|SS3.10 Ecological Implications of Terrestrial Inputs into Lakes and Ponds|
|Date: Tuesday, June 11, 2002|
|Time: 3:15:00 PM|
|Moreno-Amich, R, , University of Girona, Girona, Spain, firstname.lastname@example.org|
|Brucet, S, , University of Girona, Girona, Spain, email@example.com|
|Quintana, X, D, University of Girona, Girona, Spain, firstname.lastname@example.org|
|CHANGES IN THE SHAPE OF AQUATIC INVERTEBRATES’ BIOMASS-SIZE SPECTRA AT ECOLOGICAL SCALING IN A FLUCTUANT ECOSYSTEM (EMPORDĄ WETLANDS, NE SPAIN)|
|Organism abundance is inversely proportional to size, as show the biomass-size spectrum at the primary scaling (whole community). There is a secondary or ecological scaling identifiable at functional-group level (phytoplankton, zooplankton, fish) more closely linked to food requirements in relation to biomass density distributions and predator-prey size ratios. This ecological scaling is more obvious in lightly-structured and fluctuating systems, where the shape is variable from lineal to curved according to the ecological situation.
The biomass spectrum, at ecological scaling, of free-living invertebrates in a fluctuating basin of Empordą wetlands was analyzed by adjustment to a model based on the Pareto distribution. Under flooding conditions biomass-size spectra fit a lineal model (Pareto Type I) better, whereas in confinement conditions fit better a no lineal one (Pareto type II). These results suggest that under flooding conditions, nutrient and OM inputs cause population growth, especially of small-sized organisms, resulting in a linear spectrum. During confinement conditions interactions between species would acquire more relevance due to the lack of resources, favouring the displacement of biomass toward larger sizes. The result is a curved spectrum and a decrease of diversity.