Effects of Eelgrass (Zostera Marina) Habitat Loss on Epifaunal Abundance and Diversity PDF Download

Author: Brendan J. Reed
Publisher:
ISBN:
Category :
Languages : en
Pages : 78

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Author:
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 30

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Exposure of contaminants in coastal areas has been on the rise with increasing urbanization of natural environments. These contaminants are known to effect organisms in multiple ways, such as directly increasing mortality, or indirectly altering many of their behaviors, such as sensing predators and foraging. Since seagrass habitats are heavily influenced by anthropogenic factors, organisms found in these ecosystems often experience constant exposure to non-degradable contaminants such as heavy metals. Eelgrass (Zostera marina) persistence is promoted by mesograzers (small crustaceans and gastropods) that control competing epiphytic algae growing on seagrass blades. Along with nutrient levels, this top-down control of a dominant competitor (algae) plays a substantial role in dictating eelgrass health, particularly at high levels of eelgrass structural complexity. However, mesograzers can be negatively affected by contaminants at high levels. I conducted a manipulative field experiment on epifaunal colonization of eelgrass in San Diego Bay, and a companion lab experiment on epifaunal grazing, to determine how epiphytic algae, the mesograzer community, and rates of herbivory are interactively affected by dissolved copper and habitat structural complexity. In the field, copper spiked plaster blocks and artificial seagrass units were used to create realistic pulse events of contamination for two levels of habitat structural complexity. I found that the abundance of epiphytic algae decreased with increasing copper, but that copper had no effect on epifaunal abundance or diversity, which responded strongly only to habitat structural complexity. In the lab experiment, I found complex interactive effects of copper concentration and habitat complexity on grass shrimp grazing rates. Low elevated levels of copper resulted in higher grazing in low complexity vs. high complexity eelgrass, in contrast to trends in ambient and high levels of copper as well as in previous experiments. In both low and high structural complexity eelgrass, grass shrimp grazing impact was highest when copper was elevated compared to ambient levels. In order to set effective regulations, understanding both the direct and indirect interactions between organisms and their environment is key in conserving and managing eelgrass habitat.

Author: Danielle Healey
Publisher:
ISBN:
Category :
Languages : en
Pages : 116

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Author: Grace Ha
Publisher:
ISBN: 9781658412452
Category :
Languages : en
Pages :

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Seagrass - marine flowering plants that create underwater meadows through-out temperate and tropical coastal waters - are important foundation species, acting as key nursery grounds for many commercial and recreational fisheries, performing ecosystem functions including flow modification and sediment stabilization, and providing habitat to diverse and productive communities of marine life. Given the decline of seagrass globally, there is particular need for documenting and understanding the dynamics of seagrass ecosystems. Focusing on the eelgrass (Zostera marina L.) beds of Bodega Harbor, California, USA, I approached this task through methods that incorporated natural history, field research, statistical analysis, and taxonomy. In Chapter 1, I conducted a 16-month survey of eelgrass and its epifauna and analyzed species abundances in the context of the extreme warm-water event known as "The Blob" that occurred along the Californian coastline in 2014. My research found a diverse invertebrate assemblage comprising mostly native detritivore-grazers, which contrasted sharply with nearby San Francisco Bay, which has been dominated by invasive species. Invertebrate population dynamics correlated closely to that of the eelgrass they inhabited, and in general, both habitat and epifauna declines coincided with increasing seawater temperatures. In Chapter 2, I used eelgrass as a model system to test the role of camouflage in predator-prey interactions. I conducted field experiments, testing whether prey survival was affected by color-matching between prey and habitat, using the green amphipod, Ampithoe lacertosa and artificial habitats made of eelgrass, and clear, red, and green plastic ribbon. With seine nets and underwater video recordings, I also collected data on fish predator abundance and diversity. Although generalized linear regressions in-dicated habitat color significantly affected prey survival, greater color-matching did not predict greater prey survival. Further analysis using structural equation modeling indicated that the effect of habitat on prey survival was significantly mediated by fish density and, to a lesser degree, fish diversity. Even after taking these effects into account, I did not find survival to clearly correspond to increasing color-match between prey and habitat. These results were consistent with the equivocal conclusions of previous studies on the anti-predator hypothesis of camouflage, altogether suggesting further theory development and experimentation is needed to explain the frequency of apparent camouflage in nature. In Chapter 3, I described a new species of porcellidiid copepod - found during the epifaunal surveys I conducted in 2013-2014. This was the first porcellidiid copepod species to be described from North America, although porcellidiid copepods have been previously recorded in Northeast Pacific coastal surveys. Porcellidium species nova n. sp., can be distinguished by a deep cleft in the female genital double somite, a lack of plumulose setae and three coupling denticles (two bulbous denticulate pads and one smooth protrusion) on the male antennule, and clear coloration with purple/maroon bands across the first and last metasomes. I have provided a partial revision to a key to Porcellidium species, along with a discussion of the natural history and distribution of porcellidiid copepods along the Northeastern Pacific coastline.

