are marine benthic invertebrates with worldwide distribution in oceans, occuring from intertidal zones to great depths. The brief planctonic lifetime of ascidians result in a restricted natural dispersion, indicating a potential high endemism. However, in response to the rapid economical development in coastal cities, constructions of harbors and other maritime facilities have favored the introduction of exotic species. In order to establish a baseline for monitoring purposes, a study of the ascidian fauna from Ceara state, northeastern coast of Brazil, was conducted on Pecem Harbor (offshore), as well as on its older counterpart, Mucuripe Harbor (inshore). All collected specimens were identified to the lowest possible taxonomic resolution. As a result, from 38 species found (31 and 30 to Mucuripe and Pecem Harbors, respectively) 16 are new records for the region, and 2 (underlined) were also previously unknown for the Brazilian coast: Ascidia sydneiensis, Ascidia sp.1, Ascidia sp.2, Cnemidocarpa irene, Didemnum cineraceum, Didemnum perlucidum, Didemnum sp., Diplosoma sp., Distaplia bursata, Distaplia sp., Ecteinascidia cf. styeliodes, Eusysntyela sp., Lissoclinum sp., Polyandrocarpa anguinea, Polycarpa tumida e Styela canopus. In spite of the restricted occurrence on harbors, 18 were classified introduced, 9 natives and 7 criptogenic species. The ascidian assemblages were clearly different between harbors (p=0,000), but dominated by two main species: S. canopus and M. exasperatus, even though D. cineraceum and Distaplia sp. were also among the most frequent species observed at Pecem and Mucuripe Harbor, respectively. An increase of species richness was observed in the middle depths (3-4m), with slight decrease for later depth samples. Colonial ascidians were the most representative in richness, but Styelidae was the most important family regarding the number of introduced species. The statistical analysis showed differences between depths (p=0,000), but ascidians assemblages present at Mucuripe Harbor were more clearly stratified, possibly by the influence of external factors such as longer submersion time of pilings and higher turbidity. In conclusion, ascidians are an important group colonizing the pilings at both harbors, but further studies on the harbors and vicinities are need to detect and, if possible, avoid ecological and economical impacts related to invasive ascidians.

Understanding how coral reefs respond to natural disturbances is fundamental to assess their resistance and resilience, particularly in a context of climate change. Therefore, and given the escalating frequency and intensity of bleaching events, it is essential to evaluate responses of communities in space and time to disentangle the mechanisms underlying ecological changes. Here, I analyzed a dataset comprising 59 reefs, resulting from 6 years (2014-2016) of a coral reef benthic monitoring program in the Saudi Arabian Red Sea. It encompasses the 2015/2016 mass bleaching event and spans three different geographic regions: north (Duba and Al Wajh), central (Jeddah and Thuwal), and south (Al Lith, Farasan Islands and Farasan Banks). The results indicate significant differences between regions and through time. Coral assemblages from the southern region were the most affected by the 2015 bleaching event, where in some reefs, hard and soft corals cover dropped to <2% in 2017. Important changes in community structure were observed through time in the three regions, with a shift to a macroalgae, turf algae and CCA dominance. Different environmental drivers (salinity, sea surface temperature, fishing index, distance to shore, and photosynthetically active radiation) were analyzed, and highlighted a regionally-based response of the communities to these potential drivers of change. Overall, the examined Red Sea benthic communities presented dynamic patterns in composition. Distance decay plots based on presence/absence showed a general increase in similarity throughout multiple spatial scales in 2019, when compared to previous years. This finding suggests a loss in biodiversity due to thermal anomalies and bleaching events, evidenced by a homogenization (i.e., increase similarity) in the composition of the benthic communities. I document here a patterns of dominance of a few benthic groups with time and a decrease in branching corals. This study provides baseline information about changes in coral reef benthic community structure and identifies environmental factors with a higher impact on a regional scale. This information can be used to guide conservation efforts in these highly biodiverse ecosystems.The resulting datasets can be valuable for anticipating responses of coral communities under future climate scenarios.

