Browsing by Subject "marine biology"
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Item Epifaunal Assemblages on Deep-water Corals in Roatan, Honduras(2012-10-30) Lavelle, KatherineDeep-water corals provide complex habitat structure for diverse assemblages of invertebrates and fishes. Similar to shallow coral reefs, oyster reefs, and seagrass beds, these complex biogenic structures serve many ecosystem functions: (a) as prey items; (b) sites for reproduction; (c) feeding stations, elevating suspension feeders above the benthos; and (d) refuges from predation. Because deep-sea corals provide some of the only three-dimensional habitats in the deep-sea, they may host distinct assemblages of epifauna. Non-destructive video surveys of deep-water coral assemblages were made to depths of 700 m at eight sites off Roatan, Honduras in May and December, 2011. Abundance, species richness, and distribution of epifauna were measured for 305 corals. We observed sixteen morphospecies of coral and twenty-six morphospecies of epifauna. Coral and epifaunal abundances were highest in the 335-449 m depth zone. Some epifauna had high fidelity for a single coral species or for a few species of similar morphological complexity. Other coral species had overlapping assemblages of habitat generalists. This is the first research on the biodiversity of deep-sea coral communities in Roatan, Honduras, and provides information on the assemblages, their depth distributions and ecological interactions.Item Linking Ecological Function and Ecosystem Service Values of Estaurine Habitat Types Associated with a Barrier Island System(2012-12-10) Francis, Jeffrey MichaelEcosystem services are benefits humans receive as a function of natural processes. Many current studies seek to express these benefits as an economic value per unit of habitat type without quantifying the ecological functions that allow for the provision of ecosystem services. This study is designed to model each habitat type in an effort to explicitly link the major estuarine habitat types of Mustang Island (oyster reefs, seagrass meadows, and intertidal salt marsh) to their contribution to Nitrogen cycling services. First, a dynamic biomass model of each foundational species was created using Simile, a declarative modeling framework. Second, a monthly snapshot of Nitrogen captured in living biomass was used to quantify the contribution of each species to the Nitrogen cycling services. Finally, the amount of Nitrogen captured in living biomass was valued using a replacement cost approach. An effort was also made to link the provision of recreational fishing services provided by each aforementioned habitat type by partitioning travel costs and license sales weighted by the density of fish found in each habitat type. It was found that oyster reefs of Mustang Island contribute $173,000 yr^-1, seagrass meadows contribute $12,054,095 yr^-1, and intertidal salt marshes contribute $5,242,755 yr^-1 in potential Nitrogen cycling services. The total value of recreational fishing services within the study site was calculated to be $83.8 million dollars yr^-1. A portion of the total value was then attributed to each habitat type: Marsh edge: $2 million; Seagrass meadows: $81 million; and Oyster: $81,000 thousand. These efforts have been made to translate ecological function into economic benefit to improve communication among a wide variety of stakeholders that are more likely to understand economic value. Further refinement of both the models and the economic data necessary to support them, will have the potential to improve the applicability and results of these tools. These results, and the modeling framework through which they are calculated, provide a platform to evaluate management relevant scenarios in a simple, flexible manner that may be adjusted and transferred to other study sites given appropriate local data.Item Venting and Rapid Recompression Increase Survival and Improve Recovery for Red Snapper with Barotrauma(2012-12-01) Drumhiller, Karen LRed Snapper, Lutjanus campechanus, are the most economically important reef fish in the Gulf of Mexico. Population assessments that began in the mid-1980?s found red snapper to be severely overfished and lead to extensive regulations and harvest restrictions. As a result of these regulations many fish that are captured must be released and are known as regulatory discards. Red snapper live deep in the water column and when captured and rapidly brought to the surface they often suffer pressure-related injuries collectively known as barotrauma. These injuries include a distended abdomen and stomach eversion from the buccal cavity. High mortality of discards due to barotrauma injuries impedes recovery of the fishery. The purpose of this study was to evaluate the efficacy of two techniques designed to minimize barotrauma-related mortality: venting and rapid recompression. In laboratory experiments using hyperbaric chambers, I assessed sublethal effects of barotrauma and subsequent survival rates of red snapper after single and multiple simulated capture events from pressures corresponding to 30 and 60 m. I evaluated the use of rapid recompression and venting to increase survival and improve recovery indices, including the ability to evade a simulated predator. A condition index of impairment, the barotrauma reflex (BtR) score, was used to assess sublethal external barotrauma injuries, reflex responses, and behavioral responses. Greater capture depths resulted in higher BtR scores (more impairment). Non-vented fish had higher BtR scores than vented fish after both single and multiple decompression events. All fish in vented treatments from 30 and 60 m depths had 100% survival after a single capture event. Non-vented fish had 67% survival after decompression from 30 m and 17% survival from 60 m. Behaviorally, non-vented fish showed greater difficulty achieving an upright orientation upon release and less ability to evade a simulated predator than vented fish. Rapid recompression also greatly improved survival compared to surface-released fish with 96% of all rapidly recompressed fish surviving. These results clearly show that venting or rapid recompression can be effective tools for alleviating barotrauma symptoms, improving predator evasion after a catch-and-release event, and increasing survival. Fisheries managers should encourage the use of either of these two techniques to aid in the recovery of this important fishery.