While bacteria, phytoplankton and sponges play an important part in this week’s scientific mix, there is still a place for some leviathans, with tales of whales both living and dead…

Marine science

Fish and ships: While we think of iron as a construction material, for a lot of bacteria it is just another food source. Here is a report of a new bacterium (Halomonas titanicae) found feeding on the Titanic. ScienceDaily (Dec. 7, 2010)

Sponge cleanup: Sponges are not the easiest marine organisms to identify – a single species can adopt a wide range of shapes. Commonly microscopy can assist, by comparing the shapes and types of the internal ‘spicules’ that form a protective ‘skeleton’ for the sponge. Most recently molecular biology has been used, and on the basis of these studies a small group of sponges (the Homoscleromorpha) had been separated from the Demospongiae, despite having similar silicaceous spicules. This study, looking at mitochondrial DNA, seems to restore the status quo ante, however…
Gazave E, Lapébie P, Renard E, Vacelet J, Rocher C, et al. (2010) Molecular Phylogeny Restores the Supra-Generic Subdivision of Homoscleromorph Sponges (Porifera, Homoscleromorpha). PLoS ONE 5(12): e14290. doi:10.1371/journal.pone.0014290

Coping with the open ocean: Phytoplankton need both sunlight an nutrients to grow, so the open ocean, which has very low concentrations of essential nutrients such as phosphorus, represents a severe challenge. Recent research shows that many phytoplankton can adapt to these marine deserts. Usualy cell mempranes are composed of phospho-lipids, which as their name suggests require phosphorus. When this is in short supply, however, these phytoplankton can make a substitution, using other lipids in their place. This saves some phosphorus allowing the phytoplanton to make more DNA, and grow and reproduce. ScienceDaily (Dec. 17, 2010)

Still breathing, after 550M years… If phosphorus is important, a continuous supply of oxygen is vital to most animal life on the planet. This research shows that we share the same molecular system for sensing oxygen with the most primitive animal – a marine blob called Trichoplax adhaerens. Both of us use the sensor in the same way, to detect a lack of oxygen and adapt to it, in fact the molecular machinery appears to be completely interchangeable between humans and Trichoplax! This implies that the system has been pretty much unchanged for some 550 million years… ScienceDaily (Dec. 18, 2010)

Blooming jellyfish: Jellifish blooms in the NE Atlantic, Mediterranean and North Sea have become more common over the last 50 years. The reasons are complex, but two factors are now thought to be contributing to the blooms – increased water temperatures and over fishing. ScienceDaily (Dec. 14, 2010)

Marine fluff: How the oceans recycle carbon depends on how long organic carbon stays in the water column, where it can be re-cycled by bacteria. This study improves earlier models of settling rate by looking at the structure of the minute bits of carbon. Previously simple shapes have been assumed, here allowance is made for the porous nature of most organic aggregates, that are often 95% water by volume. These numbers are imporant in computing productivity and how efficiently the oceans can take carbon out of the atmosphere, and deposit it in deep sediments. ScienceDaily (Dec. 13, 2010)

Big and cold: Cold waters in the Bering Sea favour plankton species with larger body sizes. This is the preferred food of larger or more mature fish, which rely on the larger plankton to provide nourishment for the winter. ScienceDaily (Dec. 9, 2010)

Pays to be big: It is no accident that the largest animal ever is the blue whale – calculations show that its ability to engulf enourmous volumes of water when lunging for krill enable it to ingest 90 times more energy in a dive than the dive itself requires. The amounts of krill in each mouthfull are pretty astounding – equivalent to nearly 2,000MJ a bite. ScienceDaily (Dec. 9, 2010)

Where the young fish hang out: Juvenile fish are often quite particular about the type of habitat they frequent, Here researchers look at the diverse range of coral and seaweed habitats on Nangaloo Reef, Western Australia, and have carried out censuses of which species ar.e found where. It would appear that in amidst living corymbose (with horizontal branches) coral is the best place to be..
Wilson SK, Depczynski M, Fisher R, Holmes TH, O’Leary RA, et al. (2010) Habitat Associations of Juvenile Fish at Ningaloo Reef, Western Australia: The Importance of Coral and Algae. PLoS ONE 5(12): e15185. doi:10.1371/journal.pone.0015185

