Long-term changes in phytoplankton, zooplankton and salmon related to climate

Recently, large‐scale changes in the biogeography of calanoid copepod crustaceans have been detected in the northeastern North Atlantic Ocean and adjacent seas. Strong biogeographical shifts in all copepod assemblages were found with a northward extension of more than ° in latitude of warm‐water species associated with a decrease in the number of colder‐water species. These changes were attributed to regional increase in sea surface temperature. Here, we have extended these studies to examine long‐term changes in phytoplankton, zooplankton and salmon in relation to hydro‐meteorological forcing in the northeast Atlantic Ocean and adjacent seas. We found highly significant relationships between (1) long‐term changes in all three trophic levels, (2) sea surface temperature in the northeastern Atlantic, (3) Northern Hemisphere temperature and (4) the North Atlantic Oscillation. The similarities detected between plankton, salmon, temperature and hydro‐climatic parameters are also seen in their cyclical variability and in a stepwise shift that started after a pronounced increase in Northern Hemisphere Temperature anomalies at the end of the 1970s. All biological variables show a pronounced change which started after circa 1982 for euphausiids (decline), 1984 for the total abundance of small copepods (increase), 1986 for phytoplankton biomass (increase) and Calanus finmarchicus (decrease) and 1988 for salmon (decrease). This cascade of biological events led to an exceptional period, which is identified after 1986 to present and followed another shift in large‐scale hydro‐climatic variables and sea surface temperature. This regional temperature increase therefore appears to be an important parameter that is at present governing the dynamic equilibrium of northeast Atlantic pelagic ecosystems with possible consequences for biogeochemical processes and fisheries.     

Genetic variation and biogeography of Mertensia maritima (Boraginaceae)

To elucidate the population dynamics and biogeographic connections of Mertensia maritima in the North Atlantic we studied the genetic variation within and among 16 local populations in the Oslofjord region (south-east Norway), Finnmark (northern Norway), Iceland and Svalbard, using starch gel isozyme electrophoresis. We also tested the self-compatibility experimentally. Mertensia maritima was found to be self-compatible and able to self-pollinate by autodeposition. The total level of genetic variation was extremely low. All the screened individuals were homozygous at all loci. All individuals from the populations of mainland Norway and Iceland were isozymatically identical, whereas individuals from Svalbard differed from these at three loci (AAT-1, PGM-3 and SKD-2). The genetic identity between any population at Svalbard and any population on the mainland was 0.86. These genetic patterns may have resulted from a combination of inbreeding, frequent local population extinctions, and long-distance dispersal. The isozymatic distinctness of the Svalbard populations is consistent with the arctic distribution of the morphologically based var. tenella , here raised to subspecific rank as Mertensia maritima ssp. tenella.     

Linnaeus' Neptunea (Mollusca: Gastropoda)

Three species of the arcto-boreal, large gastropod Neptunea , described by Linnaeus in 1758 and 1771, occur in large numbers over wide areas of the inshore North Atlantic and adjacent Arctic seas and are conspicuous among Pliocene and Pleistocene molluscs in the Icelandic, North Sea, and western Mediterranean basins. Selections of lectotypes for these species from shells in the collection of the Linnean Society of London, and designations of their type localities, establish the identity of Linnaeus' neptunes and more accurately determine their geographic and geologic distribution. The geographic range of Neptunea (Neptunea) antiqua (L.), the type species, now extends from southern Norway to the northern Biscay coast of France and from the westernmost Baltic Sea to southwestern Ireland; this species also occurs in Pliocene-Holocene marine deposits in West and East Germany, Sweden, the Netherlands, England and France. Its type locality is determined to be the North Sea. N. (Neptunea) despecta (L.) lives in the eastern Canadian Arctic, off southern Greenland, the Barents Sea, and North Atlantic as far south as Massachusetts and Portugal; it also occurs in Pliocene-Holocene strata of eastern Canada, east-central Greenland, Norway (including Svalbard), the Soviet Union, Sweden and England. Its type locality is determined to be the postglacial deposits at Uddevalla in southwestern Sweden. N. (Sulcosipho) contraria (L.) now extends from the southern Biscay coast of France to Cape Spartel, Morocco; this species also occurs in Pleistocene and lower Holocene sequences of the western Mediterranean. Its type locality is determined to be Vigo Bay, Spain. A closely related fossil species, N. (S.) angulata (S. V. Wood), occurs in Pliocene and Pleistocene deposits of the North Sea basin.     

