The parasite fauna of <Emphasis Type="Italic">Arctogadus glacialis</Emphasis> (Peters) (Gadidae) from western and eastern Greenland

In all 155 specimens of the high Arctic codfish Arctogadus glacialis examined for metazoan parasites, 55 specimens were from southern and northern Baffin Bay, western Greenland, and 100 specimens from north-eastern Greenland and Scoresby Sound. A total of 20 parasite taxa were recorded. A new myxozoan Gadimyxa arctica was found in southern Baffin Bay and Scoresby Sound. The gadid myxozoan Zschokkella hildae, the digeneans Gonocerca phycidis and Lecithaster gibbosus, the gill copepod Haemobaphes cyclopterina and third-stage larvae of the nematodes Anisakis simplex and Hysterothylacium aduncum were found in Scoresby Sound only. The digenean Hemiurus levinseni and third-stage larvae of the nematode Contracaecum sp. were found at all four stations. The nematodes Ascarophis spp. were found at three stations. The parasite fauna of A. glacialis from Scoresby Sound was very similar to that of 50 specimens of the closely related Boreogadus saida from the same area.     

Current patterns in McMurdo Sound,Antarctica and their relationship to local biotic communities

Summary Current speed and direction measurements collected during summer (January–February) and sping (November–December) of 1984 indicated that currents in McMurdo Sound, Antarctica were dominated by oscillatory flow associated with diurnal tidal components (O1, K1, P1). Net flow was southward in the eastern Sound, mixed in the central Sound, and northward in the western Sound. Short term observations (<5 days) from nearshore stations indicated a similar but more sluggish pattern of tidal and mean flow. Hydrographic data collected during the same period indicated a similar pattern of cold water with low chlorophyll a content flowing northward from under the Ross Ice Shelf in the western Sound and denser, slightly warmer water with higher chlorophyll a content flowing southward in the eastern Sound. Previous studies have shown that productivity is higher in the eastern Sound than in the west, apparently due to the circulation pattern. The western Sound consists of waters from beneath the Ross Ice Shelf which have a lower phytoplankton standing stock than eastern Sound waters which enter from the north. More sluggish current speeds in the western Sound result in even lower particle fluxes past benthic consumers. Finally, more persistent ice cover in the west further inhibits in situ primary productivity.     

基于VGPM模型和MODIS数据估算梅梁湾浮游植物初级生产力

基于MODIS影像数据反演的2009年2月份至12月份太湖梅梁湾水域表面叶绿素a、悬浮物浓度以及水温数据,结合初级生产力垂向归纳模型(Vertically Generalized Production Model:VGPM)估算获得梅梁湾2009年逐月平均日初级生产力时空分布。结果表明,梅梁湾2009年年平均日初级生产力及逐月平均日初级生产力空间分布差异显著,呈现从湾内向湾口逐渐递减的趋势。时间序列分析显示,梅梁湾初级生产力季节差异显著,夏季>秋季>春季>冬季,全年初级生产力主要集中在夏季,占47.4%。通过分析VGPM模型中几个输入参数对初级生产力的影响,发现悬浮物浓度与标准化初级生产力存在显著负冥函数关系,反映沉积物再悬浮引起的悬浮物浓度增加能降低水体初级生产力。温度对初级生产力也有一定的调控与制约,与初级生产力呈现正相关趋势,在低于21℃的温度范围内与最大光合作用速率呈现正相关。     

Vertical distribution of zooplankton biomass and species in northeastern Baffin Bay related to temperature and salinity

Summary Vertical distributions of various species and stages of zooplankton at different times of the day were determined by stratified sampling with the BIONESS in northeastern Baffin Bay during early August. The water column was divided into an upper subarctic zone (>0° C, salinity < 32), a lower subarctic zone (< 0° C, salinity 32 to 34) and a deep zone of Atlantic water (>0° C, salinity 34). The upper subarctic zone was dominated by two species of pteropod molluscs; the lower subarctic water was dominated by the copepods, Calanus finmarchicus, C. glacialis and C. hyperboreus whose copepodite stages showed depth distributions that were different from one another, with the copepodite stage 5 and adult females generally shallower than the younger stages. All stages of all Calanus species were in the zone of primary production (10 to 50 m) while the copepods Pseudocalanus, Metridia and Oithona were generally found below this zone. Only C. finmarchicus and C. glacialis showed evidence of diurnal migration, migrating to the surface waters when the sun was at its lowest position on the horizon (i.e. at 0100 h).     

