Effect of dietary protein to energy ratio on growth and nitrogenous waste production of cultured dusky kob Argyrosomus japonicus

The effect of dietary protein to energy ratio (P:E) on the growth of dusky kob Argyrosomus japoni-cus was investigated as a first step towards formulating a practical diet for this potential mariculture species in South Africa. The effects of dietary protein and lipid on growth, feed conversion ratio (FCR) and nitrogenous waste production were determined in cultured juveniles (initial weight 113.8 ± 2.0 g fish^?1). Fish were fed diets that contained either 42 or 46% protein with 6, 12 or 18% lipid, within a P:E range of 20.5–26.7 g protein MJ^?1. Weight gain and specific growth rate (SGR) were significantly influenced by an interaction between dietary protein and energy (p < 0.001). An increase in dietary lipid produced increasing growth rates (ranging from 0.95 ± 0.04% to 1.10 ± 0.01% day^?1) among fish fed the 46% protein diets, with no significant differences in FCR (1.05 ± 0.02 to 1.11 ± 0.02) or protein efficiency ratio (PER; 1.95 ± 0.06 to 1.66 ± 0.02). By contrast, there was a trend of decreasing growth (0.96 ± 0.04% to 0.64 ± 0.03% day^?1) and a deterioration in FCR (1.3 ± 0.10 to 1.93 ± 0.19) and PER (1.12 ± 0.11 to 1.68 ± 0.11) with increasing dietary lipid among fish fed 42% protein diets, indicating a protein– energy imbalance. The protein and lipid levels tested here had no significant effect on total ammonia production, with a combined mean production of 2.54 ± 0.55 mg kg^?1 I^?1 h^?1, 10 hours postprandial (p = 0.68). The dietary lipid level appeared to directly determine the carcass lipid content, with the mean lipid content ranging from 4.2% to 17.8% for fish fed diets ranging from 6% to 18% respectively after 12 weeks (r² = 0.98). A 46% protein and 18% lipid (P:E ratio of 22.0 g protein MJ^?1) diet is recommended for rearing juvenile A. japonicus of a mass range of 100–300 g.     

Role of Zooplankton in the Vertical Mass Flux in the Kara and Laptev Seas in Fall

The role of zooplankton in the vertical mass flux in the Kara and Laptev seas was studied during cruise 63 of the R/V Akademik Mstislav Keldysh in August–October 2015. Mass fluxes were estimated using sediment trap samples. The maximum values of the total vertical flux (19600 mg m^?2 day^?1) and particulate organic carbon (POC) flux (464 mg C m^?2 day^?1) were measured close to the Lena River Delta in the Laptev Sea. In the Kara Sea, the total flux (80–2700 mg m^?2 day^?1) and the POC flux (17–130 mg C m^?2 day^?1) were substantially higher than the estimates published earlier. The fecal pellet flux varied from 2 to 92 mg C m^?2 day^?1 and made up 4–190% of the total organic carbon flux. The mineral composition of fecal pellets largely mirrored that of suspended particulate matter. Clay minerals in the fecal pellets were more abundant than in particulate matter in the areas with noticeable freshwater impact. The flux of zooplankton carcasses varied from 0.1 to 66.4 mg C m^?2 day^?1 and made up 0.2–72% of total POC flux. The results are discussed in relation to the abundance and composition of zooplankton, the concentration and composition of suspended particulate matter, hydrophysical conditions, and methods of sample preparation for analysis.     

尼罗系吉富罗非鱼(Oreochromis niloticus)幼鱼实用日粮中蔗糖糖蜜的养殖效果与血糖代谢变化

采用6种等蛋白质(34.4%)、等能量(16.10MJ/kg)试验日粮,研究了尼罗系吉富罗非鱼幼鱼实用日粮中蔗糖糖蜜替代小麦次粉的养殖效果与血糖代谢变化。结果表明,56d试验期间各试验组鱼均无死亡;蔗糖糖蜜替代小麦次粉40%—100%日粮组鱼的摄食量、特定生长率、饲料效益和蛋白效益均高于小麦次粉组鱼,当蔗糖糖蜜100%替代小麦次粉时,其摄食量、特定生长率和饲料效益蛋白效益比均显著性上升(P<0.05)。各试验组鱼鱼体营养成分(蛋白质、脂肪、灰分和水分)和肝体指数无显著性差异(P>0.05),肝脏结构正常。蔗糖糖蜜组鱼血浆中血糖、总蛋白、胆固醇、甘油三酯含量明显高于小麦次粉组鱼(P<0.05)。本试验结果认为,蔗糖糖蜜在尼罗系吉富罗非鱼幼鱼实用日粮中可以完全替代小麦次粉,蔗糖糖蜜对尼罗系吉富罗非鱼幼鱼具有较好的生长效益、节约日粮蛋白质效益和适口性,其主要原因与摄食蔗糖糖蜜后尼罗系罗非鱼幼鱼产生的较长时间高血糖现象有关。     

