Mesozooplankton assemblages in the shallow Arctic Laptev Sea in summer 1993 and autumn 1995

Mesozooplankton distribution and composition in the very shallow part of the Siberian Laptev Sea shelf were studied during the German-Russian expeditions “Transdrift I” (August/September 1993) and “Transdrift III” (October 1995). Maximum abundances were found close to the outflow of the Lena River (7,965 ind. m⁻³) and in the Yana river mouth (38,163 ind. m⁻³). Lowest abundances occurred in the northeast and west of the Laptev Sea (64–95 ind. m⁻³). Highest biomass values (104–146 mg DM m⁻³) were determined in the northern and northeastern part of the shallow Laptev Sea, as well as close to the river outflows, with a record biomass maximum in the Yana river mouth (270 mg DM m⁻³). Biomass minima were situated north of the Lena Delta and in the western part of the shallow Laptev Sea (0.3–1.0 mg DM m⁻³). Copepods dominated in terms of abundance and biomass. Cluster analyses separated four mesozooplankton assemblages: the assemblage “Lena/Yana” in the southern part, “Eastern-central” in the centre, “Kotelnyy” in the eastern part and “Taimyr” in the western part of the shallow Laptev Sea. The small-sized neritic and brackish-water copepods Drepanopus bungei, Limnocalanus grimaldii and Pseudocalanus major occurred in enormous numbers and made up the bulk of zooplankton abundance and biomass in the very shallow part of the Laptev Sea close to the rivers Lena and Yana. In the more northern and northeastern areas, Calanus glacialis, P. minutus and P. major were dominant copepod species, whereas Oithona similis and Acartia sp. became important in the western Laptev Sea. Appendicularians, as well as hydromedusae and the chaetognath Sagitta sp., contributed significantly to abundance and biomass, respectively, but not over the entire area studied. One can identify taxon-specific distribution patterns (e.g. Sagitta predominated the biomass in a zone between the area heavily influenced by Lena/Yana and the offshore area to the north), which differ from the patterns revealed by cluster analysis. Hydrographic features, especially the enormous freshwater inflow, apparently determine the occurrence and formation of zooplankton aggregations. Extremely high numbers of small-sized neritic and brackish-water copepods occurred locally, which were probably also supported by excellent feeding conditions.     

Summer mesozooplankton distribution near Novaya Zemlya (eastern Barents Sea)

Regional variations in mesozooplankton composition, abundance and biomass were studied during a cruise in August 2006 near Novaya Zemlya Archipelago (eastern Barents Sea) using Juday net hauls from the bottom (or 100 m depth) to the surface. A comparison with multiannual literature values revealed that the mean temperature and salinity in the south and centre of the study area were similar to typical values, while temperature in the north was significantly higher. A total of 36 species and higher taxa were identified. Mesozooplankton abundance and biomass varied from 47 to 851 ind m⁻³ and from 5 to 74 mg dry weight m⁻³, respectively. Copepods dominated the mesozooplankton community, reaching 73–98% and 61–97% of the total abundance and biomass. Calanus finmarchicus and Oithona similis were the most abundant species at all stations. The biodiversities (Shannon indices) of the mesozooplankton community varied between stations from 1.10 to 2.46 (estimated from species abundances) and from 0.19 to 1.92 (estimated from species biomasses), averaging 1.93 ± 0.127 and 1.34 ± 0.151, respectively. Three groups at the 48% level of dissimilarity of species abundance were delineated by cluster analyses. The clusters differed significantly with respect to temperature and salinity. The total mesozooplankton abundance and biomass as well as quantitative parameters of most common taxa scaled negatively with temperature.     

