SHORT COMMUNICATION Landscape-scale disturbance and protected areas: long-term dynamics of populations of the shrimp, Macrobrachium olfersi in lowland Neotropical streams, Costa Rica

Freshwater migratory shrimps, an important component of tropical aquatic ecosystems, are vulnerable to land-use change during their upstream and downstream migrations. At La Selva Biological Station in the Sarapiqu´ region of Costa Rica, shrimp population data were collected between 1988 and 1989, before massive land-use change occurred downstream that could potentially affect shrimp recruitment upstream. Using generalized linear models and a Bayesian inference framework, the relative abundance of Macrobrachium olfersi between recent (2008-2011) and historicaltimeperiods(1988-1989)wascomparedinthreestreamreaches.Shrimprelativeabundanceintwostream reaches within the protected area of La Selva was relatively constant yearly and between recent post-disturbance (2008-2011) and historical pre-disturbance (1988-89) time periods. In contrast, a stream reach bordered by pasture accessible to fishermen, showed an 87% decrease in relative abundance between recent and historical time periods suggesting site-level disturbance, possibly from fishing. The lack of change between historical and contemporary sampling periods within interior-forest stream reaches suggests that shrimp populations in protected forested reaches are resistant or resilient to certain land-use changes occurring downstream.