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The Effects Of Land Use And Habitat Quality On Fish And Macroinvertebrate Concordance Ecological Community Thresholds And Trophic Structure
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Book Synopsis The Effects of Land Use and Habitat Quality on Fish and Macroinvertebrate Concordance, Ecological Community Thresholds, and Trophic Structure by : Stephanie L. Johnson
Download or read book The Effects of Land Use and Habitat Quality on Fish and Macroinvertebrate Concordance, Ecological Community Thresholds, and Trophic Structure written by Stephanie L. Johnson and published by . This book was released on 2013 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Habitat Quality, Land Use, & Acidification by :
Download or read book Habitat Quality, Land Use, & Acidification written by and published by . This book was released on 1996 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Habitat Structure and Fish Communities of Warmwater Streams by : James R. Karr
Download or read book Habitat Structure and Fish Communities of Warmwater Streams written by James R. Karr and published by . This book was released on 1983 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Concordance Among Fish and Macroinvertebrates, Environmental Filters, and Restoration in Small Tributaries by : Amelia T. McReynolds
Download or read book Concordance Among Fish and Macroinvertebrates, Environmental Filters, and Restoration in Small Tributaries written by Amelia T. McReynolds and published by . This book was released on 2020 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small tributaries to the Great Lakes are threatened by intensifying land use, barriers to fish movement, and the resulting degradation of water quality and aquatic communities. Recently, restoration efforts have turned to these small but numerous streams as a target which may respond relatively quickly and positively to actions across the watershed. In lower Green Bay, Lake Michigan, small tributaries are scattered across a patchwork of agriculture, developed land, and forest, and have been impacted by landscape-scale stressors. Large-scale collaborative restoration efforts have identified them as a potentially valuable habitat for macroinvertebrates and fish which could play a role in the restoration of the lower Fox River-Green Bay as a system. However, it is unclear how fish and macroinvertebrate communities vary throughout this set of tributaries, and how they are shaped by dynamic environmental conditions. Given this uncertainty, it is difficult to prescribe restoration actions effectively. The first chapter of this thesis will identify environmental variables at several spatial scales that shape fish and macroinvertebrate communities and describe the concordance between these two communities at eighteen stream reaches. Two years of monitoring efforts inform this analysis while revealing strong spatial and temporal variation in stream conditions. Fish and macroinvertebrate communities respond to many of the same environmental variables at multiple spatial scales, exhibiting community concordance which is influenced by connectivity and tributary-specific environmental conditions. In the second chapter, results of this study and prior research in small tributaries to Green Bay will be used with a synthesis of the literature to make restoration recommendations. Many of the same central principles used to guide restoration in dendritic streams may be adapted and applied to small tributaries, given sufficient knowledge of each unique tributary system.
Book Synopsis Assessing Land Use and Habitat Effects on Fish and Macroinvertebrate Assemblages by : Mary Lammert
Download or read book Assessing Land Use and Habitat Effects on Fish and Macroinvertebrate Assemblages written by Mary Lammert and published by . This book was released on 1995 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fish Community Responses to the Land Use Change and Environmental Variability in Estuaries by : Andrew Tim Man Chin
Download or read book Fish Community Responses to the Land Use Change and Environmental Variability in Estuaries written by Andrew Tim Man Chin and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding how species communities respond to land use and environmental change over space and time is necessary given the rapidly changing environment that threaten species persistence. In intrinsically dynamic environments such as estuaries, the spatial and temporal environmental variability at the interface of freshwater and marine ecosystems result in species that persist with morphological or physiological adaptations to these changing environmental conditions. Yet, estuarine fish communities are facing further change as a result of the loss of functional connectivity through stream fragmentation due to culverts that impede fish passage upstream, and land use change as well as climate change among estuaries that reduce habitat quality. It is unknown how the extent of environmental change due to land use and climate change in estuaries and their associated watersheds affect estuarine fish communities in addition to natural variability. In this thesis, I determine how fish communities in estuaries respond to land use impact and environmental variability at the stream and watershed levels. The functional connectivity of species is impacted by stream fragmentation due to culverts upstream of New Brunswick estuaries and their watersheds. I show that the potential functional connectivity of species varies according to migratory traits and the ontogeny of species. In the Miramichi watershed, I assess how forest harvesting and weather fluctuations affect the density of juvenile Atlantic salmon (Salmo salar) at the watershed level. I demonstrate that accounting for the upstream forest harvesting have cumulative impacts on juvenile Atlantic salmon through each catchment downstream and over time. Within and among the estuaries, I find evidence that fish communities shift according to environmental change. My findings relating to the effects of land use and environmental variability from streams to the watersheds would result in a better predictive capacity of how estuarine fish communities will potentially change or persist.
