Relative abundances of twenty-eight dominant benthic foraminifera species of DSDP Hole 23-219 (Table 1s)

Tropical climate is variable on astronomical time scale, driving changes in surface and deep-sea fauna during the Pliocene-Pleistocene. To understand these changes in the tropical Indian Ocean over the past 2.36 Myr, we quantitatively analyzed deep-sea benthic foraminifera and selected planktic foraminifera from >125 µm size fraction from Deep Sea Drilling Project Site 219. The data from Site 219 was combined with published foraminiferal and isotope data from Site 214, eastern Indian Ocean to determine the nature of changes. Factor and cluster analyses of the 28 highest-ranked species distinguished four biofacies, characterizing distinct deep-sea environmental settings. These biofacies have been named after their most dominant species such as Stilostomella lepidula-Pleurostomella alternans (Sl-Pa), Nuttallides umbonifer-Globocassidulina subglobosa (Nu-Gs), Oridorsalis umbonatus-Gavelinopsis lobatulus (Ou-Gl) and Epistominella exigua-Uvigerina hispido-costata (Ee-Uh) biofacies. Biofacies Sl-Pa ranges from ~2.36 to 0.55 Myr, biofacies Nu-Gs ranges from ~1.9 to 0.65 Myr, biofacies Ou-Gl ranges from ~1 to 0.35 Myr and biofacies Ee-Uh ranges from 1.1 to 0.25 Myr. The proxy record indicates fluctuating tropical environmental conditions such as oxygenation, surface productivity and organic food supply. These changes appear to have been driven by changes in monsoonal wind intensity related to glacial-interglacial cycles. A shift at ~1.2-0.9 Myr is observed in both the faunal and isotope records at Site 219, indicating a major increase in monsoon-induced productivity. This coincides with increased amplitude of glacial cycles, which appear to have influenced low latitude monsoonal climate as well as deep-sea conditions in the tropical Indian Ocean.

Chemical versus structural defense against fish predation in two dominant soft coral species (Xeniidae) in the Red Sea

Soft corals of the family Xeniidae are particularly abundant in Red Sea coral reefs. Their success may be partly due to a strong defense mechanism against fish predation. To test this, we conducted field and aquarium experiments in which we assessed the antifeeding effect of secondary metabolites of 2 common xeniid species, Ovabunda crenata and Heteroxenia ghardaqensis. In the field experiment, the metabolites of both investigated species reduced feeding on experimental food pellets in the natural population of Red Sea reef fishes by 86 and 92% for O. crenata and H. ghardaqensis, respectively. In the aquarium experiment, natural concentration of crude extract reduced feeding on experimental food pellets in the common reef fish Thalassoma lunare (moon wrasse) by 83 and 85%, respectively. Moon wrasse feeding was even reduced at extract concentrations as low as 12.5% of the natural concentration in living soft coral tissues. To assess the potential of a structural anti-feeding defence, sclerites of O. crenata were extracted and mixed into food pellets at natural, doubled and reduced concentration without and in combination with crude extract at 25% of natural concentration, and tested in an aquarium experiment. The sclerites did not show any effect on the feeding behavior of the moon wrasse indicating that sclerites provide structural support rather than antifeeding defense. H. ghardaqensis lacks sclerites. We conclude that the conspicuous abundance of xeniid soft coral species in the Red Sea is likely a consequence of a strong chemical defence, rather than physical defences, against potential predators.

Tab. 1: Chupa Inlet, Kandalaksha Bay of the White Sea. Population density of the dominant boreal copepod species and daily pellet carbon flux

Data on the zooplankton community structure, gut evacuation rate and carbon content of zooplankton faecal pellets were used for assessing the contribution of zooplankton to vertical carbon fluxes in the White and Kara Seas. The results revealed strong regional and seasonal variations of pellet carbon input related to differences in structure and dynamics of the zooplankton communities in the regions studied. In the deep regions of the White Sea, maximum daily pellet carbon flux from the 0-50 m layer was observed in the spring. It reached 98 mg Corg m-2 day-1 and coincided with a strong predominance of the large arctic herbivorous copepod Calanus glacialis in the surface layers. In summer and fall, it decreased by 1 to 2 orders of magnitude due to migration of this copepod to its overwintering depths. In contrast, in the shallow coastal regions, the pellet production was low in spring, gradually increased during summer and reached its maximum of 138 mg Corg m-2 day-1 by late summer to beginning of autumn. Such a seasonal pattern was in accordance with the seasonal variation of abundance of major pellet producers, the small boreal copepods Acartia bifilosa, Centropages hamatus, and Temora longicornis. In the estuarine zone of the Kara Sea, the pellet flux was mostly formed by pellets of brackish-water omnivorous copepods. It varied from 35 mg Corg m-2 day-1 in 1997 to 96 mg Corg m-2 day-1 in 1999. In the central Kara Sea with its typical marine community, the daily flux reached 125 mg Corg m-2 day-1 in summer. The results of our calculations indicate that both in the White and Kara seas zooplankton pellet carbon contributes up to 30 % to the total carbon flux during particular seasons.

Night biomass of dominant mesozooplankton groups within the Bismark Polygon (Northeast Atlantic) in June 2001 and June-August 2002

Vertical zooplankton distribution at the northeastern periphery of the North Atlantic subtropical gyre was studied with the use of 113/140 BR nets and Mir manned submersibles. Vertical distribution of selected dominant taxonomic, ecological, and trophic groups was considered. Results were compared with data obtained at the same location in 2001 that allowed to estimate interannual variability of the planktonic community.