Temporal variability in the composition and biodiversity of free-living marine nematodes in a tropical beach (Ecuador)

Abstract:

Free-living marine nematodes are the dominant metazoans in sandy beaches and are considered as indicators for environmental changes. In order to detect the influence of environmental variables such as pluviosity, temperature, salinity, chlorophyll a, organic matter and median grain size on the nematode assemblages, inhabiting the lower tide level at an exposed Ecuadorian sandy beach were monthly sampled from June 2000 to July 2001, covering the dry (April-December) and rainy season (January-March). This period had undergone a strong La Nina cold event. Thirty seven nematode species belonging to 30 genera were found, with dominance of Daptonema and Metachromadora. those species has been reported from estuarine sites and they are able to tolerate salinity changes. The total nematode densities ranged from 359±11 ind./10 cm 2 (April 2001) to 1170±119 ind./10 cm 2 (June 2000), no significant differences between dry and rainy season were detected. The maximum nematode densities registered in Ecuador are 50% lower than in the beaches in the Mediterranean and North Sea, but 90% higher comparing with the Baltic Sea. The non-selective deposit feeders were the most abundant feeding group at the nematode community (43%), although with fluctuating dominance (4-90%). Based on the species composition analysis, sample groups were detected by ordination, reflecting the following temporal pattern:(I) June-December,(II) January and (III) February-May. Dissimilarities (71%) were found between the species of the group II and III, explained principally by highest densities of Daptonema sp. 1 (490±197 ind./10 cm 2 …

Año de publicación:

Keywords:

Fuente:

google