Author: Anne Randall Hughes
Publisher:
ISBN:
Category :
Languages : en
Pages : 262

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Author:
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Category : Electronic books
Languages : en
Pages : 31

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Seagrass is often one of several habitat types in estuarine seascape mosaics, but seagrass edge effect studies have rarely considered that neighboring habitat identity might create multiple ‘edge types’ each with unique effects on fauna. Restoration projects featuring multiple estuarine habitats may benefit from improved understanding of interactions between habitats at edges. I used an eelgrass (Zostera marina) and Olympia oyster (Ostrea lurida) living shoreline restoration experiment in southern California to test if eelgrass epifaunal community structure and predation risk vary with adjacent habitat (eelgrass-oyster and eelgrass-unvegetated sediment) and edge proximity (edge or interior). I found that effects of adjacent habitat and edge proximity on epifaunal density, richness, and diversity responses were site-specific, with oysters elevating richness and diversity in eelgrass at only one of three sites. Multivariate community analysis suggested that adjacent habitat and edge proximity altered epifaunal assemblages at that site only. Typical edge effect covariates such as habitat complexity and food availability did not appear to explain edge effects in epifaunal communities. Using tethering experiments, I found that predation risk for grass shrimp varied with adjacent habitat type and proximity to the edge, with interactive effects of adjacent habitat and edge proximity at two sites. Predation risk was lower in eelgrass patches adjacent to oysters than those adjacent to unvegetated sediments. My results suggest that after one year, oyster restoration has had moderate and variable effects on eelgrass epifaunal communities and predation risk. This living shorelines project is one of the first in southern California, and I recommend that more studies utilize restoration experiments to simultaneously test ecological theory and conserve habitats.

Author: Scott R. Marion
Publisher:
ISBN:
Category : Fragmented landscapes
Languages : en
Pages : 178

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Author: Frederick T. Short
Publisher: Univ of California Press
ISBN: 9780520240476
Category : Nature
Languages : en
Pages : 336

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Seagrasses are a vital and widespread but often overlooked coastal marine habitat. This volume provides a global survey of their distribution and conservation status.

Author: S J Hawkins
Publisher: CRC Press
ISBN: 1000452247
Category : Nature
Languages : en
Pages : 1054

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Oceanography and Marine Biology: An Annual Review remains one of the most cited sources in marine science and oceanography. The ever-increasing interest in work in oceanography and marine biology and its relevance to global environmental issues, especially global climate change and its impacts, creates a demand for authoritative refereed reviews summarizing and synthesizing the results of recent research. If you are interested in submitting a review for consideration for publication in OMBAR, please email the Editor in Chief, Stephen Hawkins, at [email protected]. For nearly 60 years, OMBAR has been an essential reference for research workers and students in all fields of marine science. This volume considers such diverse topics as the Great Barrier Reef Expedition of 1928-29, Mediterranean marine caves, macromedusae in eastern boundary currents, marine biodiversity in Korea, and development of a geo-ecological carbonate reef system model to predict responses of reefs to climate change. Seven of the peer-reviewed contributions in Volume 59 are available to read Open Access on this webpage (1, 2, 3, 4, 5, 6 and 9). An international Editorial Board ensures global relevance and expert peer review, with editors from Australia, Canada, Hong Kong, Ireland, Singapore and the United Kingdom. The series volumes find a place in the libraries of not only marine laboratories and oceanographic institutes, but also universities worldwide.

Author: Anthony W. D. Larkum
Publisher: Springer
ISBN: 331971354X
Category : Science
Languages : en
Pages : 791

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This book takes the place of “Biology of Seagrasses: A Treatise on the Biology of Seagrasses with Special Reference to the Australian Region”, co-edited by A.W.D. Larkum, A.J. MaCComb and S.A. Shepherd and published by Elsevier in 1989. The first book has been influential, but it is now 25 years since it was published and seagrass studies have progressed and developed considerably since then. The design of the current book follows in the steps of the first book. There are chapters on taxonomy, floral biology, biogeography and regional studies. The regional studies emphasize the importance of Australia having over half of the world’s 62 species, including some ten species published for Australia since the previous book. There are a number of chapters on ecology and biogeography; fish biology and fisheries and dugong biology are prominent chapters. Physiological aspects again play an important part, including new knowledge on the role of hydrogen sulphide in sediments and on photosynthetic processes. Climate change, pollution and environmental degradation this time gain an even more important part of the book. Decline of seagrasses around Australia are also discussed in detail in several chapters. Since the first book was published two new areas have received special attention: blue carbon and genomic studies. Seagrasses are now known to be a very important player in the formation of blue carbon, i.e. carbon that has a long turnover time in soils and sediments. Alongside salt marshes and mangroves, seagrasses are now recognized as playing a very important role in the formation of blue carbon. And because Australia has such an abundance and variety of seagrasses, their role in blue carbon production and turnover is of great importance. The first whole genomes of seagrasses are now available and Australia has played an important role here. It appears that seagrasses have several different suites of genes as compared with other (land) plants and even in comparison with freshwater hydrophytes. This difference is leading to important molecular biological studies where the new knowledge will be important to the understanding and conservation of seagrass ecosystems in Australia. Thus by reason of its natural abundance of diverse seagrasses and a sophisticated seagrass research community in Australia it is possible to produce a book which will be attractive to marine biologists, coastal scientists and conservationists from many countries around the world.