24 December 2009
"Protecting even small patches of water can provide conservation benefits, as long as we choose the spots wisely," said Erin Ashe, author of a recent publication on the behaviour of killer whales (in British Columbia and Washington State) and marine protected areas.
Ashe and colleagues suggested that even small protected areas, identified through feeding behaviour, can benefit highly mobile marine predators such as killer whales. They indicated this after mapping locations where killer whales were observed feeding, socializing and resting, and identifying a small area in which whales were almost three times as likely to be feeding as they were in the rest of the region.
Protecting this little area could be crucial for two reasons. First, Chinook salmon, the favourite prey of this cetacean population, has declined in the region. Second killer whales are more disturbed by boat traffic when engaged in feeding activities than when they are travelling. Researchers think that management strategies to protect feeding hotspots should give greater conservation benefits than a generic habitat protection.
Ashe E., Noren D.P., Williams R. 2009. Animal behaviour and protected areas: habitat conservation for an endangered killer whale population. Animal Conservation. DOI:10.1111/j.1469-1795.2009.00321.x
For more information:
21 December 2009
Between December 10th and 11th seven sperm whales stranded and died - on the northern coast of the Gargano Peninsula (Apulia, Italy). They were all sub-adult males.
After several meetings the experts decided what to do with the dead animals, but in the meantime the carcasses are still on the beach. Each animal will be cut into parts. Carcasses will then be buried and covered with ground and lime. The decomposition process is expected to complete in one year. At the end of this period the skeletons will be recovered, treated and displayed in museums.
Numerous hypotheses were made regarding the causes of the stranding, from plastic ingestion to seismic surveys, seaquakes, etc. But the fact is: the reasons are still unknown and the experts are working hard to find out.
19 December 2009
A recent review describes how the Mediterranean Sea could offer an idea of the disastrous future of the oceans.
This review of more than 100 studies on the Mediterranean’s changing ecological dynamics, describes the convergence of climate change and human impacts in waters that had been stable since the time of Aristotle.
Rising temperatures, disrupted deep-water hydrology, overfishing, shrinked food-webs, mass die-offs, diseases and pollution are some of the threats that are affecting the Mediterranean Sea. Other sea areas on Earth may not escape from this sad degradation destiny. The future doesn’t look so nice...
Lejeusne C., Chevaldonné P., Pergent-Martini C., Boudouresque C.F., Pérez T. 2009. Climate change effects on a miniature ocean: the highly diverse, highly impacted Mediterranean Sea. Trends in Ecology and Evolution. doi:10.1016/j.tree.2009.10.009
Little doubt is left that climate change is underway, strongly affecting the Earth's biodiversity. Some of the greatest challenges ahead concern the marine realm, but it is unclear to what extent changes will affect marine ecosystems. The Mediterranean Sea could give us some of the answers. Data recovered from its shores and depths have shown that sea temperatures are steadily increasing, extreme climatic events and related disease outbreaks are becoming more frequent, faunas are shifting, and invasive species are spreading. This miniature ocean can serve as a giant mesocosm of the world's oceans, with various sources of disturbances interacting synergistically and therefore providing an insight into a major unknown: how resilient are marine ecosystems, and how will their current functioning be modified?
For more information:
14 December 2009
12 December 2009
Between Thursday 10 and Friday 11 December a pod of seven sperm whales stranded on the coast of the Gargano Peninsula (Italy), in the Adriatic Sea.
The animals, including several males of 10+ m, are scattered along a stretch of about six km of beach. Five have already died.
Scientists from the Centro Studi Cetacei, the Natural History Museum of Milan, and the Italian universities of Bari, Padua, Pavia and Siena, among others, are on site and coordinate operations and scientific analyses.
Giovanni Bearzi and Silvia Bonizzoni, who live in Apulia not too far from the stranding area, went to have a look.
See what they found:
The water then returned: what started like a trickle, later became an event of biblical proportions which filled the Mediterranean in under two years. At peak times, the sea level rose by up to ten meters a day - the largest known flood in Earth's history.
Daniel Garcia-Castellanos of the Jaume Almera Institute of Earth Sciences in Barcelona, Spain, and colleagues, who published their work on Nature, estimate the peak flow to have been around 1000 times higher than the present Amazon river at its highest rate.
Eleonora de Sabata
For more information:
- Catastrophic flood of the Mediterranean after the Messinian salinity crisis
- Castellano's page
11 December 2009
Blue whales are not singing as they were used to do. Their songs’ tonal frequency is decreasing every year by a few fractions of an hertz.
Global warming, noise pollution, changing population dynamics and new mating strategies are the possible reasons, but none of these hypotheses provide a full explanation and researchers have not yet found the real clue.
McDonald M., Hildebrand J., Mesnick S. 2009. Worldwide decline in tonal frequencies of blue whale songs. Endangered Species Research 9:13-21.
Blue whale Balaenoptera musculus songs can be divided into at least 10 types worldwide, each type retaining the same units and similar phrasing over decades, unlike humpback whale song which changes substantially from year to year. Historical acoustic recordings dating back as far as the 1960s were examined, measuring the tonal frequencies of 1000s of blue whale songs. Within a given year, individuals match the song frequency (related to ‘pitch’ in musical nomenclature) to within less than 3%. The best documented song type, that observed offshore of California, USA, now is sung at a frequency 31% lower than it was in the 1960s. Data available for 7 of the world’s 10 known song types show they are all shifting downward in frequency, though at different rates. Any behavioral, ecological, oceanographic or anthropogenic change hypothesis seeking to explain the observed shifts should account for the worldwide occurrence of a nearly linear downward shift in the tonal frequencies of blue whale song. Hypotheses examined consider sexual selection, increasing ocean noise, increasing whale body size post whaling, global warming, interference from other animal sounds and post whaling increases in abundance. None of the commonly suggested hypotheses were found to provide a full explanation; however, increasing population size post whaling provides an intriguing and testable hypothesis that recovery is altering the sexually selected tradeoff for singing males between song amplitude (the ability to be heard at a greater distance) and song frequency (the ability to produce songs of lower pitch).
09 December 2009
Oceans for Pathi is a new nature film based on revolutionary techniques that allowed enjoying the secrets of the oceans as never before.
Thanks to remote-controlled mini helicopters and hydrodynamic cameras, the film reached the goal of ‘catching’ the ocean's most intimate events. For this purpose the crew worked in 50 different locations and filmed 80 marine species, from crabs to whales.
It took four years, 500 hours of footage and £45 million to be produced but the result must be amazing!
The film will be out for general release by the end of January 2010.
Photo by Barcroft Media: an example of how some whale footage was obtained.
More information in the DailyMail article
01 December 2009
Joe Borg, the European Fishery Commissioner, revealed that €23 million was given to fund the construction of new boats, including ultra-modern purse seiners that are able to land 100 tonnes in one haul. A further €10.5 million was given to modernise existing vessels, increasing their ability to track down and catch the tuna. Only €1 million was used to decommission vessels, but mainly for small-scale, local boats.
Spain received more than half of the subsidy, with French and Italian fleets the next biggest beneficiaries. Cyprus, Malta and Greece were also given money.
Scientists from ICCAT (International Council for the Conservation of Atlantic Tuna) believe that the bluefin tuna stock was below 15 per cent of its pre-exploitation levels.
Eleonora de Sabata