Vertical distribution and abundance of the Peruvian anchovy, Engraulis ringens, and sardine, Sardinops sagax, larvae during November 1977

Horizontal samples taken with the BIONESS at various depths on 13 stations within 115 km of the coast of Peru showed nine species of fish larvae present with the most common of these being, in order of abundance, Leuroglossus stilbius, Sardinops sagax, Diogenichthys laternatus, Merluccius gayi and Engraulis ringens . All the species except S. sagax and E. ringens showed a diurnal migration to the upper 30 m of water at night. The two above species were present in the top 30 m at all times. The size of the larvae of all species did not vary with time, depth or sample location. The numbers of larvae increased with zooplankton m⁻³ up to 1000 copepods m⁻³ above which no further increase in larvae occurred. A significant linear relationship was found between the total number of larvae m⁻² and biomass and zooplankton m⁻², but not between individual species of larvae and zooplankton biomass. Significant correlations were found between E. ringens and seven species of copepods found in the upper 50 m of water.
Polymodal analysis showed that the larval populations of all species, with the possible exception of S. sagax , were made up of more than one sub-population. From this analysis the length of the spawning season forE. ringens was estimated at 54–68 days.
A significant correlation was found between the numbers of E. ringens larvae m⁻² and the maximum concentration of chlorophyll α, as measured with Batfish, in the area of the BIONESS stations. This showed the largest numbers of larvae in areas of the highest chlorophyll concentrations.     

Are phytoplankton blooms occurring earlier in the Arctic?

Time series of satellite‐derived surface chlorophyll‐a concentration (Chl) in 1997–2009 were used to examine for trends in the timing of the annual phytoplankton bloom maximum. Significant trends towards earlier phytoplankton blooms were detected in about 11% of the area of the Arctic Ocean with valid Chl data, e.g. in the Hudson Bay, Foxe Basin, Baffin Sea, off the coasts of Greenland, in the Kara Sea and around Novaya Zemlya. These areas roughly coincide with areas where ice concentration has decreased in early summer (June), thus making the earlier blooms possible. In the selected areas, the annual phytoplankton bloom maximum has advanced by up to 50 days which may have consequences for the Arctic food chain and carbon cycling. Outside the Arctic, the annual Chl maximum has become earlier in boreal North Pacific but later in the North Atlantic.     

The zooplankton community in bays of Toulon area (northwest Mediterranean Sea,France)

The abundance and the diversity of the zooplankton community were studied during an annual cycle in three shallow bays differently affected by anthropogenic inputs of Toulon area in the northwest Mediterranean Sea (France). Environmental variables of water quality were also considered. Our results discriminated Little Bay from the La Garonne and Niel Bay. Little Bay, heavely perturbed by anthropogenic inputs, had high chlorophyll a levels, abundant zooplankton, a low diversity index, a high dominance Index and a single dominant species (Oithona nana). La Garonne Bay and Niel Bay, much less polluted, had low chlorophyll a levels, low zooplankton abundance, low dominance Index and high diversity index and eveness. In addition, O. nana occurred rarely in the latter bays. Zooplankton successions were also different between Little Bay and the two other bays.     

