Biomass and nutrient flux measurements on Holothuria atra populations on windward reef flats at Enewetak, Marshall Islands

A population survey of the holothurian, Holothuria atra, on the interisland coral reefs of Enewetak revealed average animal densities of about 3 animals m-2 in the zone of small coral heads, Median fresh weighy was 60 g, The size distribution of these animals was negatively correlated with water velocity along the reef. Ammonia release rates for three species of holothurians, H. atra, H. difficilus and Actinopyga mauritina were weight specific, The release of annnonia by H. atra on Transect II was equivalent to 9% of the total amnnonia exported from the reef proper. The release of phosphorus followed the general rules set for size - metabolism relationships. Nitrogen/phosphorus release ratios are 25:1 for 1 gram fresh weight animals and 42:1 for 60 gram animals, Urea is also releasedhttps://scholarworks.wm.edu/vimsbooks/1138/thumbnail.jp

Economic Impact of Gulf of Mexico Ecosystem Goods and Services and Integration Into Restoration Decision-Making

Sustainability of natural resources requires balancing exploitation and conservation, enabled by management based on the best available scientific and economic information. Valuation of ecosystem goods and services is an important tool for prioritizing restoration efforts, recognizing the economic importance of conserving natural capital, and raising public awareness about the contribution of healthy ecosystems to social welfare, now and for future generations. The Deepwater Horizon oil spill (DHOS) in 2010 was a Gulf of Mexico ecological and economic disaster adding to decades-long degradation of the region’s coastal and marine environment. In 2010, revenues from provisioning ecosystem goods and services generated by the five U.S. states bordering the Gulf of Mexico contributed over $2 trillion per year to the nation’s gross domestic product, including$660 billion from the coastal county revenues and $110 billion from ocean revenues. Mexico and Cuba contribute at least another$40 billion per year from their Gulf coastal and ocean economies. Total economic value of Gulf ecosystem goods and services also requires valuation of nonmarket regulating, cultural, and supporting services, which are far more difficult to assess, but add billions more dollars per year. In light of this total economic value and trends in ecosystem stressors, new investment is necessary to ensure completeness, accuracy, and availability of Gulf economic impact data. Civil and criminal settlements related to the DHOS provide unprecedented opportunities for improving integration of ecosystem goods and services into decisions that affect Gulf restoration and sustainability. This paper highlights the economic contributions of Gulf ecosystem goods and services to the nation’s welfare, and recommends actions and investments required to ensure that they are valued, and integrated into decision-making

Instructional Models for Course-Based Research Experience (CRE) Teaching

The course-based research experience (CRE) with its documented educational benefits is increasingly being implemented in science, technology, engineering, and mathematics education. This article reports on a study that was done over a period of 3 years to explicate the instructional processes involved in teaching an undergraduate CRE. One hundred and two instructors from the established and large multi-institutional SEA-PHAGES program were surveyed for their understanding of the aims and practices of CRE teaching. This was followed by large-scale feedback sessions with the cohort of instructors at the annual SEA Faculty Meeting and subsequently with a small focus group of expert CRE instructors. Using a qualitative content analysis approach, the survey data were analyzed for the aims of inquiry instruction and pedagogical practices used to achieve these goals. The results characterize CRE inquiry teaching as involving three instructional models: 1) being a scientist and generating data; 2) teaching procedural knowledge; and 3) fostering project ownership. Each of these models is explicated and visualized in terms of the specific pedagogical practices and their relationships. The models present a complex picture of the ways in which CRE instruction is conducted on a daily basis and can inform instructors and institutions new to CRE teaching

CELL-SIZE DISTRIBUTIONS OF ZOOXANTHELLAE IN CULTURE AND SYMBIOSIS

Volume: 170Start Page: 519End Page: 52

Top-Down Control of Phytoplankton by Oysters in Chesapeake Bay, USA: Reply to Newell et al. (2007)

Recently published models, which allow for spatial and temporal matching of oyster and phytoplankton populations in mainstream Chesapeake Bay, support the conclusion of Pomeroy et al. (2006; Mar Ecol Prog Ser 325:301-309) that oysters cannot, and could not, control the spring blooms that are the ultimate cause of summer hypoxia. We enlarge upon our earlier exposition of how top-down and bottom-up processes interact in Chesapeake Bay to permit the occurrence of phytoplankton blooms in spring, but not in summer

Limits to Top-Down Control of Phytoplankton by Oysters in Chesapeake Bay

Restoration of the oyster Crassostrea virginica population in Chesapeake Bay is often advocated as an easy solution for controlling phytoplankton blooms. Even at their pre-colonial densities, oysters are unlikely to have controlled blooms, despite the fact that sediment cores suggest that pre-colonial spring blooms were smaller than at present. Lack of access to all bay water and low springtime filtration rates would make it impossible for oysters to control the spring bloom and the resulting summer hypoxia. Previous studies have overestimated potential oyster filtration rates, because they extrapolated summer rates to spring conditions that are 20 degrees C cooler. Previous studies have also assumed that oysters have access to all phytoplankton, without considering the spatial separation. In Chesapeake Bay, oysters and the spring bloom are separated horizontally owing to the size of the bay and its small tidal amplitude. Indeed, a multi-species guild of suspension feeders now present in the bay should have a filtration capacity approaching that of pre-colonial oysters, but it does not control the bloom. Actual oyster filtration potential must be lower than many advocates of oyster restoration assume, and replenishing the bay with oysters is not the means of controlling blooms and hypoxia

Evaluating trade-offs of a large, infrequent sediment diversion for restoration of a forested wetland in the Mississippi delta

© 2018 Elsevier Ltd Flood control levees cut off the supply of sediment to Mississippi delta coastal wetlands, and contribute to putting much of the delta on a trajectory for continued submergence in the 21st century. River sediment diversions have been proposed as a method to provide a sustainable supply of sediment to the delta, but the frequency and magnitude of these diversions needs further assessment. Previous studies suggested operating river sediment diversions based on the size and frequency of natural crevasse events, which were large (\u3e5000 m3/s) and infrequent (active \u3c once a year) in the last naturally active delta. This study builds on these previous works by quantitatively assessing tradeoffs for a large, infrequent diversion into the forested wetlands of the Maurepas swamp. Land building was estimated for several diversion sizes and years inactive using a delta progradation model. A benefit-cost analysis (BCA) combined model land building results with an ecosystem service valuation and estimated costs. Results demonstrated that land building is proportional to diversion size and inversely proportional to years inactive. Because benefits were assumed to scale linearly with land gain, and costs increase with diversion size, there are disadvantages to operating large diversions less often, compared to smaller diversions more often for the immediate project area. Literature suggests that infrequent operation would provide additional gains (through increased benefits and reduced ecosystem service costs) to the broader Lake Maurepas-Pontchartrain-Borgne ecosystem. Future research should incorporate these additional effects into this type of BCA, to see if this changes the outcome for large, infrequent diversions