Observations made in the scientific and popular literature suggest that the characteristics of both marine and terrestrial ecosystems are changing rapidly due to increasing global air and sea temperatures. Here, we examine the hypothesis that fish species with more 'southern' distributions are increasing in the northern North Sea over time. In order to do this, 2 important databases on fish abundance collected by trawl on research cruises are interrogated. When combined, the databases cover both the entire North Sea and the Scottish west coast and span a period of 80 yr (1925 to 2004). The data take the form of length-frequencies for all species caught (> 300 different species), while additional information (e.g. age, sex, weight and stage of sexual maturity) is available for the commercially important component (e.g. cod). The trawl data suggest that the North Sea is experiencing waves of immigration by exotic, southern species (e.g. red mullet, anchovy and pilchard). The purpose of this paper is to describe and document these changes.KEY WORDS: Anchovy · Sardine · Horse mackerel · Mackerel · Long-term · North Sea · Climate Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 284: [269][270][271][272][273][274][275][276][277][278] 2004 doliolids are connected to unusual incursions of oceanic water caused by changes in the North Atlantic Oscillation (Edwards et al. 1999).Higher than average sea temperatures are correlated with low recruitment of cod at the latitudinal limits of its range (Planque & Frédou 1999, O'Brien et al. 2000. Reid et al. (2001) related abrupt changes in the abundance and composition of the plankton and fish community ca. 1988 to recent increases in the North Sea horse mackerel fishery. Pronounced increases in tropical fish in the Bay of Biscay area have been noted (Quero et al. 1998) by scientists in France, while Swaby & Potts (1999) made the first British record of the sailfin dory Zenopsis conchifer, noting that the species is advancing northwards along the continental shelf west of the British Isles at a rate of 60 km per decade. Other studies show similar patterns. Information on first records of southerly fish species caught in Cornish waters has been collated and published (Stebbing et al. 2002), and nearly 20 completely new species have been recorded (by 2001). The fish species noted include bigeyed tunny Thunnus obesus, sailfin dory Zenopsis conchifer, short-nosed seahorse Hippocampus hippocampus and barracuda Sphyraena sphyraena. In the Irish Sea, the occurrence of the warm-water species, anchovy Engraulis encrasicolus, has increased between 1990 and 1998 according to trawl data from research surveys (Armstrong et al. 1999). British commercial fishermen have also noted change. The spider-crab Maia squinado fishery, for example, is advancing steadily further northwards (Anonymous 2003).In 1996, a paper was published describing the longterm variation in the abundance of southern species in the southern North Sea (Corten & van...

Kangaroos ferment forage material in an enlarged forestomach analogous to the rumen, but in contrast to ruminants, they produce little or no methane. The objective of this study was to identify the dominant organisms and pathways involved in hydrogenotrophy in the kangaroo forestomach, with the broader aim of understanding how these processes are able to predominate over methanogenesis. Stable isotope analysis of fermentation end products and RNA stable isotope probing (RNA-SIP) were used to investigate the organisms and biochemical pathways involved in the metabolism of hydrogen and carbon dioxide in the kangaroo forestomach. Our results clearly demonstrate that the activity of bacterial reductive acetogens is a key factor in the reduced methane output of kangaroos. In in vitro fermentations, the microbial community of the kangaroo foregut produced very little methane, but produced a significantly greater proportion of acetate derived from carbon dioxide than the microbial community of the bovine rumen. A bacterial operational taxonomic unit closely related to the known reductive acetogen Blautia coccoides was found to be associated with carbon dioxide and hydrogen metabolism in the kangaroo foregut. Other bacterial taxa including members of the genera Prevotella, Oscillibacter and Streptococcus that have not previously been reported as containing hydrogenotrophic organisms were also significantly associated with metabolism of hydrogen and carbon dioxide in the kangaroo forestomach.

Punt, A. E., Deng, R. A., Dichmont, C. M., Kompas, T., Venables, W. N., Zhou, S., Pascoe, S., Hutton, T., Kenyon, R., van der Velde, T., and Kienzle, M. 2010. Integrating size-structured assessment and bioeconomic management advice in Australia's northern prawn fishery. – ICES Journal of Marine Science, 67: 1785–1801. Three species in Australia's northern prawn fishery (Penaeus semisulcatus, P. esculentus, and Metapenaeus endeavouri) are assessed using a size-structured population model that operates on a weekly time-step. The parameters of this multispecies population model are estimated using data on catches, catch rates, length frequency data from surveys and the fishery, and tag release–recapture data. The model allows for the technical interaction among the three species. The results from the multispecies stock assessment are used to calculate the time-series of catches and levels of fishing effort that maximize net present value. The bioeconomic model takes into account costs which are proportional to catches and those which are proportional to fishing effort, as well as fixed costs. The sensitivity of the results is examined by changing the assumptions regarding the values for the economic parameters of the bioeconomic model as well as those on which the assessment are based. The results suggest that fishing effort needs to be reduced in the short term to achieve economic goals, although most stocks are estimated currently to be above the stock size corresponding to maximum sustainable yield. Short-term catches and effort levels are sensitive to model assumptions, and in particular, to trends in prices and costs.

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