Dynamic patterns of dissolved nitrogen in the Southern Bight of the North Sea

Spatial and temporal variations of dissolved inorganic nitrogen (DIN) have been assessed in onshore and offshore areas of the Southern Bight on the basis of several years' measurements. They indicate that both the residual flow lines and DIN isoconcentration lines run parallel with the coast except in the vicinity of important freshwater discharge points such as the Scheldt estuary. Evidence was found that the seasonal DIN oscillations are not created through fluctuations in input conditions at the lateral boundaries, despite considerable fluctuations in these inputs which include the English Channel (from 500 tons(t) N day^?1 in June up to approximately 2000 t N day^?1 in February) and also rivers such as the Scheldt estuary (up to 50 t N day^?1 in January but less than 5 t N day^?1 in June–July). In both the onshore and offshore areas the sum of daylight phytoplanktonic nitrogen intake and sediment release of nitrogen corresponds to the observed DIN variations during most of the year. Pelagic N-mineralization from natural or grazing mortality of phytoplankton (220 mg N m^?2 day^?1 onshore at its maximum) can account for the differences (200 mg N m^?2 day^?1 onshore at its maximum), especially at the end of the phytoplankton spring bloom. Although the causes of DIN oscillations onshore and offshore are the same, the results differ because offshore (1) the vegetative season lasts longer, and (2) DIN is exhausted at the end of the phytoplankton spring bloom.     

Shark fishing effort and catch of the ragged-tooth shark Carcharias taurus in the South African competitive shore-angling fishery

An integrated telephone and on-site questionnaire survey was used to estimate total shark fishing effort and specific catch of the ragged-tooth shark Carcharias taurus by coastal club-affiliated shore-anglers, primarily along the east coast of South Africa. Mean total shark fishing effort was estimated to be 37 820 fisher-days year^?1 (95% CI = 28 281–47 359 fisher-days year^?1) with a mean cpue of 0.073 C. taurus fisher^?1 day^?1 (95% CI = 0.068–0.078 fisher^?1 day^?1). Cpue for C. taurus varied significantly along the coast and ranged from a high of 0.260 fisher^?1 day^?1 in the Eastern Cape to zero fisher^?1 day^?1 on the West Coast. The total number of C. taurus caught annually by coastal club anglers was estimated at 1 764 fish year^?1 (95% CI = 321–3 207 fish year^?1). The majority (92.1%) of young-of-the-year sharks (<1.2m total length, TL) were recorded between East London and Jeffreys Bay, suggesting that this may be the primary nursery area for C. taurus. Post-release mortality ranged from 3.8% for young-of-the-year sharks to 18.5% for adult sharks (>2.4m TL). The majority (76.2%) of anglers interviewed stated that they now fished less for sharks since the banning of vehicles on beaches in December 2001. As a result of this ban, almost half (49.2%) of interviewed anglers stated that they now fished more for non-cartilaginous species.     

Upwelling in the Southern Benguela Current

This survey of the southernmost significant upwelling site in the Benguela Current showed that the oceanography is dominated by the seasonal wind cycle of predominant S-E winds in summer and N-W winds in winter. In the upwelling season, extending from September to March, a semi-permanent plume is isolated by a pronounced oceanic front whose position varies in the short-term and is related to wind direction. Surface waters change immediately and deeper waters more slowly to fluctuations in wind. The rate of upwelling was statistically related to wind data. A maximum rate of 32 m day^?1 was found.In spring low temperature and salinity water flows northward on the shelf while between late summer and later winter oxygen-depleted water, rich in nutrients, flowed south at an estimated rate of 7–21 × 10⁴ m³ s^?1 in a counter current to the Good Hope Jet.Local depletion of oxygen occurs due to phytoplankton decomposition caused, in autumn, by falling light levels and, in summer in calm periods, by nitrate depletion (<1 μg-at N 1^?1). Primary productions is estimated at 3.7 kg C m^?2 yr^?1 with a maximum growth rate (PI_max) = 17.4–19.0 mg C mg chlorophyll a^?1 hr^?1 and half-saturation constant (K_S) = 0.4–1.1 μg-at N 1^?1. Nutrients were utilized and oxygen produced: ΔP:ΔN:ΔSi:ΔO=1:19.1 to 23.3:17.5 to 23.3:?227 to ?293. High N:Si ratios (maximum 4.28) were found in oxygen-depleted water produced locally while that coming from the north had low ratis, due to resolution of silica from the sediments and nitrate reduction. The mean zooplankton standing stock, 2.3 g dry weight m^?2, was 12% of the phytoplankton crop. In summer stocks were maximal 40–100 km and minimal 20–50 km from the coast while in winter they were maximal inshore. Little vertical migration occurred and the waters above the thermocline contained the majority of the population.     