Mesozooplankton beneath the summer sea ice in McMurdo Sound,Antarctica: abundance,species composition,and DMSP content

The summer Phaeocystis antarctica bloom increases under-ice phytoplankton biomass in McMurdo Sound, Antarctica. The magnitude of mesozooplankton grazing on this bloom is unknown, and determines whether this production is available to the pelagic food web. We measured mesozooplankton abundance and body content of dimethylsulfoniopropionate (DMSP) during the McMurdo Sound austral summer (2006 and 2006–2007). Abundance varied from 20 to 4,500 ind. m⁻³ (biomass 0.02–274.0 mg C m⁻³), with peaks in mid-December and late-January/February. Abundance was higher but total zooplankton biomass lower in our study compared to previous reports. Copepods and the pteropod Limacina helicina dominated the zooplankton in both abundance and biomass. DMSP was detected in all zooplankton groups, with highest concentrations in copepod nauplii and L. helicina (95 and 54 nmol mg⁻¹ body C, respectively). Experiments suggested that L. helicina obtains DMSP by directly grazing on P. antarctica, which often accumulates to high biomass under the summer sea ice in McMurdo Sound.     

Structure of littoral zoocenoses in the macroalgae zones of the Neva River Estuary

The biodiversity and spatial distribution of macrofauna biomass are studied for 12 sites of stonesand littoral in the Neva Estuary in 2002–2005. The highest biodiversity has been observed for chironomids and oligochaetes in the Neva Bay (36% and 24% of total species number) and in the eastern Gulf of Finland (33% and 23%). Amphipods (≤89%), molluscs (≤61%), and chironomids (≤37%) dominate by biomass. The biomass spatial distribution vary dramatically from 9 to 37 g m⁻² in the freshwater Neva Bay and from 1 to 68 g m⁻² for the other Neva Estuary areas. The bottom fauna biomass in the Neva Bay is significantly lower than in the 1980–1990’s and constitutes 20–50% of the biomass previously observed. We explain such a significant decrease by a reduction of the insects and aborigine crustaceans Gammarus lacustris Sars and Asellus aquaticus L. The invasive amphipod species Gmelinoides fasciatus (Stebbing) dominated by biomass for the study period (3.8–15.6 g m⁻², or >30% of total macrozoobenthos biomass).     

A direct comparison of the performance of the seaweed biofilters, <Emphasis Type="Italic">Asparagopsis armata</Emphasis> and <Emphasis Type="Italic">Ulva rigida</Emphasis>

The tetrasporophyte of Asparagopsis armata has been previously established as a novel seaweed biofilter for integrated land-based mariculture. The species growth and biofiltration rates were much higher than the values described in the literature for Ulva spp., the most common seaweed biofilter. However, a validation of the advantage of one species over the other requires a study of the performances of these two species in the same system at the same time. In this work, we compared the biofiltration performance and biomass yield of A. armata and Ulva rigida cultivated in the effluents of a fish farm in southern Portugal. Comparisons were performed at different water renewal rates and in two seasons of the year. The maximum total ammonia nitrogen (TAN) removal rates were similar for both species in December (2.7 and 2.8 g TAN m^–2 day^–1 for U. rigida and A. armata, respectively) and higher for A. armata (6.5 g TAN m^–2 day^–1) than for U. rigida (5.1 g TAN m^–2 day^–1) in May. Higher differences were observed when estimating the nitrogen biofiltration through the organic nitrogen yield (N yield) of the biomass produced, particularly in May. This estimate is directly related with the biomass yield and the N content in the tissue which were always higher for A. armata than for U. rigida. In December, the maximum biomass yields were 71 g dry weight (DW) m^–2 day^–1 for A. armata and 44 g DW m^–2 day^–1 for U. rigida, while in May, the yield of A. armata was 125 g DW m^–2 day^–1 and of U. rigida was 73 g DW m^–2 day^–1. This study confirmed that A. armata is indeed a more efficient biofilter than U. rigida. To the best of our knowledge, the production rates reported here are the highest ever reported for macroalgae cultivated in tanks.     

