PARENT SESSION
Contributed Oral Session 69: Marine Ecology: Habitat; Communities
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal

Scale-dependent role of physical factors on abundance patterns of benthic intertidal invertebrates.

Pech, Daniel^*,1, Bourget, Edwin², Ardisson, Pedro-Luis³, ¹ Québec-Océan, Québec, Québec, Canada² Vice-rectorat à la recherche, Sherbrooke, Québec, Canada³ CINVESTAV-IPN, Mérida, Yucatan, Mexico

ABSTRACT- In order to illustrate the utility of the multi-scale approach in ecology, we examined the change in the influence of selected physical variables on abundance of benthic intertidal species through the horizontal axis of distribution as a continuous function of spatial scale. Local spatial scales were considered at three latitudinal sites (subarctic, temperate, and tropical). The study design consisted on sampling contiguous quadrats along 100 m transects by means of digital photography. Species abundance was estimated using digital image analysis. Substratum topography, heterogeneity, orientation and temperature, and wave force, were measured and registered as physical variables. Subsampling routines were developed to generate different scale scenarios (n=20) by modifying the extent (the total area included in the study) of the observations. Results showed that physical factors and species abundance differ in their respective scales of variability. Substratum topography and heterogeneity played an important role at almost all the scale scenarios and species considered. Overall, the study shows that the selected physical variables examined have a major influence in the species abundance at spatial scales smaller than 5 m, independently of species and latitudinal sampling sites.

Key words: Scale-dependence, benthic species, physical factors, pattern