Euphausiid population structure and grazing in the Antarctic Polar Frontal Zone — austral autumn 2004

The euphausiid community structure and grazing dynamics were investigated in the West Indian sector of the Polar Frontal Zone during the austral autumn 2004. Subsurface (200m) temperature profiles indicated that an intense frontal feature, formed by the convergence of the Subantarctic Front and the Antarctic Polar Front bisected the survey area into two distinct zones, the Subantarctic Zone (SAZ) and the Antarctic Zone (AAZ). Total integrated chlorophyll a (Chl a) biomass was typical for the region (<25mg Chl a m^?2), and was dominated by picophytoplankton. Total euphausiid abundance and biomass ranged from 0.1 m^?3 to 3.1 m^?3 and from 0.1mg dry weight m^?3 to 8.1mg dry weight m^?3 respectively, and did not differ significantly between the stations occupied in the SAZ and AAZ (p > 0.05). A multivariate analysis identified two interacting mechanisms controlling the distribution patterns, abundance and biomass of the various euphausiid species, namely (1) diel changes in abundance and biomass, and (2) restricted distribution patterns associated with the different water masses. Ingestion rates were determined for five euphausiid species. Euphausia triacantha had the highest daily ingestion rate, ranging from 1 226.1ng pigment (pigm) ind^?1 day^?1 to 6 029.1ng pigm ind^?1 day^?1, whereas the lowest daily ingestion rates were observed in the juvenile Thysanoessa species (6.4–943.0ng pigm ind^?1 day^?1). The total grazing impact of selected euphausiids ranged from <0.1μg pigm m^?2 day^?1 to 20.1μg pigm m^?2 day^?1, corresponding to <0.15% of the areal Chl a biomass. The daily ration estimates of autotrophic carbon for the euphausiids suggest that phytoplankton represent a minor component in their diets, with only the sub-adult E. vallentini consuming sufficient phytoplankton to meet their daily carbon requirements.     

Nutrient exchange across the sediment-water interface in the Potomac River estuary

The flux of ammonia, phosphate, silica and radon-222 from Potomac tidal river and estuary sediments is controlled by processes occurring at the sediment-water interface and within surficial sediment. Calculated diffusive fluxes range between 0·6 and 6·5 mmol m^?2 day^?1 for ammonia, 0·020 and 0·30 mmol m^?2 day^?1 for phosphate, and 1·3 and 3·8 mmol m^?2 day^?1 for silica. Measured in situ fluxes range between 1 and 21 mmol m^?2 day^?1 for ammonia, 0·1 and 2·0 mmol m^?2 day^?1 for phosphate, and 2 and 19 mmol m^?2 day^?1 for silica. The ratio of in situ fluxes to diffusive fluxes (flux enhancement) varied between 1·6 and 5·2 in the tidal river, between 2·0 and 20 in the transition zone, and from 1·3 to 5·1 in the lower estuary. The large flux enhancements from transition zone sediments are attributed to macrofaunal irrigation. Nutrient flux enhancements are correlated with radon flux enhancements, suggesting that fluxes may originate from a common region and that nutrients are regenerated within the upper 10–20 cm of the sediment column.The low fluxes of phosphate from tidal viver sediments reflect the control benthic sediment exerts on phosphorus through sorption by sedimentary iron oxyhydroxides. In the tidal river, benthic fluxes of ammonia and phosphate equal one-half and one-third of the nutrient input of the Blue Plains sewage treatment plant. In the tidal Potomac River, benthic sediment regeneration supplies a significant fraction of the nutrients utilized by primary producers in the water column during the summer months.     

