...
A coastal zone is often described as the coastal ocean and the land adjacent to it. It covers approximately 7% (26x10^6 km2) of the surface of the interface between land and ocean. Despite its relatively modest surface area, the coastal zone is one of the most geochemically and biologically active areas in the biosphere. For example, it accounts for at least 15% of oceanic primary production; 80% of organic matter burial; 90% of sedimentary mineralization; and 50% of the deposition of calcium carbonate. It also provides 90% of the world fish catch and its economic value has been recently estimated to comprise at least 40% of the total economic value of the world's ecosystem services and natural capital. Additionally, coastal areas contain large amounts of biodiversity. However, this region is changing rapidly under human influences; about 40% of the world's population lives within 100 km of the coastline. As a result, our goal is to create solutions that would mitigate the effects of these negative influences on coastal habitats and wild fish stocks. (Gattuso et al. 2007)
In this section, we will treat the coastal zone primarily as the freshwater bodies that drain directly to the sea, the land area influencing those water bodies, and waters on the continental shelf, especially estuarine waters (where salt and freshwater mix).
...
- Thermal discharge (discharge of hot water into a receiving body; often the water was used as coolant)
- Oil spills
- Waste-water disposal !stormflow.jpg|width=651,height=434!Source: USGS
...
C) Modifying natural ecosystems. High concentrations of sediments can dislodge fill spaces in the river bottom, displacing or smothering plants, invertebrates, and insects in the delta river bed. This directly affects the food source of fish, and can result in smaller and fewer fish.
...
It is concluded that elevated levels of sediment (typically over background) may be harmful to fish (i.e. acutely lethal, or elicit sublethal responses that compromise their well-being and jeopardize survival), and in addition, negatively impact their habitat. Criteria, guidelines and recommendations, though formulated by many different government agencies, tend to be mutually supportive. At the same time they have application limitations, especially relating to the protection of aquatic organisms from the effects of sediment concentrations of tens of mg- L-1. Application of the criteria must be done while recognizing potential impacts on aquatic organisms at both the lethal and the sublethal level. Particle size and nature of the sediment must be considered as well (Birtwell 1999).
...
Nutrients are required by aquatic ecosystems for primary production; plants, often algae, absorb these nutrients and use them to grow. These plants form the base of the food chain in aquatic ecosystems. However, excess nutrients, especially nitrogenous compounds, are carried by runoff from agricultural areas and cause a phenomenon called eutrophication. The nutrients over-fertilize the ecosystem and cause an explosion in algae population--an algal bloom. When this huge mass of algae dies, however, it consumes oxygen in its decomposition, lowering the dissolved oxygen content for the waterway in general. Because aquatic organisms cannot remove oxygen from air or from water molecules, they rely upon oxygen dissolved in the water to survive; if this oxygen is depleted, the aquatic community essentially asphyxiates. Eutrophication has been a major problem in estuarine areas, like the Chesapeake Bay in Maryland, USA and continues to be a problem in freshwater lakes and ponds as well.
...
Trace metals are required for aquatic life but in higher concentrations heavy metals such as iron, lead, mercury, aluminum, and magnesium are toxic to fish, especially at low pHs (PA FBC). One reason metal toxicity is such a problem is that no natural processes exist to neutralize or remove them (Chapman, 1996). Metals also tend to accumulate in bottom sediments (Chapman, 1996), which presents a problem if those sediments are later disturbed. Industrial wastewater discharges (point source) and mining are common metal sources, although metals like lead (from automobiles) can also come from atmospheric deposition. Aluminum, cadmium, chromium, copper, iron, mercury, manganese, nickel, lead, zinc, arsenic, and selenium are the commonly monitored "metals" although beryllium, thallium, vanadium, antimony, and molybdenum are also important to monitor if it is believed they will occur in an area a pollutant source is likely to discharge them (Chapman,1996).
- Detergents, pesticides, industrial toxins, pharmaceuticals, etc.
...
| Wiki Markup |
|---|
However, extraction of materials from ecosystems is also an issue in coastal zone management. Extraction of sediments or other mining operations causes severe changes in substrate composition and the overall habitat, not to mention the possible pollutant re-suspension involved in these operations (i.e. of sediments). Extraction of water itself also changes the aquatic ecosystem in many ways-\--both from a physical and chemical standpoint. Information about the effects of dams on water quality is \[here-\-LINK TO DAMS PAGE\]. |
To address these aspects of regulation, research needs to be conducted to the determine the relationship between the status of the physical environment and the functioning of the ecosystem. For example, with dredging or sediment extraction, the functional role of the substrate formations should be investigated to discover if the extraction would negatively impact critical spawning or other ecosystem services and if any predicted damages can be redressed. Findings of such studies should then be applied to minimize disturbance to the environment if the activity still needs to occur; the principle of "avoid, minimize, compensate" as advocated in the U.S. policy towards wetlands applies here.
...