This issue we look at the behaviour of seals and jellyfish – choose the ideal holiday destination for starfish – then dive into a microbial ocean. How to manage fisheries, this time on a Chilean archipelago (there are some mitigating circumstances here, but best of luck guys), and catch up on more news from the Gulf of Mexico. One factor that we need to take on board is that the Gulf was in bad shape before the spill, and that the $20B oil spill response isn’t going to start managing the Gulf ecology properly.
Whales are left handed, flippered, whatever… Young beluga whales prefer to rest on their mother’s right hand side, so they see their mums out of their left eye – indicating a preference for processing this information in the right hemisphere of their brain… I’m not sure which flipper they’d prefer to hold a fork in…
Karenina K, Giljov A, Baranov V, Osipova L, Krasnova V, et al. (2010) Visual Laterality of Calf–Mother Interactions in Wild Whales. PLoS ONE 5(11): e13787. doi:10.1371/journal.pone.0013787
Jellyfish bloom: Swarms of the moon jelly Aurelia are a beautiful sight underwater, with their bells pulsing gently as they fish in the water column, some other species are less welcome due to their toxicity… The question is, what prompts the swarm in the first place? This paper tries to identify the causes of these phenomena, tracing it back through the complex life-history of Cotylorhiza tuberculata, which swarms in the Mediterranean on alternate years. Cotylorhiza has two transitions – planula settlement, where juvenile swimming young produced by the adult jellies find a spot on the sea-floor to turn into a polyp, and strobilation, where new jellies are released by the polyp into the water. Temperature changes have a pivotal effect on both transitions, with strobilation occurring as water warms in spring. Food availability at this time can extend the duration of the strobilation event. This paper provides some detailed insights into the life history of the jellyfish, but I wasn’t convinced that they have nailed the bi-annual swarming cycle…
Prieto L, Astorga D, Navarro G, Ruiz J (2010) Environmental Control of Phase Transition and Polyp Survival of a Massive-Outbreaker Jellyfish. PLoS ONE 5(11): e13793. doi:10.1371/journal.pone.0013793
A year in the life – of elephant seals in the Eastern Weddell Sea: The behaviour of the southern elephant seal (Mirounga leonina) shows a complex relationship with seasonal currents and ice coverage. Adult males seem to stick close to the ice edge during the Antarctic winter, while females spend a significant period of time over 1000km from the sheet, and only converge on the ice sheet towards the start of the brief summer period. The female’s and juvenile male’s strategy may be an avoidance of getting trapped beneath pack ice. Diving depths correlate with the depth of copepods and fish, which show a strong diurnal (‘Diel’) variation.
Biuw M, Nøst OA, Stien A, Zhou Q, Lydersen C, et al. (2010) Effects of Hydrographic Variability on the Spatial, Seasonal and Diel Diving Patterns of Southern Elephant Seals in the Eastern Weddell Sea. PLoS ONE 5(11): e13816. doi:10.1371/journal.pone.0013816
Echinoderms like: Intertidal regions in northern latitudes, but below the water line the highest population density and diversity of species is seen in hotspots unrelated to the latitude. Hotspots are influenced by a number of local phenomena, including salinity, productivity and pollution. This study looked at sampling sites around the globe, and found that species diversity at any site was low, between 1 and 5 species.
Iken K, Konar B, Benedetti-Cecchi L, Cruz-Motta JJ, Knowlton A, et al. (2010) Large-Scale Spatial Distribution Patterns of Echinoderms in Nearshore Rocky Habitats. PLoS ONE 5(11): e13845. doi:10.1371/journal.pone.0013845
Virus, evolved? Studies of the ‘abalone shriveling syndrome virus’ (AbSV), show it to have the characteristics of a bacteriophage coupled with the genetic material associated with creating the bacterial outer membrane, implying that it might be in the process of evolving from virus to bacterium (or vice-versa). Prokaryotes have a rather liberal attitude to sharing genetic code, so entire features can be transferred between species or strains. Rather than being stuck with recombinational fiddling that eukaryotes get bogged down in, prokaryotes tend to grab genetic material from wherever they can get it, their high fecundity means that stuff that isn’t useful can simply be bred out.
