Marine science update 19th June 2011

This issue we see that tides keep species apart – or at least prevent the different strains of the ubiquitous seaweed Fucus spp. from all merging into one species! We also see that iron rich waters result in changes to benthic communities and get an insight into how sponges form glass skeletons – a feat of materials engineering that has always amazed me. The tone is decidedly more serious in our Fisheries section, with a link to graphics showing just how much our fish stocks have declined over the last century. Actually ‘declined’ is not nearly a strong enough word for it. ‘Wiped out’ would be a little closer to the mark.

Marine science

Promiscuity on the beach: The intertidal zone is one of the most pronounced ecological gradients on the planet, and is usually visibly banded with specialised communities living in zones down from the extreme high water mark. Despite this many species on the beach are able to hybridise, a policy which might cost them their unique adaptations. This study looks at different species of the brown seaweed Fucus, and concludes that it is just the presence of the extreme gradient in exposure that keeps the species morphologically distinct.
Zardi GI, Nicastro KR, Canovas F, Ferreira Costa J, Serrão EA, et al. (2011) Adaptive Traits Are Maintained on Steep Selective Gradients despite Gene Flow and Hybridization in the Intertidal Zone. PLoS ONE 6(6): e19402. doi:10.1371/journal.pone.0019402

Ironing in the differences: The addition of iron salts to oceanic waters low in nutrients is known to encourage algal growth, and artificial addition of iron has been suggested as a means to encourage carbon dioxide uptake by phytoplankton. In this survey areas of naturally enriched oceanic waters are compared with adjacent low-iron areas. High iron concentrations correlated with higher benthic biomass, and a different species composition. THese areas were also found to be less homogeneous than their low iron counterparts.
Wolff GA, Billett DSM, Bett BJ, Holtvoeth J, FitzGeorge-Balfour T, et al. (2011) The Effects of Natural Iron Fertilisation on Deep-Sea Ecology: The Crozet Plateau, Southern Indian Ocean. PLoS ONE 6(6): e20697. doi:10.1371/journal.pone.0020697

Lean on me: Hydroids can form symbiotic relationships with corals, in which they rely on the coral’s skeleton for support and protection. This necessitates some specific adaptations in the hydroid that permit it to penetrate to the host’s skeleton, but also permit it to release itself from this, so it does not become overgrown.
Pantos O, Hoegh-Guldberg O (2011) Shared Skeletal Support in a Coral-Hydroid Symbiosis. PLoS ONE 6(6): e20946. doi:10.1371/journal.pone.0020946

Sub-sea stereo: Dolphins can generate two sound beams simultaneously. The beams are projected in different directions, and are thought to help the dolphin locate objects more precisely. ScienceDaily (June 8, 2011)

Oily weight-belt: Copepods are the prey of many fish in surface waters, so they like to hypernate in deep water during the winter, when their own algal food is scarce. This raises a problem for them in adapting their buoyancy, and it appears that they do this be having reserves of omega-3 oils, which undergo a phase change to a dense butter under pressure. This means that the tiny animals are neutrally buoyant both in surface and deep waters, and don’t have to swim to maintain depth. ScienceDaily (June 13, 2011)

Too fast for crabs: The green crab (Carcinus maenas) is less able to locate food in fast water currents, and spends longer eating the food it does catch. It is thought that the current both carries scent cues away, making it harder for the crab to find food, but also imposes a physical impediment to the crab’s getting about.
Robinson EM, Smee DL, Trussell GC (2011) Green Crab (Carcinus maenas) Foraging Efficiency Reduced by Fast Flows. PLoS ONE 6(6): e21025. doi:10.1371/journal.pone.0021025

Quick change: Rock hinds (Epinephelus adscensionis, Gulf of Mexico) seem similar to our cuckoo Wrasse, with the dominant female in a group becoming male if the existing male is removed. Both sexes of rock hind, however, can display temporary markings to defend territory. In addition the males can also show a distinctive ‘tuxedo’ pattern, with a yellow tail and black and white body. Most of the time, however, both males and females adopt a camoflaged pattern.
Kline RJ, Khan IA, Holt GJ (2011) Behavior, Color Change and Time for Sexual Inversion in the Protogynous Grouper (Epinephelus adscensionis). PLoS ONE 6(5): e19576. doi:10.1371/journal.pone.0019576

