INFLUENCE OF NITROGEN AND HALIMEDA-OPUNTI A (CHLOROPHYTA) ON THE ABUNDANCE OF POTAMILLA SP (POLYCHAETA, SABELLIDAE) IN FIELDS OF THALASSIA-TESTUDINUM

Nitrogen, as a nutrient, is considered a rate-limiting factor. Additio nally to the pool nutrients. abundance of particular species can be de termined by biomass of seagrass and plant architecture, including alga e associated to Thalassia meadows. To test this, three sampling statio ns of T testudinum beds were studied at Morrocoy National Park Venezue la (10-degrees 52'N-69-degrees 16'W). At each, a 20 X 20 meter plot wa s marked permanently and, at least, ten random quadrats were sampled m onthly during 13 months. Nitrogen contents in sediments arid biomass o f H. opuntia influence positively the abundance of Potamilla sp. (A= 2 1.49; B= 6.0; C= 1.05). Both parameters showed the following gradient: A>B>C (r= 0.6549; p<0.01). The influence of the algae was noted parti culary on the Morisita dispersion index (Ig).