Structural Complexity, Seascape Patchiness, and Body Size Interactively Mediate Seagrass Habitat Value for a Fish Mesopredator PDF Download
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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: 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: Publisher: ISBN: Category : Languages : en Pages : 35
Book Description
Habitat structure is a chief determinant of the distribution of organisms in many systems, but is not often known whether organism-habitat associations are driven primarily by interactions with other species (e.g., higher predator-induced mortality rates in poor quality habitat) or by active habitat selection. Moreover, active habitat selection may be modified by factors such as perceived predation risk or food availability. In seagrass habitat, positive associations between faunal abundance and habitat structure are common and may be due both to high survival in structurally complex microhabitats or to active selection. We tested whether two species that are abundant in eelgrass (Zostera marina) habitat, the epifaunal grass shrimp Hippolyte californiensis and the mesopredatory juvenile giant kelpfish Heterostichus rostratus select habitat based on structural complexity, and if patch selectivity is modified by predation risk and food levels. Experiments to determine habitat preferences consisted of comparing the distribution of grass shrimp and kelpfish within mesocosms in which they had a choice of high or low complexity eelgrass vs. mesocosms in which they had no choice, as well as a field experiment testing how the propensity of grass shrimp to remain within eelgrass patches varied with structural complexity and predator presence. Generally, grass shrimp and kelpfish preferred high complexity seagrass over low complexity seagrass, but trends differed between species and between experiments with and without predators. Grass shrimp exhibited relatively modest preference for high complexity habitat in mesocosms as well a tendency to change preference to low complexity seagrass when a predatory threat was present in high complexity seagrass. In contrast, in naturally occurring seagrass beds shrimp exhibited a clear preference for high complexity seagrass during the day, but not at night when they may move among patches. Juvenile giant kelpfish exhibited a strong preference for high complexity seagrass even when a predatory threat was present in high complexity seagrass and food was made available in low complexity seagrass, though kelpfish displayed antipredator behaviors only when predators were present. Our research highlights the importance of considering the covariation of several factors when trying to predict habitat selection and species distributions in seagrass beds.
Author: Stacy Nicole Trackenberg Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Biogenic coastal habitats such as salt marshes, seagrasses, and oyster reefs, support diverse faunal communities and can serve as nursery areas by enhancing the abundance, growth, and survival of juvenile fish and crustaceans. The structure and complexity of these biogenic habitats can strongly influence the composition of marine faunal communities and contribute to their roles as nursery areas. It is imperative to understand how nursery areas are defined in the ecological literature as these definitions are applied to nursery area management across the United States. Further, the relative importance of how habitat structural attributes, which are influenced by abiotic and biotic factors, shape faunal communities within these nursery areas is critical to understand these important coastal ecosystems. My dissertation focuses on (1) how nursery frameworks in the ecological literature have evolved and how these frameworks are applied to state management of nursery areas; (2) how abiotic and biotic factors influence the restoration success and complexity of seagrass meadows; and (3) how, in turn, this habitat complexity influences faunal community composition and structure. For my first chapter, I found six overarching frameworks to define and delineate nursery areas in the ecological literature: measures of juvenile abundance and vital rates, habitat characteristics, seascape connectivity, populations fitness and contribution to adult biomass, and persistence. Of the 23 coastal states, only seven explicitly protect nursery areas and of these seven states, the aforementioned frameworks are not equally applied. Gathering and analyzing data necessary to integrate higher-order metrics (e.g., connectivity and biomass contribution) to designate nurseries will require significant research investment and greater collaboration between ecologists and fisheries scientists. My second chapter combines two years of observational seagrass and faunal surveys with a habitat preference experiment to investigate to which degree multiple seagrass complexity metrics influence the composition and abundance of faunal communities in North Carolina seagrass beds. Trawl surveys revealed that taller canopied seagrass beds support higher faunal abundances and species richness than shorter canopied beds, however this was not true across all species. There were species-specific relationships between complexity metrics and abundances, with these relationships shifting between the two years of our study, potentially due to the range of sampling months each year. Pinfish (Lagodon rhomboides), the most common fish found in North Carolina seagrass meadows demonstrated a preference for deep seagrass beds, but only preferred taller canopies when these areas also offered increased blade surface area. In Chapter 3, I conducted field surveys of natural seagrass beds to understand the spatio-temporal distribution and morphology of seagrasses in North Carolina coastal sounds and used these observations to inform a field transplantation experiment of the subtropical seagrass species, Halodule wrightii. Seagrass morphology differed across sampling months but only canopy height differed across depth. Depth was also influential in transplantation success with higher survival of intertidal seagrass transplants compared to subtidal. Considerations of both structural complexity and physical setting of the habitat are therefore imperative for a comprehensive approach in understanding how habitats as well as their faunal communities are responding to future changes across ecosystem settings.
