Ostracoda (Crustacea) as ecological indicators: a case study from Iberian Mediterranean brooks
Mezquita, Francesc; Griffiths, Huw I.; Domínguez, María I.; Lozano-Quilis, Miguel A.
published: Feb 15, 2001
ArtNo. ESP141015004001, Price: 29.00 €
Although ostracods are common inhabitants of most types of continental water bodies, their ecologies are generally poorly known. Despite this, there is a genuine need for data on species-habitat relationships, particularly because of the recent expansion of their use in Quaternary palaeoecology. We studied the responses of ostracod assemblages to environmental gradients in a variety of Mediterranean brooks. These differed in their geographical and geological settings, water chemistries and degrees of anthropogenic disturbance. The use of Canonical Correspondence Analysis (CCA) showed that the main sources of assemblage variation were related to the physical and chemical properties of the host environment. CCA separated species that inhabited chloride-rich, shallow streams on evaporitic rocks at medium altitudes, from deeper, lowland streams with higher carbonate than chloride contents. The second axis of CCA reflected ostracod species segregations derived from nutrient (nitrate) pollution of aquifers. It also showed a gradient from high altitude sites with high BMWP' values, to disturbed lowland sites that were nitrate-enriched and had high oxygen concentrations. Multivariate logistic regression showed that Sarscypridopsis lanzarotensis and Heterocypris salina both relate to waters with low alkalinities with respect to calcium and, in the former case, also to high relative chloride contents. Both species are good indicators of aquatic ionic composition, which is related to local geology. Our results also suggest that Herpetocypris brevicaudata, a common ostracod in the area, may be valid as indicator of clean waters. Despite these findings, further data are required before Ostracoda can be used effectively to monitor water quality. However, the present survey provides evidence that supports their potential in the assessment of the present and past conditions of flowing waters.