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Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 45
Book Description
Habitat use of a species is a vital component in explaining the dynamics of natural populations. For mobile marine species such as fishes, describing habitat heterogeneity at a seascape scale is essential because it quantifies the spatial extent to which fishes are interacting with their environment. Here, we explored the relationships between habitat metrics and the density and size of coastal rocky reef fishes across a seascape that is naturally fragmented. Multibeam sonar and GIS analysis were employed to create a seascape map that explicitly depicted bathymetry and spatial configuration of rocky reefs in southern California. Georeferenced subtidal transect surveys were conducted across this seascape to describe habitat attributes, including the density of macroalgae, and record the number and size of fishes. To compare the relative influence of habitat metrics, individual variables were grouped into macroalgae, bathymetry, and spatial configuration components, allowing for comparisons of within-patch to surrounding habitat metrics in describing the numerical density, biomass density, average size, and maximum size of five abundant rocky reef fishes. We found that responses to different habitat components were dependent on particular species, the choice of spatial scale, and the inherent characteristics of the seascape itself. Notably, the relative influence of seascape components were dependent on the configuration of the seascape; where fishes in a more isolated and less-connected seascape were more influenced by spatial configuration than a seascape with greater habitat connectedness. This study demonstrates that explicit habitat maps allow for a more comprehensive understanding of population structure when describing fishes across large spatial scales.
Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 45
Book Description
Habitat use of a species is a vital component in explaining the dynamics of natural populations. For mobile marine species such as fishes, describing habitat heterogeneity at a seascape scale is essential because it quantifies the spatial extent to which fishes are interacting with their environment. Here, we explored the relationships between habitat metrics and the density and size of coastal rocky reef fishes across a seascape that is naturally fragmented. Multibeam sonar and GIS analysis were employed to create a seascape map that explicitly depicted bathymetry and spatial configuration of rocky reefs in southern California. Georeferenced subtidal transect surveys were conducted across this seascape to describe habitat attributes, including the density of macroalgae, and record the number and size of fishes. To compare the relative influence of habitat metrics, individual variables were grouped into macroalgae, bathymetry, and spatial configuration components, allowing for comparisons of within-patch to surrounding habitat metrics in describing the numerical density, biomass density, average size, and maximum size of five abundant rocky reef fishes. We found that responses to different habitat components were dependent on particular species, the choice of spatial scale, and the inherent characteristics of the seascape itself. Notably, the relative influence of seascape components were dependent on the configuration of the seascape; where fishes in a more isolated and less-connected seascape were more influenced by spatial configuration than a seascape with greater habitat connectedness. This study demonstrates that explicit habitat maps allow for a more comprehensive understanding of population structure when describing fishes across large spatial scales.
Author: David R. Schiel Publisher: Univ of California Press ISBN: 0520961099 Category : Nature Languages : en Pages : 412
Book Description
The largest seaweed, giant kelp (Macrocystis) is the fastest growing and most prolific of all plants found on earth. Growing from the seafloor and extending along the ocean surface in lush canopies, giant kelp provides an extensive vertical habitat in a largely two-dimensional seascape. It is the foundation for one of the most species-rich, productive, and widely distributed ecological communities in the world. Schiel and Foster’s scholarly review and synthesis take the reader from Darwin’s early observations to contemporary research, providing a historical perspective for the modern understanding of giant kelp evolution, biogeography, biology, and physiology. The authors furnish a comprehensive discussion of kelp species and forest ecology worldwide, with considerations of human uses and abuses, management and conservation, and the current and likely future impacts of global change. This volume promises to be the definitive treatise and reference on giant kelp and its forests for many years, and it will appeal to marine scientists and others who want a better appreciation and understanding of these wondrous forests of the sea.
