PARENT SESSION
Poster Session 17: Modelling
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Macrophytes and invertebrate communities: fractal structure of plants and multifractal size spectra of invertebrates.

Momo, Fernando^*,2, Feijoó, Claudia¹, Casset, María¹, Doyle, Santiago¹, Álvarez, Analía¹, García, María¹, ² Instituto de Ciencias, Los Polvorines, Argentina¹ Programa de Investigación en Ecología Acuática, Luján, Argentina

ABSTRACT- We examined the relationships between the structural complexity of three submersed macrophytes (Egeria densa , Ceratophyllum demersum and Potamogeton striatus ), and the size spectra of their associated invertebrates. The plants were sampled with a 180 m net capturing all the invertebrate associated with each plant. Invertebrates were fractionated by size in six classes: upper 0.2, 0.5, 1, 2, 5, and 10 millimeters. For each class the number of individuals and the biomass (DW) were measured. The fractal dimension (D) of the plants were measured by the box counting method and show significant differences among plants, being C. demersum the most complex (D = 1.83), followed by E. densa (D = 1.75) and P. striatus (D = 1.59). Invertebrates size spectra, measured using both, biomass and diameter classes, were significantly different among plants but showed multifractal characteristics (non linear relationships between diameter class and numbers, and diameter class and group biomass) This fact suggests that size distribution can be driving by two factors: refuge availability (greater for the smaller species) and competitive interaction (dependent on size, metabolic rate, and food supply).

Key words: Fractals, Communities, Macrophytes, Invertebrates