三门湾浮游动物的季节变动及微型浮游动物摄食影响

2002年8月、11月、2003年2月和5月,在三门湾进行了4个航次生物、化学和水文等专业综合调查。根据采集的浮游动物样品的分析鉴定及海上现场实验结果,对浮游动物的群落组成、生物量、丰度、多样性指数的分布和季节变动及其浮游动物对浮游植物的摄食影响进行研究。结果表明,三门湾浮游动物有67属,89种,16类浮游幼体,主要可划分为4个生态类群：以近岸低盐类群为主,其优势种为中华哲水蚤Calanus sinicus、真刺唇角水蚤Labidocera etwhaeta、捷氏歪水蚤Tortanus derjugini、太平洋纺锤水蚤Acartiapacifica、中华假磷虾Pseudeuphausia sinica和百陶箭虫Sagitta bedoti等。半咸水河口类群、暖水性外海类群和广布种相对较少。浮游动物生物量和丰度的平面分布趋势除了夏季有所差异外,其它季节基本一致。2月份和5月份,浮游动物生物量和丰度,从湾顶向湾口呈逐渐增加趋势;8月份,湾口区生物量最高,而丰度高值区出现在湾顶部;11月份,生物量和丰度的平面分布相对均匀。浮游动物种类多样性指数有明显的季节变化,其动态变化与浮游动物种数和丰度的变化一致。微型浮游动物对浮游植物存在摄食压力,且有季节变化,摄食率的变化在0．18．0．68d^-1,微型浮游动物的摄食率低于相同季节的浮游植物生长率。微型浮游动物对浮游植物摄食压力的变化范围为16．1％-49．1％d^-1,对初级生产力摄食压力的变化在58．3％-83．6％d^-1。11月份,微型浮游动物对浮游植物和初级生产力的摄食压力均出现最高值。     

Pheopigment dynamics,zooplankton grazing rates and the autumnal ammonium peak in a Mediterranean lagoon

The dilution technique was used to estimate chlorophyll and pheopigment, net and gross production as well as zooplankton grazing over a 12-month period in a coastal lagoon in Southern France. Chlorophyll a (Cha) based gross growth rates of phytoplankton ranged from undetectable in February to 2.6 day⁻¹ in June, corresponding to 3.8 divisions per day. Cha-based grazing rates ranged from undetectable in February to 1.1 d⁻¹ in June. The seasonal growth pattern of picoplankton was similar to that of the whole community, with a peak in July, corresponding to four divisions per day. Grazing processes represented from 20 to 150% of the phytoplankton daily growth, and the grazing pressure was stronger on small phytoplankton cells than on larger cells. Gross growth rates of phytoplankton were related to zooplankton grazing rates, and both were related to water temperature. Mesozooplankton which escaped sampling or oysters had to be also invoked as additional sinks for the primary production. In the fall, pheopigment concentrations greater than chlorophyll concentrations coincided with high ammonium levels in the water column. Pheopigment a production rates were highly correlated to chlorophyll -based microzooplankton grazing rates. The pheopigment a to chlorophyll a ratio was correlated with ammonium concentrations and could be used an index of the balance between ammonium supply (degradation) and demand (uptake by phytoplankton). In addition, pheopigment degradation rates in absence of grazing could be related to irradiance, indicating photo-degradation of these compounds.     

Environmental factors influencing diurnal distribution of zooplankton and ichthyoplankton

The diurnal vertical distribution of a large number of speciesof zooplankton, icbthyoplankton and micronekton were determinedin the top 150 m in three locations in the Shelf Water, on theNova Scotia Shelf, and Slope and on Georges Bank during springand fall periods. Species were categorized as to their trophiclevel and their type of diurnal migration behaviour. The influenceof temperature, salinity, and water density on the diurnal verticaldistribution of the species was examined. Temperature was foundto have the greatest influence on the distribution of the largestnumber of species. Diurnal migration behavior of the same speciesin Shelf and Slope water and at different times of the yearwas examined. Results showed that species changed their behaviorin the two water masses, while some species changed their migrationbehavior at different times of the year. During the night inApril the most abundant copepod species, Calanus finmarchicus,making up about 80% of the biomass, was found concentrated abovethe thermocline and the main chlorophyll layer. The majorityof the less abundant species of copepods were found below thethermocline and the chlorophyll layer. At night in August thetwo most abundant copepod species, Centropoger typicus and Paracalanusparvus, making up at least 80% of the zooplankton biomass, werealso concentrated above the thermocline and the main chlorophyllLayer. Three species of copepods were concentrated at the depthof the main chlorophyll layer and two species were concentratedbelow the chlorophyll layer and thermocline. The vertical distributionof other zooplankton and ichthyoplankton species was examinedin relation to the thermocline and chlorophyll layer. Relationshipsbetween concentrations of six species of fish larvae and allspecies of copepods in the same samples showed a general increasein the numbers of larvae m^–3 as the numbers of copepodsm^–3 increased in a range of 500–4000 m^–3.However, the concentration of Merluccius bilinearis decreasedas the concentration of copepods exceeded 4000 m^–3 suggestingthat high concentrations of copepods may not be a favourableenvironment for the larvae.     

