Nutrition and food limitation of deposit-feeders. II. Differential effects of Hydrobia totteni and Ilyanassa obsoleta on the microbial community

We examined the effects of the mud snails Hydrobia totteni and Ilyanassa obsoleta on microbial communities of sediments in microcosms. Varying density of Hydrobia, and the presence of Ilyanassa, exerted no effect on steady state bacterial standing stock. This is probably related to the rapid recovery rate of bacteria, despite efficient grazing...

Nutrition and food limitation of deposit-feeders. I. The role of microbes in the growth of mod snails (Hydrobiidae)

A series of laboratory microcosm experiments demonstrate that somatic growth of the deposit-feeding gastropod, Hydrobia totteni, is related strongly to microalgal standing stock. Microalgal standing stock is, in turn, determined by the relative rates of grazing and recovery...

The importance of microalgae, bacteria and particulate organic matter in the somatic growth of Hydrobia totteni

Laboratory microcosm experiments reveal that benthic microalgae (filamentous blue-green and diatoms) probably constitute the bulk of nutrition in the somatic growth of the deposit feeding mud snail Hydrobia totteni. Despite an apparent excess of nitrogen in the particulate fraction of the sediment, H. totteni grows only about 42% as much in the dark as in the light. Growth in the dark is probably explained by the utilization of filamentous blue greens and, to a lesser extent, bacteria. The additional growth in the light is probably explained by benthic diatoms, as shown in previous studies. Standing-stocks of micro-organisms (bacteria and microalgae) and snail densities (0.5 cm–2, 2.0 cm–2) in laboratory treatments lie within the range of field conditions. A comparison of snail growth in oxidized and nonoxidized sediments, shows that particulate organic matter typically found in salt marsh sediments does not contribute substantially to somatic growth in H. totteni. Added rations of the seaweed Ulva rotundata also did not affect snail growth. Much of the available nitrogen may have been mineralized into the water column because Ulva is readily decomposed

Grazing and control of coral reef community structure by Diadema antillarum Philippi (Echinodermata: Echinoidea): A preliminary study

The grazing activities of the tropical echinoid Diadema antillarum Philippi can markedly influence the structure of the shallow-water epibenthic coral reef community. The elimination of an entire Diadema population from a patch reef in St. Croix, U.S. Virgin Islands resulted in a great increase in macro-algal biomass, alterations in species composition, shifts in dominance, an increase in species numbers, and a decrease in equitability...

Climate change, precipitation and impacts on an estuarine refuge from disease

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e18849, doi:10.1371/journal.pone.0018849.Oysters play important roles in estuarine ecosystems but have suffered recently due to overfishing, pollution, and habitat loss. A tradeoff between growth rate and disease prevalence as a function of salinity makes the estuarine salinity transition of special concern for oyster survival and restoration. Estuarine salinity varies with discharge, so increases or decreases in precipitation with climate change may shift regions of low salinity and disease refuge away from optimal oyster bottom habitat, negatively impacting reproduction and survival. Temperature is an additional factor for oyster survival, and recent temperature increases have increased vulnerability to disease in higher salinity regions. We examined growth, reproduction, and survival of oysters in the New York Harbor-Hudson River region, focusing on a low-salinity refuge in the estuary. Observations were during two years when rainfall was above average and comparable to projected future increases in precipitation in the region and a past period of about 15 years with high precipitation. We found a clear tradeoff between oyster growth and vulnerability to disease. Oysters survived well when exposed to intermediate salinities during two summers (2008, 2010) with moderate discharge conditions. However, increased precipitation and discharge in 2009 reduced salinities in the region with suitable benthic habitat, greatly increasing oyster mortality. To evaluate the estuarine conditions over longer periods, we applied a numerical model of the Hudson to simulate salinities over the past century. Model results suggest that much of the region with suitable benthic habitat that historically had been a low salinity refuge region may be vulnerable to higher mortality under projected increases in precipitation and discharge. Predicted increases in precipitation in the northeastern United States due to climate change may lower salinities past important thresholds for oyster survival in estuarine regions with appropriate substrate, potentially disrupting metapopulation dynamics and impeding oyster restoration efforts, especially in the Hudson estuary where a large basin constitutes an excellent refuge from disease.Funding was provided by the Hudson River Foundation, grant number 00607A, and the New York State Department of Environmental Conservation (MOU 2008)

THE LATITUDINAL COMPENSATION HYPOTHESIS: GROWTH DATA AND A MODEL OF LATITUDINAL GROWTH DIFFERENTIATION BASED UPON ENERGY BUDGETS. I. INTERSPECIFIC COMPARISON OF OPHRYOTROCHA (POLYCHAETA: DORVILLEIDAE)

Volume: 165Start Page: 686End Page: 69

Trophic group and evolution in bivalve molluscs

Volume: 17Start Page: 579End Page: 58

Marine biology : function, biodiversity, ecology /

Includes bibliographical references and index

LATITUDINAL DIFFERENTIATION IN EMBRYONIC DURATION, EGG SIZE, AND NEWBORN SURVIVAL IN A HARPACTICOID COPEPOD

Volume: 168Start Page: 419End Page: 43