Patterns of meiofauna (especially nematodes) in physical disturbed Ecuadorian sandy beaches

Meiofauna was studied at two sandy beaches along the Ecuadorian coast between August 1999 and February 2001 (with seasonal intervals), a sheltered beach with high recreational use and an exposed beach with fishing activities. Meiofauna densities ranged between 376 and 2388 ind./10 cm2. Despite La Niña event, no clear seasonal trends could be detected in the meiofauna abundances. Nematodes represented between 21-81 % of the total meiofauna at the sheltered beach and 76-95 % at the exposed beach, followed by turbellarians and gastrotrichs. A total of 40 genera belonging to 19 families were identified. and Omicronema were the dominant genera at the sheltered beach, while Metachromadora, Rhynchonema, Paracyatholaimus, Ceramonema and Gonionchus were more dominant at the exposed site. Despite the different genus composition, the general genus diversity was similar in both sites. However, a clear difference was present in the feeding types Non-selective deposit feeders were dominant (42 %) followed by predators/ omnivores (26 %) and epistrate feeders (24 %). Multivariate analysis demonstrated that the meiofauna and nematode communities remain different between the two beaches with regard to the temporal variation as well: so each beach, although only 28 km apart from each other but clearly different in sediment texture, does have an own meiofauna and nematode composition