Restoring and Protecting Marine Habitat The Role of Engineering and Technology (1994) / Chapter Skim
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2 Scientific and Engineering Perspectives
2 Scientific and Engineering Perspectives
Pages 18-30
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From page 18... ...
The third section sketches the too frequent situation where technology, including engineering technology, has intruded on marine habitats, uninformed or unconcerned about the consequences for their ecological functioning. ECOLOGICAL SETTING An ecosystem has numerous components that are all interdependent to some degree.
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From page 19... ...
Natural processes and human activities that affect commercially valuable fish and shellfish species also affect the less conspicuous species that provide food, influence habitat, and decompose and recycle nutrients in a given system. With the interdependencies of ecosystems in mind, it is clear that human activities that degrade or destroy any marine habitat affect the whole marine ecosystem in the area that is influenced.
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From page 20... ...
Complicating these ecological stresses are the increased human uses of the coastal zone, uses that sometimes exceed the ability of some marine organisms to adjust. Human activity has modified marine habitats in ways that science is just beginning to understand; the most conspicuous is habitat loss.
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From page 21... ...
THE SCOPE OF COASTAL ENGINEERING Engineering practice in the coastal zone has several general objectives including prediction of sediment transport, movement of surface water and groundwater, and shore evolution and to development and implementation of structural or other means to alter coastal water movement and shore evolution (Mehta, 1990~. In addition to engineering activities that are conventionally considered within the domain of coastal engineering, these general objectives encompass relevant aspects of dredging technology, soil and geotechnical engineering, water resource engineering including wastewater treatment and disposal, and civil construction practices related to soils and structures.
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From page 22... ...
In particular, the complexities of natural systems make it difficult to predict accurately the final form and function of habitat in any coastal engineering project. Thus, in addition to engineering considerations, setting habitat management objectives is conditioned by scientific and societal factors as well.
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From page 23... ...
Many completed habitat restoration and creation projects constructed with dredged material are functioning to design specifications (Landin et al., 1989c; USACE, 1986~. It is clear, however, that despite the successful use of marine sediments in well-founded marine habitat restoration projects, many marine habitat management projects are likely to stimulate controversy.
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From page 24... ...
Engineering success is defined as meeting project goals and objectives that were agreed on prior to construction. If project goals do not effectively address habitat needs and issues of scale in space and time, the result may or may not be a fully functioning marine habitat or, more realistically, a product positioned to achieve functional objectives over an agreedto time scale (Risser, 1988; Westman, 1991~.
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From page 25... ...
The need for team effort is well recognized by leading practitioners involved in creation or restoration of coastal wetlands and of shallow water and intertidal marine habitats; the coastal engineer typically works with a wet-soil scientist, a sedimentologist, a hydrologist, a biologist, and a systems ecologist, among others. For engineers specializing in environmental work, the multidisciplinary nature of the work requires general familiarity with a broad range of topics across and outside the engineering disciplines.
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From page 26... ...
Documented examples of habitat destruction and adverse effects of human-related activity include seagrass habitat losses from changes in water quality and from propeller damage from recreational and commercial craft, coral reef damage and loss from ship groundings and propeller strikes; species decline from pollutants and impoundments, wetland losses from disruption of sediment transport and from construction of bulkheads; loss of intertidal flushing, and waterlogging following hydrologic impoundment. The full ecological impacts are usually less obvious, especially in the near term, and are subject to intense debate.
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From page 27... ...
Although the full extent of sea level is not known, the apparent eustatic rise in sea level places a demand on the scientist and the coastal engineer to reconsider fundamental approaches to protecting, improving, and creating wetlands (NRC 1987a, 1989b, 1990a, 1990c; Titus, 19881. Both coastal development and marine habitat management have often assumed a relatively stable RMSL except in coastal Louisiana where the rate of change is obvious and subsidence is also a factor.
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From page 28... ...
. These facts argue for the initiation of both short- and long-term strategies to perfect restoration technology and apply it aggressively to the problem of historical wetland loss and the future threat of accelerated sea level rise.
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From page 29... ...
The application of coastal engineering capabilities and technologies may be sound from an engineering perspective but not beneficial to organisms affected by engineering work. Habitat management objectives are not well developed from an engineering perspective and are also conditioned by societal and scientific factors, including the effects of relative sea level rise.
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From page 30... ...
Use of dredged material in habitat restoration work, concern over the chemical properties of sediments, and questions over natural functioning stimulate considerable controversy. But some dredged material is also a resource that is needed for constructing habitat projects in coastal ecosystems.
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