Carbon Flows Through the Pelagic Sub-food Web in Two Basins of the Chilean Patagonian Coastal Ecosystem: the Significance of Coastal–Ocean Connection on Ecosystem Parameters

Abstract

The fjords and channels of the Chilean Patagonia are unique, and their high biological diversity is mainly associated with physicochemical characteristics of local water masses. The topography, depth, and extension of the Patagonian basins affect the extent to which water is exchanged between the inner and outer parts of the fjords, determining the marine productivity, biomass levels and energy flows through the pelagic food web. Coastal basins with high connectivity to the adjacent ocean and nutrient supply (e.g., the Inner Sea of Chiloe (ISCh)) might be predicted to have higher productivity and biomass than the relatively shallow, small-sized fjords and channels (e.g., Moraleda Channel (MCh)). To determine the ecotrophic and ecosystem-level similarities and differences of these two basins, we built two static and mass-balanced trophic models using Ecopath software. The models of planktonic communities were based on data collected during three scientific cruises conducted in 2006 and 2007. Diet, secondary production, and consumption rates were obtained from previously published data. The models’ results suggested that areas adjacent to the ocean (ISCh) had 61 % higher biomass, 44 % more biomass consumed, and a 17 % greater efficiency in the transfer of energy than inshore (MCh) areas. By characterizing the trophic position and linkages of the planktonic groups with a multi-taxa approach, we were able to analyze the roles of key species and functional groups that modulate the described biomass and energy flows under different conditions in two basins of the Chilean Patagonian coastal system.