Analysis of large-scale spatio-temporal trends of Ostrea puelchana beds in Northern Patagonian gulfs, Argentina

DOLDAN, MARÍA DEL S.; MORSAN, ENRIQUE M.; ZAIDMAN, PAULA C.; KROECK, MARINA A.

MARINE ENVIRONMENTAL RESEARCH

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2014 vol. 101 p. 196 - 207

0141-1136

Wild oyster populations have declined severely worldwide, however fluctuations of South Atlantic populations are poorly documented. We explored the changes in the abundance of Ostrea puelchana population of Northern Patagonia, Argentina, by linking data from palaeontological, archaeological and informal sources, with time series data from fishing, ecological and studies of oyster pathology. The focal area for this study is the San Matías Gulf (SMG, 40° 50´ to 42° 15´ S, 63° 5? to 65° 10´ W). Populations of O. puelchana were inferred from sub-fossil deposits (>700 years ago) throughout the gulf, but were documented in surveys a century ago only in the NW coast. More recently, new populations have established in the NE and southern regions of the gulf. We proposed that the O.puelchana populations of the NW of the SMG have declined as a consequence of epizootic infections by Bonamia exitiosa while populations of the NE of the gulf have expanded and increased apparently not influenced by dredge activities. Dredge fisheries for scallops took place in the 1970s and 1980s on the NE coast of the gulf but had a low impact on oyster beds. Coincident with epizootic infections by B. exitiosa and other possible local causes, oyster populations in the northwestern region declined after 1996. The southward expansion of oyster population at latitudes beyond the historical distribution range might reflect long-term adequate environmental conditions for larval survival on the NE and S of the SMG. On the other hand, oyster population contraction pattern on the NW coast of the gulf occurred at smaller spatial and temporal scale and was caused by local factors.