Abstract
Suspension feeders (mollusks) are currently by far the world’s largest marine non-fed cultured production of animals [14]. This vast production capacity relies on their capacity to exploit the largest trophic resource in the marine environment, the seston. The seston comprises plankton and inorganic and organic matter in suspension. This multifaceted food resource varies on spatial and temporal scales with respect to concentration, biopolimeric composition, energy content and nutritional value [2-7, 9].
The seston food source, and the ecological and physical processes that control this food supply, fuels growth, sets the production capacity and determines the ecological carrying capacity of low trophic animal aquaculture [7, 8, 10, 11]. However, a unifying approach for quantifying this food resource that can explain growth, production and ecological carrying capacity is currently lacking.
Proxies of seston abundance and nutritional quality are typically converted to energy content units (J g-1) using a constant factor to estimate the capacity of the food supply to support bivalve production. The factors commonly used are 47.7 J mg-1 for phytoplankton carbon [16] and 23.4 J mg-1 for living organic “particle” [15]. There are few published studies on the energy content of mixed seston [1, 6, 12, 13, 17, 18] and to our knowledge none that has directly measured the temporal energy content of seston. Since the temporal variation in the relationship between the food proxy and the actual energy content of the seston is not known, there is a large potential for erroneous interpretation of the capacity of the ambient food resource to support aquaculture.
The presentation will summarize the temporal (interannually) variation in energy content of marine costal seston as determined by direct calorimetry.
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