Book Synopsis An Examination of the Effects of Land Use and Land Cover on Macroinvertebrate Communities at Two Landscape Scales by : Tanya Sulikowski
Download or read book An Examination of the Effects of Land Use and Land Cover on Macroinvertebrate Communities at Two Landscape Scales written by Tanya Sulikowski and published by . This book was released on 2013 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Impacts of Land Use on the Habitat and Macroinvertebrate Assemblage of the Tributaries of the Lower Brazos River by : Frances Patricia Lash
Download or read book Impacts of Land Use on the Habitat and Macroinvertebrate Assemblage of the Tributaries of the Lower Brazos River written by Frances Patricia Lash and published by . This book was released on 2011 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ecological research on stream and river ecosystems aims to gain an understanding of the dynamic and complex impacts of environmental factors on biotic communities within riverine landscape (riverscape). Human activities significantly impact both terrestrial and aquatic ecosystems. Local environmental factors are known to influence the structure and function of stream ecosystems and biodiversity. The patterns of benthic macroinvertebrate distribution are related to the natural and human influenced variation of environmental factors. Ecologists assess stream physical and biological conditions in response to human land use activities using ecological indicators. This study is an assessment of the ecological condition of the Lower Brazos River Watershed. Macroinvertebrate assemblage structure was compared from 33 sites within the 6 subbasins differing in land use type and degree. Land use within the subbasins was measured using data from the National Land Use Database. Benthic macroinvertebrate samples were collected and a variety of physiochemical variables were measured. Multivariate analysis grouped the subbasins using habitat variables and macroinvertebrate assemblages. Decreasing habitat heterogeneity resulted in a decline of diversity and richness of organisms. Differences in the richness and diversity of the macroinvertebrate assemblages are attributed to habitat structure and land use. This study highlights the importance of considering both local habitat and landscape parameters of watersheds in stream biological assessments to understand the response of benthic communities to disturbances.
Book Synopsis Impact of Land Use Practices on Fisheries Ecology on Two Rivers in North Central Texas by : Farron F. Fiedler (Jr.)
Download or read book Impact of Land Use Practices on Fisheries Ecology on Two Rivers in North Central Texas written by Farron F. Fiedler (Jr.) and published by . This book was released on 2019 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Land use, habitat quality index (HQI), fish index of biotic integrity (IBI), and water quality measures were made at four equidistant sites along each of two rivers in North Central Texas. The major land use and chemistry differences in the North Bosque River (NBR) and Paluxy River (PR) were concentrated animal feeding operations (CAFO) and permitted cows, orthophosphate (OP) levels, and algal growth. The NBR has numerous CAFOs and two wastewater treatment plants (WWTPs), mainly concentrated within the upper reach of the river. The PR has only four CAFOs and no WWTP, within the study area. Despite the environmental impacts to the NBR, habitat quality indices on both rivers were similar except for algal abundance. Fish IBI measures indicated presence of intolerant fish species and benthic invertivores (darters) at all sites on the PR, while no intolerant species or benthic invertivores (darters) were found at any NBR sites. The percentage of piscivore fish was greater in the PR than in the NBR. However, the percentage of total fish that were piscivores in the NBR increased with the distance from the area of concentrated nonpoint source pollution. The PR had greater biodiversity and more natural OP levels when compared to the NBR. The PR lowest reach had only 0.0011 mg/L OP compared to 0.2607 mg/L OP in the NBR upper most reach. Fish species located in PR but, are absent from NBR are sensitive to dissolved oxygen and nutrient levels. Environmental factors which may have caused the sensitive species to be extirpated from NBR are assumed to be due to land use differences.