Author: Samuel Charles Ginther Publisher: ISBN: Category : Languages : en Pages : 85
Book Description
The susceptibility of ecosystems to the introduction of non-native species has increased drastically with the development of advanced transportation technologies. It is now quite common for organisms to be easily transported by humans across physiological, ecological, or behavioral barriers that once served as natural population constraints. Despite this increased rate of introductions to locations that were previously unreachable, most organisms that are introduced perish because they are not able to withstand the new environmental pressures of the introduced location, or there are simply not enough conspecifics to perpetuate the population. However, when introduced organisms are able to thrive and reproduce, they may have devastating economic or ecological consequences. A new opportunity to document and understand the effects of an invasive alga on native community members has presented itself in southern Californian waters. Native to northeastern Asia, Sargassum horneri is a macroalga that was presumably transported in ballast water and discovered in Long Beach Harbor in 2003. By 2006 it had spread to the western side of Santa Catalina Island, California, and within a year spread along the entire leeward coast, forming dense stands in numerous areas. Although not all exotic species are ecologically harmful, S. horneri has attributes (fast growing and occurs in high densities) that may allow it to readily establish and out compete marine flora critical to the community structure of fishes. The purpose of this study aimed to document the effects of S. horneri on kelp forest fishes at Santa Catalina Island, California. I first employed observational, correlative methods to explore the role of S. horneri in shaping biotic and abiotic habitat characteristics of reefs and fish assemblages. I also explored habitat characteristics that predict fish assemblage structure, as well as species-specific responses of fish to habitat predictor variables during 4 distinct time periods. Fish assemblages changed over the course of my 4 sampling periods, and a number of habitat variables (including S. horneri) explained variation in fish assemblage during those times. However, there is more evidence that favors M. pyrifera as a driver of fish assemblage change, as indicated by species-level responses. Additionally, a field experiment testing whether the removal of S. horneri from reef areas affected the fish assemblage was used to evaluate whether patterns documented in the observational portion of my study that could be attributed to S. horneri do in fact appear to be caused by the invasive alga. Removing S. horneri from established areas of reef did not affect multivariate or univariate metrics of fish assemblage over the course of 7 sampling periods. Removal and control (unaltered) areas of reef contained strikingly similar fish assemblages, fish richness, and fish densities over time. Despite a drastic change in reef landscape, it appears that M. pyrifera, rather than S. horneri, was a more significant driver of differences in kelp forest fish assemblages observed in my study. Second, I compared the role of relatively low-lying S. horneri and vertically extensive M. pyrifera in shaping recruitment patterns of a popular sport fish (Paralabrax clathratus) by using an observational and experimental study. I first examined kelp bass recruit abundance on naturally standing S. horneri and M. pyrfera to better understand how fish recruitment rates differ between the introduced and native species. Additionally, I experimentally isolated 3 treatments (M. pyrifera only, S. horneri only, and M. pyrifera and S. horneri together) over a sandy bottom to understand whether the presence of S. horneri, and increased benthic complexity for young fish, enhances kelp bass recruitment. An overwhelming majority of kelp bass recruited to M. pyrifera, and larger recruits were located in the bottom two-thirds of the thalli. Kelp bass recruitment was were observed with S. horneri, regardless of whether the alga was alone or paired with M. pyrifera. Similar to my observational results, larger kelp bass recruits were observed in the bottom third of M. pyrifera treatments. Additionally, I found that the presence of larger, predatory conspecifics explained a spatial pattern of declining recruitment rates across treatment plots. My study presents the first evidence that S. horneri negatively impacts the recruitment of an important southern California reef fish. Results from both of my studies offer contrasting outlooks on S. horneri's role in southern California kelp forests. When focusing on the entire fish assemblage, little evidence is in favor of S. horneri as a driver of kelp forest fish structure. However when focusing on a particular early life history characteristic of a common kelp forest fish, the effects of S. horneri are dramatically negative. The contrasting results of my studies are important reminders for the need of additional studies to generate a more comprehensive understanding of this invasive alga's impact on kelp forest organisms.
Author: Parker H. House Publisher: ISBN: Category : Languages : en Pages : 95
Book Description
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.
Author: Ivan Nagelkerken Publisher: Springer Science & Business Media ISBN: 9048124069 Category : Science Languages : en Pages : 617
Book Description
Mangrove forests, seagrass beds, and coral reefs are circumtropical ecosystems that are highly productive, and provide many important biological functions and economic services. These ecosystems cover large surface areas in the shallow tropical coastal seascape but have suffered from serious human degradation, especially in the last few decades. Part of their diversity, productivity, and functioning seems to be based on their juxtaposition. Especially in the last decade significant advances have been made on new insights into their ecological connectivity. This authoritative book provides a first-time comprehensive review of the major ecological interactions across tropical marine ecosystems that result from the mutual exchange of nutrients, organic matter, fish, and crustaceans. A group of leading authors from around the world reviews the patterns and underlying mechanisms of important biogeochemical and biological linkages among tropical coastal ecosystems in 15 chapters. Included are chapters that review cutting-edge tools to study and quantify these linkages, the importance of such linkages for fisheries, and how tropical ecosystems should be conserved and managed for sustainable use by future generations. The book uses examples from all over the world and provides an up-to-date review of the latest published literature. This book is a ‘must read’ for professionals working on the conservation, management, and ecology of mangrove, seagrass and coral reef ecosystems.
Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 52
Book Description
Seagrasses form important coastal habitats that promote the foraging and survival of mesopredators. Variation in seagrass habitat structure at local and seascape scales mediates foraging success and survival, but the interactive effects of structure at these scales rarely is quantified when evaluating nursery habitat function. For my thesis, I tested how the interactions of multiscale habitat structural variation on juvenile fish body size mediates the value of seagrass habitat through survival and foraging success. In Chapter 1, I tested the hypothesis that in eelgrass (Zostera marina) optimal structural complexity (SC) for juvenile giant kelpfish (Heterostichus rostratus) changes through ontogeny. I found that habitat selection differed with kelpfish size: small and large fish selected high and low SC respectively. Smaller kelpfish experienced lower predation risk and higher foraging in high SC, suggesting high SC is selected by these fish because it minimizes risk and maximizes growth potential. Larger kelpfish experienced lower predation risk and higher foraging in high and low SC respectively, suggesting they select low SC to maximize foraging efficiency. My study highlights that trade-offs between predation risk and foraging can occur within a single habitat type, that studies should consider how habitat value changes through ontogeny, and that seagrass nursery habitat value may be maximal when within-patch variability in SC is high. In Chapter 2, I used a spatially explicit individual-based model to examine how seagrass fragmentation influences foraging and survival of a mesopredator, and how these relationships are influenced by SC, body size, and mesopredator and prey densities. I found that mesopredator survival and foraging dropped beyond threshold levels of habitat area (60 and 30% respectively) and depended on level of SC in the seascape. The relationship between habitat area and foraging did not depend on SC or body size, but did depend on organismal densities: when mesopredators and prey densities increased with decreasing habitat area, foraging was highest in highly fragmented seascapes. My results suggest that small- and large-scale habitat structure jointly dictate the value of a nursery habitat, and the effects of survival and foraging should consider interactions with habitat structure at multiple scales.
Author: Simon J. Pittman Publisher: John Wiley & Sons ISBN: 111908444X Category : Science Languages : en Pages : 653
Book Description
Seascape Ecology provides a comprehensive look at the state-of-the-science in the application of landscape ecology to the seas and provides guidance for future research priorities. The first book devoted exclusively to this rapidly emerging and increasingly important discipline, it is comprised of contributions from researchers at the forefront of seascape ecology working around the world. It presents the principles, concepts, methodology, and techniques informing seascape ecology and reports on the latest developments in the application of the approach to marine ecology and management. A growing number of marine scientists, geographers, and marine managers are asking questions about the marine environment that are best addressed with a landscape ecology perspective. Seascape Ecology represents the first serious effort to fill the gap in the literature on the subject. Key topics and features of interest include: The origins and history of seascape ecology and various approaches to spatial patterning in the sea The links between seascape patterns and ecological processes, with special attention paid to the roles played by seagrasses and salt marshes and animal movements through seascapes Human influences on seascape ecology—includes models for assessing human-seascape interactions A special epilogue in which three eminent scientists who have been instrumental in shaping the course of landscape ecology offer their insights and perspectives Seascape Ecology is a must-read for researchers and professionals in an array of disciplines, including marine biology, environmental science, geosciences, marine and coastal management, and environmental protection. It is also an excellent supplementary text for university courses in those fields.
Author: Harold Mooney Publisher: Univ of California Press ISBN: 0520278801 Category : Nature Languages : en Pages : 1008
Book Description
This long-anticipated reference and sourcebook for CaliforniaÕs remarkable ecological abundance provides an integrated assessment of each major ecosystem typeÑits distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of CaliforniaÕs ecological patterns and the history of the stateÕs various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the stateÕs ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of CaliforniaÕs environment and curious naturalists.
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Author: David R. Schiel
Author: Samuel Charles Ginther
Author: Parker H. House
Author: Ivan Nagelkerken
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Author: Christopher Derek Stallings
Author: Simon J. Pittman
Author: Harold Mooney
Author: Dr. Silvia Opitz