Thalassiosira punctigera (Castr.) comb, nov., a widely distributed marine planktonic diatom

Examination of type material showed that 8 taxa must be reduced to synonomy with Thalassiosira punctigera (Castr.) comb, nov., an extremely variable species as to size and valve structure. Preliminary experiments indicated a certain relationship between the areola size and the temperature at which clonal cultures had been grown. While previously known from the North Pacific and the South Atlantic Oceans in addition to a single record from the Caribbean Sea it has since 1979 been recorded regularly in the Skagerrak (between Denmark and Norway).     

Status of the world's baleen whales

No global synthesis of the status of baleen whales has been published since the 2008 IUCN Red List assessments. Many populations remain at low numbers from historical commercial whaling, which had ceased for all but a few by 1989. Fishing gear entanglement and ship strikes are the most severe current threats. The acute and long‐term effects of anthropogenic noise and the cumulative effects of multiple stressors are of concern but poorly understood. The looming consequences of climate change and ocean acidification remain difficult to characterize. North Atlantic and North Pacific right whales are among the species listed as Endangered. Southern right, bowhead, and gray whales have been assessed as Least Concern but some subpopulations of these species ‐ western North Pacific gray whales, Chile‐Peru right whales, and Svalbard/Barents Sea and Sea of Okhotsk bowhead whales ‐ remain at low levels and are either Endangered or Critically Endangered. Eastern North Pacific blue whales have reportedly recovered, but Antarctic blue whales remain at about 1% of pre‐exploitation levels. Small isolated subspecies or subpopulations, such as northern Indian Ocean blue whales, Arabian Sea humpback whales, and Mediterranean Sea fin whales are threatened while most subpopulations of sei, Bryde's, and Omura's whales are inadequately monitored and difficult to assess.     

Population structure of Purple Sandpipers (Calidris maritima) as revealed by mitochondrial DNA and microsatellites

The Purple Sandpiper (Calidris maritima) is a medium‐sized shorebird that breeds in the Arctic and winters along northern Atlantic coastlines. Migration routes and affiliations between breeding grounds and wintering grounds are incompletely understood. Some populations appear to be declining, and future management policies for this species will benefit from understanding their migration patterns. This study used two mitochondrial DNA markers and 10 microsatellite loci to analyze current population structure and historical demographic trends. Samples were obtained from breeding locations in Nunavut (Canada), Iceland, and Svalbard (Norway) and from wintering locations along the coast of Maine (USA), Nova Scotia, New Brunswick, and Newfoundland (Canada), and Scotland (UK). Mitochondrial haplotypes displayed low genetic diversity, and a shallow phylogeny indicating recent divergence. With the exception of the two Canadian breeding populations from Nunavut, there was significant genetic differentiation among samples from all breeding locations; however, none of the breeding populations was a monophyletic group. We also found differentiation between both Iceland and Svalbard breeding populations and North American wintering populations. This pattern of divergence is consistent with a previously proposed migratory pathway between Canadian breeding locations and wintering grounds in the United Kingdom, but argues against migration between breeding grounds in Iceland and Svalbard and wintering grounds in North America. Breeding birds from Svalbard also showed a genetic signature intermediate between Canadian breeders and Icelandic breeders. Our results extend current knowledge of Purple Sandpiper population genetic structure and present new information regarding migration routes to wintering grounds in North America.     

Glacial survival does not matter – II: RAPD phylogeography of Nordic Saxifraga cespitosa

