Browsing by Subject "Coral Reefs"

Now showing 1 - 4 of 4

Open Access
Assessing Fishing Pressure in a Small-Scale Fishery in St. Eustatius, Dutch Caribbean
(2020-04-24) Cullinan, Grace
World fisheries are an important source of food and income for millions of people around the world, and represents a billion dollar industry (FAO, 2018). As a result, research on fisheries has mainly focused on large, commercial fisheries and less on small-scale, subsistence and artisanal fisheries (Anticamara et al., 2011). The result is a perceived lack of data from small-scale fisheries, and therefore less is known about their impact on the surrounding environment and importance to the communities that utilize them. Recent research on small-scale fisheries (SSF) has shown that data deficiencies can impact sustainability efforts, and have a large impact on small island developing states (Nash et al. 2016, Gill et al. 2019). Global fisheries are at risk, and SSF even more so, as anthropogenic effects reduce catch, change the range distribution of fish, change productivity, and drive the decline of fish stocks (Brander, 2010; Doney et al., 2012; Hanich et al., 2018). In order to curb these potentially dangerous declines, more research and capital needs to be invested in researching small-scale fisheries. St. Eustatius, a small island developing nation, which is part of the Dutch Caribbean, has a marine park surrounding the entire island from the high water line down to 30 meters, as well as two marine reserves. As a small developing island territory, maintaining their coral reef ecosystem and their reef fisheries is important for the island economy, nutrition, and food security (de Graaf et al., 2015). However, up until now the effects of different gear types and fishing pressure on the surrounding coral reefs, fish populations, fish size, and how those trends have changed over time in St. Eustatius has been poorly understood. In this Masters Project, we will utilize the fisheries landings data and GCRMN data collected by STENAPA to assess fishing intensity and its potential effects on the surrounding reef ecosystem, in an effort to help with future management strategies, and offer a cost effective approach to addressing some of the knowledge gaps surrounding St. Eustatius fisheries.
Open Access
Land Use Planning in Maui, Hawaii, to Prevent Sedimentation of Fringing Coral Reefs
(2011-04-28) Crane, Kathryn
One of the greatest threats to coral reefs of the Hawaiian Islands is sedimentation from land-based sources. Sedimentation occurs when runoff from storm events carries terrigenous sediments into the marine environment. Once in the marine environment it increases turbidity and eventually settles onto the coral, effectively smothering it. The severity of sedimentation depends on the type of sediment, the sediment load, and the residence time of the sediment. Land use that results in exposed soil, such as development, causes an increase in sedimentation. Because sedimentation begins on land, the policies addressing it must also be focused on the land. Current land use policy in Maui does not effectively address sedimentation, as it only tries to minimize the total sediment load. Land use policy does not address residence time of the sediment. Residence time is limited by wave exposure. Where wave exposure is higher, sediment is removed faster, thus having less impact on the coral. In order to effectively limit the impact of sedimentation, there must be spatially explicit land use regulations that require sediment filtration, density restriction, increased limits to total exposed soil, impervious surface restrictions, while encouraging habitat restoration and open space preservation, in areas where wave exposure is low. To better understand spatial and temporal variations in wave exposure in Maui, I created a GIS-based model of nearshore wave exposure. Using a model such as the one described here to identify critical areas that are more susceptible to sedimentation could result in more effective management of Maui’s reefs.
Open Access
Living Shorelines for Coastal Resilience: Developing a Decision Support Framework to Analyze Coral Reef Restoration Sites
(2020-04-22) Anderson, Kris
Communities around the world seek coastal resilience solutions, as storms increase in intensity and high tide flooding occurs more frequently. With these changes, demand grows to understand and measure the impacts of ecosystem protection and restoration efforts. While previous studies investigated the role of coral reefs in shoreline protection, few offer a comprehensive approach to inform effective restoration and resilience decisions. This research focuses on developing a decision support framework to analyze coral restoration sites and inform coastal resilience decisions through a matrix comparison approach. The research design assembles a literature review, analytic framework development, and analysis built upon case study sites, coastal resilience data, and an information matrix to communicate results. Application of the framework revealed a lack of consistent data across case study sites and points to focus areas for future research. The methodology of the decision support framework offers a general approach, applicable to a broad range of living shorelines and restoration scenarios.
Open Access
The Dynamics of Wave-Driven Reef Pass Jets and Coral Population Recovery on an Island
(2021) Torres, Walter I
Ocean circulation is integral to reef ecosystem health and resilience; waves and currents replenish nutrients, transport coral and fish larvae between populations, and moderate temperatures. On many reefs, wave-driven or tidal flow through reef passes is the dominant mechanism of exchange with the open ocean. The fate of the jet as it flows onto the forereef slope, however, is understudied. In this study, numerical simulations of wave-driven flow on an idealized coral island with periodically spaced reef passes were conducted and examined across a range of planetary rotation and bottom friction conditions. For higher latitude, lower friction cases, adjacent jets interacted due to the deflection of the jet by planetary rotation and weak attenuation by friction - a previously undescribed phenomenon. The physics of reef pass jet deflection were then examined using a novel reformulation of the barotropic vorticity balance in terms of flow curvature. The resultant curvature gradient equation was used to interpret a series of idealized numerical modeling experiments of a barotropic outflow jet onto a slope in shallow water using a depth-averaged circulation model (ROMS). The trajectory of the jet was explained by the curvature dynamics along its center streamline, with topography, planetary rotation, and bottom friction strongly influencing the course. Articulating the key processes of nearfield jet deflection in terms of curvature distilled the complex 2D phenomenon into a tractable 1D initial value problem, exhibiting predictive skill and clarifying the poorly understood dynamics of a nonlinear feature. A third element of this work examined population dynamics on reefs. Larval flux, as determined by demography and hydrodynamics, is integral to the recovery of a subpopulation after a disturbance, but few studies have connected annual time-scale coral population dynamics to larval recruitment.Here, a model for coral population growth was developed that synthesized metapopulation theory with classical population dynamics. It was validated against a case study of remarkable coral recovery after near extirpation. Model simulations suggest that a combination of steady background larvae source and favorable local growth conditions explain the recovery of coral on this reef, implying that the succeeding coral colonies are likely endogenic.