Whale fall: Dead whales that sink to the seafloor represent a massive resource to animals that live at depth. These studies in Monteray Bay show that the first colonisers are sharks, hagfish and crabs, that remove the flesh from the bones. After this bone eating worms and snails take over, until over a period of a decade or so the entire carcas disappears. ScienceDaily (Dec. 6, 2010)

Conservation

Family wipe-out: Entanglement in fishing gear is a common cause of death in cetaceans, in this study on the rare Franciscana dolphin (Pontoporia blainvillei) it is found that entrapped dolphins are often related – with mother and calf being the most common co-victims.
Mendez M, Rosenbaum HC, Wells RS, Stamper A, Bordino P (2010) Genetic Evidence Highlights Potential Impacts of By-Catch to Cetaceans. PLoS ONE 5(12): e15550. doi:10.1371/journal.pone.0015550

Turf war: Tropical corals only occur where herbivores graze seaweed back and prevent it from choking the corals. This study looks at how nutrient abundance and herbivore numbers interact on corals in the Caribbean. In this study the increased levels of nutrients and reduced levels of herbivores encouraged the growth of algal turf, at the expense of the coral.
Vermeij MJA, van Moorselaar I, Engelhard S, Hörnlein C, Vonk SM, et al. (2010) The Effects of Nutrient Enrichment and Herbivore Abundance on the Ability of Turf Algae to Overgrow Coral in the Caribbean. PLoS ONE 5(12): e14312. doi:10.1371/journal.pone.0014312

Biodiversity on the western European margin: This paper attempts to provide baseline measurements of biodiversity. It provides a brief overview of the study area – the North Sea and NE Atlantic, and an introduction to the sampling methods deployed over the past 250 years. This if followed by an estended discussion of how species richness changes with latitude and depth through the study region. The area covered by the paper is, however, very large, and it is difficult to pick out any simple trends.
Narayanaswamy BE, Renaud PE, Duineveld GCA, Berge J, Lavaleye MSS, et al. (2010) Biodiversity Trends along the Western European Margin. PLoS ONE 5(12): e14295. doi:10.1371/journal.pone.0014295

Turtle zone: One of the problems with conserving species like marine turtles is that they migrate over vast areas of the worlds oceans. This is a geomatic study bringing together the results of all available prior studies to map threats to species. The intention is to work out how to extend protection to turtles beyond their nesting beaches, to ensure genetically viable populations are maintained.
Wallace BP, DiMatteo AD, Hurley BJ, Finkbeiner EM, Bolten AB, et al. (2010) Regional Management Units for Marine Turtles: A Novel Framework for Prioritizing Conservation and Research across Multiple Scales. PLoS ONE 5(12): e15465. doi:10.1371/journal.pone.0015465

Fisheries and exploitation

Fisheries assessments at the level of the individual fish: A study following Lingcod (Ophiodon elongatus), tagged to allow researchers to watch their development, and how they interact with other groups. The fish were shown to spend several months at certain seamounts, with brief periods of absence, before moving to another mount. Lingcod fisheries on the East coast of the US and Canada have been overfished for some time, and this study helps to elucidate their behaviour and how individuals disperse into the population as a whole, helping to evaluate how local populations inter-breed.
Bishop MA, Reynolds BF, Powers SP (2010) An In Situ, Individual-Based Approach to Quantify Connectivity of Marine Fish: Ontogenetic Movements and Residency of Lingcod. PLoS ONE 5(12): e14267. doi:10.1371/journal.pone.0014267

Thrashed bottoms all round: Following a recent report in the New Scientist about the benefits of bottom trawling comes a strong, and sensible, refutation. [Sorry guys, reefs, and even communities of sea-pens, take years to establish. About the only thing that can survive repeated ploughing is nephrops, which is why it is about the only commercial species left in so much of the UK’s territorial waters.] By Kevin Zelnio in Deep Sea News, on December 7th, 2010.

