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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2006.05.007 Byline: J.W. Fleeger (a), K.R. Carman (a), P.B. Weisenhorn (a), H. Sofranko (a), T. Marshall (a), D. Thistle (b), J.P. Barry (c) Keywords: Carbon dioxide; Meiobenthos; Nematodes; Size distribution; Biovolume; Monterey Canyon Abstract: One proposal for ameliorating global warming is to sequester large amounts of carbon dioxide in the deep ocean, but the environmental consequences of sequestration for sediment-dwelling animals are poorly known. In a previous publication, we reported that [approximately equal to]80% of benthic copepods were killed in an experimental release of CO.sub.2 off northern California at 3262m. The effects of this release on nematodes are reported here. We examined samples of nematodes taken inside two 'corrals' into which CO.sub.2 was directly injected (providing an extreme endpoint for CO.sub.2 exposure) and taken near to and far from this CO.sub.2 source. After 30 days, pore-water pH was unchanged ([approximately equal to]7.8) at the sediment-water interface far ([approximately equal to]40m) from corrals, but pH profiles were reduced by [approximately equal to]0.75 near ([approximately equal to]2m) corrals. Corral pH was highly acidic (5.4 in a measurement from a subsequent experiment). Fifty randomly selected nematodes from each of four vertical layers from the 14 cores were photographed. They were assigned to a tail group (based on morphology), and individual biovolume was estimated from measurements of body length and width. Although nematode abundance (expressed as total nematodes and by tail group) was not affected, length, width, and individual biovolume significantly differed between near and far samples. Median nematode biovolume examined across tail group and core layer increased by [approximately equal to]48% inside and near corrals. Differences between near and corral samples were always less than differences between near and far samples. However, nematode length:width ratio did not differ between near and far, and the shapes of length, width, and biovolume frequency distributions were similar in all samples. We postulate that the nematode community throughout the upper 3cm suffered a high rate of mortality after exposure to CO.sub.2, and that nematodes were larger because postmortem expansions in body length and width occurred. Decomposition rates were probably low and corpses did not disintegrate in 30 days. The observable effects of a reduction in pH to about 7.0 after 30 days were as great as an extreme pH reduction (5.4), suggesting that 'moderate' CO.sub.2 exposure, compared to the range of exposures possible following CO.sub.2 release, causes high mortality rates in the two most abundant sediment-dwelling metazoans (nematodes and copepods). Author Affiliation: (a) Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803-1725, USA (b) Department of Oceanography, Florida State University, Tallahassee, FL 32306-4320, USA (c) Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA Article History: Received 4 August 2005; Revised 17 May 2006; Accepted 20 May 2006

Hydrogen sulfide discharge at cold seep sites is recorded as enrichment in the barium to calcium (Ba/Ca) ratio in shells of vesicomyid clams collected live from cold seeps in Monterey Canyon and the Cascadia margin. A direct relationship between increased Ba fluxes from cold seeps and Ba incorporation into shells was established for the Cascadia margin site. For the Monterey canyon site, a 2-yr episode of high fluid flow centered on 1992 was inferred from coherent changes in the Ba/Ca profiles of three Calyptogena kilmeri shells. Comparison with precipitation and [[delta].sup.18]O data indicates that this high-flow period may have been driven by an increase in rainfall after the 1988--1990 California drought. High-resolution records preserved in clam shells are shown to be useful in elucidating characteristics, history, and possible mechanisms driving fluid discharge at continental margin seeps, thus establishing their potential use as paleotracers of fluid seepage events.

Changes in the invertebrate fauna of a California rocky intertidal community between the period 1931 to 1933 and the period 1994 to 1994 indicate that species, ranges shifted northward, consistent with predictions of change associated with climate warming. Of 45 invertebrate species, the abundances of eight of nine southern species increased and the abundances of five of eight northern species decreased. No trend was evident for cosmopolitan species. Annual mean shoreline ocean temperatures at the site increased by 0.75 ° C during the past 60 years, and mean summer maximum temperatures from 1983 to 1993 were 2.2 ° C warmer than for the period 1991 to 1931., Responses of natural communities to gradual climate change are expressed as latitudinal shifts in species, abundances and migration of geographic range boundaries. Such changes are best known for centuries or [...]

