Estuarine Ecology Pdf
Gregory Monty
In the newly revised third edition of Estuarine Ecology, a team of distinguished ecologists presents the current knowledge in estuarine ecology with particular emphasis on recent trends and advances. The book is accessible to undergraduate students while also providing a welcome summary of up-to-date content for a more advanced readership.
Perfect for students of estuarine ecology, environmental science, fisheries science, oceanography, and natural resource management, Estuarine Ecology will also earn a place in the libraries of professionals, government employees, and consultants working on estuary and wetlands management and conservation.
The Coastal and Estuarine Ecology Lab (CEEL) is a collection of scientists that study aquatic ecology, community ecology, and spatial ecology in the Biological Sciences Department at the Virginia Institute of Marine Science, William & Mary.
The questions we ask are broad, so our research integrates across organizational scales of ecology including linkages between animal behavior, populations, communities, ecosystems, and macrosystems. We address system-specific questions for the purposes of management and conservation, and theoretical questions for the purposes of advancing ecological understanding.
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The Marine & Estuarine Ecology Lab at SERC studies interactions among species and the ways that individual animals, communities and ecosystems respond to changes in the environment. We are fascinated by the complexity of natural systems, but have also focused much of our research on the consequences of the ways that human activities have altered our natural environment. We are particularly interested in how responses of individual organisms and variation among species shape the patterns we see over large spatial scales and in complex biological assemblages.
Our ecosystems and the organisms within them are exposed to a multitude of stressors that result from both human activities and natural variability, and our best hope for understanding, managing, and restoring these systems lies in considering the complexity of ecological systems in the context of the complex ways we have altered the environment. Most of our research is conducted in Chesapeake Bay and its tributaries, but we have also worked in mangrove islands in Belize and Panama, and have used cross-system comparisons to uncover global patterns.
Human population growth and rising sea levels have led to dramatic changes in ecosystems at the land-water interface. Forests have been replaced with housing, agriculture, and industries that increase nutrient, sediment, and contaminant loads to adjacent waters. Natural shorelines have been reinforced with stone riprap and bulkheads to slow erosion. And native vegetation is increasingly replaced with invasive species that may not provide the same benefits within the nearshore ecosystem.
Oxygen is fundamental to life. This is true whether we consider people on land or the majority of animals and plants in estuaries, coastal waters and the open ocean. Hypoxia (low dissolved oxygen concentrations) or deoxygenation (the decline in dissolved oxygen concentrations) occurs when oxygen consumption by organisms through respiration exceeds oxygen production through photosynthesis by phytoplankton and aquatic plants, as well as mixing or diffusion of atmospheric oxygen into the water.
Nutrients from agriculture, human waste and other sources cause hypoxia through a multi-step process. Initially, these nutrients stimulate production of phytoplankton just as fertilizers stimulate growth of grass on lawns and agricultural crops on farms. However, the phytoplankton produced exceeds what other organisms can consume, and the excess, dying phytoplankton sink into bottom waters where respiring microbes deplete the water of oxygen as they decompose this bounty. The invention and use of chemical fertilizers and growing human populations have led to an explosive increase in the number of sites around the world that experience hypoxia.
Global warming, acidification and deoxygenation are all linked. Like hypoxia, acidification results from respiration by plants and animals in our oceans and coastal waters because respiration that consumes oxygen also produces carbon dioxide, which acidifies water. In addition, increasing atmospheric carbon dioxide acidifies as it dissolves in oceans and coastal waters. Increasing atmospheric carbon dioxide also causes global warming, which increases respiration rates of organisms, and thus, oxygen depletion and carbon dioxide release into waters. Finally, warming of surface waters increases the difference in density between surface and deeper water layers, which reduces contact between subsurface waters and the oxygen-rich atmosphere.
Ensuring that fisheries are sustainable and continue to produce yields for future generations is a critical topic in marine ecology. In the Marine Ecology lab at SERC, we conduct ongoing research on Eastern oysters to see how they are affected by environmental stressors, with the aim of sharing our results with stakeholders in the oyster fishery: fishermen, restoration ecologists, and aquaculture facility managers. Our current project seeks to determine how oysters exposed to stressors as juveniles grow and develop over the long term into adulthood. By measuring their growth and overall fitness over time, we can see how these exposures as juveniles impact the oysters, and provide recommendations on how restoration and aquaculture efforts can maximize their return on investment.
Each fall semester as a part of the BIO260 Occidental Biology Course (Biodiversity of Marine Ecosystems), students conduct beach seine surveys in several estuarine and open coastline sites in the Southern California area. Sites surveyed have ranged from Crystal Cove in Malibu to the Port of Los Angeles. The survey data is then compiled and analyzed for undergraduate independent research projects.
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.[1] Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.[2]
Many estuaries suffer degeneration from a variety of factors including soil erosion, deforestation, overgrazing, overfishing and the filling of wetlands. Eutrophication may lead to excessive nutrients from sewage and animal wastes; pollutants including heavy metals, polychlorinated biphenyls, radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion.[3][4]
The word "estuary" is derived from the Latin word aestuarium meaning tidal inlet of the sea, which in itself is derived from the term aestus, meaning tide. There have been many definitions proposed to describe an estuary. The most widely accepted definition is: "a semi-enclosed coastal body of water, which has a free connection with the open sea, and within which seawater is measurably diluted with freshwater derived from land drainage".[1] However, this definition excludes a number of coastal water bodies such as coastal lagoons and brackish seas.
A more comprehensive definition of an estuary is "a semi-enclosed body of water connected to the sea as far as the tidal limit or the salt intrusion limit and receiving freshwater runoff; however the freshwater inflow may not be perennial, the connection to the sea may be closed for part of the year and tidal influence may be negligible".[3] This broad definition also includes fjords, lagoons, river mouths, and tidal creeks. An estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides. The effects of tides on estuaries can show nonlinear effects on the movement of water which can have important impacts on the ecosystem and waterflow. The seawater entering the estuary is diluted by the fresh water flowing from rivers and streams. The pattern of dilution varies between different estuaries and depends on the volume of freshwater, the tidal range, and the extent of evaporation of the water in the estuary.[2]
Drowned river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border.
The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River, Chesapeake Bay, and Delaware Bay along the Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast.[5]
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