Don’t bite your clients! Male cleaner fish beat up spouses who get greedy and take a nip out of their clients. [Social and sexual make-up of cleaner fish is again similar to our cuckoo Wrasse, with a single dominant male and a harem of up to 16 females, the largest female will change sex if the dominant male is removed] ScienceDaily (June 16, 2011)

How sponges grow glass: Sponges split ointo two families, depending upon whether they have calcareous or silica-based spines, which form a skeleton. The sponge Suberites domuncula – commonly found on the shells inhabited by hermit crabs – starts growing a silica spicule within a cell. The first structure is an internal canal, down which the cell inserts silicasomes. Pores in the silicasomes allow the access of aquaporin, which initiates hardening of the bio-silicate.
Wang X, Wiens M, Schröder HC, Schloßmacher U, Pisignano D, et al. (2011) Evagination of Cells Controls Bio-Silica Formation and Maturation during Spicule Formation in Sponges. PLoS ONE 6(6): e20523. doi:10.1371/journal.pone.0020523

Jellies impact marine food web: Jellyfish are in direct competition for plankton with fish, but have now been shown to have a secondary impact on marine bacteria. Soluble organic material from jellyfish tends to be used by bacteria for respiration, rather than recycling vital trace nutrients. As a consequence jellyfish short-circuit the marine food web, resulting in any carbon dioxide that is absorbed by photosynthesis being quickly dumped back into the atmosphere. ScienceDaily (June 6, 2011)

Richer at the edges? The boundaries between different biological landscapes (ecotones) provide both opportunities and threats – species living close to an edge may be more exposed to predators, or the area may encourage species mixing and greater diversity. This study looks at how the diversity of gastropods changed at the boundaries between reefs and seagrass (Posidonia and Amphibolis) beds. [In this instance there appears to be no edge effect, with species richenss and biomass both quickly converging on the values expected for the bulk reef or seagrass ecosystem with no peak or trough at the interface.]
Tuya F, Vanderklift MA, Wernberg T, Thomsen MS (2011) Gradients in the Number of Species at Reef-Seagrass Ecotones Explained by Gradients in Abundance. PLoS ONE 6(5): e20190. doi:10.1371/journal.pone.0020190

Larder raid: GPS-dataloggers attached to adult Peruvian pelicans Pelecanus thagus confirm that they forage at night.
Zavalaga CB, Dell’Omo G, Becciu P, Yoda K (2011) Patterns of GPS Tracks Suggest Nocturnal Foraging by Incubating Peruvian Pelicans (Pelecanus thagus). PLoS ONE 6(5): e19966. doi:10.1371/journal.pone.0019966

A coral’s cholesterol count: Corals contian a mix of lipid types which can be split into two classes – storage (an energy reserve) and structural (used to build cells – e.g. cholesterol). This study finds that the balance between these is determined by the requirements of both the coral and their symbiont algae Symbiodinium.
Cooper TF, Lai M, Ulstrup KE, Saunders SM, Flematti GR, et al. (2011) Symbiodinium Genotypic and Environmental Controls on Lipids in Reef Building Corals. PLoS ONE 6(5): e20434. doi:10.1371/journal.pone.0020434

Too salty? One of the genes responsible for sensing how salty the environment is has been identified in the cyanobacterium Synechocystis sp..
Liang C, Zhang X, Chi X, Guan X, Li Y, et al. (2011) Serine/Threonine Protein Kinase SpkG Is a Candidate for High Salt Resistance in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803. PLoS ONE 6(5): e18718. doi:10.1371/journal.pone.0018718

Don’t go eating that yellow snow: The organic particulates that rain down from the productive surface waters into the oceans deeps have been, rather poetically, referred to as ‘marine snow’. For the full health warning read Hannah Waters in Culturing Science, August 19, 2010

