Download or read book Habitat Complexity as a Determinant of Juvenile Blue Crab Survival written by Jessica L. Schulman and published by . This book was released on 1996 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Juvenile Blue Crab Survival in Nursery Habitats written by Amanda Marie Bromilow and published by . This book was released on 2017 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. To reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the role of habitat, body size, finfish predation, and cannibalism on the survival of one of the most ecologically and economically important species in Chesapeake Bay: the blue crab Callinectes sapidus. In field tethering experiments, survival probability of juvenile blue crabs in York River nursery habitats (i.e. seagrass beds, sand flats) increased significantly and additively with crab size and SAV cover. Images of predation events during tethering experiments revealed cannibalism by adult blue crabs to be a major source of juvenile mortality. Gut content analyses from three field studies identified seven predators of juvenile blue crabs in lower Chesapeake Bay nursery habitats: adult blue crabs, striped bass Morone saxatilis, red drum Sciaenops ocellatus, silver perch Bairdiella chrysoura, weakfish Cynoscion regalis, Atlantic croaker Micropogonias undulatus, and oyster toadfish Opsanus tau. Using frequency of consumption and diet proportion metrics, I determined striped bass, red drum, and silver perch to be the most impactful finfish predators on juvenile mortality, in addition to cannibalism. Atlantic croaker and oyster toadfish play minor roles in juvenile mortality in Chesapeake Bay nursery habitats. The probability of juvenile crabs being present in a predator’s gut was also significantly higher in seagrass beds than in unvegetated sand flats. Food web dynamics are an important aspect of ecosystem-based fisheries management. Understanding the ecological interactions between populations, and their environment, can provide insight into natural population fluctuations of valuable fishery species such as the blue crab. This thesis demonstrated the positive effects of body size and SAV cover on juvenile crab survival, indicating the importance of seagrass nursery habitat for blue crab population dynamics in Chesapeake Bay. However, despite the predator refuge offered by SAV, high densities of predators and prey in seagrass beds resulted in greater consumption of juveniles in those habitats. Key predators of juvenile blue crabs were also identified and their relative impacts were estimated. The predator-prey relationships revealed in this thesis were integrated into a revised food web for blue crabs in Chesapeake Bay, in the hopes of informing future ecosystem-based management efforts.
Download or read book Juvenile Blue Crab Callinectes Sapidus Habitat Utilization and Survival written by Kenneth W. Able and published by . This book was released on 1990 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marine Freshwater Research written by and published by . This book was released on 1995 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings written by Vincent Guillory and published by . This book was released on 1999 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Juvenile Blue Crab Callinectes Sapidus Response to Altered Nursery Habitat written by Megan Wood and published by . This book was released on 2017 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Habitats of Chesapeake Bay have been altered due to anthropogenic impacts and climate change. Due to these human disturbances, seagrasses have been extirpated from many areas in lower Chesapeake Bay and persisting beds face future losses as water temperatures continue to rise. Further loss of seagrass habitat will negatively impact juvenile blue crabs (Callinectes sapidus) that use seagrass beds as nursery grounds. Habitat degradation allows for more successful introductions of exotic species, and the communities formed from the mixing of native and exotic species are known as emerging ecosystems. Gracilaria vermiculophylla, an exotic macroalga, may be an emerging nursery habitat for juvenile blue crabs in Chesapeake Bay; however the extent to which the alga is present and used as a nursery by juvenile blue crabs are largely unknown. I investigated algal distribution in the shallow littoral areas of the York River, a subestuary of Chesapeake Bay, over two years (2013 – 2014) and found that G. vermiculophylla presence correlated with salinity and that algal presence and biomass increased with seagrass presence, although biomass was generally low. The alga was present in areas where seagrasses have been lost, and is therefore likely providing nursery habitat in these areas of high megalopal recruitment. Benthic epifaunal communities had lower species richness and were less abundant in G. vermiculophylla relative to seagrass, while benthic infaunal communities had lower species richness but similar abundance in the alga relative to seagrass. Juvenile blue crab densities were similar in the alga and seagrass, although seagrass supported about 3 times as many first and second instar crabs than G. vermiculophylla. Young juvenile blue crabs preferred seagrass, which may be due to epifaunal prey preference, and G. vermiculophylla likely represents a secondary nursery habitat. Juvenile blue crab growth rates of crabs 15 – 50 mm carapace width were similar in the alga, native seagrass, and unvegetated habitat, indicating that growth does not drive ontogenetic shifts in habitat use by larger (20 – 30 mm carapace width) juveniles. Similar growth rates also suggest that G. vermiculophylla performs similarly to seagrass as a nursery habitat in terms of providing resources for growth. Simulations of density-dependent migration of young juvenile blue crabs between habitat types suggest that G. vermiculophylla may mediate continued seagrass loss, at least in part. Together, these results increase our understanding of an emerging Chesapeake Bay ecosystem and the impacts that changes to nursery habitats have on the juvenile component of the blue crab population.
Download or read book Seagrasses Biology Ecology and Conservation written by Anthony W. D. Larkum and published by Springer Science & Business Media. This book was released on 2007-05-16 with total page 691 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seagrasses are unique plants; the only group of flowering plants to recolonise the sea. They occur on every continental margin, except Antarctica, and form ecosystems which have important roles in fisheries, fish nursery grounds, prawn fisheries, habitat diversity and sediment stabilisation. Over the last two decades there has been an explosion of research and information on all aspects of seagrass biology. However the compilation of all this work into one book has not been attempted previously. In this book experts in 26 areas of seagrass biology present their work in chapters which are state-of–the-art and designed to be useful to students and researchers alike. The book not only focuses on what has been discovered but what exciting areas are left to discover. The book is divided into sections on taxonomy, anatomy, reproduction, ecology, physiology, fisheries, management, conservation and landscape ecology. It is destined to become the chosen text on seagrasses for any marine biology course.
