Leatherback turtles are popular this issue, with scientists tracking them across the Atlantic, how they thermo-regulate, and how to stop them ending up in the soup… Otherwise there is a nice bit of experimental work ‘proving’ that faster flow = more life (this doesn’t mean that low-flow = no life, however!). We are also, perhaps, getting closer to understanding why coral bleaching occurs at a molecular level.

Marine science

Get in the flow: Based on experiments in Alaska and Maine, where variable width channels were constructed to constrict current flow, researchers have found that diversity of benthic invertebrate life such as barnacles, sea squirts, corals and sponges was greatest in the area where current flow was fastest. Most divers would agree with this observation (it may be why Gordon likes diving the Creran narrows so much!), but these elegant experiments provide some basis for the observation. ScienceDaily (Nov. 17, 2010)

Do corals get sun-stroke? When exposed to sunlight the symbiotic algae (specialised dinoflagellates) generate oxygen and fix carbon as sugars. The sugars are an important food for the coral, but in bright, shallow waters, the sunlight can cause damage to the corals tissues. In addition, the algae also produce a lot more oxygen than the coral can use in respiration, and these high oxygen levels are associated with coral tissue damage. In short, while the symbiosis is essential for the health of the coral, it comes at a price. High levels of sunlight oblige the coral to synthesise a ‘sun-screen’ of UV-protective amino acids. Short periods of high light intensity do not appear to invoke an anti-oxidant response, which is only seen after prolonged exposure to elevated temperatures. The ejection of the algal symbiont that occurs in bleaching events may be associated with the disruption of communication between host and symbiont, though the molecular pathway that provokes this change is not elucidated.
Starcevic A, Dunlap WC, Cullum J, Shick JM, Hranueli D, et al. (2010) Gene Expression in the Scleractinian Acropora microphthalma Exposed to High Solar Irradiance Reveals Elements of Photoprotection and Coral Bleaching. PLoS ONE 5(11): e13975. doi:10.1371/journal.pone.0013975

Dino diversity: Dinoflagellates are one of the three imporant groups of eukaryotic phytoplankton (the others being coccolithophorids and diatoms). They are important primary producers in the ocean, as well as being vital coral symbionts and less welcome causes of some planktonic blooms. This study uses DNA bar-coding to quantify the diversity of dinoflagellates. It shows that there is very considerable genetic diversity within each species, and probably a very much larger number of distinct speices than previously thought.
Stern RF, Horak A, Andrew RL, Coffroth M-A, Andersen RA, et al. (2010) Environmental Barcoding Reveals Massive Dinoflagellate Diversity in Marine Environments. PLoS ONE 5(11): e13991. doi:10.1371/journal.pone.0013991

Turbo crust: Scientist from Woods Hole have found a new tectonic mechanism active in the ocean crust. It seems that magma is being injected into the overlying sediment up to 50km away from the plate boundaries. On entering the sediment layer the magma spreads sideways, forming new rock sills beneath the ocean floor. The sills raise the temperature of the overlying sediments, and are associated with rich biological communities, and massive releases of methane gas, driven out of the organic material in the sediment. While they have only been observed in the Gulf of California, it is expected that the features are associated with most ocean ridges. ScienceDaily (Nov. 16, 2010)

New squid on the block: Scientists examining samples from the 2009 seamounts cruise in the Indian Ocean have discovered a new species of squid in the family Chiroteuthidae. ScienceDaily (Nov. 15, 2010)

Killer algae in the deep: Some of the algae associated with toxic blooms in shallow waters have been identified awayfrom land. The worry is that if ocean fertilisation programs were to start, for example by adding iron to oceanic surface waters, then this might encourage blooms or harmfull algae, as well as the species that are wanted to sequester carbon dioxide. ScienceDaily (Nov. 13, 2010) [Note: It is thought that production of toxins by algae only starts to happen in a bloom, when lots of algal cells are close together]

Turtles tracked: Leatherback turtles have been tracked in the Atlantic, to show their migration routes and feeding grounds. Initial migration routes are determined by oceanic currents, the young turtles drifting with them until they find a good feeding ground. The feeding grounds are not fixed locations, but are rather discovered by the turtle, and reflect the amounts of prey present at that time.
Fossette S, Girard C, López-Mendilaharsu M, Miller P, Domingo A, et al. (2010) Atlantic Leatherback Migratory Paths and Temporary Residence Areas. PLoS ONE 5(11): e13908. doi:10.1371/journal.pone.0013908

Turtle gloves: While leatherback turtles do not maintain a constant body temperature, they do regulate it such that their bodies are 8°C warmer than the surrounding water in sub-polar waters, while they are generally less than 4°C warmer than the surrounding waters in the tropics. This paper shows that they regulate temperature by being more active in colder water. A second physiological component to thermo-regulation is obsreved, this is attributed to the turtles redirecting blood flow away from extremities in cold water.
Bostrom BL, Jones TT, Hastings M, Jones DR (2010) Behaviour and Physiology: The Thermal Strategy of Leatherback Turtles. PLoS ONE 5(11): e13925. doi:10.1371/journal.pone.0013925

Swim closer to me: Male desert goby’s put more effort into courtship displays if they have not seen a potential mate for some time, wheras if females are common, they tend to be choosey about who they court. While these are fresh water fish, their behaviour implies that other fish may show more complex courtship behaviour than has previously been recognised. ScienceDaily (Nov. 12, 2010).