It has been suggested that many arctic-alpine plant species have limited dispersal ability and cannot have arrived in Scandinavia and the arctic archipelago of Svalbard by long-distance dispersal after a total glaciation. It has therefore been proposed that such species must have survived the entire glaciation(s) in ice-free refugia in southern Norway, northern Norway and Svalbard. We investigated random amplified polymorphic DNA (RAPD) variation among 28 populations from Norway and Svalbard of one of these arctic-alpine 'short-distance dispersers', the selfing polyploid Saxifraga cespitosa . In an analysis of molecular variance ( AMOVA ), more variation was found among populations within the three postulated refugia regions (45%) than among these regions (25%). Spatial autocorrelation (Mantel) analyses showed that the genetic distance monotonously increased with increasing geographical distance. In UPGMA and PCO analyses, the populations from Norway and Svalbard formed a south–north cline that continued across the Barents Sea barrier. The results suggest that there has been recent dispersal among the three postulated refugia regions and thus that postglacial dispersal into these refugia regions from other distant areas also must represent a possibility. The observed geographical pattern of the genetic variation may have been established after expansion from different source areas outside the North European ice sheet and/or from different refugia areas 'within' the ice sheet, but it is probably not possible to distinguish among these alternatives. The results for S. cespitosa are consistent with a dynamic late- and postglacial scenario with extensive plant dispersal, and support the conclusion from our previous study of the outbreeding Saxifraga oppositifolia ; the hypothesis of glacial survival in Norway and/or Svalbard is superfluous.     

Incongruent phylogeographies in spite of similar morphology, ecology, and distribution:Phippsia algida andP. concinna (Poaceae) in the North Atlantic region

Phylogeographic and taxonomic relationships among 54 North Atlantic populations of the snowbed grass genusPhippsia were investigated based on isozymes and genetically based morphological variation. The results support recognition of two distinct species,P. algida andP. concinna, the latter with at least two subspecies. Both of these self-fertilizing arctic pioneer species were genetic allotetraploids almost without intrapopulational variation. The two species showed strikingly different phylogeographies in the North Atlantic region in spite of their similarity in morphology, habitat ecology, mating system, and dispersal ecology, and in spite of their present cooccurrence in many geographic areas, sometimes even in the same snowbeds. The same electrophoretic multilocus phenotype was observed in all populations ofP. algida, and although this species showed considerable morphological variation, the variation was unstructured geographically. Thus,P. algida showed a pattern similar to other arctic species investigated in the North Atlantic region; it has probably dispersed postglacially across the sea barriers among Greenland, Svalbard, Iceland, and Scandinavia. In contrast,P. concinna was virtually fixed for different multilocus phenotypes in the three main geographic areas analyzed (S Norway, Svalbard, Greenland), corresponding to fairly distinct divergence in morphology. This pattern suggests absence of postglacial among-area dispersal ofP. concinna in spite of all of its similarities with its congener; it may have immigrated to the North Atlantic from different source areas and/or survived the last glaciationin situ.     

The biodiversity of zooplankton communities of the west arctic seas

Based on the data from ten cruises that were carried out in 2001–2009, the structure of zooplankton communities was assessed in the Western Arctic seas using the estimated biodiversity indices. The greatest number of taxa was revealed in the south, southeast, and north of the Barents Sea. The average number of taxa in the sample was at a maximum off the coast of the Svalbard Archipelago. The greatest value of the Shannon index was registered within the Murmansk coastal water mass (Barents Sea) and Svalbard Archipelago. The median values of the evenness of the abundance of fauna were 0.5–0.6. A trend to a reduction of the biodiversity parameters of zooplankton communities with increasing square of water area water area was found. An inverse correlation between the Shannon and evenness indices for the total zooplankton abundance was revealed.     

Decline of an arctic top predator: synchrony in colony size fluctuations, risk of extinction and the subpolar gyre

Analysis of synchrony in population fluctuations is a central topic in ecology. It can help identify factors that regulate populations, and also the scales at which these factors exert their influence. Using long-term data from seven Brünnich’s guillemot colonies in Svalbard, Norway, we determined that year to year population fluctuations were synchronized in six of the seven colonies. The seventh colony was located farther away and in a different oceanographic system. Moreover, all seven colonies have declined significantly since the late 1990s following a very similar pattern. If the rate of population decline does not change, Brünnich’s guillemots in Svalbard have a high probability of becoming quasi-extinct within the next 50 years. The high synchrony between the different colonies could further increase this risk of extinction. Our results indicate that environmental forcing plays a role in the colony size fluctuation of Brünnich’s guillemot (i.e., a Moran effect). These fluctuations are well explained by changes in the subpolar gyre in the region where Brünnich’s guillemots overwinter. This subpolar gyre weakened in the mid-1990s, leading to a warming of the North Atlantic. Our study indicates that this basin-scale shift in the subpolar gyre is closely related to the decline in Brünnich’s guillemot in Svalbard. Our results suggest that the causal mechanism linking changes in oceanographic conditions in the North Atlantic and Brünnich’s guillemot population dynamics are likely mediated, at least partly, by changes in recruitment.     