Book Synopsis The Influence of Land Use and Mediterranean Seasonality on California Stream Fishes by : Kristina Yoshida
Download or read book The Influence of Land Use and Mediterranean Seasonality on California Stream Fishes written by Kristina Yoshida and published by . This book was released on 2015 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Freshwaters ecosystems support extraordinary biodiversity relative to their extent and provide important societal benefits. As such, freshwater environments and biota are often heavily impacted by anthropogenic activities. Freshwater fishes in Mediterranean-climate regions are especially impacted because of large human populations in these regions and extensive agricultural production, extensive river modification for flood control and to meet societal demands, and because these systems are heavily invaded by non-native organisms. The distribution and ecology of freshwater fishes in Mediterranean-climate regions are also influenced by the distinct wet and dry periods and the high inter-annual variability in precipitation. Thus, efforts to manage and conserve native fishes in Mediterranean-climate regions require understanding both the effects of human disturbance and the strong seasonality that characterizes these regions. In this dissertation, I examine the relationship between land use and Mediterranean seasonality on freshwater fishes in streams within the greater San Francisco Bay region in California, USA. In my second chapter, I use a multivariate approach to explore variability among fish communities in 25 Bay Area watersheds. I found that a combination of local (water conductivity) and watershed-scale factors (percent forested watershed, watershed area, elevation) were important predictors of fish communities across sites. Furthermore, watershed-scale factors had indirect effects on fish communities through their influence on a local-scale factor, water conductivity. The results of this chapter highlight the importance of considering both the direct and indirect effects of watershed-scale factors on freshwater fish communities. In my third chapter, I continued my analysis of land use and fish communities with a focus on contemporary land change. For this chapter, I performed a resurvey study, surveying the habitat and fish communities in 32 sites in the Alameda Creek Watershed that had been surveyed by Dr. Robert Leidy in the mid-1990s, including sites in the rapidly urbanizing Livermore Valley region. Again using a multivariate approach, I found that the increase in urbanization across an approximately 16-year period was related to change in fish community composition, a decline in native species richness, and a decline in a common native cyprinid - changes that were not observed in another part of the watershed that has experienced little land use change in the last 16 years. The relationship between land use change and fish community change was strongest when considering land use change at a local scale. These results suggest that ongoing land change alters fish communities and that contemporary resurveys are an important tool for examining how freshwater taxa respond to recent and ongoing environmental change. In my final chapter, I assessed how seasonal drought, a characteristic feature of Mediterranean-climate systems, influenced food webs in a small intermittent stream in Marin County, CA that provides rearing habitat for threatened steelhead trout (Oncorhynchus mykiss). I used stable isotopes of carbon and nitrogen to characterize food web structure and the trophic position of a suite of predators in this system, including O. mykiss and several macroinvertebrate predators. I compared food web snapshots across time, as well as between permanent and temporary pools. I found that the intermittent stream food web remained relatively stable across time and did not differ between pool types. However, I also found significant changes in the trophic position, niche width, and mean [delta]13C values for aquatic predators. This study provides an important first look at the trophic ecology of an imperiled fish species in intermittent streams during the summer drought season, and emphasizes that food chain length increases across the drought season, possibly because invertebrate prey are concentrated with declining water levels. In conclusion, my research shows that anthropogenic factors at the watershed scale influence instream conditions and freshwater fish communities, and emphasizes that contemporary changes in land use can have subtle changes on fish community structure, which may be indicative of future declines of extirpations of native fishes. Finally, my research shows that changing conditions across the summer drought season lead to shifts in the trophic ecology of some, but not all, aquatic predators, including threatened steelhead trout. Overall my research contributes to a growing body of research that demonstrates how multi-scale natural and anthropogenic factors influence freshwater fishes in Mediterranean-climate region.
