Mecki Kronen

Human-Mediated Loss of Phylogenetic and Functional Diversity in Coral Reef Fishes

Beyond the loss of species richness, human activities may also deplete the breadth of evolutionary history (phylogenetic diversity) and the diversity of roles (functional diversity) carried out by species within communities, two overlooked components of biodiversity. Both are, however, essential to sustain ecosystem functioning and the associated provision of ecosystem services, particularly under fluctuating environmental conditions. We quantified the effect of human activities on the taxonomic, phylogenetic, and functional diversity of fish communities in coral reefs, while teasing apart the influence of biogeography and habitat along a gradient of human pressure across the Pacific Ocean. We detected nonlinear relationships with significant breaking points in the impact of human population density on phylogenetic and functional diversity of parrotfishes, at 25 and 15 inhabitants/km(2), respectively, while parrotfish species richness decreased linearly along the same population gradient. Over the whole range, species richness decreased by 11.7%, while phylogenetic and functional diversity dropped by 35.8% and 46.6%, respectively. Our results call for caution when using species richness as a benchmark for measuring the status of ecosystems since it appears to be less responsive to variation in human population densities than its phylogenetic and functional counterparts, potentially imperiling the functioning of coral reef ecosystems.

Surveying seafood consumption - a methodological analysis

This paper addresses the need to establish a fast, effective and reliable method for collecting fish and seafood consumption data at the village level. Two different approaches, a community participatory and a classical survey one were tested and validated against each other. Using fully structured questionnaire surveys also reliability of results obtained from household and individual interviews were compared. Furthermore, taking fresh fish consumption as an example, three different methods were assessed to approximate best per capita consumption. Approaches and methods are validated in terms of time and human resource requirements, and data quality by comparing data sets obtained in Polynesian and Melanesian communities. Adding efficiency criteria, adoption of household average consumption surveys is concluded to best combine reliable data and least time and financial requirements. Per capita fresh fish consumption was found to best estimated using a simplified WHO system that takes into account gender-age correction factors.