La lapa pulmonada Siphonaria lessonii Blainville 1827 como bioindicador de contaminación ambiental: ¿Cuáles son los biomarcadores más apropiados?

LANDRO, SONIA M.; TESO, VALERIA; ARRIGHETTI, FLORENCIA

Congreso; X CLAMA Congreso Latinoamericano de Malacología; 2017

The pulmonate limpet Siphonaria lessonii has a wide distribution in South America, and is the most abundant gastropod in the rocky intertidal in the coast of Buenos Aires. Recent studies have evaluated the use of this species as a bioindicator of pollution,nevertheless, little is known about the effects of pollutants on the digestive gland (DG) and the effects on external features. Thus, the aim of the present study is to evaluate the presence of tissue-level biomarkers in this gastropod´s DG and analyse external morphological variations, including the presence of microstructural alterations in the shell. The study was performed in three populations exposed to different degrees of anthropogenic impact in the coast of Buenos Aires (Villa Gesell: reference zone, Mar del Plata Faro: mid-impacted zone, Mar del Plata Port: highly-impact zone). Samplings were collected from April 2014 to April 2015 during the lowest tides and only adult specimens (>8 mm in length) were included in the analysis. Small portions of DG from 30 specimens from each locality were fixed in Bouin?s solution, dehydrated, embedded in Historesin® (Leica?) and cut at 5 µm. Finally, the slides were stained with hematoxylin-eosin and examined under light microscopy. A shell geometric morphometric analysis was performed through an Elliptic Fourier Analysis and PCA, to study morphological variations; whereas small portions of the shells were observed under SEM and EDS analysis to study microstructural alterations. Finally, individual shell thickness was measured (n= 10) under a stereomicroscope to the nearest 0.01 mm. Our results indicate that four different cell types are present in the DG of S. lessonii: digestive, basophilic, vacuolated and pigmented cells. In specimens that live in a highly impacted area several histopathological alterations in the epithelium were observed including: increase number of pigmented cells, changes in the morphology of vacuolated cells and evidence of a high inflammatory response. The external alterations observed were shell morphometric variations and a decrease in the thickness of the shells in the highly-impacted area. No changes in elemental composition were found.