Big Advantage for the Small

New research out of IFM-GEOMAR makes the case that:

... reduced body size is the third universal ecological response to global warming in aquatic systems besides the shift of species ranges toward higher altitudes and latitudes and the seasonal shifts in life cycle events.

Read the article at PNAS:
Global warming benefits the small in aquatic ecosystems.[Subscription Required]

Read the press release at IFM-GEOMAR

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Study: Icelandic cod stock is imperiled

Via PLoS ONE
A new study out of the Institute of Biology at the University of Iceland finds it likely that the Icelandic cod stock is imperiled and recommends immediate action be taken to avert a collapse similar to that of the northern cod of Newfoundland.

Can anything be done to avert collapse? Upon collapse of the northern cod of Newfoundland the Canadian government imposed a moratorium on fishing [11]. Such a drastic measure if imposed in Iceland doubtless would avert collapse. Alternatively management measures that shifted fishing from shallow-water to deep-water or measures that distributed fishing effort evenly over all depth ranges by controlling fishing by different gear also could possibly help avert collapse.

However, we consider that such strategies would be difficult to implement. Alternatively we speculate and suggest that it may be possible to avert collapse by adopting a different strategy of removing selection pressures against shallow-water adapted AA and AB fish. This highlights the use of evolutionary thinking for management and conservation issues. Given that current practices are ineffective in protecting shallow-water adapted fish, we suggest that immediate action is required.

Intense Habitat-Specific Fisheries-Induced Selection at the Molecular Pan I Locus Predicts Imminent Collapse of a Major Cod Fishery
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Crabs go deep to avoid hot water

Via the National Oceanography Centre, Southampton, UK:

Researchers from the National Oceanography Centre, Southampton, have drawn together 200 years’ worth of oceanographic knowledge to investigate the distribution of a notorious deep-sea giant – the king crab. The results, published this week in the Journal of Biogeography, reveal temperature as a driving force behind the speciation and radiation of a major seafloor predator; globally, and over tens of millions of years of Earth’s history.

In deep seas all over the world, around 100 species of king crabs live largely undiscovered. The fraction that we have found includes some weird and wonderful examples - Paralomis seagrantii has its eight walking legs and claws entirely covered in long fur-like setae; while related group Lithodes megacanthus grows to lengths of 1.5 metres, and has 15-20-cm long defensive spines covering its body. At temperatures of around 1- 4ºC, these crabs thrive in some of the colder waters on Earth; living and growing very slowly, probably to very old ages. Only in the cooler water towards the poles are king crabs found near the water surface – though temperatures found around some parts of the Antarctic (below 1ºC) are too extreme for their survival.

Read the entire release here.
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Surviving mass extinction by bridging the benthic/planktic divide

Via PNAS Early Edition:
Kate F. Darling, et. al. provide evidence for a tychopelagic existence for the planktic foraminifera Streptochilus globigerus citing its relation to the benthic Bolivina variabilis. The evolution from a benthic to planktic existence was generally viewed as a one-time event per clade. This finding shows the possibility that the tychopelagic foraminifera have the capability to quickly recolonize the planktic domain after extinction events.

Evolution of planktic organisms from benthic ancestors is commonly thought to represent unidirectional expansion into new ecological domains, possibly only once per clade. For foraminifera, this evolutionary expansion occurred in the Early–Middle Jurassic, and all living and extinct planktic foraminifera have been placed within 1 clade, the Suborder Globigerinina. The subsequent radiation of planktic foraminifera in the Jurassic and Cretaceous resulted in highly diverse assemblages, which suffered mass extinction at the end of the Cretaceous, leaving an impoverished assemblage dominated by microperforate triserial and biserial forms. The few survivor species radiated to form diverse assemblages once again in the Cenozoic. There have, however, long been doubts regarding the monophyletic origin of planktic foraminifera.

We present surprising but conclusive genetic evidence that the Recent biserial planktic Streptochilus globigerus belongs to the same biological species as the benthic Bolivina variabilis, and geochemical evidence that this ecologically flexible species actively grows within the open-ocean surface waters, thus occupying both planktic and benthic domains. Such a lifestyle (tychopelagic) had not been recognized as adapted by foraminifera. Tychopelagic are endowed with great ecological advantage, enabling rapid recolonization of the extinction-susceptible pelagic domain from the benthos. We argue that the existence of such forms must be considered in resolving foraminiferal phylogeny.

Published online before print July 2, 2009, doi: 10.1073/pnas.0902827106

Read the article at PNAS[subscription required].
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