A cracker of crazy stuff from the ocean this issue: Our contribution to shark week this year might be a shark with a hump – or the camel with very sharp teeth… Plus buzzing lobsters, binary snails and when to fix your beach defenses. Perhaps the best news this issue is the partial recovery of the Grand Banks fishing area. White fish stocks had been reduced close to extinction, and this set up feedback loops that resulted in smaller fish and squid taking over, as they ate what few young fish that were born. After over 20 years of ban, however, there are signs that the cod are coming back… Lessons? – Stop fishing before you hit stock bottom (unless you can survive 30 years without work that is)!
The shark with a hump: What is the similarity between a shark and a camel? Apparently their immune B-cell based adaptive immune systems are an example of convergent evolution. This adaptation is only found in cartilaginous fish and camelids, and is thought to be related to high urea concentrations in shark’s blood, and extreme adaptation to arid climates in camels. Both conditions result in higher than usual electrolyte concentrations in the blood stream, where the B-cells work, and the adaptation results in an antigen binding protein that is better able to cope under these conditions.
Flajnik MF, Deschacht N, Muyldermans S (2011) A Case Of Convergence: Why Did a Simple Alternative to Canonical Antibodies Arise in Sharks and Camels? PLoS Biol 9(8): e1001120. doi:10.1371/journal.pbio.1001120
Pliers or fingers? The bottlenosed dolphin (Tursiops sp.) generally hunts for prey using echo-location, and can even use this technique to find buried fish, but occasionally it puts a basket sponge over its nose and probes the sediment directly instead of using echo-location. This work shows that dolphins only use tools when the substrate is mixed, so it is hard to spot buried food, or when they are hunting for prey other than bony fish. The absence of a swim-bladder makes prey more difficult to spot by echo-location.
Patterson EM, Mann J (2011) The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.). PLoS ONE 6(7): e22243. doi:10.1371/journal.pone.0022243
Cape crèche: What are the crietria that make undersea promontories and capes such attractive places for fish to spawn? Previously it was thought that the presence of currents that sweep the young out to sea was the important factor. This study shows the contrary, with most spawning sites being associated with stable eddies that keep the young fish close to the shore.
Karnauskas M, Chérubin LM, Paris CB (2011) Adaptive Significance of the Formation of Multi-Species Fish Spawning Aggregations near Submerged Capes. PLoS ONE 6(7): e22067. doi:10.1371/journal.pone.0022067
Buzzing lobsters: Usually crustacea make a noise by rubbing limbs together, in a similar manner grass hoppers, here, however, we find that some lobsters are able to make a buzzing sound by vibrating their carapaces. Fewer than 5% of the lobsters tested made the noise, but at 118 decibels it is an effective deterrent to (small) hungry fish… by Zen at NeuroDojo, July 15, 2011
Light keeps starvation at bay: The sea-slug Elysia clarki is capable of keeping chloroplasts taken from its algal food viable in its digestive system for considerable periods of time. This means that the slug can generate a proportion of its food photosynthetically, and this ability in turn delays its response to starvation conditions for several weeks, until the photosynthetic chloroplasts degrade below a useful level.
Middlebrooks ML, Pierce SK, Bell SS (2011) Foraging Behavior under Starvation Conditions Is Altered via Photosynthesis by the Marine Gastropod, Elysia clarki. PLoS ONE 6(7): e22162. doi:10.1371/journal.pone.0022162
What jumbo had for lunch: Isotopic analysis has been used to track foraging patterns in jumbo squid (Dosidicus gigas). Taking several samples along the gladius (main body of the squid) follows the foraging back through the life of the squid. The isotope patterns show periods of eating on the move during migration, and patterns where food sources are more stable. Several habitats may be being exploited by the squid during their lifespan.