Innocent,transit, and archipelagic sea lanes passage

Abstract

Norway is involved in two maritime boundary disputes with the Soviet Union. In relation to Svalbard, the Soviet Union argues that the archipelago has a continental shelf and an exclusive economic zone (EEZ) of its own to which all parties to the Svalbard Treaty have equal access. This is disputed by Norway, which maintains that such a view of the matter implies an expansive interpretation of the Svalbard Treaty for which there is no support in international legal practice. In the Barents Sea there is a continuing dispute between Norway and the Soviet Union over the proper location of the continental shelf and EEZ boundaries. This article sets out some of the reasons behind the different arguments on which the two base their respective cases, and the reasons why Norway in the absence of a delineated boundary has refused to accept Soviet proposals for economic cooperation in the disputed ocean area. Major emphasis is placed on the confluence of several circumstances inter alia, geopolitical and historical factors, a strongly asymmetrical power relationship, and legal ambiguity.     

Distributional and demographic consequences of Pleistocene climate fluctuations for a marine demersal fish in the north-eastern Atlantic

Aim The Pleistocene glaciations were the most significant historical event during the evolutionary life span of most extant species. However, little is known about the consequences of these climate changes for the distribution and demography of marine animals of the north‐eastern Atlantic. The present study focuses on the phylogeographic and demographic patterns of the sand goby, Pomatoschistus minutus (Teleostei: Gobiidae), a small marine demersal fish. Location North‐eastern Atlantic, Mediterranean, Irish, North and Baltic seas. Methods Analysis was carried out by sequencing the mtDNA cytochrome b gene of sand gobies from 12 localities throughout the species’ range, and using this information in combination with published data of allozyme markers and mtDNA control region sequences. Several phylogenetic methods and a network analysis were used to explore the phylogeographic pattern. The historical demography of P. minutus was studied through a mismatch analysis and a Bayesian skyline plot. Results Reciprocal monophyly was found between a Mediterranean Sea (MS) clade and an Atlantic Ocean (AO) clade, both with a Middle Pleistocene origin. The AO Clade contains two evolutionary significant units (ESUs): the Iberian Peninsula (IB) Group and the North Atlantic (NA) Group. These two groups diverged during Middle Pleistocene glacial cycles. For the NA Group there is evidence for geographic sorting of the ancestral haplotypes with recent radiations in the Baltic Sea, Irish Sea, North Sea and Bay of Biscay. The demographic histories of the Mediterranean Clade and the two Atlantic ESUs were influenced mainly by expansions dated as occurring during the Middle Pleistocene glaciations and post‐Eem, respectively. Main conclusions The pre‐LGM (Last Glacial Maximum) subdivision signals were not erased for P. minutus during the LGM. Middle Pleistocene glaciations yielded isolated and differently evolving sets of populations. In contrast to the case for most other taxa, only the northern Atlantic group contributed to the post‐glacial recolonization. The historical demography of Mediterranean sand gobies was influenced mainly by Middle Pleistocene glaciations, in contrast to that of the Atlantic populations, which was shaped by Late Pleistocene expansions.     

