(b) Benthic ecosystems

Destruction of the sea bed and benthic life through trawling.

The species diversity of pelagic ecosystems is low compared to benthic ecosystems.

Marine Micropaleontology 18 3 Emiliani C (1991) Planktic planktonic, nektic nektonic, benthic benthonic .

Rowe, Benthic biomass and surface productivity , Fertility of the Sea, J. D. Costlow, ed.

It is estimated that only 1 larva in every 20,000 survives to the benthic phase.

These can be broadly divided into the pelagic (water column) and the benthic (seabed) ecosystems.

These services include food production and provision of habitats for aquatic invertebrates, fish, benthic infauna and plants.

In addition, bottom fisheries are known to induce considerable damage to benthic habitats and other underwater features.

A distinctive fauna has been identified close to the seabed known as the hyper benthic or benthopelagic fauna.

These conditions will slowly spread into the creeks, with serious consequences to marine bottom dwelling species and benthic fauna.

And it's destroying that precious benthic community on the bottom, things like sponges and corals, that critical habitat for other animals.

The pelagic and benthic environments are high in biodiversity,5 suggesting a greater number of species exist in the sea than on land.

Bottom trawling in high intensity fishing areas can cause long term damage to the structure of the sea bed and to benthic life.

Based on the results of this survey, Saudi Arabia states that impacts of the 1991 oil spills persist in near shore subtidal benthic environments.

An abundance of large predators such as cetaceans are also attracted to these localities, which may be regarded as pelagic and benthic hot spots.

132 Koslow and Smith S. J. Hall, Is offshore oil exploration good for benthic conservation? , Trends in Ecology and Evolution, vol. 16, No. 1 (2001).

There are also emerging molecular, chemical, optical and acoustical technologies, which will help to improve the understanding of biological diversity in the pelagic and benthic environments.

152 Koslow and Smith P. A. Jumars, Limits in predicting and detecting benthic community responses to manganese nodule mining , Marine Mining, vol. 3, No. 1 2 (1981) K.

cit., 2001 R. Sharma and others, Sediment redistribution during simulated benthic disturbance and its implications on deep seabed mining , Deep Sea Research Part II, vol. 48, No. 16 (2001).

Some are extremely common one study in the coastal waters of southwestern Australia found that the four most abundant stingaree species constituted over 17 of the biomass of benthic fishes.

Deep water fisheries often target features, such as seamounts and ridges, where food inputs advected by topographically enhanced currents support benthic communities dominated by hard and soft corals, sponges and other suspension feeders.

It includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile, benthic existence.

While mining of crusts may be far more localized than that of nodules, the distribution of seamount benthic species may also be far more restricted.115 Management of mining effects must also take account of fishing activities.

The evidence provided by Iran to support its claim that there was a reduction in mangrove cover includes remote sensing evaluation of cover change, analysis of tree enzyme changes, benthic community analysis and chemical analysis of total petroleum hydrocarbons ( TPH ) and heavy metals.

Bottom trawls pick up these benthic communities as by catch or otherwise reduce them to rubble.110 Given the slow growth of deep water corals and uncertain rates of recruitment, the re establishment of deep water coral reefs will probably take centuries to millennia.

Many questions regarding diversity and distribution will require simultaneous studies in conventional and molecular taxonomy.50 Old records of species, including distribution information, are probably highly inaccurate.9 Revising classification of species will require a large amount of human effort, as sorting benthic macrofaunal and meiofaunal samples is a lengthy procedure and requires skilled parataxonomists.

Another autonomous underwater vehicle frequently used in deep sea explorations is the Woods Hole Oceanographic Institution vehicle ABE (Autonomous Benthic Explorer), which is intended for long duration deployment of up to one year.54 It runs on batteries and, at present, can survey the sea floor at depths up to 5,000 metres on dives lasting more than a day.

Trenches affect the sedimentation rates of nearby abyssal habitats by trapping sediment that would otherwise be transported to the abyssal plain where it could create perturbations, eradicating benthic assemblages on occasion, generating mosaics of isolated habitats within which speciation of taxa with limited dispersive ability occur, thus contributing to high regional diversity.14 The knowledge of how these events take place is poorly documented.

Direct injection of CO2 into the deep ocean is being considered for ocean depths greater than 500 metres, where CO2 may exist in liquid or solid gas hydrate form.143 The principal impact on mesopelagic and benthic ecosystems is likely to be reduced pH values and, for those organisms directly in the path of the CO2 plume, physiological stress caused by an elevated partial pressure of CO2.

Sanders and R. R. Hessler, Ecology of the deep sea benthos , Science, vol. 163 (1969) J. F. Grassle and N. J. Maciolek, Deep sea species richness regional and local diversity estimates from quantitative bottom samples , The American Naturalist, vol. 139, No. 1, vol. 2 (1992) P. J. D. Lambshead, Recent developments in marine benthic biodiversity research , Oceanis, vol. 19 (1993) G. C. B. Poore and G. D.

(New York, Gordon Beach, 1971) S. Emerson, Organic carbon preservation in marine sediments , Carbon Cycle and Atmospheric CO2 Natural Variations, Archean to Present, E. T. Sundquist and W. Broecker, eds. (Washington, D.C., American Geophysical Union, 1985) C. R. Smith and others, Latitudinal variations in benthic processes in the abyssal equatorial Pacific control by biogenic particle flux , Deep Sea Research Part II, vol. 44, No. 9 (1997).

Although hot spots in species diversity are located mainly in the subtropics, hot spots of productivity with a high importance to pelagic predators have also been located in temperate and polar zones.36 Hot spots should form natural focuses for conservation measures to protect both pelagic and benthic habitats, especially in the subtropics where the biodiversity across many trophic levels and groups of organisms is very high.37