Microbes in the Gulf of Maine: A survey of everything from viruses to phytoplankton in this area estimates a minimum abundance of cell-based microbes as 1.7×1025 organisms. This may equate to a species richness of between 105 to 106 taxa.
Li WKW, Andersen RA, Gifford DJ, Incze LS, Martin JL, et al. (2011) Planktonic Microbes in the Gulf of Maine Area. PLoS ONE 6(6): e20981. doi:10.1371/journal.pone.0020981

Invertebrate vaccination: It looks like some invertebrates can be primed against disease, though the mechanism remains unclear.
Pope EC, Powell A, Roberts EC, Shields RJ, Wardle R, et al. (2011) Enhanced Cellular Immunity in Shrimp (Litopenaeus vannamei) after ‘Vaccination’. PLoS ONE 6(6): e20960. doi:10.1371/journal.pone.0020960

DNA barcoding delimits species: Fast barcoding techniques prove robust enough to pick out species of bivalve in Chinese waters.
Chen J, Li Q, Kong L, Yu H (2011) How DNA Barcodes Complement Taxonomy and Explore Species Diversity: The Case Study of a Poorly Understood Marine Fauna. PLoS ONE 6(6): e21326. doi:10.1371/journal.pone.0021326

Conservation

A bad place to live? A study that looks into how the local environment influences disease in corals. The underlying associations between disease prevalence and 14 different predictor variables (biotic and abiotic) are reported.
Aeby GS, Williams GJ, Franklin EC, Kenyon J, Cox EF, et al. (2011) Patterns of Coral Disease across the Hawaiian Archipelago: Relating Disease to Environment. PLoS ONE 6(5): e20370. doi:10.1371/journal.pone.0020370

Marlin don’t like being tagged: [Tagging is a vital part of our studies into the lives of the larger marine organisms, it allows us to fill in gaps in our understanding of their life-cycles and behaviour. It also allows us to see which areas of the sea they make most use of, and so plan conservation strategies. This only works if the animal being tagged continues to behave normally, however…]
Sippel T, Holdsworth J, Dennis T, Montgomery J (2011) Investigating Behaviour and Population Dynamics of Striped Marlin (Kajikia audax) from the Southwest Pacific Ocean with Satellite Tags. PLoS ONE 6(6): e21087. doi:10.1371/journal.pone.0021087

Eels don’t like being tagged either.
Methling C, Tudorache C, Skov PV, Steffensen JF (2011) Pop Up Satellite Tags Impair Swimming Performance and Energetics of the European Eel (Anguilla anguilla). PLoS ONE 6(6): e20797. doi:10.1371/journal.pone.0020797

Boning up: Scientists now know a little more about the bone fish resident in Caribbean waters, with observations of pre-spawning aggregations of fish in deeper water than previously suspected for the species. ScienceDaily (June 7, 2011)

Eel today, gone tomorrow: The European eel in Sweden is now thought to be critically endangered, having collapsed to a few percent of its population only 50 years ago. mnagement policies in place are thought to be too lenient with local fisheries to permit it to survive. ScienceDaily (June 7, 2011)

Stranded statistics: Genetic barcoding of carcasses from dolphin strandings may not accurately reflect the genetic makeup of the population as a whole, so care must be taken with inferrences based on this data. [contrast with below]
Bilgmann K, Möller LM, Harcourt RG, Kemper CM, Beheregaray LB (2011) The Use of Carcasses for the Analysis of Cetacean Population Genetic Structure: A Comparative Study in Two Dolphin Species. PLoS ONE 6(5): e20103. doi:10.1371/journal.pone.0020103

Stranding stats reflect population: Keeping a track of stranded cetaceans may be a cheap and reliable way of following what is happening to the population a a whole. [Contrast with above] ScienceDaily (June 8, 2011)

Where are the marine reserves? Reserves established a decade ago have allowed fish populations to recover, so how come so little of the marine system is protected? Bruce Barcott in Environment 360, 16 Jun 2011

Deep Sea Conservation Coalition: Is calling for the United Nations General Assembly to secure a moratorium on high seas bottom trawling and protect deep-water species that are often slow growing and very susceptible to over fishing.