Lorrain A, Argüelles J, Alegre A, Bertrand A, Munaron J-M, et al. (2011) Sequential Isotopic Signature Along Gladius Highlights Contrasted Individual Foraging Strategies of Jumbo Squid (Dosidicus gigas). PLoS ONE 6(7): e22194. doi:10.1371/journal.pone.0022194
Programming snails: Simple programs can duplicate the self-aggregation behaviour of littorinid snails (which group together to protect against dessication) – if they are living on simple artificial surfaces. Real rock surfaces with nooks and cranies permit a wider range of behaviour that is less impacted by hot dry days…
Stafford R, Williams GA, Davies MS (2011) Robustness of Self-Organised Systems to Changes in Behaviour: An Example from Real and Simulated Self-Organised Snail Aggregations. PLoS ONE 6(7): e22743. doi:10.1371/journal.pone.0022743
Gingerbread house: Shrimps that make their homes in sponges are not, it appears, innocent squatters, but are adapted to eating their abode…
Ďuriš Z, Horká I, Juračka PJ, Petrusek A, Sandford F (2011) These Squatters Are Not Innocent: The Evidence of Parasitism in Sponge-Inhabiting Shrimps. PLoS ONE 6(7): e21987. doi:10.1371/journal.pone.0021987
The rocks make the worm: The tubeworm Riftia pachyptila is one of the hallmark species of deep hydrothermal vents. This study shows that they are quite genetically diverse, and may be quite strongly adapted to their specific geochemical niche.
Robidart JC, Roque A, Song P, Girguis PR (2011) Linking Hydrothermal Geochemistry to Organismal Physiology: Physiological Versatility in Riftia pachyptila from Sedimented and Basalt-hosted Vents. PLoS ONE 6(7): e21692. doi:10.1371/journal.pone.0021692
Conservative worms: 12% of the polychaet worms identified in Canadian waters are thought to inhabit three oceans – Atlantic, Arctic and Pacific, based on morphological criteria. This genetic barcoding study of cytochrome COI shows that despite appearances there are large differences in genetics between Pacific and Arctic/Atlantic populations. The study suggests that there are a number of cryptic species lurking amongst those previously identified.
Carr CM, Hardy SM, Brown TM, Macdonald TA, Hebert PDN (2011) A Tri-Oceanic Perspective: DNA Barcoding Reveals Geographic Structure and Cryptic Diversity in Canadian Polychaetes. PLoS ONE 6(7): e22232. doi:10.1371/journal.pone.0022232
Life on kelp: This study from Sydney Harbour (Australia) indicates that epiphytes such as bryozoans are strongly influenced by what the kelp they are growing on is growing on in turn. Man-made substrates, such as pilings increased the density of the introduced species Membranipora membranacea, possibly as these structures provided shade which indirectly influeces the population of predatory urchins…
Marzinelli EM, Underwood AJ, Coleman RA (2011) Modified Habitats Influence Kelp Epibiota via Direct and Indirect Effects. PLoS ONE 6(7): e21936. doi:10.1371/journal.pone.0021936
The startled anemone: Individual beadlet anemones exhibit ‘personality’ in the way they respond to being startled.
Briffa M, Greenaway J (2011) High In Situ Repeatability of Behaviour Indicates Animal Personality in the Beadlet Anemone Actinia equina (Cnidaria). PLoS ONE 6(7): e21963. doi:10.1371/journal.pone.0021963
The written world: A report of the global biodiversity of sea-pens (Pennatulacea) [of the approximately 200 species only two are common in the shallow waters around the UK coastline].
Williams GC (2011) The Global Diversity of Sea Pens (Cnidaria: Octocorallia: Pennatulacea). PLoS ONE 6(7): e22747. doi:10.1371/journal.pone.0022747
Harpooned! A detailed investigation of the structure and genetics of the nematocyst in the starlet sea anemone Nematostella vectensis.
Zenkert C, Takahashi T, Diesner M-O, Özbek S (2011) Morphological and Molecular Analysis of the Nematostella vectensis Cnidom. PLoS ONE 6(7): e22725. doi:10.1371/journal.pone.0022725
How do you do that? A strategy for analysing the differences in gene expression between sessile (polyp) and motile (medusoid) phases in the cnidarian Nanomia bijuga.
Siebert S, Robinson MD, Tintori SC, Goetz F, Helm RR, et al. (2011) Differential Gene Expression in the Siphonophore Nanomia bijuga (Cnidaria) Assessed with Multiple Next-Generation Sequencing Workflows. PLoS ONE 6(7): e22953. doi:10.1371/journal.pone.0022953
Seagrass food web: The food-web structure of seagrass habitats studied on the Canadian Atlantic coast were found to change with human impacts, such eutrophication. The authors conclude that the spatial scale of the analysis is critical for determining results, with point studies often being dominated by local factors that obscure statistically significant regional effects.
