First survey of macroinfauna in the Mar del Plata Harbor (Argentina), and the use of polychaetes as pollution indicators

Abstract

Harbors share a number of similar problems, such as water and sediment pollution. In this work we analyze spatial variation of macroinfauna, with special emphasis in polychaete abundance to characterize the environmental health of Mar del Plata Harbor. Twelve stations were sampled with replicated 0.05 m 2 van Veen grabs, with environmental variables from the water column and sediments in December 2001. Polychaetes (23 of 35 taxa) constituted 62% of the total abundance. A multi dimensional scaling analysis and a redundancy analysis showed three groups of stations: one at the mouth of the port, with healthy environmental conditions and characterized by Mediomastus sp., Maldanidae and Aglaophamus uruguayi; other in the inner harbor, with poor environmental conditions and inhabited only by Capitella capitata sp., and a third intermediate and more diverse group with Polydora spp., Tharyx sp., Mediomastus sp., Capitella capitata sp., and Capitella sp. Differences among pre-defined groups were significant. It is hypothesized that strong hydrodynamics affects the stations at the mouth, as shown by low organic content and the dominance of sandy sediments. In the inner harbor, poor environmental conditions are due to restricted water movement, prevalence of silt sediments, and high content of pollutants. Abundance of Capitella spp. correlated to total organic carbon content, except in the inner harbor. It is possible that high concentrations of hydrocarbons in the inner harbor explain the low abundance of these species, as well as the absence of other benthic animals, and the low diversity values. Polychaetes are useful pollution indicators in this harbor.