Biogenic debris from the pelagic tunicate, Oikopleura dioica, and its role in the vertical transport of a transuranium element

The accumulation and retention of ²⁴¹Am by the pelagic tunicate Oikopleura dioica were examined using laboratory cultures and radiotracer methodology. Animals (i.e., trunks and tails) and discarded empty houses accumulated Am from seawater, giving volume/volume concentration factors of 59±8 and 10±1, respectively. The half-time for retention of Am in empty labelled houses transferred to non-contaminated seawater was 29 h; the retention half-time of Am in houses discarded by larvaceans feeding on Am-labelled diatoms was 219 h; the half-time of Am in fecal pellets produced by animals feeding on a monospecific diet of diatoms was 134 h, and 247 h for fecal pellets from animals fed a mixed diet. Approximately 30% of filtered cells remained in houses after the houses were discarded. Sinking rates of discarded houses and fecal pellets were found to vary with temperature and size, ranging from 26–157 m day^?1 (house) and from 25–166 m day^?1 (fecal pellets). The ubiquity and abundance of appendicularians, together with their prodigious production of houses (e.g., 10±2 houses day^?1 at 17°C for each experimental animal) point to their potential significance in the vertical transport of Am, and probably other reactive metals, to intermediate depths in the ocean.     

Spatio‐temporal dynamics and biomass of Cymodocea nodosa in Bekalta (Tunisia,Southern Mediterranean Sea)

Leaf growth, biomass and production of Cymodocea nodosa were measured from October 2006 to September 2007 in Monastir Bay (Tunisia). Shoot density showed a clear seasonal pattern, increasing during spring and summer and decreasing during fall and winter. Monthly mean shoot density ranged between 633 ± 48 and 704 ± 48 shoots?m^?2. The monthly average total biomass ranged between 560 ± 37 and 646 ± 32 g dry weight (DW)?m^?2. Total biomass varied significantly among stations and sampling times but did not show seasonal variation. Leaf plastochrone intervals varied seasonally, with an annual average of 28–30 days. Leaf productivity was highest in August (2.61 g DW?m^?2?day^?1) and lowest in February (0.35 g DW?m^?2?day^?1). Annual belowground primary production varied from 263 to 311 g DW?m^?2?year^?1. Annual leaf production was approximately equal for all the stations (from 264 to 289 g DW?m^?2?year^?1). Variability in water temperature, air temperature and salinity explained the annual variability in biological characteristics. Changes in belowground and total biomass were not correlated with seasonal variability in the environmental parameters monitored. Additionally, a literature review was conducted of C. nodosa features at other Mediterranean sites, encompassing 30 studies from 1985 to 2014.     

Microbial nitrogen transformations in sediments and inorganic nitrogen fluxes across the sediment/water interface on the South Island West Coast,New Zealand

In January 1982, sediment microbial N transformations and inorganic N fluxes across the sediment/water interface were studied at nine sites off the South Island West Coast, New Zealand. The sediments showed a great variety in physical, chemical and biological properties. The sediment organic matter had a molar $\text{C}\text{N}$ ratio of 5.9–10.9, and the total $\text{N}\text{P}$ ratio was 1.2–4.0. The denitrification capacity in the top 7.5 cm of sediment was 0.1–77.2 mmol N m^?2 day^?1 and generally declined with increasing sediment depth. The in situ denitrification rate was 0.02–1.84 mmol N m^?2 day^?1 and highest activities were generally found in surface sediments and at 6–7.5 cm depth. Denitrification accounted for 82–100% of total nitrate reduction. Net N mineralization was indirectly estimated at 0.6–2.4 mmol N m^?2 day^?1, and the experimental determination of this N transformation gave 0.6–3.2 mmol N m^?2 day^?1. Denitrification accounted for 3–75% of net N mineralization. The diffusive flux of ammonium and nitrate across the sediment/water interface was 0.1–0.7 and 0.1–0.6 mmol N m^?2 day^?1, respectively.     

The continental shelf pump for CO2 in the North Sea—evidence from summer observation

