Population dynamics of the native oyster Ostrea puelchana d'Orbigny, 1842 in north-Patagonian gulfs, Argentina: a multiscale spatial approach

Abstract

Global losses of oyster populations urgently necessitate evaluating the status of underdocumented populations. The north-Patagonian Ostrea puelchana metapopulation changed in recent decades: certain beds grew and expanded; others became depleted by the Bonamia exitiosa epizootic. We surveyed eight oyster beds from the San Matías and San Jos´e gulfs; assessing the extension, demographic structure, and density-distribution pattern of each. We integrated biologic and environmental data on different spatial and temporal scales. Beds from the northestern and southern coasts continued expanding; while the northwestern beds— decimated by B. exitiosa in mid-1990—evidenced signs of recovery. We observed an en velope relationship between adult density and carriage incidence, suggesting a density-dependent compensation. Temporal data revealed decreased mean O. puelchana shell heights during recent decades. We discuss the success of extractive closures for long-term management and stress the effectiveness of a multiscale approach to determine the density-dependent processes structuring and driving marine-bivalve–population development.