Article

Marine Biology

, Volume 92, Issue 4, pp 489-503

Nematode fauna in the sulphide-rich brine seep and adjacent bottoms of the East Flower Garden, NW Gulf of Mexico

IV. Ecological aspects
  • P. JensenAffiliated withMarine Biological Laboratory, University of Copenhagen

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Abstract

Nematodes sampled quantitatively in 1980 along a 96-m-long sulphide-rich brine seep gradient system in the NW Gulf of Mexico are characterized and compared with species from bottoms adjacent and beyond the influence of the brine. The age structure indicates permanent living populations within and outside the gradient system. Species composition shows a thiobiotic association and an oxybiotic association of nematodes, and each association is composed of two subgroups with a fifth group of species living in the ecotone. Such a distinction can also be shown in terms of dominance-diversity. The thiobiotic species are regarded as derived from their oxybiotic relatives and not the reverse. Nematodes describe environmental complexity since slenderness of the body correlates with the amount of dissolved sulphide in the environment. Body elongation, i.e. higher proportion of body surface area per unit body volume and shorter body radius, is suggested to be an adaptation to low oxygen tension in the environment as well as an adaptation to epidermal uptake of dissolved organic matter as additional nourishment of thiobiotic species. Analyses of buccal cavity structures and species distribution patterns show resource partitioning among most abundant species and congeneric species. Deposit feeders have a size diversity of buccal cavities similar to that of epistrate feeders and ominivore-predators. Deposit feeding prevails in the thiobios, but not in the oxybios.