Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island
The response of altered sex ratio in southern elephant seals due to environmental stress was analysed. Data were collected at King George Island from 1980 to 1994. Significant retreats in the ice cover during El Niño events strongly suggest environmental stress during this period along the Bellingsh...
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ftunibueairesbd:paper:paper_01718630_v268_n_p293_Vergani 2023-05-15T13:42:26+02:00 Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island Bilenca, David Norberto 2004 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01718630_v268_n_p293_Vergani https://hdl.handle.net/20.500.12110/paper_01718630_v268_n_p293_Vergani unknown https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01718630_v268_n_p293_Vergani http://hdl.handle.net/20.500.12110/paper_01718630_v268_n_p293_Vergani El Niño ENSO King George Island La Niña Mirounga leonina Sex ratio Southern elephant seals El Nino La Nina pinniped Antarctica South Shetland Islands elephant Mammalia Phocidae Pinnipedia 2004 ftunibueairesbd https://doi.org/20.500.12110/paper_01718630_v268_n_p293_Vergani 2023-02-16T01:59:16Z The response of altered sex ratio in southern elephant seals due to environmental stress was analysed. Data were collected at King George Island from 1980 to 1994. Significant retreats in the ice cover during El Niño events strongly suggest environmental stress during this period along the Bellingshausen Sea, a zone where female elephant seals from King George Island feed during their pregnancy. Randomly chosen weaning elephant seal pups (n = 1178) were sexed at Stranger Point (King George Island, 62° 14' S, 58° 30' W) over 5 km of beach from 1985 to 1994. Adult sex ratio was also determined annually from 1980 to 1994 as the ratio between maximum number of bulls and females on land. The theoretical pup sex ratio was assumed as 1:1 according to background information. Adult sex ratio was calculated as 1:6. To define the occurrence of El Niño Southern Oscillation (ENSO) during the study period, a sea surface temperature (SST) index called 'Niño 3.4' for the region 5°N to 5° S, 120° E to 170° W was considered. Monthly SST anomalies were obtained from the Climate Prediction Center (CPC, NOAA). To provide an annual index of anomaly strength (IAS), the monthly adjusted oscillation index climatology (AOIC) was averaged. Accumulated values during the whole study period showed that during El Niño years (1987, 1991, 1992) the proportion of pups was significantly biased in favour of females (p < 0.01). During normal years (1986, 1990, 1993, 1994) and La Niña years (1985, 1988, 1989), accumulative values showed a greater proportion of male pups to females (p < 0.05), Using the 1:1 hypothesis, we found during El Niño years a 9% reduction in the male segment, whereas in non-El Niño years a recovery of 7 % was observed (3 % during normal years and 4 % during La Niña years. To see the influence of accumulative values of pup sex ratio in adult sex ratio, a theoretical adult proportion was calculated as 1:6. To test this hypothesis, information on adult sex ratio taken from King George Island between 1980 and 1994 (n = 14 ... Other/Unknown Material Antarc* Antarctica Bellingshausen Sea Elephant Seal Elephant Seals King George Island Mirounga leonina South Shetland Islands Southern Elephant Seals Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires) Bellingshausen Sea King George Island South Shetland Islands Stranger Point ENVELOPE(-58.618,-58.618,-62.262,-62.262) |
institution |
Open Polar |
collection |
Biblioteca Digital FCEN-UBA (Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires) |
op_collection_id |
ftunibueairesbd |
language |
unknown |
topic |
El Niño ENSO King George Island La Niña Mirounga leonina Sex ratio Southern elephant seals El Nino La Nina pinniped Antarctica South Shetland Islands elephant Mammalia Phocidae Pinnipedia |
spellingShingle |
El Niño ENSO King George Island La Niña Mirounga leonina Sex ratio Southern elephant seals El Nino La Nina pinniped Antarctica South Shetland Islands elephant Mammalia Phocidae Pinnipedia Bilenca, David Norberto Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island |
topic_facet |
El Niño ENSO King George Island La Niña Mirounga leonina Sex ratio Southern elephant seals El Nino La Nina pinniped Antarctica South Shetland Islands elephant Mammalia Phocidae Pinnipedia |
description |
The response of altered sex ratio in southern elephant seals due to environmental stress was analysed. Data were collected at King George Island from 1980 to 1994. Significant retreats in the ice cover during El Niño events strongly suggest environmental stress during this period along the Bellingshausen Sea, a zone where female elephant seals from King George Island feed during their pregnancy. Randomly chosen weaning elephant seal pups (n = 1178) were sexed at Stranger Point (King George Island, 62° 14' S, 58° 30' W) over 5 km of beach from 1985 to 1994. Adult sex ratio was also determined annually from 1980 to 1994 as the ratio between maximum number of bulls and females on land. The theoretical pup sex ratio was assumed as 1:1 according to background information. Adult sex ratio was calculated as 1:6. To define the occurrence of El Niño Southern Oscillation (ENSO) during the study period, a sea surface temperature (SST) index called 'Niño 3.4' for the region 5°N to 5° S, 120° E to 170° W was considered. Monthly SST anomalies were obtained from the Climate Prediction Center (CPC, NOAA). To provide an annual index of anomaly strength (IAS), the monthly adjusted oscillation index climatology (AOIC) was averaged. Accumulated values during the whole study period showed that during El Niño years (1987, 1991, 1992) the proportion of pups was significantly biased in favour of females (p < 0.01). During normal years (1986, 1990, 1993, 1994) and La Niña years (1985, 1988, 1989), accumulative values showed a greater proportion of male pups to females (p < 0.05), Using the 1:1 hypothesis, we found during El Niño years a 9% reduction in the male segment, whereas in non-El Niño years a recovery of 7 % was observed (3 % during normal years and 4 % during La Niña years. To see the influence of accumulative values of pup sex ratio in adult sex ratio, a theoretical adult proportion was calculated as 1:6. To test this hypothesis, information on adult sex ratio taken from King George Island between 1980 and 1994 (n = 14 ... |
author |
Bilenca, David Norberto |
author_facet |
Bilenca, David Norberto |
author_sort |
Bilenca, David Norberto |
title |
Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island |
title_short |
Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island |
title_full |
Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island |
title_fullStr |
Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island |
title_full_unstemmed |
Effects of El Niño and La Niña events on the sex ratio of southern elephant seals at King George Island |
title_sort |
effects of el niño and la niña events on the sex ratio of southern elephant seals at king george island |
publishDate |
2004 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01718630_v268_n_p293_Vergani https://hdl.handle.net/20.500.12110/paper_01718630_v268_n_p293_Vergani |
long_lat |
ENVELOPE(-58.618,-58.618,-62.262,-62.262) |
geographic |
Bellingshausen Sea King George Island South Shetland Islands Stranger Point |
geographic_facet |
Bellingshausen Sea King George Island South Shetland Islands Stranger Point |
genre |
Antarc* Antarctica Bellingshausen Sea Elephant Seal Elephant Seals King George Island Mirounga leonina South Shetland Islands Southern Elephant Seals |
genre_facet |
Antarc* Antarctica Bellingshausen Sea Elephant Seal Elephant Seals King George Island Mirounga leonina South Shetland Islands Southern Elephant Seals |
op_relation |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01718630_v268_n_p293_Vergani http://hdl.handle.net/20.500.12110/paper_01718630_v268_n_p293_Vergani |
op_doi |
https://doi.org/20.500.12110/paper_01718630_v268_n_p293_Vergani |
_version_ |
1766167766508765184 |