Abstract:
A novel classification system was applied to the
sea level anomaly (SLA) environment around Marion Island.
We classified the SLA seascape into habitat types and calculated
percentage of habitat use of ten juvenile southern elephant
seals (SES). Movements were compared to SLA and SLA
slope values indicative of ocean eddy features. This classification
provides a measure of habitat change due to seasonal
fluctuations in SLA. Some of the seals made two migrations in
different seasons, each of similar duration and proportions of
potential foraging behaviour. The seals in this study did not use
any intense eddy features, but their behaviours varied with SLA
class. Potential foraging behaviour was positively influenced
by negative SLA values (i.e. areas of below average sea surface
height). Searching behaviour during the winter was more likely
at eddy edges where high SLA slope values correlated with
low SLA values. Though the seals did not forage within newly
spawned eddies, they did forage near the sub-Antarctic front.
Plankton and other biological resources transported by eddies formed at the subtropical convergence zone are evidently concentrated
in this region and enhance the food chain there, forming
a foraging ground for juvenile SES from Marion Island.
