a b s t r a c tIn an era of human activities, global environmental changes, habitat loss and species extinction, conservation strategies are a crucial step toward minimizing biodiversity loss. For instance, oceans acidification and land use are intensifying in many places with negative and often irreversible consequences for biodiversity. Biodiversity hotspots, despite some criticism, have become a tool for setting conservation priorities and play an important role in decision-making for cost-effective strategies to preserve biodiversity in terrestrial and, to some extent, marine ecosystems. This area-based approach can be applied to any geographical scale and it is considered to be one of the best approaches for maintaining a large proportion of the world's biological diversity. However, delineating hotspots includes quantitative criteria along with subjective considerations and the risk is to neglect areas, such as coldspots, with other types of conservation value. Nowadays, it is widely acknowledged that biodiversity is much more than just the number of species in a region and a conservation strategy cannot be based merely on the number of taxa present in an ecosystem. Therefore, the idea that strongly emerges is the need to reconsider conservation priorities and to go toward an interdisciplinary approach through the creation of science-policy partnerships.

No abstract

No abstract

The rapid physical changes affecting the Arctic Ocean alter the growth conditions of primary producers. In this context, a crucial question is whether these changes will affect the composition of phytoplankton communities, augment their productivity, and eventually enhance food webs. We combined satellite and model products with in situ datasets collected during fall and provide new insights into the response of phytoplankton biomass and production in the Canadian Arctic by comparing an interior shelf (Beaufort Sea) and an outflow shelf (Baffin Bay). Correlation analysis was used to distinguish between seasonal and interannual variability and revealed that most biological variables are responding to the interannual pressures of climate change. In southeast Beaufort Sea, a change in phytoplankton community composition occurred, with a significant increase in diatoms from 2% (2002) to 37% (2010-2011) of the total protist abundance. In 2011, photosynthetic picoeukaryotes were twice as abundant as in 2002. For these two phytoplankton groups, abundance was correlated with the duration of the open-water period, which also increased and affected vertical stratification and sea-surface temperature. In contrast, there was a sharp decline in centric diatom abundance as well as in phytoplankton biomass and production in northern Baffin Bay over the years considered. These decreases were linked to changes in seasonal progression and sea-ice dynamics through their impacts on vertical stratification and freshwater input. Overall, our results highlight the importance of stratification and the duration of the open-water period in shaping phytoplankton regimes-either oligotrophic or eutrophic-in marine waters of the Canadian Arctic.

In remote marine areas, biogenic productivity and atmospheric particulate are coupled through dimethylsulfide (DMS) emission by phytoplankton. Once in the atmosphere, the gaseous DMS is oxidized to produce H 2 SO 4 and methanesulfonic acid (MSA); both species can affect the formation of cloud condensation nuclei. This study analyses eight years of biogenic aerosol evolution and variability at two Arctic sites: Thule (76.5 • N, 68.8 • W) and Ny Ålesund (78.9 • N, 11.9 • E). Sea ice plays a key role in determining the MSA concentration in polar regions. At the beginning of the melting season, in April, up to June, the biogenic aerosol concentration appears inversely correlated with sea ice extent and area, and positively correlated with the extent of the ice-free area in the marginal ice zone (IF-MIZ). The upper ocean stratification induced by sea ice melting might have a role in these correlations, since the springtime formation of this surface layer regulates the accumulation of phytoplankton and nutrients, allowing the DMS to escape from the sea to the atmosphere. The multiyear analysis reveals a progressive decrease in MSA concentration in May at Thule and an increase in July August at Ny Ålesund. Therefore, while the MSA seasonal evolution is mainly related with the sea ice retreat in April, May, and June, the IF-MIZ extent appears as the main factor affecting the longer-term behavior of MSA.2 of 12 stronger cooling through direct radiative forcing. Conversely, the contributions to cloud condensation nuclei precursors from MSA and from DMS-derived sulfate/sulfuric acid are comparable, leading to similar changes in the aerosol indirect effect [3].While nonsea salt (nss) SO 4 2− has many sources in addition to biogenic activity (e.g., volcanic and anthropic), MSA is uniquely due to biogenic sources. For this reason, MSA concentration records in ice cores were used to investigate past climate through marine primary production which, in turn, is related to sea ice and other environmental parameters [4,5]. Indeed, the MSA atmospheric concentration is regulated by multiple processes that can be summarized into two main categories: (i) biotic factors such as primary productivity and phytoplankton species and (ii) abiotic factors that include air and sea temperatures, marine mixing layer depth, wind speed, sea-air exchange, atmospheric concentration of oxidants (O 3 , OH, and BrO), gas phase versus aqueous phase oxidation pathways, radiation, and, in polar regions, sea ice. The Arctic plays an important role in the global climate system. The Arctic is warming at a rate almost two times larger than the global average rate (Serreze et al., [6] and references therein). At the same time, the Arctic sea ice area has decreased at a rate of 2.7% per decade [7]. These factors are expected to influence the primary production and biogenic compounds sea-air exchange in the Arctic Ocean [8].Recent studies (e.g., Boyce et al., [9]) suggest that global marine primary production has been declining during the last century and is expe...