Soil nutrients affect spatial patterns of aboveground biomass and emergent tree density in southwestern Borneo

Studies on the relationship between soil fertility and aboveground biomass in lowland tropical forests have yielded conflicting results, reporting positive, negative and no effect of soil nutrients on aboveground biomass. Here, we quantify the impact of soil variation on the stand structure of mature Bornean forest throughout a lowland watershed (8–196 m a.s.l.) with uniform climate and heterogeneous soils. Categorical and bivariate methods were used to quantify the effects of (1) parent material differing in nutrient content (alluvium > sedimentary > granite) and (2) 27 soil parameters on tree density, size distribution, basal area and aboveground biomass. Trees ≥10 cm (diameter at breast height, dbh) were enumerated in 30 (0.16 ha) plots (sample area = 4.8 ha). Six soil samples (0–20 cm) per plot were analyzed for physiochemical properties. Aboveground biomass was estimated using allometric equations. Across all plots, stem density averaged 521 ± 13 stems ha⁻¹, basal area 39.6 ± 1.4 m² ha⁻¹ and aboveground biomass 518 ± 28 Mg ha⁻¹ (mean ± SE). Adjusted forest-wide aboveground biomass to account for apparent overestimation of large tree density (based on 69 0.3-ha transects; sample area = 20.7 ha) was 430 ± 25 Mg ha⁻¹. Stand structure did not vary significantly among substrates, but it did show a clear trend toward larger stature on nutrient-rich alluvium, with a higher density and larger maximum size of emergent trees. Across all plots, surface soil phosphorus (P), potassium, magnesium and percentage sand content were significantly related to stem density and/or aboveground biomass (R _Pearson = 0.368–0.416). In multiple linear regression, extractable P and percentage sand combined explained 31% of the aboveground biomass variance. Regression analyses on size classes showed that the abundance of emergent trees >120 cm dbh was positively related to soil P and exchangeable bases, whereas trees 60–90 cm dbh were negatively related to these factors. Soil fertility thus had a significant effect on both total aboveground biomass and its distribution among size classes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Energy flow and subsidies associated with the complex life cycle of ambystomatid salamanders in ponds and adjacent forest in southern Illinois

Breeding adults and metamorphosing larval amphibians transfer energy between freshwater and terrestrial ecosystems during seasonal migrations and emergences, although rarely has this been quantified. We intensively sampled ambystomatid salamander assemblages (Ambystoma opacum,A. maculatum, and A. tigrinum) in five forested ponds in southern Illinois to quantify energy flow associated with egg deposition, larval production, and emergence of metamorphosed larvae. Oviposition by female salamanders added 7.0–761.4 g ash-free dry mass (AFDM) year⁻¹ to ponds (up to 5.5 g AFDM m⁻² year⁻¹). Larval production ranged from 0.4 to 7.4 g AFDM m⁻² year⁻¹ among populations in three ponds that did not dry during larval development, with as much as 7.9 g AFDM m⁻² year⁻¹ produced by an entire assemblage. Mean larval biomass during cohort production intervals in these three ponds ranged from 0.1 to 2.3 g AFDM m⁻² and annual P/B (production/biomass) ranged from 4 to 21 for individual taxa. Emergent biomass averaged 10% (range=2–35%) of larval production; larval mortality within ponds accounted for the difference. Hydroperiod and intraguild predation limited larval production in some ponds, but emerging metamorphs exported an average of 70.0±33.9 g AFDM year⁻¹ (range=21.0–135.2 g AFDM year⁻¹) from ponds to surrounding forest. For the three ponds where larvae survived to metamorphosis, salamander assemblages provided an average net flux of 349.5±140.8 g AFDM year⁻¹ into pond habitats. Among all ponds, net flux into ponds was highest for the largest pond and decreased for smaller ponds with higher perimeter to surface area ratios (r ² =0.94, P<0.05, n=5). These results are important in understanding the multiple functional roles of salamanders and the impact of amphibian population declines on ecosystems. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Zooplankton biomass in tropical reservoirs in southern Brazil

