The concept of shifting baselines—changes in historical reference points used in environmental assessments—illuminates a foundational challenge when evaluating the health of ecosystems and seeking to ...restore degraded wildlife populations. In this important book, Victor S. Kennedy examines the problem of shifting baselines for one of the most productive aquatic resources in the world: the Chesapeake Bay. Kennedy explains that since the 1800s, when the Bay area was celebrated for its aquatic bounty, harvest baselines have shifted downward precipitously. Over the centuries, fishers and hunters, supported by an extensive infrastructure of boats, gear, and processing facilities, overexploited the region’s fish, crustaceans, terrapin, and waterfowl, squandering a profound resource. Beginning with the colonial period and continuing through the twentieth century, Kennedy gathers an unparalleled collection of scientific resources and eyewitness reports by colonists, fishers, managers, scientists, and newspaper reporters to create a comprehensive examination of the Chesapeake’s environmental history. Focusing on the relative productivity and health of its fisheries and wildlife and highlighting key species such as shad, oysters, and blue crab, Shifting Baselines in the Chesapeake Bay helps readers understand the remarkable extent of the Bay’s natural resources in the past so that we can begin to understand what has changed since, and why. Such knowledge can help illustrate the Bay’s potential fertility and stimulate efforts to restore this pivotal maritime system’s ecological health and productivity.
Nonnative oysters in the Chesapeake Bay National Research Council; Division on Earth and Life Studies; Ocean Studies Board ...
2004, 20040206, 2004-02-09, 1999-12-31
eBook, Book
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Nonnative Oysters in the Chesapeake Bay discusses the proposed plan to offset the dramatic decline in the bay's native oysters by introducing disease-resistant reproductive Suminoe oysters from Asia. ...It suggests this move should be delayed until more is known about the environmental risks, even though carefully regulated cultivation of sterile Asian oysters in contained areas could help the local industry and researchers. It is also noted that even though these oysters eat the excess algae caused by pollution, it could take decades before there are enough of them to improve water quality.
In essence this book deals with an area that contributes significantly to the pollution and degradation of Chesapeake Bay, but has been completely overlooked in many of the efforts to restore the ...Bay, specifically, the federal military pollution sources. The book also recognizes for the first time, that efforts to restore the Bay have failed because of violation of a fundamental precept of environmental cleanup; that is, to sample the site and see what is there. The Bay itself has never been sampled. Thus this book presents a view of the environmental condition of Chesapeake Bay that is totally unique. It covers a part of the history of the Bay that is not widely known, including how the Bay was formed. It presents a mixture of science, military history, and novel solutions to the Bay's degradation. In so doing, the author examines the military use of the Bay and reveals the extent of munitions dumpsites containing nitrogen and phosphorus as well as chemical warfare material, and how this is effecting the environment. The book concludes with the author's own clean-up plan that, if implemented, would go a long way to restoring health to Bay. The book is supplemented with many photographs and maps.
Anthropogenic nutrient enrichment of estuaries is a problem dramatically transforming coastal ecosystems worldwide (Diaz and Rosenberg 2008). Despite significant public and private sector resources ...dedicated to curbing point and non-point sources of nutrient loading, many of the symptoms of eutrophication, such as low bottom water dissolved oxygen (DO) and loss of sea grasses, have not abated (Kemp et al. 2009). Recently, studies have suggested that many eutrophied estuaries, such as the Chesapeake Bay (Hagy et al. 2004), the Gulf of Mexico (Turner et al. 2008), and in Danish coastal waters (Conley et al. 2007), have exhibited a totally unexpected response to nutrient reduction: hypoxic volume has continued to increase while nutrient loading has plateaued or decreased. This unexpected result has spawned a number of hypotheses. One is a regime shift, an abrupt change between contrasting persistent states (deYoung et al. 2008). Another possibility is that the time lag between reductions and their effects is longer than previously suspected. Whether the current state-of-the-art eutrophication models can detect or even forecast regime shifts or time lags is unknown because they have not been run over long enough time scales to detect these changes. However, these models are being used to determine Total Maximum Daily Loads (TMDLs) and to forecast the impact of TMDLs on water quality that would occur over long time periods.Dischargers and regulatory agencies need to know whether these models can make reliable long term forecasts that correctly predict the observed time lags. The primary objective for the end of the project is to finalize validating the model simulations with model-data comparisons of nutrient and oxygen levels. We will also be investigating whether reductions in diagenesis rates results in carryover organic material for subsequent years. Finally, we plan to manipulate stratification to reflect long term trends report by Scully (2010) and Murphy et al (2011). Regardless of the results, early indications suggest that the Bay was less susceptible to hypoxia formation early in the process of increases in nutrient loading (1950-1980). Additionally, understanding estuarine resilience whether mediated by biological (e.g., phytoplankton community composition, filter feeder capacity) or physical (e.g., changes in stratification intensity or sea level rise), is an important goal for the future of TMDL modeling, especially when these models are used in long term simulations.
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