Recognizing culture, and diverse sources of knowledge, can improve assessments

Increased carbon dioxide (CO 2 ) concentration in the atmosphere will change the balance of the components of carbonate chemistry and reduce the pH at the ocean surface. Here, we report the effects of increased CO 2 concentration on the early development of the sea urchins Hemicentrotus pulcherrimus and Echinometra mathaei. We examined the fertilization, early cleavage, and pluteus larval stage to evaluate the impact of elevated CO 2 concentration on fertilization rate, cleavage rate, developmental speed, and pluteus larval morphology. Furthermore, we compared the effects of CO 2 and HCl at the same pH in an attempt to elucidate any differences between the two. We found that fertilization rate, cleavage rate, developmental speed, and pluteus larval size all tended to decrease with increasing CO 2 concentration. Furthermore, CO 2 -seawater had a more severe effect than HCl-seawater on the fertilization rate. By contrast, the effects on cleavage rate, developmental speed, and pluteus larval morphology were similar for CO 2 -and HCl-seawater. Our results suggest that both decreased pH and altered carbonate chemistry affect the early development and life history of marine animals, implying that increased seawater CO 2 concentration will seriously alter marine ecosystems. The effects of CO 2 itself on marine organisms therefore requires further clarification.

[1] The decision to sequester CO 2 in the deep ocean should ultimately be based not only upon what would happen to deep sea marine biota but also upon what would happen to surface organisms if nothing were done to limit atmospheric CO 2 . Thus such a decision should be based on a proper understanding of long-term chronic effects, from the globalscale perturbation in near-surface ocean CO 2 , in addition to acute effects, from large local increases in CO 2 caused by purposeful sequestration. Here we focus on the long-term chronic effects of CO 2 on shallow water benthic organisms that have calcium carbonate shells. With two duplicate 6 month manipulative experiments, we demonstrate that a 200 ppm increase in CO 2 adversely affects the growth of both gastropods and sea urchins. Thus even moderate increases in atmospheric CO 2 that could well be reached by the middle of this century will adversely affect shallow water marine benthic organisms. This provides another reason, beyond concerns for climate, to enhance efforts to limit increases in atmospheric CO 2 to the lowest possible levels.Citation: Shirayama, Y., and H. Thornton (2005), Effect of increased atmospheric CO 2 on shallow water marine benthos, J. Geophys.

An olfactory receptor (OR) multigene family is responsible for the well-developed sense of smell possessed by terrestrial tetrapods. Mammalian OR genes had diverged greatly in the terrestrial environment after the fish-tetrapod split, indicating their importance to land habitation. In this study, we analysed OR genes of marine tetrapods (minke whale Balaenoptera acutorostrata, dwarf sperm whale Kogia sima, Dall's porpoise Phocoenoides dalli, Steller's sea lion Eumetopias jubatus and loggerhead sea turtle Caretta caretta) and revealed that the pseudogene proportions of OR gene repertoires in whales were significantly higher than those in their terrestrial relative cattle and also in sea lion and sea turtle. On the other hand, the pseudogene proportion of OR sequences in sea lion was not significantly higher compared with that in their terrestrial relative (dog). It indicates that secondary perfectly adapted marine vertebrates (cetaceans) have lost large amount of their OR genes, whereas secondarysemi-adapted marine vertebrates (sea lions and sea turtles) still have maintained their OR genes, reflecting the importance of terrestrial environment for these animals.

No abstract