Spatio-temporal distribution of Atlantic searobins (Prionotus spp.) in relation to estuarine dynamics (Río de la Plata, Southwestern Atlantic Coastal System)

The relationship between the distributions of Atlantic searobins (Prionotus punctatus and Prionotus nudigula) and environmental factors was evaluated in the Southwestern Atlantic Coastal Ecosystem (34e41 S). Two hundred and forty-six sampling stations were analyzed between 1993 and 2000 at three different environmental scales (1000, 100, 10 km). The spatial patterns in the Atlantic searobins’ distribution were examined by means of cluster analysis while, the BIO-ENV process was used to estimate the associations of the species’ distribution with depth, bottom temperature and bottom salinity. The Atlantic searobin species have a persistent spatial distribution pattern in the coastal ecosystem. Prionotus punctatus inhabits the environment influenced by the estuarine waters of the Rı´o de la Plata, while P. nudigula inhabits the coastal shelf system, with wider depth ranges, lower bottom temperatures, and higher bottom salinity. Although both species show a persistent spatial distribution, the patterns change seasonally in an onshoreeoffshore direction, as well as in a northesouth direction. The bottom salinity has the greatest influence on the spatial distribution of both Atlantic searobins, with the variation of both distribution areas being mainly associated with the wind driven discharge of estuarine water from the Rı´o de la Plata.