Red biofuel: A strain of yeast has been found that can digest galactose, allowing red algae to be fermented to produce biofuels. ScienceDaily (Dec. 16, 2010)

Pollution

Oil in the core: The depth of water around the Deepwater Horizon has made analysis of what has happened to the seabed around the rig very difficult. This blog post is, therefore, one of the first to conclusively show oil in the sediments around the site. By Dr Bik, Deep Sea News, December 16th, 2010

Slippery figures: Latest oil spill roundup from Deep Sea News indicates that seafood may not be safe, whilst legal debates start over the actual magnitude of the leak. Deep Sea News, December 12th, 2010

Whale monitor: Sperm whales living in the Pacific Ocean have been found to have been exposed to organic pollutants including polycyclic aromatic hydrocarbons (PAHs) and pesticides such as DDT. Whales living around the Galapagos were found to be amongst the most heavily contaminated. ScienceDaily (Dec. 7, 2010)

Climate change

COP16 Draft Accord: The UNFCCC meeting in Cancun ended on the 12th November 2010 with an agreement to limit carbon dioxide emissions to levels that will keep global warming to less than 2 degrees celsius above pre-industrial levels. The agreement includes a proposed $100 billion a year fund to assist poorer countries finance emission reductions. This is not as bad as it might have been, though it does not have the binding force of a treaty, and there is scepticism that the CO₂ reduction proposed (even if achieved) will not keep warming below the stated target.

Bering sea – ice free: Deep sediment cores indicate that the Bering Sea was free of ice through out the year during the last warm period, 3.5 to 4.5 million years ago. The study also suggests that mixing between warm surface waters and deep waters was greater than current climate models predict. ScienceDaily (Dec. 13, 2010)

Blue-green-bloom: The cyanobacteria Trichodesmium, colloquially ‘sea sawdust’, are responsible for fixing between 25 and 50% of the nitrogen in tropical waters. Increased CO₂ levels is known to increase both biomass and nitrogen fixation by these species. This study looks at how genes are regulated when Trichodesmium are exposed to increased temperatures and CO₂ levels. The study looked at a doubling of CO₂ partial pressure, and an increase in temperature from 25°C to 31°C. Under these conditions, the researchers saw significant up-regulation of genes involved with photosynthesis and nitrogen metabolism.
Levitan O, Sudhaus S, LaRoche J, Berman-Frank I (2010) The Influence of pCO2 and Temperature on Gene Expression of Carbon and Nitrogen Pathways in Trichodesmium IMS101. PLoS ONE 5(12): e15104. doi:10.1371/journal.pone.0015104

Stirring it up: Heat in the surface waters of the world’s oceans feeds into the overlying atmosphere, driving convection currents that take moisture laden water high into the atmosphere, and powering storms. As global temperatures increase, therefore, should we expecst an increase in severity and/or number of storms? Here it is argued that while surface water tempaeratures are going up, so is the threshold temperature for driving convection* currents. ScienceDaily (Nov. 7, 2010)
[* this may depend upon the difference in temperature between the sea’s surface and the overlying atmosphere.]

Now breath out: Carbon dioxide exchange rates between the ocean and the atmosphere have now been measured at higher wind speeds than ever before. Surface waters are ususally slightly super-saturated with gasses in comparison to the overlying atmosphere. This is due to a lot of exchange occurring under pressure from small bubbles trapped in the water column by breaking waves. These measurements are essential for climate models, which need to know accurately how carbon dioxide moves between the atmosphere and the ocean under as wide a range of natural conditions as possible. ScienceDaily (Dec. 7, 2010)

Reefs of time: State of the art aquaria have been set up to see how corals respond to the increased temperatures and carbon dioxide levels expected over the next 50 t0 100 years. ScienceDaily (Dec. 7, 2010)