Coll M, Schmidt A, Romanuk T, Lotze HK (2011) Food-Web Structure of Seagrass Communities across Different Spatial Scales and Human Impacts. PLoS ONE 6(7): e22591. doi:10.1371/journal.pone.0022591
Bloom populations: We know now that phytoplankton species are not homogeneous. This study shows that even single blooms may be contributed to by several sub-populations. During a long-lived bloom in the Gulf of Maine (US, 2005) the dominant sub-population changed over time.
Erdner DL, Richlen M, McCauley LAR, Anderson DM (2011) Diversity and Dynamics of a Widespread Bloom of the Toxic Dinoflagellate Alexandrium fundyense. PLoS ONE 6(7): e22965. doi:10.1371/journal.pone.0022965
Moored PCR: A moored sensor in Monterey Bay (US) monitored genes and gene products from a wide range of organisms for 28 days. The sensor allows gene abundances to be assessed autonomously, underwater in near real-time and referenced against prevailing chemical, physical and bulk biological conditions.
Preston CM, Harris A, Ryan JP, Roman B, Marin R III, et al. (2011) Underwater Application of Quantitative PCR on an Ocean Mooring. PLoS ONE 6(8): e22522. doi:10.1371/journal.pone.0022522
Managing coastal infrastructure: Man made structures dominate much of our coastline, and their management and maintenance is associated with the loss of species such as mussels and oysters, that normally dominate hard substrates, and their replacement with opportunistic species such as biofilms and seaweeds. Much of the problem is associated with sediment disturbance, which can effect a much wider area than that associated with the work itself. This paper suggests that the impact can be lessened by carrying out maintenance work at times of the year when dominant species are quiescent.
Airoldi L, Bulleri F (2011) Anthropogenic Disturbance Can Determine the Magnitude of Opportunistic Species Responses on Marine Urban Infrastructures. PLoS ONE 6(8): e22985. doi:10.1371/journal.pone.0022985
Dolphin count: It is claimed that aerial survey of cetaceans in the new Pelagos Sanctuary in the Mediterranean provides robust estimates of population levels.
Panigada S, Lauriano G, Burt L, Pierantonio N, Donovan G (2011) Monitoring Winter and Summer Abundance of Cetaceans in the Pelagos Sanctuary (Northwestern Mediterranean Sea) Through Aerial Surveys. PLoS ONE 6(7): e22878. doi:10.1371/journal.pone.0022878
Deep impact: What are likely to be the consequences of mans impact on the deep sea? – This paper tries to identify ecosystems particularly at risk from exploitation, including cold-water corals and seamount communities.
Ramirez-Llodra E, Tyler PA, Baker MC, Bergstad OA, Clark MR, et al. (2011) Man and the Last Great Wilderness: Human Impact on the Deep Sea. PLoS ONE 6(8): e22588. doi:10.1371/journal.pone.0022588
Shark society: Genetic studies on the scalloped hammerhead shark, Sphyrna lewini, were used to estimate the genetic structure of the population. The study indicated that most populations expanded rapidly between 90,000 and 140,000 years ago, and that the sharks now live in small, nearly isolated communities. The current population is estimated to be between 2 and 3 orders of magnitude (100-1000x) smaller than in the past. The start of the decline in numbers may predate human predation. Studies were based on 221 individuals caught by fishermen.
Nance HA, Klimley P, Galván-Magaña F, Martínez-Ortíz J, Marko PB (2011) Demographic Processes Underlying Subtle Patterns of Population Structure in the Scalloped Hammerhead Shark, Sphyrna lewini. PLoS ONE 6(7): e21459. doi:10.1371/journal.pone.0021459
Fisheries and exploitation
Cod to be back: After nearly 30 years cod have finally started to return to the Grand Banks and Eastern Scotia shelf off Canada. Stocks are still weak but the fishing ban appears to have worked, partially reversing the effect of fisheries that had forced many commercial species to local extinction in the 1970’s. ScienceDaily (July 28, 2011)
Fish, plankton and birds in the North Sea: Clupeids like the herring are postulated to control a large part of the North Sea ecosystem because they are the intermediate between plankton and higher trophic levels, such as seabirds and seals. Herring populations are found to directly influence that of overwintering seabirds. Fishing pressures, which have historically switched between cod and herring, therefore have a major impact on the entire ecosystem.