Feeding ecology of the lantern fish Benthosema glaciale in a subarctic region

Summary The myctophid, Benthosema glaciale, was found to occur in the region of Davis Strait, but not in northern Baffin Bay. The factors that limited its northern range were believed to be the cold temperature and the long periods of day light in Baffin Bay. During the day B. glaciale was found at a depth of between 300 and 900 m with the population concentrating at about 500 m. At night about 46% of the population migrated to the upper 65 m to feed on copepods, primarily Calanus finmarchicus stage V and C. hyperboreus stage IV for which they showed a high degree of selectivity. The weight of stomach contents of fish with 100% full stomachs was equal to about 3% of their body weight. Feeding occurred mainly at night in the upper layers above the coldest layer of water with a temperature of about 0.5 °C. The biomass of zooplankton and myctophids m^-2 were similar to those for these groups on the Nova Scotia slope during June. The fish fed on the same size range of prey in Davis Strait as on the Nova Scotia slope even though the zooplankton species composition was different in the two regions.     

Hierarchical Classification of Narwhal Subpopulations Using Social Distance

Effective wildlife management and conservation require knowledge of distribution, sex composition, and age structure of a population. We explored the distribution of the Baffin Bay narwhal (Monodon monoceros) population in August 2013 by documenting sex and age distribution across the Canadian Arctic Archipelago covering 2,317,152 km². For 6,314 narwhals identified in 3,393 aerial images taken across the Eastern Canadian Arctic, we calculated a matrix of swimming distances between all individuals. We then used a quantitative clustering approach to partition our dataset (partitioning around the medoids). The clusters obtained from the analysis supported the delimitation of the 5 narwhal management stocks currently used by the Department of Fisheries and Oceans but did not support the hypothesized division of Jones Sound and Smith Sound stocks. Across the 5 clusters, male:female ratios varied between 0.72 and 1.44 and the proportion of newborns relative to the number of females varied between 0.07 and 0.18. As a highly detailed snapshot of narwhal distribution across a very large region, our study is a step toward better documentation of the basic population information required for stock assessment, sustainable harvest, and habitat protection of narwhals in an era of rapid Arctic change. © 2019 The Wildlife Society.     

Geochemistry and Microbial Populations in Sediments of the Northern Baffin Bay,Arctic

The Northern Baffin Bay between Greenland and Canada is a remote Arctic area restricted in primary production by seasonal ice cover, with presumably low sedimentation rates, carbon content and microbial activities in its sediments. Our aim was to study the so far unknown subseafloor geochemistry and microbial populations driving seafloor ecosystems. Shelf sediments had the highest organic carbon content, numbers of Bacteria and Archaea, and microcosms inoculated from Shelf sediments showed highest sulfate reduction and methane production rates. Sediments in the central deep area and on the southern slope contained less organic carbon and overall lower microbial numbers. Similar 16S rRNA gene copy numbers of Archaea and Bacteria were found for the majority of the sites investigated. Sulfate in pore water correlated with dsrA copy numbers of sulfate-reducing prokaryotes and differed between sites. No methane was found as free gas in the sediments, and mcrA copy numbers of methanogenic Archaea were low. Methanogenic and sulfate-reducing cultures were enriched on a variety of substrates including hydrocarbons. In summary, the Greenlandic shelf sediments contain vital microbial communities adapted to their specific environmental conditions.     

Geographic variation in cranial morphology of narwhals (Monodon monoceros) from Greenland and the eastern Canadian Arctic

We analyzed variation in nine non-metric and eight metric variables in the skulls of 132 narwhals (Monodon monoceros) from five localities in Greenland (Inglefield Bredning, Melville Bay, Uummannaq, Disko Bay, and Scoresby Sound) and one in the eastern Canadian Arctic (Eclipse Sound). Metric variables were used to compare the combined Disko Bay and Uummannaq samples with the samples from Inglefield Bredning and Scoresby Sound using three different multivariate techniques for each sex. None of the results were significant. Seven of the non-metric variables were independent of age and sex and were used in comparing samples from the six localities. No differences were found among the four localities in West Greenland, but differences were found in two of the non-metric variables between the combined West Greenland sample and the one from Scoresby Sound. A major shortcoming of the analysis based on metric data was the small sample size from several of the areas, which resulted in low statistical power. Genetic as well as environmental factors could explain the differences detected here between narwhals living along the west and the east coasts of Greenland.     