Evolve away from that: The ability of corals to survive in a rapidly changing marine ecosystem – threatened by climate change, pollution and exploitation – may depend upon how quickly they can evolve. This paper is a preliminary study of the plasticity of genomes of Acropora millepora and Acropora palmata.
Voolstra CR, Sunagawa S, Matz MV, Bayer T, Aranda M, et al. (2011) Rapid Evolution of Coral Proteins Responsible for Interaction with the Environment. PLoS ONE 6(5): e20392. doi:10.1371/journal.pone.0020392

Antarctic diversity: South Georgia is in a unique location, in the middle of the Antarctic circum-polar current, and south of the polar front. The shelf around South Georgia has now been reported to be the most diverse marine area in the Southern Ocean. The species in the area have not been recorded very often, and many may be rare. In addition, a large number are thought to be close to the edge of their range, and may find it hard to cope with climate change.
Hogg OT, Barnes DKA, Griffiths HJ (2011) Highly Diverse, Poorly Studied and Uniquely Threatened by Climate Change: An Assessment of Marine Biodiversity on South Georgia’s Continental Shelf. PLoS ONE 6(5): e19795. doi:10.1371/journal.pone.0019795

Little skate (Leucoraja erinacea) genome workshop: Dr Bik in Deep Sea News, May 28th, 2011

Fish predictor: A model combining seabottom topography (roughness, curvature, slope etc.) and geography (distance to shore or shelf, water depth) has proven successful in predicting the habitat ranges of three reef fish species. The dominant factor in predicting the range of fish was the distance to shore (or shelf), followed by the tortuosity/complexity (slope of slope) of the surface.
Pittman SJ, Brown KA (2011) Multi-Scale Approach for Predicting Fish Species Distributions across Coral Reef Seascapes. PLoS ONE 6(5): e20583. doi:10.1371/journal.pone.0020583

Disease transfer: A study on the US Pacific coast finds evidence that diseases associated with terrestrial animals are finding their way aquatic populations is being found after post mortems of marine mammals. ScienceDaily (May 25, 2011)

Fisheries and exploitation

Just how much have our fisheries declined in the last century? The map published by the Guardian shows estimated fish stocks for 1900 and 2000 in the North Atlantic. There is a reference to original work published by Christensen et al. in Fish and Fisheries, 2003, 4, 1-24.

Fisheries activty on the Great Barrier Reef: Study showing how fisheries activity has changed since 1990, with increases in the areas protected from trawl fisheries. [The number of boats, and days spent fishing declined, but the catch per boat or day spent fishing increased].
Grech A, Coles R (2011) Interactions between a Trawl Fishery and Spatial Closures for Biodiversity Conservation in the Great Barrier Reef World Heritage Area, Australia. PLoS ONE 6(6): e21094. doi:10.1371/journal.pone.0021094

Madagascar! More than the penguins will go hungry as fish stocks have been plundered by unregulated local fisheries and European fishing fleets during a period of prolonged political unrest. Two thirds of the Madagascan population face hunger. ScienceDaily (June 17, 2011)

Are fisheries subsidies bad for everyone? A hindcasting model reviewing how the subsidies system in the North Sea have influenced fisheries profits and ecological stability. The suggestion here is that subsidies had a negative impact on both marine biomass and fisheries profitability.
Heymans JJ, Mackinson S, Sumaila UR, Dyck A, Little A (2011) The Impact of Subsidies on the Ecological Sustainability and Future Profits from North Sea Fisheries. PLoS ONE 6(5): e20239. doi:10.1371/journal.pone.0020239

Abalone in trouble: Fisheries for the Northern Abalone in British Columbia (Canada) were closed in 1990 to allow stocks to recover, but so-far to very little effect, largely due to poaching. Recent studies, however, show that increases in CO2 will further undermine this species. ScienceDaily (May 26, 2011)

Fraudulent fish finder: The European Commissions Joint Research Centre claims that a battery of new technicques based on molecular technologies (genetics, genomics, chemistry and forensics) can answer questions of species and provenance, advances are necessary to police illegal fisheries. ScienceDaily (May 28, 2011)

Pollution

Nuclear cruise: Scientific expedition to follow the effects of leaked radiation from the Fukushima Daiichi nuclear plant in Japan. Dr Bik in Deep Sea News, June 6th, 2011.

