Ocean warming has a negative impact on the condition of elephant seals, reveals a study published in the Open Access journal BMC Biology. High ocean temperatures observed from 1975 to the late 1990s are correlated with a 28% decrease in the weight of elephant seal pups. Elephant seals are shown to be sensitive to ocean temperature changes associated with both long-term 25-year cycles and short-term 3-4 year cycles such as those caused by El Niño.
Sea lions and fur seals that feed near their rookeries at the surface of the ocean are known to be very sensitive to water temperature changes, as an increase in water temperature usually causes their prey to migrate to cooler areas, depleting local food resources and resulting in pup starvation. Elephant seals, which feed in deep waters, were previously thought to be better buffered against ocean temperature changes than other sea mammals.
A study by Dr Burney Le Boeuf and Dr David Crocker from the University of California in Santa Cruz, shows that as waters get warmer the average weight of an elephant seal pup decreases. Weaning weights are a direct indicator of food availability to mother seals during their pregnancy. Because their prey has migrated to colder waters, female seals have to swim further and spend more time searching for food. As a result, they gain less body mass while pregnant and have fewer reserves to draw on during nursing. Nursing pups get all nourishment from their mothers; changes in ocean temperature therefore directly affect the weight, and the survival rate, of the pups.
To assess the impact of temperature changes on food availability to elephant seals, Le Boeuf and Crocker monitored the weight of 2750 elephant seal pups over a period of 29 years, from 1975 to 2004. During this time the ocean temperature increased to the highest on record in 1997-98, after the most intense El Niños of the century in 1982-83 and 1997-98, before cooling again in 2000.The pups, from a rookery located in central California, were weighed within 10 days of weaning.
Le Boeuf and Crocker’s results show that the pups’ mean weaning weight declined from 146 kg in 1976 to 115 kg in 1999. This coincided with an increase in mothers’ foraging time of about 36% (as well as a decrease in mass gained). After 1999, however, the declining trend abruptly stopped and the weaning weight of the pups increased to eventually reach 130 kg. This change coincided with the cooling of the ocean at the beginning of the new century.
"Despite ranging widely and foraging deeply in cold waters beyond coastal thermoclines in the northeastern Pacific, elephant seals are impacted significantly by ocean thermal dynamics", conclude the authors.
Le Boeuf and Crocker add that monitoring the mean weaning weight of elephant seal pups can therefore help track changes in ocean temperature cycles.
This press release is based on the article:
Ocean climate and seal condition Burney J Le Boeuf, Daniel E Crocker BMC Biology 2005, 3:9 (28 March 2005)
This article is available free of charge, according to BMC Biology’s Open Access policy at http://www.biomedcentral.com/1741-7007/3/9
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
100 % Organic Farming in Bhutan – a Realistic Target?
15.06.2018 | Humboldt-Universität zu Berlin
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
22.06.2018 | Life Sciences
22.06.2018 | Physics and Astronomy
22.06.2018 | Life Sciences