In order to test the hypothesis that zooplankton biomass distribution (total and taxonomic groups) was influenced by the nutrient concentration and primary productivity distribution in three tropical reservoirs, subsurface samples were taken in the fluvial, transitional and lacustrine regions of three reservoirs (oligotrophic, mesotrophic and eutrophic) in southern Brazil (Paraná State) in March and September 2002. Zooplankton biomass ranged from 0.04 to 264.47 mg DW m⁻³. Higher biomass values were observed for cladocerans (73.60%; 0.01–259.86 mg DW m⁻³), followed by copepods (22.05%; 0.01–69.69 mg DW m⁻³) and rotifers (4.35%; 0.01–11.52 mg DW m⁻³). In general, the total zooplankton, rotifer, cladoceran and copepod biomass, and chlorophyll-a and total nutrient concentrations showed a similar longitudinal distribution within the reservoirs. Total zooplankton, rotifer and cladoceran biomass were related to the chlorophyll-a concentration, and zooplankton biomass was related to the total phosphorus distribution. This may have been due to the significant multicolinearity between the chlorophyll-a and total phosphorus concentrations. Cyanobacteria influenced the taxonomic group biomass results by interfering with the filter feeding in larger zooplankton species, which favoured the dominance of smaller species. As regards the longitudinal distribution of copepod biomass, cyanobacteria biomass determined the displacement of the microcrustaceans to the fluvial region of Iraí Reservoir. Our results supported the hypothesis formulated and the primary productivity was the major predictor of the zooplankton biomass distribution in the reservoirs. Handling editor: S. Dodson     

Transpiration and whole-tree conductance in ponderosa pine trees of different heights

Changes in leaf physiology with tree age and size could alter forest growth, water yield, and carbon fluxes. We measured tree water flux (Q) for 14 ponderosa pine trees in two size classes (12 m tall and ∼40 years old, and 36 m tall and ∼ 290 years old) to determine if transpiration (E) and whole-tree conductance (g _t) differed between the two sizes of trees. For both size classes, E was approximately equal to Q measured 2 m above the ground: Q was most highly correlated with current, not lagged, water vapor pressure deficit, and night Q was <12% of total daily flux. E for days 165–195 and 240–260 averaged 0.97 mmol m^–2 (leaf area, projected) s^–1 for the 12-m trees and 0.57 mmol m^–2 (leaf area) s^–1 for the 36-m trees. When photosynthetically active radiation (I _P) exceeded the light saturation for photosynthesis in ponderosa pine (900 μmol m^–2 (ground) s^–1), differences in E were more pronounced: 2.4 mmol m^–2 (leaf area) s^–1 for the 12-m trees and 1.2 mmol m^–2 s^–1 for the 36-m trees, yielding g _t of 140 mmol m^–2 (leaf area) s^–1 for the 12-m trees and 72 mmol m^–2 s^–1 for the 36-m trees. Extrapolated to forests with leaf area index =1, the 36-m trees would transpire 117 mm between 1 June and 31 August compared to 170 mm for the 12-m trees, a difference of 15% of average annual precipitation. Lower g _t in the taller trees also likely lowers photosynthesis during the growing season. Received: 19 April 1999 / Accepted: 23 March 2000     

Development of an attached microalgal growth system for biofuel production

Algal biofuel production has gained a renewed interest in recent years but is still not economically feasible due to several limitations related to algal culture. The objective of this study is to explore a novel attached culture system for growing the alga Chlorella sp. as biodiesel feedstock, with dairy manure wastewater being used as growth medium. Among supporting materials tested for algal attachment, polystyrene foam led to a firm attachment, high biomass yield (25.65 g/m², dry basis), and high fatty acid yield (2.31 g/m²). The biomass attached on the supporting material surface was harvested by scraping; the residual colonies left on the surface served as inoculum for regrowth. The algae regrowth on the colony-established surface resulted in a higher biomass yield than that from the initial growth on fresh surface due to the downtime saved for initial algal attachment. The 10-day regrowth culture resulted in a high biodiesel production potential with a fatty acid methyl esters yield of 2.59 g/m² and a productivity of 0.26 g/m⁻² day⁻¹. The attached algal culture also removed 61–79% total nitrogen and 62–93% total phosphorus from dairy manure wastewater, depending on different culture conditions. The biomass harvested from the attached growth system (through scraping) had a water content of 93.75%, similar to that harvested from suspended culture system (through centrifugation). Collectively, the attached algal culture system with polystyrene foam as a supporting material demonstrated a good performance in terms of biomass yield, biodiesel production potential, ease to harvest biomass, and physical robustness for reuse.     