Two congeneric damselfly species, Enallagma traviatum and E. aspersum, dominate the littoral macroinvertebrates of Bays Mountain Lake and of the adjacent fish-free Ecology Pond, respectively (northeastern Tennessee, USA). Extending previous experimental studies, we test seven hypotheses concerning the role of fish (bluegill sunfish, Lepomis macrochirus) and larvaldragonfly (Anax junius) predation, competitive effects on damselflies, and the interaction between competition and predation, in determining invertebrate dominance in these communities. Three types of experiments were conducted: an enclosure experiment within Ecology Pond, an outdoor replicated tub experiment, and a laboratory behavior experiment. The in-situ enclosure experiment showed that E. traviatum larvae were more susceptible to Anax predation than were E. aspersum larvae; a tendency toward greater vulnerability to fish of E. aspersum compared with E. traviatum was not statistically significant. The outdoor tub experiment confirmed both of these trends with statistically significant results. In the tubs, both predators inhibited feeding of both zygopterans (as indicated by reduced fecal mass), particularly for E. aspersum in the presence of fish. This effect appears to have been primarily indirect, mediated through exploitation of the zooplankton. We also detected competitive effects of E. traviatum on E. aspersum: E. traviatum reduced the emergence and increased the exposure above the substrate of E. aspersum. In the absence of predators, E. traviatum inhibited feeding of E. aspersum via interference. In the laboratory behavior experiment, predators inhibited crawling by E. aspersum. E. aspersum was more exposed than was E. traviatum; it swam and crawled more than did E. traviatum, considerably increasing these movements at night. Over all, E. traviatum consistently appeared to be the more cryptic of the two species, and E. aspersum appeared to be much more active. Our results suggest an explanation for the clear difference in structure between communities like Bays Mountain Lake and Ecology Pond: predaceous fish eliminate large invertebrate predators and shift the community toward cryptic forms at relatively low densities, reflecting the effects of both predation and exploitation competition. In the absence of fish, large invertebrate predators are less able to deplete littoral invertebrates but may favor the more active forms, perhaps because these are better able to avoid invertebrate predators.

Throughout the world, birds represent the primary type of wildlife that people experience on a daily basis. However, a growing body of evidence suggests that alterations to the acoustic environment can negatively affect birds as well as humans in a variety of ways, and altered acoustics from noise pollution has the potential to influence human interactions with wild birds. In this thesis, I investigated how anthropogenic noise impacts daily behavior as well as community structure of wild birds. In the first component of this thesis, I assessed the distance at which a bird initiates flight or escape behavior (i.e., flight initiation distance or FID) in varying acoustic conditions. I surveyed 12 songbird species from three foraging guilds, ground foragers, canopy gleaners, and hawking flycatchers, and I predicted FIDs to decrease, remain the same, and increase with noise exposure, respectively. Contrary to expectations, the canopy gleaning and flycatching guilds exhibited mixed responses, with some species exhibiting unchanged FIDs with noise while others exhibited increased FIDs with noise. However, FIDs of all ground foraging species and one canopy gleaner decreased with noise levels. In the second component, I examined the feeding of wild birds, an increasingly popular recreational activity throughout North America that promotes increased sense of wellbeing by connecting people with wildlife and nature. I tested how experimental noise influences abundance, species richness, community structure and foraging behavior of songbirds at maintained bird feeders. By measuring activity levels of all species that utilized the feeders exposed to intervals of quiet and noisy conditions, I found noise to be a significant predictor of community turnover. Specifically, noise exposure resulted in increased feeder activity for two species, and decreased activity for one species. I also confirmed previous research conducted in the laboratory indicating white-crowned sparrows decrease their foraging rate under noise conditions, presumably as a trade off with visual vigilance. Considering the interactions of humans and wild birds, the results from my two thesis components indicate that the acoustic environment can play a role in how species of different foraging guilds respond to birdwatchers and what species visit bird feeders.

The Moose River Basin in northern Ontario is an important large river system, however very little is known about its aquatic invertebrate community. As macro invertebrates are an integral part of river ecosystems, I conducted an initial assessment of the aquatic invertebrate community structure in the Moose River Basin, at both a fine, and a basin-wide, scale. The fine scale study used invertebrate data collected at five reaches within a 30km stretch of the Groundhog River. The examination of the invertebrate community at a basin-wide scale was accomplished using meta-analysis techniques on twenty-two studies conducted on various rivers within the Basin. The effect of the following factors on community structure were examined: i) the use of different sampling devices, ii) water depth, iii) substrate type, iv) sampling in two consecutive years, and v) spatial scale. I found that the use of various sampling devices resulted in significantly different estimates of community structure. This strongly suggests that consistent sampling protocols are necessary to effectively compare results within, and among, studies. The effect of water depth on community structure was inconclusive, as too few samples were collected to overcome the confounding effects of substrate type. Substrate type had a significant effect on community structure, with greater invertebrate richness and diversity found in fine substrate in the Groundhog River study, but with no consistent patterns at the basin-wide scale. Invertebrate richness and diversity did not differ significantly in the Groundhog River between two consecutive years. In both the fine-scale and the basin-wide studies, the distribution of aquatic invertebrates varied among sites within a river reach, and among reaches within a river. To further examine the biological and physical processes affecting community structure at the fine-scale, consistent sampling protocols should be employed, which may also allow basin-wide trends to emerge. / Thesis / Master of Science (MS)

