Growth of the pulmonate limpet Siphonaria lessoni (Blainville) in a rocky intertidal area affected by sewage pollution

TABLADO, A.; LÓPEZ GAPPA, J.; MAGALDI, N.H.

JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY

Elsevier

Año: 1994 vol. 175 p. 211 - 226

0022-0981

Growth of Siphonaria lessoni (Blainville) was studied at two rocky intertidal sites near Quequén (38º 35’ S, 58º 42’ W), Argentina. One of them was severely affected by sewage pollution and the other was located in a natural area without visible signs of organic enrichment. Results obtained through periodical sampling, recapture of marked specimens and controlled reciprocal translocations between both areas demonstrated increased growth (9.7 mm after one year) and low densities in the vicinity of the outfall. This area is characterized by an abundance of cyanophytes, diatoms and opportunist, ephemeral green algae, and also by the total absence of the mytilid Brachidontes rodriguezi (d’Orbigny). On the other hand, in unpolluted areas monopolized by B. rodriguezi at mid-intertidal levels, densities were high and growth was slower (6.2 mm after two years). Growth was also increased in specimens experimentally transported or swept by waves from the mussel community to tide pools dominated by the green algae Ulva latuca L. Growth in the natural environment or in enriched areas was remarkably lower than values reported in a previous study on floating substrata within Mar del Plata (38º03’ S, 57º33’ W) harbour (19.5 mm after one year). A positive correlation between growth and mortality rates was observed. Due to considerable habitat-induced variations in growth rates, estimation of age as a function of size in this species may be unreliable without taking into account the surrounding environment. Results obtained in the present study emphasize the influence of primary production and of the presence of other sessile organisms on the population dynamics of S. lessoni.