The American Lobster (Homarus americanus) is trapped primarily with finfish baits that are becoming more costly and difficult to acquire as stocks dwindle. Thus, alternative bait options should be considered. We made video recordings of lobster foraging responses in the laboratory to compare the attractiveness of the invasive green crab (Carcinus maenas) bait, two traditional finfish baits and an inert control. Solitary lobsters approached and handled all three biological baits with similar latencies and spent similar time in contact with the biological baits. In contrast, lobsters took longer to approach and handle, and spent significantly less time in contact with control bait. As green crabs were statistically indistinguishable in attractiveness from traditional baits in our laboratory setting, we suggest field trials should test this alternate bait in circumstances more directly relevant to the fishery. [ABSTRACT FROM AUTHOR]

Abstract: The effects of low-pH, high-pCO2 conditions on deep-sea organisms were examined during four deep-sea CO2 release experiments simulating deep-ocean C sequestration by the direct injection of CO2 into the deep sea. We examined the survival of common deep-sea, benthic organisms (microbes; macrofauna, dominated by Polychaeta, Nematoda, Crustacea, Mollusca; megafauna, Echinodermata, Mollusca, Pisces) exposed to low-pH waters emanating as a dissolution plume from pools of liquid carbon dioxide released on the seabed during four abyssal CO2-release experiments. Microbial abundance in deep-sea sediments was unchanged in one experiment, but increased under environmental hypercapnia during another, where the microbial assemblage may have benefited indirectly from the negative impact of low-pH conditions on other taxa. Lower abyssal metazoans exhibited low survival rates near CO2 pools. No urchins or holothurians survived during 30–42 days of exposure to episodic, but severe environmental hypercapnia during one experiment (E1; pH reduced by as much as ca. 1.4 units). These large pH reductions also caused 75% mortality for the deep-sea amphipod, Haploops lodo, near CO2 pools. Survival under smaller pH reductions (ΔpH<0.4 units) in other experiments (E2, E3, E5) was higher for all taxa, including echinoderms. Gastropods, cephalopods, and fish were more tolerant than most other taxa. The gastropod Retimohnia sp. and octopus Benthoctopus sp. survived exposure to pH reductions that episodically reached −0.3pH units. Ninety percent of abyssal zoarcids (Pachycara bulbiceps) survived exposure to pH changes reaching ca. −0.3pH units during 30–42 day-long experiments. [Copyright &y& Elsevier]

Abstract: One proposed approach to ameliorate the effects of global warming is sequestration of the greenhouse gas CO2 in the deep sea. To evaluate the environmental impact of this approach, we exposed the sediment-dwelling fauna at the mouth of the Monterey Submarine Canyon (3262m) and a site on the nearby continental rise (3607m) to CO2-rich water. We measured meiobenthic nematode population and community metrics after ∼30-day exposures along a distance gradient from the CO2 source and with sediment depth to infer the patterns of mortality. We also compared the nematode response with that of harpacticoid copepods. Nematode abundance, average sediment depth, tail-group composition, and length: width ratio did not vary with distance from the CO2 source. However, quantile regression showed that nematode length and diameter increased in close proximity to the CO2 source in both experiments. Further, the effects of CO2 exposure and sediment depth (nematodes became more slender at one site, but larger at the other, with increasing depth in the sediment) varied with body size. For example, the response of the longest nematodes differed from those of average length. We propose that nematode body length and diameter increases were induced by lethal exposure to CO2-rich water and that nematodes experienced a high rate of mortality in both experiments. In contrast, copepods experienced high mortality rates in only one experiment suggesting that CO2 sequestration effects are taxon specific. [Copyright &y& Elsevier]