Book Synopsis The Influence of Urbanization on Streams by : Gregory J. Knothe
Download or read book The Influence of Urbanization on Streams written by Gregory J. Knothe and published by . This book was released on 2012 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Streams throughout the U.S. have been historically subjected to degradation due to urbanization, agriculture and industry. The influence of urbanization on stream ecosystems is difficult to evaluate, due to many interacting variables. Previous studies have found that the degree of urbanization influences flow regime, pollutant loading and resulting fish community structure. Our study investigated the influence of urbanization on hydrology, physical habitat, water quality, and resulting fish community structure at 8 coastal streams located in Southeastern Texas. Streamflow, physical habitat, water quality and fish community data were collected at these sites during 2011. The stream sites were selected to represent a variety of land uses ranging from highly urbanized, to minimally urbanized or reference conditions. In order to determine the degree of urbanization within each watershed ArcGIS software was used to assess land use. Total impervious area (TIA) and percent impervious area (PIA) was used for each watershed as a simple index of urbanization. TIA and PIA were estimated using 2006 impervious surface data obtained from the United States Geological Survey. Various fish community metrics including the Index of Biological Integrity (IBI), Shannon-Weiner diversity index, Pielou's evenness and species richness, were used to evaluate the impact of urbanization on fish community structure. Estimated land use data was compared to IBI scores, fish community metrics, water quality, and physical habitat. Several statistical analysis methods including Pearson correlation analysis, Analysis of Variance (ANOVA), principle component analysis and cluster analysis were used to evaluate the response of fish communities to land use and associated hydrology, physical habitat, and water quality. We found that IBI scores and stream fish diversity were negatively correlated with PIA. We also observed positive correlations between PIA/TIA and orthophosphate and combined nitrate and nitrite concentrations among the sites. We did not observe any strong correlations between the amount of impervious area within the upstream watershed and physical habitat metrics, with the exception of a negative correlation between TIA with mean instream cover, riparian width and tree canopy cover. Our study suggests that future management plans could include a threshold of impervious area for a watershed, in order to protect or promote biological integrity and water quality.
Book Synopsis Effects of Spatial and Temporal Heterogeneity on Fish Use and Trophic Structure in a Restored Tidal Marsh by : Daniel J. Larkin
Download or read book Effects of Spatial and Temporal Heterogeneity on Fish Use and Trophic Structure in a Restored Tidal Marsh written by Daniel J. Larkin and published by . This book was released on 2006 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Spatial Habitat Variation in a Great Plains River by :
Download or read book Spatial Habitat Variation in a Great Plains River written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigated spatial variation in fish assemblage and food web structure in the Kansas River, USA in relation to habitat changes. Fishes were collected at ten sites throughout the Kansas River for assessing assemblage structure in summer 2007 using fish community metrics and at 3 sites in 2006 for food web structure using stable isotope analysis. Satellite imagery indicated riparian habitat on the Kansas River was dominated by agriculture in the upper reaches (>35%) and tended to increase in urban land use in the lower reaches (>58%). Instream habitat complexity also decreased with increased urban area (25%) becoming more channelized. Jaccard's similarity and percent similarity indices suggested that large-bodied fishes show changes in species presence and composition longitudinally within the river. Also, reaches directly above Bowersock Dam in Lawrence, Kansas and below the Johnson County Weir, near Kansas City, Kansas had low percent similarity compared to other reaches, suggesting the dam and the weir affect community composition. Canonical correspondence analysis indicated that species that prefer high velocity flows and sandy substrate (blue sucker and shovelnose sturgeon) are associated with the upper river reaches. Also, there was a higher abundance of omnivorous and planktivorous fish species in the lower more channelized river. The lower reaches contain more tolerant, macrohabitat generalist species and the upper river contained more intolerant, fluvial specialist species. Fish, macroinvertebrates, and detritus were collected at three river reaches classified as the heterogeneous instream habitat (40% grass islands and sand bars) intermediate (22% grass islands and sand bars), and homogeneous (6% grass islands and sand bars) instream habitat reaches in June 2006. Riparian land use (proportion as agricultural and urban) was related to instream habitat with homogeneous areas having more urban riparian area compared to the heterogeneous and intermediate reaches. The heterogeneous habitat reach had higher variability in [Delta][superscript]13C for fish classified as piscivores/invertivores (P=0.029) and macroinvertebrates (P=0.004) suggesting the complex habitat in the heterogeneous habitat reach provided more variable food sources. The [Delta}15N values also indicated that ten of the twelve fish species tended to consume prey at higher trophic levels in the heterogeneous habitat reach suggesting a more complex food web. Land use practices are leading to homogenization of instream habitat and this homogenization of habitats may be related to food web diversity and trophic position of fishes. Conserving intolerant, native species in the Kansas River may require maintaining suitable habitat for these species and restoration of impacted areas of the river.
