We have three articles on how fish sense their surroundings in marine science this issue – from electrosensory arrays of sharks and rays, which help them oreintate themeselves in the water column and hunt for food, to a sense of smell that warns fish about predator activity on the reef. We end in climate change with a paper from PLoS 1 about how changes in carbon dioxide levels effect gene regulation in marine snails…

Marine science

Where am I looking? Scientists have polotted the geometry of electro-sensory pores in several sharks and rays to see if they can work out how these fish perceive electric fields in their environment. The results suggest that in hammerheads and sandbar sharks the sense is primarily directional, to aid the animal navigate or orientate themeselves in the water column. In stingrays, however, the senses are focussed towards the snout, and directed into the substrate, and almost certainly assist the animal find prey burried in the mud.
Rivera-Vicente AC, Sewell J, Tricas TC (2011) Electrosensitive Spatial Vectors in Elasmobranch Fishes: Implications for Source Localization. PLoS ONE 6(1): e16008. doi:10.1371/journal.pone.0016008

Green vision: Recent research indicates that sharks, like dolphins, are colour blind. It looks like both animals have highly sensitive eyes for the green light, which may be an example of convergent evolution, making the most of the light penetrating into the water column. ScienceDaily (Jan. 19, 2011)

Quick reactions on the reef: This study of lemon damselfish (Pomacentrus moluccensis) looks at how prey fish assess the threat level using scent, and use this information to work out the local predation risk. Fish were readily conditioned to recognise the scent of predators, by combining this with an alarm cue, and when subsequently exposed to the smell of predators alone, were found to spend less time foraging.
Mitchell MD, McCormick MI, Ferrari MCO, Chivers DP (2011) Coral Reef Fish Rapidly Learn to Identify Multiple Unknown Predators upon Recruitment to the Reef. PLoS ONE 6(1): e15764. doi:10.1371/journal.pone.0015764

New to science: A new species of isopod Politolana sanchezi has been described from the El Cachucho Marine Protected Area in teh Bay of Biscay. 40 other species are currently being evaluated to see if they have previously been described elsewhere. ScienceDaily (Jan. 20, 2011)

Specialisation in birds: We think of animals as having pre-programmed life-choices, but while they do not have the same diversity of life-styles as modern humans (from socialite to scrounger), each bird within a species can adopt different hunting and foraging patterns so fitting its own personal ecological niche. ScienceDaily (Jan. 13, 2011)

Barnacle tree shake-up: Charles Darwin thought that the barnacle family tree could be elucidated through examination of the number of plates in their shells. Genetic analysis has now shown this to be an over-simplification. Review by Kevin Zelnio in Deep-Sea News, January 10th, 2011

Worms in the core: This is a comparison of nematode commmunities from sediment cores taken at three locations – the deep Arctic, Bermudan shelf and Gulf of Mexico. Nematodes have an important role in the carbon cycle of sediments – often contributing a large precentage of the living organic matter in them. They fulfil a number of roles within the sediment, and the come in a range of sizes. the question asked by the authors is, effectively, ‘is size the only difference?’. i.e. can we just look at the large nematodes (greater than 1mm long) to get a picture of the activity of all nematodes in the sample? Clearly this would be a useful simplification for anyone attempting to understand biological activity within the sediment, unfortunately the populations appear to be distinct.
Sharma J, Baguley J, Bluhm BA, Rowe G (2011) Do Meio- and Macrobenthic Nematodes Differ in Community Composition and Body Weight Trends with Depth? PLoS ONE 6(1): e14491. doi:10.1371/journal.pone.0014491

Stressed ‘shrimps’: Krill (Euphausia superba) are adapted to live in antarctic waters, where they are the predominant predator of the phytoplankton that bloom in the brief summer months. This study of gene expression in these crustacea show that they are (in comparison to crustacea from warmer waters) over expressing a number of stress proteins. It is thought that these may help the krill cope with cold antarctic waters.
Clark MS, Thorne MAS, Toullec J-Y, Meng Y, Guan LL, et al. (2011) Antarctic Krill 454 Pyrosequencing Reveals Chaperone and Stress Transcriptome. PLoS ONE 6(1): e15919. doi:10.1371/journal.pone.0015919

Feeds as it breaths: The shrimp Rimicaris exoculata inhabits deep sea vents. It has enlarged gill chambers to house bacteria which are though to provide the shrimp with food.
Hügler M, Petersen JM, Dubilier N, Imhoff JF, Sievert SM (2011) Pathways of Carbon and Energy Metabolism of the Epibiotic Community Associated with the Deep-Sea Hydrothermal Vent Shrimp Rimicaris exoculata. PLoS ONE 6(1): e16018. doi:10.1371/journal.pone.0016018

Stinking seas: Two point six billion years ago the Earth’s oceans had substantial quantities of dissolved hydrogen sulphide – a highly toxic gas that smells of rotten eggs. ScienceDaily (Jan. 10, 2011)