Author: Johan Albin Gustafson Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 316
Book Description
Abstract : One central challenge in the study of seagrass meadows is explaining the abundance and diversity of nekton associated with these productive habitats. While many models have been proposed to explain fish use of seagrass habitats, mainly focusing on their nursery and predator-avoidance values based on the complex habitat structure, most empirical studies were conducted on relatively large patches using catch data collected from invasive capture methods. Seagrass meadows on peri-urban coasts, however, continually being threatened and fragmented, while invasive surveying techniques could bias fish abundance data. This thesis aims to determine if small remnant Zostera capricorni patches in a peri-urban estuary provide small mobile fish with a flow-refuge within a strong tidal flow environment, using non-invasive video surveying techniques to monitor fish abundance and behaviour. The hydrodynamic characteristics of three small patches of Z. capricorni were measured using in situ deployment of Acoustic Doppler Current Profilers (ADCP) at the front and rear of the patches during tidal current flow between 20 and 30 cm/s. Seagrass canopies of densities and morphologies covered by these patches significantly baffled the free-stream flow (X), creating a near-zero, turbulent free, within-canopy hydraulic environment 0.25m from the canopy{u2019}s leading edge. Flows were deflected over the canopy surface causing the leaves to bend, compressing the canopy and thereby reducing the vertical flux under high flows. While lower flows were still significantly reduced, a small vertical flux occurred, with large turbulent eddies generating from the canopy friction. The hydraulic environment behind the patch was significantly different to that at the patch{u2019}s front {u2013} characterised by near zero flows and turbulent fluctuations (at 0m), and flow velocities increasing with downstream distance. This effect was noticeable due to the velocity above the canopy being significantly reduced from flows above the canopy (fast). This difference diminished with downstream distance, gradually resembling the front profile. The rear environment close to the patch edge matched those of other flow-refuges.
Author: Jeffrey C. Carrier Publisher: CRC Press ISBN: 1420080482 Category : Nature Languages : en Pages : 748
Book Description
Since the award-winning first volume, The Biology of Sharks and Their Relatives, published in 2004, the field has witnessed tremendous developments in research, rapid advances in technology, and the emergence of new investigators beginning to explore issues of biodiversity, distribution, physiology, and ecology in ways that eluded more traditional
Author: L. Hansson Publisher: Springer Science & Business Media ISBN: 9401107173 Category : Science Languages : en Pages : 364
Book Description
This series presents studies that have used the paradigm of landscape ecology. Other approaches, both to landscape and landscape ecology are common, but in the last decade landscape ecology has become distinct from its predecessors and its contemporaries. Landscape ecology addresses the relationships among spatial patterns, temporal patterns and ecological processes. The effect of spatial configurations on ecological processes is fundamental. When human activity is an important variable affecting those relationships, landscape ecology includes it. Spatial and temporal scales are as large as needed for comprehension of system processes and the mosaic included may be very heterogeneous. Intellec tual utility and applicability of results are valued equally. The Inter national Association for Landscape Ecology sponsors this series of studies in order to introduce and disseminate some of the new knowledge that is being produced by this exciting new environmental science. Gray Merriam Ottawa, Canada Foreword This is a book about real nature, or as close to real as we know - a nature of heterogeneous landscapes, wild and humanized, fine-grained and coarse-grained, wet and dry, hilly and flat, temperate and not so temper ate. Real nature is never uniform. At whatever spatial scale we examine nature, we encounter patchiness. If we were to look down from high above at a landscape of millions of hectares, using a zoom lens to move in and out from broad overview to detailed inspection of a square meter we would see that patterns visible at different scales overlay one another.
Author: Ilkka Hanski Publisher: Morgan Kaufmann ISBN: Category : Science Languages : en Pages : 536
Book Description
This volume presents a review of metapopulation biology. It describes key theories of study and applies the best field studies to the conservation of species in fragmented landscapes. The work explains and critically assess the value of the metapopulation concept for field studies and conservation.
Author: Peter Frank Scogings Publisher: John Wiley & Sons ISBN: 1119081106 Category : Science Languages : en Pages : 794
Book Description
Insights on current research and recent developments in understanding global savanna systems Increasingly recognized as synonymous with tropical grassy biomes, savannas are found in tropical and sub-tropical climates as well as warm, temperate regions of North America. Savanna Woody Plants and Large Herbivores examines the interactions between woody plants and browsing mammals in global savannas—focusing primarily on the C4 grassy ecosystems with woody components that constitute the majority of global savannas—and discusses contemporary savanna management models and applications. This much-needed addition to current research examines topics including the varying behavior of browsing mammals, the response to browsing by woody species, and the factors that inhibit forage intake. Contributions from an international team of active researchers and experts compare and contrast different savanna ecosystems, offering a global perspective on savanna functioning, the roles of soil and climate in resource availability and organism interaction, and the possible impacts of climate change across global savannas. Fills a gap in literature on savanna management issues, including biodiversity conservation and animal production Applies concepts developed in other biomes to future savanna research Complements contemporary books on savanna or large herbivore ecology Focuses on the woody component of savanna ecosystems and large herbivore interactions in savannas Compares tree-mammal systems of savannas and other eco-systems of temperate and boreal regions Provides numerous case studies of plant-mammal interactions from various savanna ecosystems Savanna Woody Plants and Large Herbivores is a valuable addition to those in fields such as ecology, wildlife and conservation biology, natural resource management, and environmental science.
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Author: Stacy Nicole Trackenberg
Author: Johan Albin Gustafson
Author: Jeffrey C. Carrier
Author: Society for Ecological Restoration International
Author: L. Hansson
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Author: Ilkka Hanski
Author: Peter Frank Scogings