Effects of periodic environmental hypoxia on predation of a tethered polychaete, Glycera americana: implications for trophic dynamics

Hypoxia and anoxia have significant deleterious ecological effects on living resources throughout many estuarine and marine ecosystems worldwide. Brief periods of low oxygen have the potential to facilitate transfer of benthic production to higher trophic levels as many benthic infaunal species have shallower sediment depth distributions during hypoxic events. In August-September 1994, a time-lapse camera equipped with a water quality datalogger was used to document in situ exploitation of a tethered prey organism (Glycera americana Leidy) by mobile fish and crustacean predators during alternating normoxia-hypoxia cycles in the York River, Virginia, USA. Based on photographic and diver observations, this hypoxia-induced benthic-pelagic transfer of production is more likely to occur when environmental dissolved oxygen concentrations rise above an apparent threshold between 1 and 2 ml 1(-1). When oxygen concentrations decline below approximately 1.5 ml 1(-1) (30% O-2 saturation), the response of the predator to increased prey availability is abruptly interrupted. There is no energy gain by the predator until oxygen concentrations rise above this critical threshold level. It is suggested that predators return to affected areas and resume feeding activity before stressed infauna are able to return to normal positions in the sediment

Above Reproach? The U.S. Supreme Court\u27s Ethical Issues

With society scrutinizing the American criminal justice system, a standard of ethics becomes ever so important for law enforcement officials, members of the bench, and correctional personnel. Creating a code of conduct not only benefits the individual players in the criminal justice system but it also protects the integrity of each institution. Unfortunately, one of the most important judicial branches in the criminal justice system, the United States Supreme Court, does not have, nor follow an ethical code of conduct. This creates a problem for criminal justice practitioners, the media, and society. This article examines the current requirements for a sitting Supreme Court Justice when facing an ethical dilemma and addresses the steps a Justice should take. The Justices have responded by questioning the need for a code of conduct and have challenged recently proposed legislation to address ethical concerns raised by the media as it has investigated the actions and behaviors of the Justices on the High Court. Addressing the critical issue of enforcement, the authors support the oversight of an Inspector General to address ethical issues facing the members of the U.S. Supreme Court

A Global Perspective On The Effects Of Eutrophication And Hypoxia On Aquatic Biota And Water Quality

Development associated with human populations has led to the globalization of many environmental problems. In marine systems, the most serious of these problems are directly related to the process of eutrophication. The increased production of organic matter in these marine systems associated with eutrophication is the primary factor impacting species abundance and composition and dissolved oxygen budgets. Oxygen, which is essential to maintaining balance in ecosystem processes through its role in mediating microbial and metazoan activities, has declined to critically low levels in many systems, which has led to the development of hypoxia (/l) and anoxia (0 ml O2/l). Currently, most oxygen depletion events are seasonal, but trends toward longer periods that could eventually lead to persistent hypoxic or anoxic conditions are emerging. Over the last 50 years, there has been an increase in the number of systems reporting problems associated with low dissolved oxygen. Currently there are over 100 hypoxic/anoxic areas around the globe, ranging in size fromkm2, that exhibit a graded series of responses to oxygen depletion, ranging from no obvious change to mass mortality of bottom fauna. Ecosystems currently severely stressed by eutrophication induced hypoxia continue to be threatened with the loss of fisheries, loss of biodiversity, alteration of food webs, and simplification of energy flows.https://scholarworks.wm.edu/vimsbooks/1014/thumbnail.jp

Settlement and survival of the oyster Crassostrea virginica on created oyster reef habitats in Chesapeake Bay

Efforts to restore Crassostrea virginica oyster reef habitats in Chesapeake Bay typically begin with the placement of hard substrata, such as oyster shell, in the form ofthreedimensional mounds on the seabed to serve as a base for oyster recruitment and growth. A shortage of sufficient volumes of oyster shell for creating large-scale reefs has led to widespread use of other materials, such as surf clam (Spisula solidissima) shell, as a substitute for oyster shell. We monitored oyster recruitment, survival, and growth on intertidal and subtidal reefs constructed shucked oyster and surf clam shell. Results indicate that oyster settlement occurred on both substrate types throughout the monitoring period but high levels of postsettlement mortality occurred on clam shell mounds. On the subtidal clam shell mound, the quality of the substrate material varied with reef elevation with large shell fragments and intact valves scattered around the reef base and small, tightly packed shell fragments paving the crest and flank of the reef mound. The abundance of oysters on this reef reflected this distribution where oysters were more abundant and larger at the reef base and less abundant and smaller on the crest of the reef. Oyster shell reefs supported greater oyster growth and survival and offered the highest degree of structural complexity. We suggest that the availability of interstitial space and appropriate settlement surfaces account for the observed differences in oyster abundance across the reef systems. The patterns observed give context to the importance of substrate selection in similar restoration activities