Book Synopsis Determinants of Trophic Structure in Ecological Communities by : Shaun Turney
Download or read book Determinants of Trophic Structure in Ecological Communities written by Shaun Turney and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Ecological communities are complex, and this complexity can obscure their underlying patterns and natural laws. One way to understand communities is to summarize their most important characteristics using consistent measures. Community structure is a set of measures of composition, abundance, distribution, and interaction that describe an ecological community over space and time. Trophic structure is an important aspect of community structure, and relates to energy and nutrient flow, especially the distribution of organisms across trophic levels. Trophic level is the energetic distance of an organism from the base of production - its average position in the food chains to which it belongs. Due to energetic inefficiencies, we generally predict that organisms decrease in number and biomass with trophic level, forming trophic pyramids (known as "pyramids of numbers" and "pyramids of biomass", respectively). Other, non-pyramidal trophic structures are also common, and trophic structure is affected by variables at multiple ecological scales. The objective of this thesis is to investigate determinants of trophic and community structure, including latitude, ecosystem type, biome transition, community composition, and body size. While pyramids of numbers and pyramids of biomass are well-studied, few have investigated the trophic distribution of diversity. Using a meta-analysis approach, I found that, on average, large published food webs form pyramids of species richness, with a decrease in number of species as trophic level increased. Trophic diversity structure was correlated to centrality, latitude, ecosystem type, and study identity.Community structure varies spatially, as can be seen even by a casual observer at interfaces between biomes. I studied how macroinvertebrate and soil prokaryote communities changed latitudinally along the forest-tundra biome transition in the Yukon, and how the communities responded to other environmental variables. I found that the communities differed between sites, changed along the latitudinal transect, and responded to environmental variables at multiple scales, including active layer depth, lichen cover, and road proximity. Loss of predators can have profound effects on community structure. I used an experimental approach to investigate the effect of spider assemblage composition and diversity on prey consumption. I hypothesized that diverse assemblages would consume more prey due to niche complementarity and sampling effects. I found, however, that the spiders were generalist and intraguild predators, and that the one-species assemblage consumed the most prey. Spider body size affects its trophic niche, energy requirements, and interspecific interactions, and as a result, body size mediates the relationship between spider assemblage composition and prey consumption. The body size of an organism affects how it interacts with other organisms and its biological rates. I used a meta-analytic approach to test several prediction regarding the relationship between body mass and trophic properties of terrestrial vertebrate predators: Accipitridae (hawks, eagles, and their relatives), Felidae (cats), and Serpentes (snakes). I found that the predators chose prey smaller than themselves, within a predictable mass range. Prey taxonomic diversity increased with Serpentes mass. Counter to theory, Felidae trophic level decreased with body mass, and Felidae and Accipitridae predator-prey body mass ratio increased with trophic level. We currently live in the Anthropocene, an epoch characterized by anthropogenic geological, atmospheric, and biological change. These changes are affecting community structure, which in turn is affecting human access to the benefits provided by nature. Therefore, it is important that we continue to study community structure and the variables that affect it, so that we can predict and respond to ecological change in the Anthropocene. " --
Book Synopsis Baseline Assessment of Fish Communities, Benthic Macroinvertebrate Communities, and Stream Habitat and Land Use, Big Thicket National Preserve, Texas, 1999-2001 by : James Bruce Moring
Download or read book Baseline Assessment of Fish Communities, Benthic Macroinvertebrate Communities, and Stream Habitat and Land Use, Big Thicket National Preserve, Texas, 1999-2001 written by James Bruce Moring and published by . This book was released on 2003 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Impacts of Land Use Disturbance on Fish and Aquatic Macroinvertebrate Assemblages in the Nolichucky River Watershed by : Hayley Sonia Gotwald
