daveman
Diamond Member
Southern Elephant Seals of Maritime Antarctica
Hmmmm...
Background
Southern elephant seals (Mirounga leonina) are apex predators of Antarctic marine food webs; and the authors say that knowledge of the status of elephant seal populations "provides insights into the environmental status of Antarctica." Therefore, and seeking such knowledge ...
What was done
... Gil-Delgado et al. derived estimates of southern elephant seal subpopulation sizes on two beach areas of Byers Peninsula (Southern Beaches and President Beaches), which are believed to be the main distribution areas of the animals on Livingston Island (of Antarctica's South Shetland Islands), according to Aguayo and Torres (1967), who first monitored their populations there in the 1960s. The Gil-Delgado et al. team did much the same thing more recently via seal counts they conducted along numerous transects at a distance of 50 m from the shoreline (some in excess of 11 km in length), which they traversed on foot "using binoculars and approaching to large groups when spotted," between 22 December 2008 and 1 January 2009. And they indicate that the number of pups they counted was used to estimate the total elephant seal population by multiplying their numbers by a conversion factor of 3.5, which they note "has often been used in inventories of southern elephant seal populations," citing the studies of Laws (1994) and Lewis (1996).
What was learned
The eight Spanish researchers report that the final numbers they derived represent an increase of 150% since the sub-population they studied was first counted some 30 years ago.
What it means
Gil-Delgado et al. say that their "finding of an increased subpopulation on Byers Peninsula" suggests that "the entire South Georgia stock may also be increasing instead of being stable as currently assumed." In addition, they note that "the occurrence of southern elephant seals breeding in recent times and in areas located at higher latitudes, such as Anvers island (ASPA 113, 2009), suggests that the breeding range of this species is expanding." And, therefore, they conclude that "habitat availability for southern elephant seals in Antarctica could increase as a result of climate change, thus providing additional suitable breeding habitats," as suggested at the turn of the century by the observations of McMahon and Campbell (2000).
Southern elephant seals (Mirounga leonina) are apex predators of Antarctic marine food webs; and the authors say that knowledge of the status of elephant seal populations "provides insights into the environmental status of Antarctica." Therefore, and seeking such knowledge ...
What was done
... Gil-Delgado et al. derived estimates of southern elephant seal subpopulation sizes on two beach areas of Byers Peninsula (Southern Beaches and President Beaches), which are believed to be the main distribution areas of the animals on Livingston Island (of Antarctica's South Shetland Islands), according to Aguayo and Torres (1967), who first monitored their populations there in the 1960s. The Gil-Delgado et al. team did much the same thing more recently via seal counts they conducted along numerous transects at a distance of 50 m from the shoreline (some in excess of 11 km in length), which they traversed on foot "using binoculars and approaching to large groups when spotted," between 22 December 2008 and 1 January 2009. And they indicate that the number of pups they counted was used to estimate the total elephant seal population by multiplying their numbers by a conversion factor of 3.5, which they note "has often been used in inventories of southern elephant seal populations," citing the studies of Laws (1994) and Lewis (1996).
What was learned
The eight Spanish researchers report that the final numbers they derived represent an increase of 150% since the sub-population they studied was first counted some 30 years ago.
What it means
Gil-Delgado et al. say that their "finding of an increased subpopulation on Byers Peninsula" suggests that "the entire South Georgia stock may also be increasing instead of being stable as currently assumed." In addition, they note that "the occurrence of southern elephant seals breeding in recent times and in areas located at higher latitudes, such as Anvers island (ASPA 113, 2009), suggests that the breeding range of this species is expanding." And, therefore, they conclude that "habitat availability for southern elephant seals in Antarctica could increase as a result of climate change, thus providing additional suitable breeding habitats," as suggested at the turn of the century by the observations of McMahon and Campbell (2000).
Hmmmm...