Biomass changes and trophic amplification of plankton in a warmer ocean

Ocean warming can modify the ecophysiology and distribution of marine organisms, and relationships between species, with nonlinear interactions between ecosystem components potentially resulting in trophic amplification. Trophic amplification (or attenuation) describe the propagation of a hydroclimatic signal up the food web, causing magnification (or depression) of biomass values along one or more trophic pathways. We have employed 3‐D coupled physical‐biogeochemical models to explore ecosystem responses to climate change with a focus on trophic amplification. The response of phytoplankton and zooplankton to global climate‐change projections, carried out with the IPSL Earth System Model by the end of the century, is analysed at global and regional basis, including European seas (NE Atlantic, Barents Sea, Baltic Sea, Black Sea, Bay of Biscay, Adriatic Sea, Aegean Sea) and the Eastern Boundary Upwelling System (Benguela). Results indicate that globally and in Atlantic Margin and North Sea, increased ocean stratification causes primary production and zooplankton biomass to decrease in response to a warming climate, whilst in the Barents, Baltic and Black Seas, primary production and zooplankton biomass increase. Projected warming characterized by an increase in sea surface temperature of 2.29 ± 0.05 °C leads to a reduction in zooplankton and phytoplankton biomasses of 11% and 6%, respectively. This suggests negative amplification of climate driven modifications of trophic level biomass through bottom‐up control, leading to a reduced capacity of oceans to regulate climate through the biological carbon pump. Simulations suggest negative amplification is the dominant response across 47% of the ocean surface and prevails in the tropical oceans; whilst positive trophic amplification prevails in the Arctic and Antarctic oceans. Trophic attenuation is projected in temperate seas. Uncertainties in ocean plankton projections, associated to the use of single global and regional models, imply the need for caution when extending these considerations into higher trophic levels.     

Maritime Delimitation in the Arctic: The Barents Sea Treaty

During a visit to Norway by the Russian president in the spring of 2010, the president and the Norwegian prime minister surprisingly announced agreement on a delimitation line in the Barents Sea ending almost 40 years of negotiations. The agreement was signed in Murmansk on 15 September 2010. This article presents the background of the dispute and undertakes an assessment of the agreement and its implications for the Barents Sea, Svalbard, and other Arctic maritime delimitations.     

The North Atlantic subpolar gyre and the marine migration of Atlantic salmon Salmo salar: the ‘Merry‐Go‐Round’ hypothesis

One model for marine migration of Atlantic salmon Salmo salar proposes that North American and southern European stocks (<62° N) move directly to feeding grounds off west Greenland, then overwinter in the Labrador Sea, whereas northern European stocks (>62° N) utilize the Norwegian Sea. An alternate model proposes that both North American and European stocks migrate in the North Atlantic Subpolar Gyre (NASpG) where S. salar enter the NASpG on their respective sides of the Atlantic, and travel counterclockwise within the NASpG until returning to natal rivers. A review of data accumulated during the last 50 years suggests a gyre model is most probable. Freshwater parr metamorphose into smolts which have morphological, physiological and behavioural adaptations of epipelagic, marine fishes. Former high‐seas fisheries were seasonally sequential and moved in the direction of NASpG currents, and catches were highest along the main axis of the NASpG. Marking and discrimination studies indicate mixed continental origin feeding aggregations on both sides of the Atlantic. Marked North American smolts were captured off Norway, the Faroe Islands, east and west Greenland, and adults tagged at the Faroes were recovered in Canadian rivers. Marked European smolts were recovered off Newfoundland and Labrador, west and east Greenland, and adults tagged in the Labrador Sea were captured in European rivers. High Caesium‐137 (¹³⁷Cs) levels in S. salar returning to a Quebec river suggested 62·3% had fed at or east of Iceland, whereas levels in 1 sea‐winter (SW) Atlantic Canada returnees indicated 24·7% had fed east of the Faroes. Lower levels of ¹³⁷ Cs in returning 1SW Irish fish suggest much of their growth occurred in the western Atlantic. These data suggest marine migration of S. salar follows a gyre model and is similar to other open‐ocean migrations of epipelagic fishes.     

Geographic variation in the time‐frequency characteristics of high‐frequency whistles produced by killer whales (Orcinus orca)

Investigating intraspecific variation in acoustic signals can indicate the extent of isolation and divergence between populations and adaptations to local environments. Here we analyze the variation in killer whale high‐frequency (>17 kHz) whistles recorded off Norway, Iceland, and in the North Pacific. We used a combination of methods including multivariate comparisons of spectral and temporal parameters and categorization of contours to types. Our results show that spectral and temporal characteristics of high‐frequency whistles recorded in the North Pacific show significant differences from whistles recorded in the Northeast Atlantic, being generally stereotyped, lower in frequency, and slightly longer in duration. Most high‐frequency whistles from the North Pacific were downsweeps, whereas this was one of the least common types recorded in the Northeast Atlantic. The repertoire of whistles recorded in Norway was similar to Iceland, but whistles produced in Norway had significantly lower maximum frequency and frequency range. Most methods were able to discriminate between whistles of the North Pacific and the Northeast Atlantic, but were unable to consistently distinguish whistles from Iceland and Norway. This suggests that macro‐ and microgeographic differences in high‐frequency whistles of killer whales may reflect historical geographic isolation between ocean basins and more recent divergence between adjacent populations.     