Fauchald P, Skov H, Skern-Mauritzen M, Johns D, Tveraa T (2011) Wasp-Waist Interactions in the North Sea Ecosystem. PLoS ONE 6(7): e22729. doi:10.1371/journal.pone.0022729
Cost-benefit for no-take zones: No-take zones have an immediate and negative impact on fishermen, so it is important to demonstrate that they do regenerate fish stocks, and lead to long-term sustainability. Benjamin Jones July 19, 2011, Marine Conservation News
Cleaner needed: The hagfish is facing increasing pressure from some fisheries, despite that fact that its recycling activities are beneficial for other, more commercially valuable, species such as cod and flounder. Benjamin Jones July 30, 2011, Marine Conservation News
Energetics and survival: Pacific bluefin tuna seem to live life on the edge, with wild populations having very small reserves to deal with starvation. Wild fish grow more slowly than cultivated fish larely because they live at lower average water temperatures, rather than due to a difference in diet.
Jusup M, Klanjscek T, Matsuda H, Kooijman SALM (2011) A Full Lifecycle Bioenergetic Model for Bluefin Tuna. PLoS ONE 6(7): e21903. doi:10.1371/journal.pone.0021903
Biofuels from the oceans: Early thoughts on farming seaweed in coastal waters. Benjamin Jones in Marine Conservation News, July 15, 2011
I remember: Fishermen’s recollections of the numbers of top predators (dolphins and sharks) they used to see when fishing indicates that there has been a significant decline in sightings over the last 60 years. This decline correlates with the decline in commercial fish stocks they were preying on.
Maynou F, Sbrana M, Sartor P, Maravelias C, Kavadas S, et al. (2011) Estimating Trends of Population Decline in Long-Lived Marine Species in the Mediterranean Sea Based on Fishers’ Perceptions. PLoS ONE 6(7): e21818. doi:10.1371/journal.pone.0021818
No acute effects on nearshore fisheries: Comparisons of numbers of fish larvae caught within seagrass nurseries after the Deepwater Horizon accident and those in previous years indicate that the spill has had no acute ffect on fish stocks within the effected areas. Many species in fact showed a larger population than seen in previous years, with no change in species mix following the spill. The reason for this better-than-expected result is not clear, but concern for these fisheries now moves to whether there is any chronic effect of the spill.
Fodrie FJ, Heck KL Jr (2011) Response of Coastal Fishes to the Gulf of Mexico Oil Disaster. PLoS ONE 6(7): e21609. doi:10.1371/journal.pone.0021609
Weedy plankton: Increased CO2 levels result in thinner calcite skeletons in coccolithophorids. ScienceDaily (Aug. 3, 2011)
Acid bait: A study on the brown dottyback (Pseudochromis fuscus) shows that Ocean acidification may reduce how readily fish can detect prey in the water by impairing their sense of smell.
Cripps IL, Munday PL, McCormick MI (2011) Ocean Acidification Affects Prey Detection by a Predatory Reef Fish. PLoS ONE 6(7): e22736. doi:10.1371/journal.pone.0022736
Ice-shelf collapse triggers community change: Collapses of the Larsen ice shelf in 1995 and 2002 have changed benthic conditions for nematodes living in the underlying sediments. The loss of ice has resulted in a greater influx of food during the summer phytoplankton bloom, and a corresponding change in the types and numbers of nematodes living in these areas.
Hauquier F, Ingels J, Gutt J, Raes M, Vanreusel A (2011) Characterisation of the Nematode Community of a Low-Activity Cold Seep in the Recently Ice-Shelf Free Larsen B Area, Eastern Antarctic Peninsula. PLoS ONE 6(7): e22240. doi:10.1371/journal.pone.0022240