Characteristics of two distinct high-light acclimated algal communities during advanced stages of sea ice melt

Biological characteristics of ice-associated algal communities were studied in Darnley Bay (western Canadian Arctic) during a 2-week period in July 2008 when the landfast ice cover had reached an advanced stage of melt. We found two distinct and separate algal communities: (1) an interior ice community confined to brine channel networks beneath white ice covers; and (2) an ice melt water community in the brackish waters of both surface melt ponds and the layer immediately below the ice cover. Both communities reached maximum chlorophyll?a concentrations of about 2.5?mg?m^?3, but with diatoms dominating the interior ice while flagellates dominated the melt water community. The microflora of each community was diverse, containing both unique and shared algal species, the latter suggesting an initial seeding of the ice melt water by the bottom ice community. Absorption characteristics of the algae indicated the presence of mycosporine-like amino acids (MAAs) and carotenoid pigments as a photoprotective strategy against being confined to high-light near-surface layers. Although likely not contributing substantially to total annual primary production, these ice-associated communities may play an important ecological role in the Arctic marine ecosystem, supplying an accessible and stable food source to higher trophic levels during the period of ice melt.     

Zooplankton boom and ice amphipod bust below melting sea ice in the Amundsen Gulf, Arctic Canada

Early summer in the Arctic with extensive ice melt and break-up represents a dramatic change for sympagic–pelagic fauna below seasonal sea ice. As part of the International Polar Year-Circumpolar Flaw Lead system study (IPY-CFL), this investigation quantified zooplankton in the meltwater layer below landfast ice and remaining ice fauna below melting ice during June (2008) in Franklin Bay and Darnley Bay, Amundsen Gulf, Canada. The ice was in a state of advanced melt, with fully developed melt ponds. Intense melting resulted in a 0.3- to 0.5-m-thick meltwater layer below the ice, with a strong halocline to the Arctic water below. Zooplankton under the ice, in and below the meltwater layer, was sampled by SCUBA divers. Dense concentrations (max. 1,400 ind. m⁻³) of Calanus glacialis were associated with the meltwater layer, with dominant copepodid stages CIV and CV and high abundance of nauplii. Less abundant species included Pseudocalanus spp., Oithona similis and C. hyperboreus. The copepods were likely feeding on phytoplankton (0.5–2.3 mg Chl-a m⁻³) in the meltwater layer. Ice amphipods were present at low abundance (<10 ind. m⁻²) and wet biomass (<0.2 g m⁻²). Onisimus glacialis and Apherusa glacialis made up 64 and 51% of the total ice faunal abundance in Darnley Bay and Franklin Bay, respectively. During early summer, the autochthonous ice fauna becomes gradually replaced by allochthonous zooplankton, with an abundance boom near the meltwater layer. The ice amphipod bust occurs during late stages of melting and break-up, when their sympagic habitat is diminished then lost.     

Effects of environmental variation and spatial distance on Bacteria,Archaea and viruses in sub-polar and arctic waters

We investigated the influence of environmental parameters and spatial distance on bacterial, archaeal and viral community composition from 13 sites along a 3200-km long voyage from Halifax to Kugluktuk (Canada) through the Labrador Sea, Baffin Bay and the Arctic Archipelago. Variation partitioning was used to disentangle the effects of environmental parameters, spatial distance and spatially correlated environmental parameters on prokaryotic and viral communities. Viral and prokaryotic community composition were related in the Labrador Sea, but were independent of each other in Baffin Bay and the Arctic Archipelago. In oceans, the dominant dispersal mechanism for prokaryotes and viruses is the movement of water masses, thus, dispersal for both groups is passive and similar. Nevertheless, spatial distance explained 7–19% of the variation in viral community composition in the Arctic Archipelago, but was not a significant predictor of bacterial or archaeal community composition in either sampling area, suggesting a decoupling of the processes regulating community composition within these taxonomic groups. According to the metacommunity theory, patterns in bacterial and archaeal community composition suggest a role for species sorting, while patterns of virus community composition are consistent with species sorting in the Labrador Sea and suggest a potential role of mass effects in the Arctic Archipelago. Given that, a specific prokaryotic taxon may be infected by multiple viruses with high reproductive potential, our results suggest that viral community composition was subject to a high turnover relative to prokaryotic community composition in the Arctic Archipelago.     