Biomass carbon stocks and their changes in northern China’s grasslands during 1982–2006

Grassland covers approximately one-third of the area of China and plays an important role in the global terrestrial carbon (C) cycle. However, little is known about biomass C stocks and dynamics in these grasslands. During 2001–2005, we conducted five consecutive field sampling campaigns to investigate above-and below-ground biomass for northern China’s grasslands. Using measurements obtained from 341 sampling sites, together with a NDVI (normalized difference vegetation index) time series dataset over 1982–2006, we examined changes in biomass C stock during the past 25 years. Our results showed that biomass C stock in northern China’s grasslands was estimated at 557.5 Tg C (1 Tg=10¹² g), with a mean density of 39.5 g C m⁻² for above-ground biomass and 244.6 g C m⁻² for below-ground biomass. An increasing rate of 0.2 Tg C yr⁻¹ has been observed over the past 25 years, but grassland biomass has not experienced a significant change since the late 1980s. Seasonal rainfall (January–July) was the dominant factor driving temporal dynamics in biomass C stock; however, the responses of grassland biomass to climate variables differed among various grassland types. Biomass in arid grasslands (i.e., desert steppe and typical steppe) was significantly associated with precipitation, while biomass in humid grasslands (i.e., alpine meadow) was positively correlated with mean January-July temperatures. These results suggest that different grassland ecosystems in China may show diverse responses to future climate changes.     

Basin scale distribution of zooplankton in the Ligurian Sea (north-western Mediterranean) in late autumn

Mesozooplankton biomass and abundance were evaluated in epipelagic waters at 59 stations covering the Italian sector of the Ligurian Sea (north-western Mediterranean) in December 1990. This region is characterised by a cyclonic circulation which encloses a central divergence zone and is associated with a main thermohaline front offshore the western Ligurian coast. At the end of autumn, mesozooplankton biomass (range: 0.80–4.24 mg DW m⁻³) and the abundance (range: 83.8–932 ind. m⁻³) were lower in the divergence zone. On the contrary, in the Ligurian frontal zone at the periphery of the divergence and on the eastern continental shelf the greatest values of biomass and abundance were recorded. Copepods and appendicularians dominated the mesozooplankton community, the main taxa being the copepods Clausocalanus spp. (46% of total zooplankton) and Oithona spp. (15%) and the appendicularian Fritillaria spp. (12%). Three hydrological sub-regions, i.e. the divergence, the eastern continental shelf and the periphery of the divergence, were characterised by different zooplankton communities and characteristic species. Environmental differences between the three zones were mainly related to changes in bottom topography, sea surface temperatures and quantity of particulate organic matter. Vertical mesozooplankton abundance and taxa distribution from the surface to 1,900 m depth were also examined in one station. The results showed that the bulk of the community was concentrated in the upper 200 m, small copepods being dominant particularly in the upper 50 m. The copepod community was more diversified in sub-superficial waters, with a maximum observed in the 200–400 m layer. The distributions of main zooplankton taxa described in epipelagic waters in the eastern Ligurian Sea in autumn were compared with their distribution at surface in the north-western Mediterranean obtained by sampling performed with the Continuous Plankton Recorder in 1997–1999. The analysis of the zooplankton community in CPR samples confirms the dominance of small copepods (Paracalanus spp., Clausocalanus spp., Oithona spp.) and appendicularians in the north-western Mediterranean in late autumn-winter and shows that their distribution is mainly related to the main mesoscale hydrographic features characterising this basin. Guest editors: S. Souissi & G. A. Boxshall Copepoda in the Mediterranean: Papers from the 9th International Conference on Copepoda, Hammamet, Tunisia     

