FISH BEHAVIORS IN COMPLEX LANDSCAPES
FUNCTIONAL CONNECTIVITY FROM A REEF FISH PERSPECTIVE
There have been few studies on functional connectivity in marine organisms, despite its importance for the effectiveness of Marine Protected Areas.
- We translocated 102 individuals to sites varying in sand gap width and in configuration: Continuous, Detour (U-shaped reef path) and Patch.
- The probability of crossing the sand gap dropped below 50% when its width was >1.85 m in Detour and >3.90 m in Patch configuration.
- This study quantifies for the first time the size and steepness of a barrier to movement in a marine organism, and it provides evidence for effects of both landscape configuration and conspecific distribution on functional connectivity (see Turgeon et al. 2010).
fISH Anti-predator responses and tactics in complex landscapes
Flight initiation distance (FID) - the distance at which an organism begins to flee an approaching threat - is an important component of antipredator behavior. We used parrotfish species to test the effect of a diver on FID, escape speed - represented by the swimming gait; i.e. using the whole body propulsion or just the pectoral fins when fleeing, in relation to swimming capacity and body size. More particularly, we explore if antipredator traits are showing examples of compensation or co-specialization (see Miller et al. 2011). We also tested how escape responses change threat from humans (ex. protection status such as the Barbados Marine Reserve vs. reef experiencing spearfishing see Gotanda et al. 2009).
Factors limiting fish distribution, abundance and diversity
A squirrelfish, using its diurnal shelter
Many fish species spend all or much of their time closely associated with physical structure, such as clusters of algae, plants or coral, under rocks or in shells, caves, holes or the interstitial spaces of rubble. These “shelters”, may reduce predation risk, may provide feeding and reproduction sites and may offer protection from strong currents. For these reasons, shelters may be a limiting resource for coral reef fishes.
We examined microhabitat shelter use by Holocentrus rufus, a squirrelfish, and provide evidence of selectivity of refuges (see Ménard et al. 2008, for additional details). On a larger scale experiment, we quantified the abundance of shelters and estimated shelters availability on two reefs and explored how shelters abundance and availability relates to physical characteristics of the reefs and examined how shelter abundance and availability affect the abundance, occupancy and species richness of shelter-using fish (see Ménard et al. 2012).
We examined microhabitat shelter use by Holocentrus rufus, a squirrelfish, and provide evidence of selectivity of refuges (see Ménard et al. 2008, for additional details). On a larger scale experiment, we quantified the abundance of shelters and estimated shelters availability on two reefs and explored how shelters abundance and availability relates to physical characteristics of the reefs and examined how shelter abundance and availability affect the abundance, occupancy and species richness of shelter-using fish (see Ménard et al. 2012).
HABITAT SELECTION IN JUVENILE ATLANTIC SALMON
During my master degree, I compared the capacity of logistic regression and classification tree models to predict microhabitat use of active (i.e. feeding fish) and resting fish juvenile Atlantic salmon, Salmo salar, in a small stream in eastern Quebec (Gaspesia Peninsula).
We found that the spatial distribution of active fish differed markedly from that of resting fish, apparently as a result of the selection for water greater than about 30 cm depth by active fish and for the presence of rocky cover by resting fish. Large rocks are likely to be a limiting factor to juvenile Atlantic salmon abundance in small streams (see Turgeon and Rodriguez, 2005 for further details).
We found that the spatial distribution of active fish differed markedly from that of resting fish, apparently as a result of the selection for water greater than about 30 cm depth by active fish and for the presence of rocky cover by resting fish. Large rocks are likely to be a limiting factor to juvenile Atlantic salmon abundance in small streams (see Turgeon and Rodriguez, 2005 for further details).