The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m−2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean.

The Arctic is undergoing widespread warming. In order to understand the impact of climate change on Arctic marine food webs, we studied the at-sea distribution of foraging little auks in contrasting conditions of the Greenland Sea. While the eastern side of the Greenland Sea has experienced recent warming, the western side is still dominated by cold, Arctic water in the East Greenland Current. We hypothesized that foraging little auks would be found in greatest abundance in cold Arctic waters bearing more lipid-rich prey, allowing them to deliver more energy-rich food to their chicks. To test our hypotheses, we made ship-borne bird observations and zooplankton tows, as well as analyses of chick meals at 2 little auk colonies adjacent to 3 distinct water masses in the Greenland Sea. Associated with the coldest water in the East Greenland Current, we found the highest concentrations of large Calanus copepods (C. glacialis and C. hyperboreus), as well as the highest concentrations of foraging little auks, indicating a relationship that is likely to be disrupted by increasing water temperatures. To assess potential future impacts of ocean warming, we used a coupled atmosphere-ocean global climate model (AOGCM) to predict Greenland Sea sea-surface temperatures over the study area at the end of the 21st century. Our results suggest that 4 of 8 little auk breeding colonies in the North Atlantic may be negatively impacted as temperatures exceed the thermal preferenda of large Calanus, which is the preferred prey of little auks during the breeding season.

Calanoid copepods of the genus Calanus represent an important, nutrient-rich food source for a multitude of Arctic marine organisms. Although morphologically very similar, their life histories and ecological roles differ. Because the distribution of Calanus glacialis and C. finmarchicus corresponds to Arctic and Atlantic water masses, respectively, they are regularly used as climate indicators. A correct identification of these species is therefore necessary in many ecological, environmental and climatological studies. In this study, we aimed at validating the traditionally used morphological characteristics (combining prosome length and copepodite stage) for separation of species of Calanus by using molecular tools (PCR-RFLP of the 16S mtDNA). A total of 418 specimens of copepodite stages CIV, CV and CVI(af) from three Arctic fjords have been identified both morphologically and genetically. We find that the morphological identification systematically overestimates the abundance of C. finmarchicus at the expense of C. glacialis. Hence, parts of the C. glacialis populations are found to be structurally smaller and the within population size range thus larger than previously assumed. Consequently, using the traditional morphological species delimitation poses a serious problem in the use of these two species as indicators of Atlantic versus Arctic water masses and thus as climatic indicators. Furthermore, it obscures our understanding of the life history differences between the two species and of their relative importance as food for a number of ecologically and economically important species in the Arctic.

An account is given of the benthic marine algae (and sea grasses) collected on the 1965 Royal Society Expedition to the Solomon Islands. The known algal flora is fairly typical of such a tropical area, comprising some 71 species of Chlorophyta, 27 of Phaeophyta, 121 of Rhodophyta and 14 of Cyanophyta. Pseudobryopsis solomonensis , P. gracilis, Caulerpa spathulata and Cryptonemia ? subdichotoma are newly described. Seven species of sea grasses are also recorded.

Widespread ocean acidification (OA) is modifying the chemistry of the global ocean, and the Arctic is recognized as the region where the changes will progress at the fastest rate. Moreover, Arctic species show lower capacity for cellular homeostasis and acid-base regulation rendering them particularly vulnerable to OA. In the present study, we found physiological differences in OA response across geographically separated populations of the keystone Arctic copepod Calanus glacialis. In copepodites stage CIV, measured reaction norms of ingestion rate and metabolic rate showed severe reductions in ingestion and increased metabolic expenses in two populations from Svalbard (Kongsfjord and Billefjord) whereas no effects were observed in a population from the Disko Bay, West Greenland. At pH T 7.87, which has been predicted for the Svalbard west coast by year 2100, these changes resulted in reductions in scope for growth of 19% in the Kongsfjord and a staggering 50% in the Billefjord. Interestingly, these effects were not observed in stage CV copepodites from any of the three locations. It seems that CVs may be more tolerant to OA perhaps due to a general physiological reorganization to meet low intracellular pH during hibernation. Needless to say, the observed changes in the CIV stage will have serious implications for the C. glacialis population health status and growth around Svalbard. However, OA tolerant populations such as the one in the Disko Bay could help to alleviate severe effects in C. glacialis as a species. K E Y W O R D SArctic, ingestion rate, metabolic rate, ocean acidification, pCO2, pH, reaction norm, zooplankton