Join the mob (why fish school): Primarily grouping for protection, groups of fish and other marine organisms adopt a shape that minimises their surface area – where fish can get picked off by predators. When predators are present, this means atickt packed sphere, but normally the grouping must trade off protection in numbers for the ability to forage for food, and the need to come to the surface of the shoal periodically to get oxygen! This nice review looks at the reasons for shoaling, and the types of shape that a shoals commonly adopt. Hannah Waters in Scientific American, Nov 10, 2010

Shrimps in stone: The discovery of a fossilised shrimp that is about 360 million years old. The fossil is very similar in appearance to modern shrimps. ScienceDaily (Nov. 10, 2010)

Conservation

What drives reef recovery? The recover of reefs in American Samoa was followed after hurricane Heta in 2003. The study indicated that recovery was fastest in areas with high water quality and high densities of herbivorous fish. Other parameters such as substrate and location were less important.
Houk P, Musburger C, Wiles P (2010) Water Quality and Herbivory Interactively Drive Coral-Reef Recovery Patterns in American Samoa. PLoS ONE 5(11): e13913. doi:10.1371/journal.pone.0013913

Callum Roberts on Marine Protected Areas (MPAs): This article reviews Callum Robert’s talk on MPAs, and how important no-take areas are for protecting marine biodiversity. Deep Sea News, November 9th, 2010

Fisheries and exploitation

Turtle soup: Government bans don’t prevent Madagascan villagers taking rare turtles, and their estimated annual catch is 16,000 individuals. The researchers advocate acknowledging that small scale fisheries exist and are imporant to indigenous populations, and these people involved in the conservation project. They do, after all, have an interest in ensuring the survival of their food resource. ScienceDaily (Nov. 12, 2010)

A fish’s story: How have fish been impacted by exploitation over the last hundred years? This paper looks at how amateur naturalists’ observations can be used to fill in the gaps in our knowledge of fish populations in the Mediterranean before the first annual landing data were recorded in 1874.
Fortibuoni T, Libralato S, Raicevich S, Giovanardi O, Solidoro C (2010) Coding Early Naturalists’ Accounts into Long-Term Fish Community Changes in the Adriatic Sea (1800–2000). PLoS ONE 5(11): e15502. doi:10.1371/journal.pone.0015502

Fish shortage helps scrape the barrel: Choice fish have become so scarce on the Coromandel coast of India that fish species tradiationally seen as worthless by-catch are now commanding a market. The worry is that this trade will help maintain fishing effort, so resulting in yet more degredation of the marine resource. Heok Hee Ng in Practical Fishkeeping, 11 November 2010 via Deep Sea News

Bluefin black-market threat: When there is a $4B blackmarket in sushi, you need active regulation to prevent fish being hunted to extinction. Marine Conservation News, November 09, 2010

Pollution

Bad decisions contributed to accident: An interim report by a committee of the National Academy of Engineering and National Research Council provides a review of events leading to the Deepwater Horizon incident. Tests on the Blow Out Preventer are still not available, however, so we don’t have a complete picture of the technical reasons for the accident. This being the case the search for the person most responsible is, perhaps, premature. ScienceDaily (Nov. 17, 2010)

Oil enters marine food chain: Study provides evidence that oil is being taken up by plankton in the Gulf, so it is just a matter of time before it works its way up the food chain. It is not clear as yet what the human health implications will be. Deep Sea News, November 8th, 2010

Climate change

Rising levels of UV causes sunburn in whales: For some years scientists have notes blisters on the backs of individuals from a number of whale species. This study shows that the skin damage observed is similar to that experienced by people suffering from sunburn. The increase in UV is due either to ozone depletion, or to changes in cloud cover. ScienceDaily (Nov. 9, 2010)
[Since the implementation of the Montreal Protocol, levels of CFC’s and other ozone depleting chemicals have been reducing. The atmosphere is a big place, however, and significant improvements to the ozone layer are not expected before ca. 2025 (Wikipedia article on ozone depletion). A time lag worth bearing in mind when we consider CO₂ emissions…]

Bitter reefs: Threatened corals such as Elkhorn (Acropora palmata) find increased carbon dioxide levels difficult even in non-calcified stages of their life-cycle. This may make reproduction and regeneration of corals more problematic if the carbon dioxide release that causes acidification continues. ScienceDaily (Nov. 13, 2010)