Infaunal communities along a sediment moisture gradient in a hypersaline lake in Bonaire, Netherlands Antilles
From the abyssal plain to the intertidal zone, benthic fauna are adapted to a variety of extreme physical environments. Shallow water soft-sediment infauna must face rapid environmental changes that could result in fluctuations of oxygen levels, salinity, temperature, or water availability. In the case of closed systems where rainfall is the only significant source of water input, some infauna must adapt to desiccation and high levels of salinity. The result of this dynamic environment is an infaunal community demonstrating an evolutionary path of morphological and behavioral adaptations to periods of environmental stressors. The infaunal community structure of a hypersaline inland lake along a sediment moisture gradient was examined in Saliña Matijs, Bonaire, Netherlands Antilles. Saliña Matijs is a very shallow hypersaline lake comprised of soft, anoxic muddy sediment with a heavy algal layer consistently exposed to high heat intensity. The weather pattern on Bonaire results in high rainfall for short periods of time, followed by prolonged sun exposure. This results in a very dynamic environment where the lake becomes quickly expanded and irregularly saturates the drier sediments. Twelve infaunal core samples and four sediment samples (7.5 cm diameter, 5 cm depth) were collected at four locations with decreasing sediment moisture (20 m to -15 m from the water line). There were gastropod juveniles and adults at all locations, with higher numbers of juveniles in cores with lowest moisture content. The presence of fish scales in every core suggested the presence of a population of small fish. Cluster analysis results show the highest community similarity between the second driest core and the core taken 15 m into the lake.