|Marine benthic hypoxia: a review of its ecological effects and the behavioural responses of benthic macrofauna|
Diaz, R.J.; Rosenberg, R. (1995). Marine benthic hypoxia: a review of its ecological effects and the behavioural responses of benthic macrofauna. Oceanogr. Mar. Biol. Ann. Rev. 33: 245-303
In: Oceanography and Marine Biology: An Annual Review. Aberdeen University Press/Allen & Unwin: London. ISSN 0078-3218, more
|Authors|| || Top |
- Diaz, R.J.
- Rosenberg, R., more
In this review the effects of hypoxia on benthic fauna are summarized and detailed information is given on (1) the impact on community structure and function in fjords, estuaries, coastal and offshore areas (2) behavioural changes (3) recovery processes (4) ecosystem energy flow implications, and (5) tolerance in experimental studies.There is no other environmental variable of such ecological importance to coastal marine ecosystems that has changed so drastically in such a short period as dissolved oxygen. While hypoxic and anoxic environments have existed through geological time, their occurrence in shallow coastal and estuarine areas appears to be increasing, most likely accelerated by human activities. Ecological problems associated with the occurrence of low oxygen are increasing on a global scale. The oxygen budgets of most major estuarine and coastal ecosystems have been adversely affected mainly through the process of eutrophication, which acts as an accelerant or enhancing factor to hypoxia and anoxia, and when coupled with adverse meteorological and hydrodynamic events, hypoxia increases in frequency and severity. The area of hypoxic and anoxic bottom water is even increasing within systems that historically are considered oxygen stressed. Many ecosystems that are now severely stressed by hypoxia appear to be near or at a threshold. Should oxygen concentrations become slightly lower, catastrophic events may overcome the systems and alter the productivity base that leads to fisheries species. Examples of such events are becoming increasingly common. At what point permanent damage will result is difficult to say. To dare there is no large system that has recovered after development of persistent hypoxia or anoxia. The only exception may be small systems where pollution inputs have ceased and recovery initiated from surrounding non-affected areas.The expanding occurrence of hypoxia and anoxia continues to bring about significant structural changes in benthic communities and to affect benthic-pelagic coupling. Restoring ecosystem balance and reversing the trend of increasing hypoxia and anoxia will require dealing with the global problem of coastal eutrophication and determining how to reduce the production of organic matter in sensitive estuarine and coastal areas.