Ecological functions of constructed oyster reefs along an environmental gradient in Chesapeake Bay: Final Report

Oyster reef habitat restoration within the Chesapeake Bay has as its objectives not only the enhancement of the commercially important oyster stocks, but also the restoration of associated assemblages of organisms and, most importantly, the restoration of ecological functions associated with natural reef communities. Despite our efforts to date, many uncertainties still exist with respect to achieving these restoration goals. These include long-term information on the temporal sequence of community development on new reef substrate, evaluating oyster recruitment patterns (a) across restored reef systems and (b) in relation to resident brood stocks. In this study we sought to characterize the development of resident assemblages on and transient visitors to a variety of constructed reef bases. This study provided a means with which to examine a variety of inter/intra-system processes by coupling the monitoring of resident reef assemblages with characterizations of the transient assemblages (particularly higher trophic levels) in different reef systems. Models of oyster reef community interactions can be generated by synthesizing oyster population data and trophic information over small (system wide) and large (regional) geographic scales

Created mangrove wetlands store belowground carbon and surface elevation change enables them to adjust to sea-level rise

Mangrove wetlands provide ecosystem services for millions of people, most prominently by providing storm protection, food and fodder. Mangrove wetlands are also valuable ecosystems for promoting carbon (C) sequestration and storage. However, loss of mangrove wetlands and these ecosystem services are a global concern, prompting the restoration and creation of mangrove wetlands as a potential solution. Here, we investigate soil surface elevation change, and its components, in created mangrove wetlands over a 25 year developmental gradient. All created mangrove wetlands were exceeding current relative sea-level rise rates (2.6 mm yr(-1)), with surface elevation change of 4.2-11.0 mm yr(-1) compared with 1.5-7.2 mm yr(-1) for nearby reference mangroves. While mangrove wetlands store C persistently in roots/soils, storage capacity is most valuable if maintained with future sea-level rise. Through empirical modeling, we discovered that properly designed creation projects may not only yield enhanced C storage, but also can facilitate wetland persistence perennially under current rates of sea-level rise and, for most sites, for over a century with projected medium accelerations in sea-level rise (IPCC RCP 6.0). Only the fastest projected accelerations in sea-level rise (IPCC RCP 8.5) led to widespread submergence and potential loss of stored C for created mangrove wetlands before 2100

17‐Beta Hydroxysteroid Dehydrogenase 13 Is a Hepatic Retinol Dehydrogenase Associated With Histological Features of Nonalcoholic Fatty Liver Disease

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148371/1/hep30350.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148371/2/hep30350_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148371/3/hep30350-sup-0001-Supinfo.pd

Ecosystem development after mangrove wetland creation : plant–soil change across a 20-year chronosequence

This paper is not subject to U.S. copyright. The definitive version was published in Ecosystems 15 (2012): 848-866, doi:10.1007/s10021-012-9551-1.Mangrove wetland restoration and creation efforts are increasingly proposed as mechanisms to compensate for mangrove wetland losses. However, ecosystem development and functional equivalence in restored and created mangrove wetlands are poorly understood. We compared a 20-year chronosequence of created tidal wetland sites in Tampa Bay, Florida (USA) to natural reference mangrove wetlands. Across the chronosequence, our sites represent the succession from salt marsh to mangrove forest communities. Our results identify important soil and plant structural differences between the created and natural reference wetland sites; however, they also depict a positive developmental trajectory for the created wetland sites that reflects tightly coupled plant-soil development. Because upland soils and/or dredge spoils were used to create the new mangrove habitats, the soils at younger created sites and at lower depths (10–30 cm) had higher bulk densities, higher sand content, lower soil organic matter (SOM), lower total carbon (TC), and lower total nitrogen (TN) than did natural reference wetland soils. However, in the upper soil layer (0–10 cm), SOM, TC, and TN increased with created wetland site age simultaneously with mangrove forest growth. The rate of created wetland soil C accumulation was comparable to literature values for natural mangrove wetlands. Notably, the time to equivalence for the upper soil layer of created mangrove wetlands appears to be faster than for many other wetland ecosystem types. Collectively, our findings characterize the rate and trajectory of above- and below-ground changes associated with ecosystem development in created mangrove wetlands; this is valuable information for environmental managers planning to sustain existing mangrove wetlands or mitigate for mangrove wetland losses