Data on the distribution of dissolved inorganic carbon (DIC) and partial pressure of CO₂ (pCO₂) were obtained during a cruise in the North Sea during late summer 2001. A 1° by 1° grid of 97 stations was sampled for DIC while the pCO₂ was measured continuously between the stations. The surface distributions of these two parameters show a clear boundary located around 54°N. South of this boundary the DIC and pCO₂ range from 2070 to 2130 μmol kg⁻¹ and 290 to 490 ppm, respectively, whereas in the northern North Sea, values range between 1970 and 2070 μmol kg⁻¹ and 190 to 350 ppm, respectively. The vertical profiles measured in the two different areas show that the mixing regime of the water column is the major factor determining the surface distributions. The entirely mixed water column of the southern North Sea is heterotrophic, whereas the surface layer of the stratified water column in the northern North Sea is autotrophic. The application of different formulations for the calculation of the CO₂ air–sea fluxes shows that the southern North Sea acts as a source of CO₂ for the atmosphere within a range of +0.8 to +1.7 mmol m⁻² day⁻¹, whereas the northern North Sea absorbs CO₂ within a range of −2.4 to −3.8 mmol m⁻² day⁻¹ in late summer. The North Sea as a whole acts as a sink of atmospheric CO₂ of −1.5 to −2.2 mmol m⁻² day⁻¹ during late summer. Compared to the Baltic and the East China Seas at the same period of the year, the North Sea acts a weak sink of atmospheric CO₂. The anticlockwise circulation and the short residence time of the water in the North Sea lead to a rapid transport of the atmospheric CO₂ to the deeper layer of the North Atlantic Ocean. Thus, in late summer, the North Sea exports 2.2×10¹² g C month⁻¹ to the North Atlantic Ocean via the Norwegian trench, and, at the same period, absorbs from the atmosphere a quantity of CO₂ (0.4 10¹² g C month⁻¹) equal to 15% of that export, which makes the North Sea a continental shelf pump of CO₂.     

Productivity of dinoflagellate blooms on the west coast of South Africa,as measured by natural fluorescence

The biomass and productivity of phytoplankton populations inshore on the west coast of South Africa were investigated towards the end of the upwelling season, a period when high-biomass dinoflagellate blooms are common. Productivity was estimated from natural fluorescence measurements (P_NF ), using photosynthesis (P) v. irradiance (E) relationships (P_E ) and by means of the in situ ¹⁴C-method (P_C ) A linear regression of P_NF productivity against P_C and P_E productivities yielded a slope of 0.911 and an r ₂ of 0.83 (n = 41). Physical and biological variability was high inshore, reflecting alternating periods of upwelling and quiescence. Mean chlorophyll inshore (within a 12 m water column) ranged from 0.7 to 57.8 (mean = 8.9) mg·m^&minus3, mean P_NF productivity ranged from 8.4 to 51.0 (mean = 24.6) mgC·m^?3·h^?1 and daily integral P_NF productivity from 0.8 to 4.8 (mean = 2.3) gC·m^?2·day^?l. Transects sampled during active and relaxation phases of upwelling had different chlorophyll distributions. High chlorophyll concentrations (sometimes >50 mg·m^?3) were associated with surface blooms within the region of the upwelling front. Estimates of daily water-column P_NF productivity within these frontal blooms ranged from 4.0 to 5.6 gC·m^?2·day^?1. With relaxation of wind stress, blooms dominated by dinoflagellates flooded shorewards and often formed red tides. Chlorophyll concentrations of > 175 mg·m^?3 and productivity rates > 500 mgC·m^?3·h^?1 and 12 gC·m^?2·day^?1 were measured during a particularly intense red tide. Offshore, the water column was highly stratified with a well-defined subsurface chlorophyll maximum layer within the pycnocline region. Estimates of daily water-column P_NF productivity ranged from 2.4 to 4.0 gC·m^?2·day^?1 offshore. The high productivity of shelf waters on the West Coast in late summer can be ascribed largely to dinoflagellate populations and their success in both upwelling systems and stratified conditions.     

Feeding selectivity of calanoid copepods on phytoplankton in Jangmok Bay,south coast of Korea

Grazing impacts of calanoid copepods on size-fractionated phytoplankton biomass [chlorophyll (Chl)-a] were measured in Jangmok Bay, Geoje Island, Korea, monthly from November 2004 to October 2005. The ingestion rate of calanoid copepods on total phytoplankton biomass ranged between 1 and 215 ng Chl-a copepod^?1 day^?1 during bottle incubations. Results indicated that microphytoplankton (> 20 μm) was the primary food source for calanoid copepods in grazing experiments on 3 phytoplankton size categories (< 3 μm, 3–20 μm, and > 20 μm). The ingestion rate on microphytoplankton showed a significant increase (r = 0.93, p < 0.01) with Chl-a concentration. Nanophytoplankton (3–20 μm) showed a negative ingestion rate from June 2005 to October 2005, but the reason is not completely understood. Calanoid copepods were unable to feed efficiently on picophytoplankton (< 3 μm) due to unfavorable size. Calanoid copepods removed between 0.1% and 27.7% (average, 3.6 ± 15.8%) of the phytoplankton biomass daily during grazing experiments. Grazing pressure was high in winter and early spring (January–March: 15.6–27.7%), while low in summer (June–August: ?33.1–0.0%) and autumn (September–November: ?1.4–5.1%). Results suggest that calanoid copepods play an important role in controlling the biomass and size structure of phytoplankton in winter and early spring.     

