POPULATION DYNAMICS AND SECONDARY PRODUCTION IN A SANDY BEACH POPULATION OF SCOLELEPIS SQUAMATA (POLYCHAETA : SPIONIDAE)
Souza, J.R.B.1,2 & Borzone, C.A.1
1Centro de Estudos do Mar, Universidade Federal do Paraná. Av. Beira Mar s/n, Pontal do Sul, Pontal do Paraná , PR, 83255-000, Brazil
2Curso de Pós-Graduação em Zoologia UFPR, bolsista do CNPq.
Scolelepis squamata is a common component of sandy beach environments. The species has a wide geographical distribution, occurring almost globally in tropical to temperate coastal waters. The species is dominant in Brazilian intertidal beaches, showing high tolerances to different environmental conditions. However, little is known of its population dynamics and secondary production. From February 1992 to March 1993, the distribution, population dynamics and secondary production of Spionidae in Atami Beach (South Brazil) was studied. The organisms were concentrated in a narrow band in the upper intertidal zone, reaching maximal densities of 20.277 individuals.m2. Peaks of abundance occurred in July 1992 and February 1993, with 318.735 and 91.680 inds.m-2, respectively. Ovigerous females were present all year round, but in the highest proportions in February and August. Two recruitment peaks were observed; one in April and the other in October. The population was shown to be multi-annual, with two identified cohorts. The average life-span was 0.49 and 0.66 year-1, and the mortality was 5.52 and 2.52, for each cohort, respectively. Mean annual biomass was 0.21 g m-2, and the total annual production was 0.545 g m-2 y. The P/B ratio was 2.97 y-1 which is relatively low, particularly when compared with other species of a similar life span. Scolelepis squamata therefore showed r-strategist characteristics (sensu McArthur), with a short life span, large reproductive effort, and a high dispersal capacity.