Last gasp: Long periods of very low oxygen concentrations persisted in the marine ecosystem even after the Late Ediacaran (600MYA), the time when oxygen levels first came up to modern levels. These low oxygen events appear to have had a considerable impact on animal species, causing mass extinctions. ScienceDaily (Jan. 5, 2011)

Conservation

Fish benefit reefs: An 18 year study of Kanya’s coral reefs shows that over-fishing allows urchins to flourish. These in turn graze the coraline algae that are important for the formation of many types of tropical reefs. ScienceDaily (Jan. 14, 2011)

Oil platform in whale territory: A new platform is to be built close to the crucial feeding ground of the endangered Western North Pacific gray whale. This group of whales has declined to around 130 animals, which feed off Sakhalin Island in the Russian Far East. ScienceDaily (Jan. 17, 2011)

Conserving sturgeon: Tagging studies on sturgeon show that they forage over a very wide area, and will require a conservation effort over a large part of this range if it is to be successful. ScienceDaily (Jan. 7, 2011)

Fisheries and exploitation

Not so lousey: Open net salmon farms have previously been implicated in spreading pests into wild populations. This re-analysis of the ‘Broughton crash’, where wild salmon populations off the Broughton Archipelago of Western Canada were severely effected in 2002/3, indicates that sea lice from fish farms have no significant effect on the wild salmon population. This is in contradiction to earlier studies. ScienceDaily (Jan. 18, 2011)

Safe to eat sensor: A new sensor promises to cut the testing times for shellfish from two days to 30 minutes. The detector monitors the toxins responsible for paralytic shellfish poisons, which kill 25% of all people poinsoned. Portable sensors are now possible, which should cut the amount of transport required to testing facilities, and improve the freshness of the product on sale. ScienceDaily (Jan. 11, 2011)

Pollution

Complex geo/cryo-chemistry of mercury: It looks like mercury is re-cycled in the arctic environment, first oxidising and depositing on ice, then as the ice melts it is taken back into the food chain, and converted to (toxic) methylmercury. ScienceDaily (Jan. 20, 2011)

Time saver: Report preview indicates that while the three companies at the heart of the Gulf Oil Spill did not delibarately cause the catastrophy, their actions leading up to it were designed to save time, rather than to ensure the safety of the operation. By Dr Bik in Deep-Sea News, on January 9th, 2011

US and Norwegian safety cultures compared: In the US rig safety is managed by an adversarial system of rig management vs. government regulation. In Norway a third component is added, the workers unions. Does this make it safer? ScienceDaily (Jan. 7, 2011)
[The Montara oil spill in 2009 was on a rig part owned by Norway, so any wishful thinking about better management practices had still better be backed up by some pretty solid disaster plans.]

Methane sink: Bacteria in the Gulf of Mexico have reduced methane concentrations down to normal background levels in 120 days. ScienceDaily (Jan. 7, 2011)

Climate change

The elbow test: Hot water is associated with coral bleaching events, but how does it effect other marine organisms? This study examins the effects in situ, by looking at larval settlement on hotplates placed in the marine environment at Swan Estuary in Perth, Australia. The plates were warmed about half a degree warmer than a set of control plates. The study showed considerable differences in the densities of settling species in the two environments, and a greater density of life settling on the warmer plates.
Smale DA, Wernberg T, Peck LS, Barnes DKA (2011) Turning on the Heat: Ecological Response to Simulated Warming in the Sea. PLoS ONE 6(1): e16050. doi:10.1371/journal.pone.0016050

Seawater scrubber: A mix of seawater and crushed limestone may be an effective means for stripping carbon dioxide out of power-station flue gasses. Flushing this into the sea afterwards is described as having enhancing effects on the marine ecosystem, reducing oceanic acidity. [This might depend on what else gets scrubbed out of the flue though]. ScienceDaily (Jan. 19, 2011)

Cold currents: At the end of the last ice it appears there were a number of occasions when the formation of deep water in the North Atlantic was repeatedly switched on and off in a series of abrupt events. These changes had dramatic effects on the European climate, as when the formation is shut off, temperatures in Europe fell by 10°C. ScienceDaily (Jan. 15, 2011)

The bitter seas: How increasing ocean acidification may impact snails, particularly those inhabiting high latitudes. The experimenters look at how adult snails (Laternula elliptica) developed in seawater equilibrated with both higher concentrations of carbon dioxide (increased acidity), and higher pH (reduced acidity). The snails were evaluated for gene expression and general metabolic fitness. All of the snails were found to be fitter after the experiment (120 days duration) than at the start, but the snails exposed to increased carbon dioxide levels were sustaining a higher metabolic rate, indicating slightly greater stress, and had significantly increased expression of genes associated with shell formation. Snails exposed to elevated pH also showed signs of stress relative to the controls, but here genes associated with shell formation were down-regulated.
Cummings V, Hewitt J, Van Rooyen A, Currie K, Beard S, et al. (2011) Ocean Acidification at High Latitudes: Potential Effects on Functioning of the Antarctic Bivalve Laternula elliptica. PLoS ONE 6(1): e16069. doi:10.1371/journal.pone.0016069