Zhuang J, Cai G, Lin Q, Wu Z, Xie L (2010) A Bacteriophage-Related Chimeric Marine Virus Infecting Abalone. PLoS ONE 5(11): e13850. doi:10.1371/journal.pone.0013850
Hydrogen power: Hydrogen makes up a small, but siginifcant, component of the Earth’s atmosphere, its geochemical cycle is complex, but largely associated with bacterial action. This study shows that cyanobacteria in the marine environment use hydrogen in nitrogen fixation, but do not appear to be able to generate hydrogen. In contrast fresh water bacteria are able to both take up hydrogen and to generate it.
Barz M, Beimgraben C, Staller T, Germer F, Opitz F, et al. (2010) Distribution Analysis of Hydrogenases in Surface Waters of Marine and Freshwater Environments. PLoS ONE 5(11): e13846. doi:10.1371/journal.pone.0013846
Bugs in the sea floor: These days we are suprised to find sterile environments on the Earth, so this report of the microbial communities living in the ocean’s crust is not unexpected. Genetic analysis suggests that they may be surviving by metabolising hydrocarbons created by geological processes even deeper underground – making them another example of life on earth that is not ultimately dependent upon the sun for energy.
Mason OU, Nakagawa T, Rosner M, Van Nostrand JD, Zhou J, et al. (2010) First Investigation of the Microbiology of the Deepest Layer of Ocean Crust. PLoS ONE 5(11): e15399. doi:10.1371/journal.pone.0015399
Bugs and algae get it together: Many micro-organisms live in communities bound together by sticky secretions, and these sectretions in turn have the effect of binding any sediment they might be living in together. This study looks at how natural assemblages of micro-algae and bacteria change the strength of the sediment they are living in, and how much sticky matrix they were putting down. While the development of cohesion within the sediment was very rapid after colonisation by the micro-organisms, the study did not demonstrate any synergism between bacteria and micro-algae. Sediment binding stabilises estuarine (and other) environments, allowing the establishment of a rich ecosystem that is ultimately largely dependent on these micro-organisms for food.
Lubarsky HV, Hubas C, Chocholek M, Larson F, Manz W, et al. (2010) The Stabilisation Potential of Individual and Mixed Assemblages of Natural Bacteria and Microalgae. PLoS ONE 5(11): e13794. doi:10.1371/journal.pone.0013794
Vitamin whale: This study shows some of the ways cetaceans have adapted their body chemistry to living in the marine ecosystem. Examining the amino-acid composition of blood and urine, the researchers find that cetaceans have increased concentrations of urea, carnosine and 3-methylhistidinein their blood plasma. Urea probably helps prevent de-hydration (a problem when you live in salty water), whilst the other two amino acids are known to have anti-oxidant function. Cetacean tissues are subject to increased oxidative stress when they re-oxygenate after diving, so the anti-oxidants may have a role in permitting the animals to take on more oxygen ready for the next dive – without burning up!
Miyaji K, Nagao K, Bannai M, Asakawa H, Kohyama K, et al. (2010) Characteristic Metabolism of Free Amino Acids in Cetacean Plasma: Cluster Analysis and Comparison with Mice. PLoS ONE 5(11): e13808. doi:10.1371/journal.pone.0013808
Are stranded cetaceans deaf? Whale strandings are unfortunately common the world over, this study asks whether or not the phenomenon is associated with hearing impairment, which would influence their echo-sounding/location capability. This study suggests that while this may be a factor in some strandings, the hearing of the animals, that were investigated after stranding in this study, did no show significant impairment.