Structure and grazing impact of the mesozooplankton community during late summer 1994 near South Georgia, Antarctica

Mesozooplankton abundance, community structure and grazing impact were determined during late austral summer (February/March) 1994 at eight oceanic stations near South Georgia using samples collected with a Bongo and WP-2 nets in the upper 200-m and 100-m layer, respectively. The zooplankton abundance was generally dominated by copepodite stages C3–C5 of six copepod species: Rhincalanus gigas, Calanus simillimus, Calanoides acutus, Metridia spp., Clausocalanus laticeps and Ctenocalanus vanus. Most copepods had large lipid sacs. All copepods accounted for 41–98% of total zooplankton abundance. Juvenile euphausiids were the second most important component contributing between 1 and 20% of total abundance. Pteropods, mainly Limacina inflata, were important members of the pelagic community at two sites, accounting for 44 and 53% of total abundance. Average mesozooplankton biomass in the upper 200 m was 8.0 g dry weight m⁻², ranging from 4.3 to 11.5 g dry weight m⁻². With the exception of Calanussimillimus, gut pigment contents and feeding activity of copepod species were low, suggesting that some species, after having stored large lipid reserves, had probably started undergoing developmental arrest. Daily mesozooplankton grazing impact, measured using in situ gut fluorescence techniques and in vitro incubations, varied widely from <1 to 8% (mean 3.5%) of phytoplankton standing stock, and from 5 to 102% (mean 36%) of primary production. The highest grazing impact was found northeast of the island co-incident with the lowest phytoplankton biomass and primary production levels. Received: 30 October 1996 / Accepted: 23 February 1997     

Bacterioplankton of the Gdansk Basin,Baltic Sea

The numbers, biomass, and production of bacterioplankton were determined in the Russian Sector of the Gdansk Basin (Baltic Sea) in 2007–2009. Significant spatial and temporal variations were determined. During the year, bacterial activity increased with increasing water temperature and higher availability of organic substrates. The lowest bacterial production (0.01–31.63 mg C m⁻³ day⁻¹) was observed in late winter and late autumn, while the highest (0.17–341.70 mg C m⁻³ day⁻¹) occurred in spring and summer. Since bacterial numbers and biomass were found to depend on the weather conditions and the terrigenous inflow, significant variations were observed from year to year. The highest and lowest numbers and biomass of bacterioplankton determined in summer were 0.09–1.10 × 10⁶ cells mL⁻¹ and 2–22 mg C m⁻³ for July 2007 and 1.96–11.23 × 10⁶ cells mL⁻¹ and 23–123 mg C m^–3 for July 2009. The values of these parameters were the highest along the coast and decreased towards the open sea.     

The spring mesozooplankton community at South Georgia: a comparison of shelf and oceanic sites

Mesozooplankton (predominantly 200–2000 μm) were sampled at a shelf and an oceanic station close to South Georgia, South Atlantic, during austral spring (October/November) 1997. Onshelf zooplankton biomass was extremely high at 10–16 g dry mass m⁻² (0–150 m), 70% comprising the small neritic clausocalaniid copepod Drepanopus forcipatus. Large calanoid species, principally Calanoides acutus and Rhincalanus gigas, contributed only 8–10%. At the oceanic station, biomass in the sampled water column (0–1000 m) was ∼6.5 g dry mass m⁻² and 4–6 g dry mass m⁻² in the top 200 m. Here, large calanoids composed 40–50% of the standing stock. Antarctic krill (Euphausia superba) occurred in low abundances at both stations. Vertical profiles obtained with a Longhurst Hardy Plankton Recorder indicated that populations of C. acutus and R. gigas, which overwinter at depth, had completed their spring ascent and were resident in surface waters. Dry mass, carbon and lipid values were lower than found in summer but were consistent with overwintered populations. Phytoplankton concentrations were considerably higher at the oceanic station (2–3 mg chlorophyll a m⁻³) and increased over the time on station. In response to this, egg production of both large calanoid species and growth rates of R. gigas approached those measured in summer. Onshelf phytoplankton concentrations were lower (<1 mg m⁻³), and low egg production rates suggested food limitation. Here phytoplankton rations equivalent to 6% zooplankton body C would have been sufficient to clear primary production whereas at the oceanic station daily carbon fixation was broadly equivalent to zooplankton carbon biomass. Accepted: 25 April 1999     