Dispersal routes and species identification of freshwater animals in Northern Europe: A review of molecular evidence

According to genetic data, North European freshwater areas were colonized from refugia along the eastern Atlantic coast, in southern and eastern basins of Baltic Sea, in Siberia, North America, and areas of the Caspian and Black seas. Probably, a refugium also existed in Southern Norway. Colonization from the sea also took place. The taxonomic position of some forms, such as members of the complex groups of Arctic chars and coregonids, was refined in the course of combined studies including morphological analysis and molecular markers.     

Phylogeography of North Atlantic intertidal tardigrades: refugia,cryptic speciation and the history of the Mid‐Atlantic Islands

Aim To analyse the phylogeographical history of intertidal tardigrades in the North Atlantic in order to improve our understanding of geographical differentiation in microscopic organisms, and to understand the potential importance of the Mid‐Atlantic Islands as stepping stones between the American and European coasts of the Atlantic Ocean. Location Twenty‐four localities from the Mid‐Atlantic Islands (Greenland, Iceland and the Faroe Islands) and both sides of the North Atlantic Ocean. Methods A mitochondrial marker (cytochrome c oxidase subunit I) was sequenced from individual tardigrades belonging to the genus Echiniscoides. The existence of cryptic species was detected using generalized mixed Yule coalescence analysis; lineage ages were estimated with relaxed clock methods; and the degree of geographical differentiation was analysed with samova analyses, haplotype networks and Mantel tests. Results Echiniscoides hoepneri, previously known only from Greenland, was recovered throughout the Mid‐Atlantic Islands. The Faroe Islands population was isolated from Greenland and Iceland, but overall genetic variation was low. The morphospecies Echiniscoides sigismundi had high genetic variation and consisted of at least two cryptic species. A northern and a southern species were both recovered on both sides of the Atlantic, but only the northern species was found on the Mid‐Atlantic Islands. The northern species showed signs of long‐term isolation between the Western and Eastern Atlantic, despite the potential of the Mid‐Atlantic islands to act as stepping‐stones. There was no sign of long‐term isolation in the southern species. The Mid‐Atlantic individuals of the northern species were of Eastern Atlantic origin, but Greenland and Iceland showed signs of long‐term isolation. The genetic pattern found in the southern species is not clearly geographical, and can probably be best explained by secondary contact between former isolated populations. Main conclusions North Atlantic intertidal tardigrades from the genus Echiniscoides showed strong geographical differentiation, and the Mid‐Atlantic Islands seemed unimportant as stepping stones across the Atlantic. The geographical variation of the northern species of E. sigismundi suggests post‐glacial recolonization from several refugia.     

New view of population genetics of zooplankton: RAD‐seq analysis reveals population structure of the North Atlantic planktonic copepod Centropages typicus

Detection of population genetic structure of zooplankton at medium‐to‐small spatial scales in the absence of physical barriers has remained challenging and controversial. The large population sizes and high rates of gene flow characteristic of zooplankton have made resolution of geographical differentiation very difficult, especially when using few genetic markers and assuming equilibrium conditions. Next‐generation sequencing now allows simultaneous sampling of hundreds to thousands of genetic markers; new analytical approaches allow studies under nonequilibrium conditions and directional migration. Samples of the North Atlantic Ocean planktonic copepod, Centropages typicus, were analysed using restriction site‐associated DNA (RAD) sequencing on a PROTON platform. Although prior studies revealed no genetic differentiation of populations across the geographical range of the species, analysis of RAD tags showed significant structure across the North Atlantic Ocean. We also compared the likelihood for models of connectivity among NW Atlantic populations under various directional flow scenarios that replicate oceanographic conditions of the sampled domain. High‐density marker sampling with RAD sequencing markedly outperformed other technical and analytical approaches in detection of population genetic structure and characterization of connectivity of this high geneflow zooplankton species.