Mann D, Hill-Cook M, Manire C, Greenhow D, Montie E, et al. (2010) Hearing Loss in Stranded Odontocete Dolphins and Whales. PLoS ONE 5(11): e13824. doi:10.1371/journal.pone.0013824
Fisheries and exploitation
A fisherman’s knowledge: Using a bioeconomic model to reconstruct how lobster fisheries have changed on a Chilean archpelago from oral and written histories. Prolonged closure of the fishery is not an option where fishermen are dependent upon it for their livelyhoods, so the authors suggest a policy of 30% no-take zone (‘marine reserve’) and engaging the local fishing community to steward the zone and catch policies, as the optimal means for rebuilding the fishery.
Eddy TD, Gardner JPA, Pérez-Matus A (2010) Applying Fishers’ Ecological Knowledge to Construct Past and Future Lobster Stocks in the Juan Fernández Archipelago, Chile. PLoS ONE 5(11): e13670. doi:10.1371/journal.pone.0013670
GFP fights cancer: Green fluorescent protein (GFP) is derived from deep sea jellyfish, which use it to create light to hunt and hide. It has become uniquitous in biochemistry, as a tag to follow which cells have taken up injected genetic material. In this latest variation, GFP has been modified to emit light of different colours, so it can be used to tag cancer in metastasis in the human body. This may offer a means for tracking down hidden cancer cells, which often errupt into new malignancies after the initial tumour has been excised. ScienceDaily (Nov. 3, 2010)
4* Algae: Aglae are a potential fuel substitute due to their rapid growth, and ability to grow in both salt and fresh water (different species!), so they can be cultured where fresh water supplies are limited. Currently there are more than 100 companies worldwide looking at algae as a fuel source, and the leaders in the field are just beginning to look at semi-scale plant, involving acres of growing ponds. At present uncertainties over cultivation and processing make it difficult to predict the cots of fuel from this source, but it is likely to be relatively expensive, compared to the current price of fossil fuels. To reduce costs, early commercial production of algal fuel will probably be inconjunction with other activity, such as waste water treatment. ScienceDaily (Nov. 3, 2010)
Gulf of Mexico dead zone: A volume of hypoxic water around the Mississippi delta, which can extend over an area of 7000 square miles. Fertiliser run-off from the Mississippi catchment area encourages an algal bloom, as the algae die, they are broken down by bacteria using up the oxygen in the water. The Gulf Dead zone is seasonal. From The Gulf of Mexico Dead Zone by Monica Bruckner, Montana State University. Via Culturing Science by Hannah Waters, November 5 2010.
‘Arctic Sunrise’ in the Gulf: The Greenpeace vessel ‘Arctic Sunrise’ is carrying out a range of environmental studies in the Gulf of Mexico following the oil spill. This post by John Hocevar, a marine biologist and the Oceans Campaign Director for Greenpeace, gives an overview of the work they are doing. Deep Sea News, November 4th, 2010
Corals damaged: With a large proportion of the oil from the Deepwater Horizon spill being held in deep water, much of the damage to marine life is invisible at the surface. This is the first report confirming damage to deep-sea corals at a depth of 1400m, 70 miles SW of the old well head. The corals have been coated, probably with oil or oil degredation products. Approximately 90% of corals in the area investigated had been damaged. Kevin Zelnio, Deep-Sea News, November 5th, 2010
Impacts, Perception, and Policy Implications… Written for the Environmental Law Institute, this covers the accident, and makes suggestions for future policy in the light of this. Linked from Marine Conservation News, November 02, 2010
Ocean acidification effects on molluscs: How will increasing CO2 levels effect marine animals that grow calcium carbonate shells? – One of the most threatened creatures appear to be pteropod molluscs. Kevin Zelnio, Scientific American guest blog, Nov 5, 2010
Oceanic U turn: Latest models show that increasing temperatures in the Atlantic may result in deep ocean currents switching directions. The current in question is the ‘meridional overturning current’ (MOC), which appears to have switched direction in the past in response to climate change, most recently during an ice-age 20,000 years ago. It is not clear how this change might feedback into the predicted climate change scenario at present. ScienceDaily (Nov. 4, 2010)