Sunscreen threat to marine life? Studies on the fresh water water flea Daphnia magna show that nanoparticulate titanium dioxide (used as the active ingredient of most sunscreens) is toxic, but quickly associates into larger, less toxic, particles in water. Prolonged exposure of daphnia to concentrations of 2 mg/L resulted in the build up of coating on the animals, and resulted in moulting problems and high mortality for the water fleas.
Dabrunz A, Duester L, Prasse C, Seitz F, Rosenfeldt R, et al. (2011) Biological Surface Coating and Molting Inhibition as Mechanisms of TiO2 Nanoparticle Toxicity in Daphnia magna. PLoS ONE 6(5): e20112. doi:10.1371/journal.pone.0020112

Legal litmus test: Perpetrators of local acidification in coastal waters can be brought to book, concludes Stanford University’s Center for Ocean Solutions. ScienceDaily (May 26, 2011)

Did bugs pig out? It has been reported that the hydrocarbons released during the Deepwater Horizon spill in the Gulf of Mexico were consumed by bacteria in the water colum within 120 days. This model is based on low oxygen concentrations monitored in the Gulf after the spill. Other scientists are less convinced by the inferencee, citing that there is a lot of uncertainly in the measurements. Methane in particular is thought to be very hard to digest. ScienceDaily (May 29, 2011)

Record dead zone predicted: Flooding of the Mississippi river this spring has swept large amounts of nutrients into the Gulf of Mexico, and a record dead zone is predicted as a consequence. (June 14, 2011) More on the deadzone: Graphs and stuff. ScienceDaily (June 14, 2011)

Climate change

Danger low oxygen! It looks like marine eutrophication may be very sensitive to climate change. Low oxygen water masses are created as bacteria decompose algae sinking through the water column. Usually they occur at some depth, where the water is cold, so bacterial growth is inhibited. Increased temperature reduces oxygen solubility on seawater and increases deep water temperatures. As a result these is less O2 to go round, and it is used up more efficiently. The result is likely to be significant increases in the size of oceanic dead zones, where higher plants and animals are unable to survive. ScienceDaily (June 18, 2011)

Ocean acidification impairs hearing in clownfish. ScienceDaily (June 4, 2011)

Sea-ice and plankton: The copepod Calanus gracialis is well adapted to its arctic environment. It stores an enourmous amount of fat in its body (compared to its body mass), to survive during the arctic winter. Each spring as the ice melts it releases phytoplankton which are preyed upon by Calanus, who use the bounty to reproduce. Later, as the ice melts entirely there is a new phytoplankton bloom, which feeds the young Calanus, and sets them up for the long winter. This is a lifecycle that is closely timed to the seasons, and may be badly disrupted by climate changes. As Calanus is a vital food source for a wide range of species, from cod to whales, this may have far-reaching consequences. ScienceDaily (June 6, 2011)

Coral calcification: To understand how corals will respond to ocean acidification it would be useful to know how they go about producing thair calcified tissues. This study is the first to be able to image corals reducing the acidity (increasing the pH) of the seawater adjacent to their calicoblastic epithelium – the area of skin that is creating the calcified material. The reduced acidity in this volume of water makes carbonate minerals less soluble, so easier to precipitate as a skeleton.
Venn A, Tambutté E, Holcomb M, Allemand D, Tambutté S (2011) Live Tissue Imaging Shows Reef Corals Elevate pH under Their Calcifying Tissue Relative to Seawater. PLoS ONE 6(5): e20013. doi:10.1371/journal.pone.0020013

CO2 seeps associated with reduced biodiversity: Natural volcanic CO2 seeps in Papua New Guinea show how our oceans may become as a result of our fossil fuel economy. The study reports reductions in biodiversity and recruitment on the reef as pH declined from 8.1 to 7.8, and predicts that reef development would cease at a pH below 7.7. ScienceDaily (May 29, 2011)

Sponges in hot water.
Cebrian E, Uriz MJ, Garrabou J, Ballesteros E (2011) Sponge Mass Mortalities in a Warming Mediterranean Sea: Are Cyanobacteria-Harboring Species Worse Off? PLoS ONE 6(6): e20211. doi:10.1371/journal.pone.0020211

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