PARENT SESSION
Contributed Oral Session 150: Evolutionary Ecology: Landscapes and Habitat
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal
Using small scale patchiness to predict large scale habitat patterns in marine grassbeds.
Gerrish, Gretchen*,1, 1 Cornell University, Ithaca, NY
ABSTRACT- From the human perspective, continuous habitats are areas that appear superficially identical and connected across a generally larger range (e.g. deciduous forest, open pelagic ocean, prairie). However, seemingly continuous habitats often contain patchy distributions of organisms and apparent physical structure when sampled at finer scales. Minor spatial variation may have large impacts on the movement and distribution of organisms that are small in relation to a large continuous habitat. I examine patchy distributions of small marine organisms in an apparently continuous habitat along the crest of the meso-American reef. Within my area of study, surrounding South Water Caye, Belize, grassbeds compose almost 80% of the substrate in a 5x5 km2 area. Although there are sporadic patch reefs and islands, turtle grass covered substrate is dominant and interconnected in the majority of areas. One resident of the seemingly continuous, homogenous grassbed habitat is a small (2 mm) bioluminescent ostracod (Photeros sp A.) found in high abundance (>100/m2) in many locations throughout the grassbeds. Distribution sampling shows ostracods have patchy abundance throughout the grassbed and that abundances may be correlated with multiple interacting fine scale physical factors, such as depth, water flow and turtle grass density. Mark and recapture studies also indicate that minor variation in water flow and turtle grass density could influence movement direction and frequency of dispersal. Additionally, juvenile instars of Photeros disperse and forage at different times than adult instars, meaning habitat interactions are both scale and life history dependant. Based on multiple empirical point measures of distribution and dispersal, taking microhabitat variation into consideration, I build a geographic information system to model predicted large scale habitat patterns.
Key words: spatial ecology, marine, GIS