舟山海域夏、秋季浮游动物的分布特征及其与环境因子的关系

为更好地了解舟山海域浮游动物的群落结构、生物量和丰度的时空分布特征及其与主要环境因子的关系,分别于2014年7月和10月进行了夏季、秋季两次生态综合调查,并用多维尺度分析法、典范对应分析法对浮游动物群落结构进行了研究。结果表明:夏季舟山海域调查的浮游动物有13类,64种,优势种为背针胸刺水蚤(Centropages dorsispinatus)、圆唇角水蚤(Labidocera rotunda)、中华哲水蚤(Calanus sinicus)、精致真刺水蚤(Euchaeta concinna)、百陶带箭虫(Zonosagitta bedoti)和真刺唇角水蚤(Labidocera euchaeta);秋季鉴定到浮游动物12类,45种,优势种为背针胸刺水蚤(Centropages dorsispinatus)、百陶带箭虫(Zonosagitta bedoti)、双生水母(Diphyes chamissonis)、瓜水母(Beroёcucumis)和中华哲水蚤。夏季浮游动物平均丰度及平均生物量(144.0 ind/m3和176.3 mg/m~3)都分别高于秋季(21.4个/m3和86.3 mg/m3);Shannon-Wiener多样性指数夏季(3.03)高于秋季(2.82),Pielou均匀度指数则是秋季(0.83)高于夏季(0.64);夏季不同区域浮游动物群落之间具有明显的差异,而秋季大部分站位群落之间差异不显著;温度、盐度、叶绿素a浓度和营养盐含量是影响舟山海域浮游动物分布的主要环境因子;与历史资料相比,舟山海域浮游动物丰度及生物量呈下降趋势,其优势种保持较稳定。     

Abundance and energy requirements of eiders (Somateria spp.) suggest high predation pressure on macrobenthic fauna in a key wintering habitat in SW Greenland

The number of common eiders (Somateria mollissima borealis) in west Greenland declined dramatically during the twentieth century, supposedly because of human activities. However, their sensitivity to alternative drivers of variation, such as climate conditions, diseases or food availability, remains unstudied. In this study, we describe prey availability and assess the trophic coupling between eiders and their macrobenthic prey in a shallow inlet, Nipisat Sound; a key wintering habitat in the south-west Greenland Open Water Area. Macrobenthic species abundance and biomass were studied, and annual production was estimated by an empirical model, including environmental characteristics, fauna composition and individual biomass. In spring 2008, average macrozoobenthic abundance and biomass were 6,912 ind m⁻² and 28.4 g ash-free dry mass (AFDM) m⁻² (647 kJ m⁻²), respectively. Annual production was estimated at 13.9 g AFDM m⁻² year⁻¹ (317 kJ m⁻² year⁻¹). During the winters of 2008–2010, we monitored the number of common eiders (S. mollissima borealis) and king eiders (Somateria spectabilis) and observed a distinct peak in abundance during winter with up to 15.000 birds in Nipisat Sound. Based on physiological costs of different activities in combination with the observed behavioural pattern, we obtained an estimate of the energy required for eiders to balance their costs of living, which amounted to 58% of the estimated total annual production of macrobenthos in Nipisat Sound. This result suggests that eider predation affects macrobenthic species composition and biomass and demonstrates the potential importance of variations in prey availability for the population dynamics of eiders in Greenland.     