The Chesapeake Bay is the largest estuary in the United States and is highly productive making it a key habitat for species like striped bass and summer flounder. Striped bass and summer flounder have exhibited changes in abundance over recent years within the Chesapeake Bay. There is a lack of understanding of how environmental factors may be impacting striped bass and summer flounder abundance and how other species may be responding to these environmental drivers. To improve our understanding of striped bass, summer flounder and the aquatic community we set out to identify the environmental drives of their abundance changes from local to global scales. The fish community in the Bay has previously shifted due to environmental perturbations, so we also investigate if the community has changed more recently. We used a hurdle model to standardize interannual abundance of fish species caught in the Chesapeake Bay from two sources of fishery-independent trawl survey data. This standardization process led to relative abundance indices for 58 late juvenile to adult species from 2002-2018, and relative abundance indices for 26 juvenile species from 1995-2019. Species with similar and contrary abundance trends with striped bass and summer flounder were identified through a correlation analysis, and life history traits were assessed between species to determine mechanisms of change. We then used nonmetric multidimensional scaling (nMDS) to see if the community structure had drastically changed, the applied a principal response curve (PRC) to investigate the spatial and functional group change of the community. Among the factors examined, sea surface temperature (SST) in the Bay has increased since 2006 based on change point analysis while the mean Bay SST range and gradient have both decreased. Striped bass have had variable abundance in the Bay but exhibited a positive correlation with increasing SST. Summer flounder have declined in abundance since 2006 in the Bay and exhibited a negative correlation with increasing SST. Striped bass and summer flounder had relationships with global climate oscillations such as the winter North Atlantic Oscillation, Atlantic Multidecadal Oscillation, and the Gulf Stream North Wall oscillation. From a community perspective, our results showed that the late juvenile to adult fish community shifted after 2011, which coincided with the freshwater surge due Hurricane Irene and Tropical Storm Lee. The increase in abundance of striped bass, Bay anchovy, and Atlantic menhaden, and decrease in abundance of summer flounder, weakfish, spot, and Atlantic croaker were the main species that contributed to the difference in community structure after 2011. The change in functional group structure after 2011 was defined by a decline in opportunistic demersal fish, and this change was significantly different in the portion of the Bay north of the Potomac River. We did not identify any significant correlation between functional groups and environmental factors but did discover the important relationship that top predators like striped bass and summer flounder have with their key fish prey species, both in presence and population trends. Long term monitoring and further research in to how the community changed over smaller periods and the distribution changes of species could improve our understanding of what is impacting the Chesapeake Bay community to inform better management strategies. / Master of Science / The Chesapeake Bay is an important habitat for many animals, including fish. Of the fish species that inhabit the Bay, striped bass and summer flounder are two highly sought after commercial and recreational species, and are top predators, which means they are economically and ecologically important. Striped bass and summer flounder have exhibited changes in abundance over recent years within the Chesapeake Bay, and there is a lack of understanding what environmental factors may be driving their abundance trends and if other species are responding similarly. To conserve striped bass and summer flounder, management strategies should consider the relationship these species have with their environment and other species. Through this research, we set out to understand what environmental factors are impacting their population trends, and the trends of the aquatic community which can be used to inform effective management decisions for the future. To accomplish our research goals, we first used a hurdle model to determine the interannual abundance of 58 adult and 26 juvenile fish species from 2002-2018 and 1995-2018 respectively. We then investigated whether any environmental factors exhibited relationships with striped bass and summer flounder. Again, through correlation analysis, we identified species with similar and contrary abundance trends with striped bass and summer flounder and compared the traits of these species to try to identify the mechanisms of their abundance trends. To visualize if and how much the fish community composition had changed over time we used nonmetric multidimensional scaling (nMDS), then applied a principal response curve (PRC) to investigate the spatial change and life history trait change in the fish community. The results showed us that striped bass and summer flounder do exhibit relationships with environmental factors. Sea surface temperature (SST) in the Bay has increased, while the range and gradient has decreased, and an increase in the mean SST occurred in 2006. We found that striped bass had variable abundance in the Bay but correlated positively with increasing SST, however summer flounder abundance has decreased since 2006 in the Bay and has a negative correlation with SST. Striped bass and summer flounder exhibited relationships with global climate-oscillations that impact the Chesapeake Bay, making those factors important to consider for their management. The results of the community assessment showed that the late juvenile to adult fish community shifted after 2011. This change in community structure coincided with a decrease in water quality and a freshwater surge in 2011 that was caused by Hurricane Irene and Tropical Storm Lee. After the community shift, striped bass, Bay anchovy, and Atlantic menhaden increased in abundance, while summer flounder, weakfish, spot and Atlantic croaker decreased in abundance. These species were the top species that contributed to the change in community structure. The change in community structure was greatest, and significant in the northern portion of the Bay. From these results we identified the important relationship between predators and prey both in species presence and abundance trends. Striped bass abundance increased alongside an increase of their key prey species, Bay Anchovy and Atlantic menhaden, while summer flounder abundance decreased along with two of their key prey species spot and Atlantic croaker. This research identified environmental factors that contribute to abundance trends of striped bass and summer flounder and highlighted the importance of multispecies interactions within the aquatic Chesapeake Bay community. Long term monitoring and more research into finer scale spatial and temporal changes of fish in the Bay could further improve management recommendations.