[Annelid Research Resources]

[Previous IPC6 abstract]


POSTER - 6th International Polychaete Conference, Brazil, August 1998

CHARACTERISTICS OF THE SEDIMENT STRUCTURE AND DYNAMIC IN AN AREA USED BY THE POLYCHAETE LAEONEREIS ACUTA

Palomo, G. & Iribarne, O.

Departamento de Biología, Universidad Nacional de Mar del Plata, Argentina.

CC 573 Correo Central Mar del Plata, (7600), Argentina.

The distribution of most marine benthic invertebrates in sediment is, in part, controlled by substrate type and properties. Conversely, the macrofauna influences geochemical properties in sediments of coastal and continental shelf environments. Sediments and associated organic matter are mixed and altered trough burrowing, ingestion, and construction of temporary or permanent dwellings. In this paper, we examine the density of the nereid polychaete Laeonereis acuta and its distribution in the middle intertidal level, the amount of sediment removed and the daily transport of sediment. The study was carried out on the intertidal mudflats along Mar Chiquita coastal lagoon, Argentina (38º 00' S - 57º 30' E). We evaluated the amount of sediment produced in sediment mounds at mid tidal level in ten sample units of 0,04 m2 . The daily rate of the sediment removed was calculated in g m-2 day-1. To evaluate the effect of the polychaetes on the sediment dynamics of the estuary we studied the sediment movement using traps. In the study area the density of the nereid polychaete Laeonereis acuta was 1324 ind m-2 (sd= 851, n= 10) in the first 5 cm of depth in the sediment; 776 ind m-2 (sd= 404, n= 10) in the layer between 5 and 10 cm depth and 216 ind m-2 (sd= 159, n= 10) between 10 and 15 cm depth. The distribution of the sediment mounds was patchy; the mean distance between any two mounds was 13.03 mm (sd= 6.11, n= 220). The amount of sediment produced in mounds at the mid tidal level was 14.22 g m-2 day-1. The daily transport of sediment varied between 47.06 and 340.45 g m-2 day-1, and the associated meiofauna included nematodes (x= 0.03 ind m-2 day-1), copepods (x= 24.95 ind m-2 day-1), ostracods (x= 23.52 ind m-2 day-1), amphipods (x= 0.23 ind m-2 day-1) and polychaete larvae (x= 1.31 ind m-2 day-1). Bioturbators redistribute marine sediments in several ways: by transporting sediment to the surface in the form of feces, or in the process of tunnelling; and by transporting sediment horizontally during feeding activities.


[Next IPC6 abstract] [Back to list of IPC6 titles ]. Web abstracts engineered by Geoff Read, with content copyright IPA and Paulo da Cunha Lana.