Seasonal changes in abundance and spatial distribution of the soil arthropods in a Japanese cedar (Cryptomeria japonica D.Don) plantation,with special reference to collembola and acarina

Seasonal changes in abundance and distribution pattern of soil micro-arthropods were studied in connection with a few environmental factors in a Japanese cedar (Cryptomeria japonica D. Don) plantation. The soil arthropods were sampled from three different depths at intervals of two months for two years. Of the collected animals (total 51000–155000 m⁻²), Collembola (20000–76000 m⁻²), oribatid mites (19000–55000 m⁻²) and carnivorous mites (6200–21000 m⁻²) were the numerically dominant animal groups. Low seasonal variations in abundance indicated their seasonal stability in population levels. The trends in seasonal fluctuation were similar among these groups and between the two years, showing bimodal pattern with little peaks in early summer and winter. The pattern of seasonal fluctuation in abundance of carnivorous mites (P _d) was significantly synchronized with that in the total abundance of Collembola and oribatid mites (P _τ). Thus, the number-ratios (P _d/P _τ) were fairly constant, ranging from 0.10 to 0.25. Seasonal changes in vertical distribution of the three animal groups showed a similar pattern for both years. The downward migrations were shown to be more affected by low temperatures in winter accompanied by snow coverage rather than by the desiccation of the surface soil in summer. All the three groups demonstrated as a whole slightly aggregated patterns of horizontal distribution throughout the two years. Temporal increases in the patchiness indices were observed from summer to autumn when the moisture content of the surface soil was low.     

Productivity and selective accumulation of carotenoids of the novel extremophile microalga <Emphasis Type="Italic">Chlamydomonas acidophila</Emphasis> grown with different carbon sources in batch systems

Cultivation of extremophile microorganisms has attracted interest due to their ability to accumulate high-value compounds. Chlamydomonas acidophila is an acidophile green microalga isolated by our group from Tinto River, an acidic river that flows down from the mining area in Huelva, Spain. This microalga accumulates high concentrations of lutein, a very well-known natural antioxidant. The aim of this study is to assess use of different carbon sources (CO₂, glucose, glycerol, starch, urea, and glycine) for efficient growth of and carotenoid production by C. acidophila. Our results reveal that growth of the microalga on different carbon sources resulted in different algal biomass productivities, urea being as efficient as CO₂ when used as sole carbon source (~20 g dry biomass m^–2 day^–1). Mixotrophic growth on glucose was also efficient in terms of biomass production (~14 g dry biomass m^–2 day^–1). In terms of carotenoid accumulation, mixotrophic growth on urea resulted in even higher productivity of carotenoids (mainly lutein, probably via α-carotene) than obtained with photoautotrophic cultures (70% versus 65% relative abundance of lutein, respectively). The accumulated lutein concentrations of C. acidophila reported in this work (about 10 g/kg dry weight, produced in batch systems) are among the highest reported for a microalga. Glycerol and glycine seem to enhance β-carotene biosynthesis, and when glycine is used as carbon source, zeaxanthin becomes the most accumulated carotenoid in the microalga. Strategies for production of lutein and zeaxanthin are suggested based on the obtained results.     

Picophytoplankton abundance in the Velikaya Salma strait,White Sea

In July-August 2009, the abundance of picophytoplankton (Pico) in the Velikaya Salma strait varied from 3.4 × 10⁶ to 19.4 × 10⁶ cells/L, while its biomass (B) was 0.8–3.3 mg C/m³. In August 2010, Pico abundance was significantly higher (up to 216 × 10⁶ cells/L and 36.8 mg C/m³). Pico consisted mainly of cyanobacteria. It constituted 13 (2009) to 28% (2010) of the total phytoplankton biomass. In April 2010, Pico numbers varied from 0.1 × 10⁶ to 0.22 × 10⁶ cells/L and its biomass was 0.05–0.28 mg C/m³. Picoeukaryotes were predominant. Pico constituted not more than 2.7% of the phytoplankton biomass. In the ice column, the integrated Pico abundance was 430 × 10⁶ cells/m² and the integrated biomass was 365 μg C/m².