Download or read book The Effect of Seagrass Habitat Fragmentation on Juvenile Blue Crab Survival written by Kevin Alexander Hovel and published by . This book was released on 1999 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Juvenile Blue Crab Callinectes Sapidus Habitat Preference in a Mesocosm Choice Experiment written by Sarah Elizabeth Scott and published by . This book was released on 2002 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Habitat Choice by Juvenile Blue Crabs in the Presence and Absence of Predators written by Jonathan Andrew Hartsell and published by . This book was released on 1999 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Human Impacts on Salt Marshes written by Brian R. Silliman and published by Univ of California Press. This book was released on 2009-06-03 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Human Impacts on Salt Marshes provides an excellent global synthesis of an important, underappreciated environmental problem and suggests solutions to the diverse threats affecting salt marshes."—Peter B. Moyle, University of California, Davis
Download or read book The Blue Crab Fishery of the Gulf of Mexico United States written by Vincent Guillory and published by . This book was released on 2001 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Utilization of Shallow Estuarine Habitats by Juvenile Blue Crabs Callinectes Sapidus Rathbun written by L. Walt Pollard and published by . This book was released on 1987 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Blue Crab Population Ecology and Use by Foraging Whooping Cranes on the Texas Gulf Coast written by Danielle Marie Greer and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2002, a proposal was submitted to divert water from the confluence of the Guadalupe and San Antonio Rivers to San Antonio, Texas. To investigate the potential impacts of diverting water from the Guadalupe Estuary, my research focused on the foraging ecology of the crane and population ecology of the blue crab, a documented crane food. During winters 2004-2005 and 2005-2006, I examined diets and optimal foraging patterns of territorial adult cranes at Aransas National Wildlife Refuge, Texas. To identify foods of greatest benefit to cranes, I used currencies of optimization to evaluate foraging gain, cost, and efficiency. Foraging benefit differed among foods, depending on the foraging currency used and resource targeted (e.g., energy). Wolfberry fruit, snails, and insects were consumed in the highest quantities, required the least foraging effort, and were generally associated with the highest foraging efficiency. Blue crabs and clams were important sources of protein and biomass. During September 2003-October 2005, I used novel artificial settlement substrates and modified methods of standard deployment to investigate the spatio-temporal patterns of blue crab terminal settlement and recruitment rates. Monitoring rates in shallow bay habitat and ponds of the interior salt-marsh revealed megalopal crabs were developmentally advanced when arriving to study sites and the extent to which young crabs infiltrated the salt-marsh increased with age. Such findings suggested sites represented optimal terminal settlement habitat and consequently critical nursery habitat. Model selection indicated water temperature before and during embryonic development was the best predictor of megalopal settlement, whereas juvenile recruitment was most influenced by recent precipitation. I studied the size-specific abundance patterns of blue crabs in and around mature salt-marsh. Using drop-trapping and throw-trapping methods, I collected monthly samples in several habitats during October 2004-March 2006. Interior-marsh habitats contained fewer but larger crabs than bay habitat. Crabs contributing greatest to biomass were smallest (11-30 mm carapace-width) in bay habitat, larger (31-80 mm) along interior-marsh pond edges, and largest (41-130 mm) in interior-marsh open water. Model selection revealed crab density was most influenced by micro-site characteristics (habitat, water column structure type and structural complexity). Overall, shallow bay provided important nursery habitat for young blue crabs and interior marsh ponds were important for dispersing juvenile and adult crabs.
Download or read book Life History of the Blue Crab written by Edward Perry Churchill and published by . This book was released on 1919 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Population Dynamics and Stock Assessment of the Blue Crab in North Carolina written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The blue crab (Callinectes sapidus) is an ecologically important estuarine predator and represents North Carolina's most important commercial fishery. Recent fishery-dependent and --independent data suggest the population is declining. The goal of this study was to increase our understanding of the status and population dynamics of the blue crab in NC by addressing the following objectives: (1) estimate population demographics of blue crabs in salt marsh creeks, (2) construct a discontinuous model of blue crab growth in NC using growth rates estimated from free-ranging blue crabs, and (3) provide a comprehensive stock assessment for the blue crab in NC. A series of complimentary laboratory and field studies assessed the nursery role of salt marsh habitats for the blue crab (Callinectes sapidus). Population demographics and movement patterns of juvenile and adult blue crabs were quantified in two tidal salt marsh creeks near Beaufort, North Carolina, USA during June -- October 2001. While there are many studies that report estimates of population density, mortality rates, or movement rates for blue crabs, this study represents one of the first attempts to estimate all quantities concurrently. Juvenile crabs were mobile within the interstices of the vegetated marsh surface during flood tide, and were equally distributed buried in intertidal marsh and adjacent mud areas during ebb tide. Juvenile crabs may experience a spatial refuge from cannibalism in the marsh surface since adult conspecifics are physically impeded by dense vegetation and rarely move far into marsh habitats. This spatial refuge in the vegetated marsh surface may be significant, since cannibalism represents a large source of mortality for this species. The relatively high use of the marsh surface by juvenile blue crabs, combined with a general lack of sampling these complex habitats, suggest that crab densities may be even higher in salt marsh systems than previously thought. Growth models c.
Download or read book Habitat Use and Growth of Juvenile Blue Crabs Callinectes Sapidus in a Seagrass Meadow and Salt Marsh Embayment written by Ronald David Anderson and published by . This book was released on 1993 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