Movements of narwhals (<Emphasis Type="Italic">Monodon monoceros</Emphasis>) from Admiralty Inlet monitored by satellite telemetry

Twenty-one narwhals tagged in 2003 and 2004 in Admiralty Inlet showed a different summer distributional pattern than previous narwhal-tracking studies from Somerset Island, Eclipse Sound and Melville Bay. The migration of the narwhals tracked from Admiralty Inlet moved out through Lancaster Sound 15 days earlier (P < 0.0001) than the narwhals summering around Eclipse Sound, whereas the Admiralty Inlet narwhals reached the mouths of Eclipse Sound 18 days later (P < 0.0001) than the Eclipse Sound summering population. The winter range of the Admiralty Inlet narwhals overlapped with the winter range of narwhals from Melville Bay and Eclipse Sound in central southern Baffin Bay and Northern Davis Strait, but not with the winter range of narwhals from Somerset Island that wintered further north. Distribution size of range, and population size did not appear to be related. An example of considerable year to year variation between area of summer and winter distribution in the 2 years was believed to be related to the sample size and number of pods of whales tagged, rather than to differences in sex or age classes.     

Sea Ice-Upper Ocean Ecosystems and Global Changes in the Arctic

In the Arctic, a clear temperature trend toward warming has been observed during the last two decades. The warming has led to a reduction in the area and thickness of the Arctic sea ice cover because of increased melting. Melt water is accumulated within the 0- to 30-m surface layer, markedly changing its hydrological and hydrochemical characteristics: this water is warmer and fresher, with lower nutrient concentrations. A stable thermocline at depths of 30–35 m weakens vertical mixing of water and hampers active exchange between nutrient-enriched water lying below the thermocline and nutrient-poor water under ice. This affects the qualitative and quantitative composition of upper-ocean phyto- and zooplankton. The changes in the climate and the ice environment cause marked alterations in the composition and structure of the biological communities of sea ice and under-ice surface water. Comparative analysis of materials collected in the anticyclonic Arctic Gyre at the ice stations Severnyi Polyus-22 (1975– 1981) and SHEBA (1997–1998) shows that over the last two decades the number of species of ice diatoms markedly decreased and the role of freshwater algae increased. The number of nematodes, copepods, amphipods, and turbellarians, which were the dominant groups in perennial ice, also declined sharply. The results suggest that the sea ice-upper ocean ecosystem is changing from typically marine to brackish-water. The main reason for these changes is probably global warming in the Arctic.     

Estimated copepod production rate and structure of mesozooplankton communities in the coastal Barents Sea during summer–autumn 2007

The southern Barents Sea is considered to be the most productive area in the Arctic Ocean; however, there are no assessments of daily production rates in the coastal waters. During the summer and autumn of 2007, we investigated the variation of mesozooplankton community structure relative to environmental conditions at 12 coastal stations. Copepods dominated the total zooplankton biomass and abundance during both periods. Diversity indices and the total biomass of zooplankton communities differed significantly between the two seasons. Cluster analyses revealed two distinct groups of stations which were associated with Ura Bay and the adjacent open sea, respectively. Daily production rates of the copepod species examined were calculated using three methods based on: (1) a temperature-dependent equation and (2) two multiple regressions that consider temperature, body weight, and chlorophyll a concentration. Significant seasonal differences for daily production rates were found using all three model equations (p?<?0.05): 358?±?188–1,775?±?791 versus 198?±?85–1,584?±?559?μg?dry?mass?m^?3?day^?1. Results of principal components analyses demonstrated that the abundance and biomass of herbivorous species were related to variation in chlorophyll a concentration while the abundance and biomass of other species (omnivorous copepods and Ctenophora) were related mainly with water temperature and salinity. Mesozooplankton biomass was higher during this study relative to previous studies. Computed copepod production rates were higher compared with other Arctic seas confirming a high productive potential of the coastal southern Barents Sea.