Download or read book Impacts of Land Use Disturbance on Fish and Aquatic Macroinvertebrate Assemblages in the Nolichucky River Watershed written by Hayley Sonia Gotwald and published by . This book was released on 2016 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Southern Appalachian watersheds of the United States are negatively affected by pesticides and fertilizers used in row crop agriculture. The objective was to determine if the amount of row crops is connected to changes in aquatic biotic assemblages draining the Nolichucky River watershed in east Tennessee. The hypothesis was the amount of row crops will negatively correlate with indices of biotic integrity (IBI) metrics for fish and benthic macroinvertebrates indicating healthy aquatic communities. For 18 sample sites in 2014 and 2015, IBI metrics were calculated. Water quality and elevation measurements were made before conducting IBIs. To assess changes in and amounts of land use/land cover (LULC), maps from 1999 to 2014 were produced with Landsat satellite imagery. Pollutant estimates (sediment, phosphorus, and nitrogen) were calculated using the Soil & Water Assessment Tool (SWAT) model. The area of row crops increased since 1999 (39 km2 in 1999 to 71 km2 in 2014). A principal component analysis was performed on LULC measurements from different scales (local, reach and catchment), water quality data, and elevation to produce a reduced set of explanatory variables that were uncorrelated but could be associated with IBI metrics. A canonical correspondence analysis associated fish metrics with LULC types: Impervious surfaces, non-row crop fields, and forest (p = 0.04 for axis 1 eigenvalue, p = 0.05 for species-environment correlations). For the benthic macroinvertebrate metrics, nonmetric multidimensional scaling found metrics indicative of poor stream health (percentage of oligochaetes and chironomids, percentage of nutrient tolerant organisms) were strongly positively associated with increasing use of row crops, impervious surfaces (p ≤ 0.01), and pollutant estimates (p ≤ 0.004). A redundancy analysis found increasing pollutant estimates were associated with fish metrics indicative of poor stream health (percentages of hybrids, piscivores, diseased fish, and number of sunfish species) (p = 0.03). When watersheds of tributary streams are converted to impervious and non-row crop field LULC, they function biologically like the larger main stem river. Although fish and benthic macroinvertebrate metrics indicated the tributary and main stem Nolichucky sites were in relatively good condition, increases in land conversion can further degrade stream biotic integrity.
Book Synopsis Direct and Indirect Impacts of Fishing on the Trophic Structure of Kelp Forest Fishes Off Southern California by : Parker H. House
Download or read book Direct and Indirect Impacts of Fishing on the Trophic Structure of Kelp Forest Fishes Off Southern California written by Parker H. House and published by . This book was released on 2015 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: In many marine ecosystems worldwide, overfishing is a prominent cause in removing large predatory fishes from ecological communities. Fluctuation in the abundance of higher trophic level species can transform an ecosystem's structure and function by altering trophic interactions through density-mediated top-down control. Accordingly, understanding the extent to which humans indirectly influence a community through altering predator abundance is of critical importance. Thus, during the summer of 2013 and 2014 the impacts of fishing on the trophic structure and community assemblage of kelp forest fishes were examined within the Southern California Bight. In 2013, I tested whether decreased abundance through fishing for higher trophic level predators relieves predation pressure on lower trophic level prey. Using a combination of underwater survey techniques, density (no. fish/100 m2) and biomass (g/100 m2) of conspicuous fish species were sampled inside and outside of three long-standing Marine Protected Areas (MPAs) off La Jolla, Santa Catalina Island, and Anacapa Island, California. I found that secondary carnivore and herbivore/omnivore trophic levels significantly decreased outside of MPAs. Inversely, the primary carnivore trophic level biomass increased outside of MPAs. Species-level results revealed a lower abundance outside MPAs of large kelp bass (> 25 cm) and higher densities of its prey, kelp perch. My results show overall fish trophic level changes due to fishing pressure, and provide support for a weakening of top-down control on the kelp perch population through the removal of predatory fishes outside MPAs. To investigate the possible return of the historically overfished apex predator of the kelp forest fish community, I censused the giant sea bass (Stereolepis gigas) population at eight sites off Santa Catalina Island from mid-June through mid-August, 2014. Three possible spawning aggregations were identified at the sites Twin/Goat, The V's, and Little Harbor. The giant sea bass population at these sites primarily consisted of individuals 1.2 - 1.3 m long (total length, TL) with small and probably newly mature fish (estimated to be 10 - 11 years old) observed in aggregations. However, larger individuals 1.8 - 1.9 m TL accounted for the majority of the population biomass. Overall, mean spawning stock biomass of giant sea bass was 36.3 kg/1000 m2. Providing a general comparison of mean biomass among the trophic levels of kelp forest fishes off Santa Catalina Island revealed a nearly top-heavy biomass pyramid. The relatively high abundance of giant sea bass provides evidence that this species is recovering at kelp forests off Santa Catalina Island, and possibly throughout the Southern California Bight. The removal or recovery of predators can greatly influence an ecosystem. As more recent studies suggest that indirect community effects of fishing and protection can take up to decades to detect, it is necessary to document the continued changes on the structure, function, and dynamics of the kelp forests and rocky reefs off southern California.