Cadmium,lead, copper,and zinc in Elminius modestus Darwin (Crustacea,Cirripedia) from Waitemata and Manukau Harbours,Auckland, New Zealand

Abstract

Concentrations of cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn) were measured in adult barnacles (Elminius modestus Darwin) from Waitemata and Manukau Harbours in the Auckland area, New Zealand. As in studies on sediments reported in the literature, it was possible to identify areas of likely anthropogenic influence, e.g., around the Auckland Harbour Bridge for Pb, Cu, and Zn. Groups of individuals with highest concentrations for these metals showed 19.8–23.8 mg Pb kg^?1, 198–266 mg Cu kg^?1, and 4460–6530 mg Zn kg^?1 (95% confidence limits, dry weight basis). Cd concentrations found for all barnacles from the Auckland area ranged from 0.8 to 3.1 mg kg^?1. Two samples from Omaha Beach, 60 km north of Auckland, were used as a reference. Accordingly, groups of individuals with lowest concentrations for Pb, Cu, and Zn could be allocated to this site using the Student‐Newman‐Keuls Multiple Range Test (0.5–1.3 mg Pb kg^?1, 8–10 mg Cu kg^?1, and 144–214 mg Zn kg^?1 ; 95% confidence limits). Only Cd concentrations were highest at Omaha Beach (8.6–12.1 mg Cd kg^?1 ). This result may have arisen from “naturally” increased bio‐availabilities of certain metals in mangrove systems which are reported in the literature. Generally, metal concentrations in barnacles from the Auckland Harbour area and from Omaha Beach were within the wider range for E. modestus as well as other barnacle species reported in the international literature.     

Light utilization efficiency of phytoplankton in the Western Subarctic Gyre of the North Pacific during summer

We investigated the water-column light utilization efficiency (Ψ) of phytoplankton photosynthesis in the Western Subarctic Gyre (WSG) of the North Pacific during summer 2008. The Ψ values (0.64–1.86 g C [g Chl a]^?1 [mol photon]^?1 m²) obtained were observed to increase significantly with decreasing daily photosynthetic available radiation (PAR) and were generally higher than those of previous studies, not only from the subarctic Pacific but also from the world’s oceans. To examine the effect of iron availability on Ψ in the WSG, Ψ values were estimated from the data of two in situ iron fertilization experiments: the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study I (SEEDS-I) and II (SEEDS-II). We found that iron availability did not affect Ψ values. Overall, this study revealed that Ψ values changed remarkably in the WSG during the summer, and that higher values were found at the stations where moderate PAR levels (ca. 10–30 mol photons m^?2 day^?1) were observed and where autotrophic flagellates predominated in the phytoplankton assemblages.     

The spatial and seasonal variation of trace metals in coastal seawater and soft tissue of <Emphasis Type="Italic">Chthamalus montagui</Emphasis> around the northwest coast of Portugal

Metal concentrations (Cd, Cr, Cu, Fe, Mn and Zn) were determined in seawaters and soft tissues of Chthamalus montagui from the northwest coast of Portugal during the four seasons of 2011. The main objectives of this work were to assess seasonal and spatial variations of metals in order to detect hot spots of contamination, to establish correlations between metals in coastal seawaters and C. montagui and to calculate metal bioaccumulation factors (BAFs) in each season. Metal concentrations in coastal seawaters ranged within Cd: 1.2–35 ng L^?1; Cr: 15–87 ng L^?1; Mn: 77–1763 ng L^?1; Cu: 126–1819 ng L^?1; Fe: 430–4048 ng L^?1 and Zn: 2889–16867 ng L^?1 and in C. montagui ranged for Cd: 0.39–1.98 mg kg^?1; Cr: 0.45–3.13 mg kg^?1; Cu: 0.93–5.70 mg kg^?1; Mn: 2.2–20.4 mg kg^?1; Fe: 135–707 mg kg^?1 and Zn: 119–782 mg kg^?1. Significant spatial and seasonal variations were found between: (i) metal concentrations in seawaters and C. montagui tissues; (ii) the distribution of metal concentrations in C. montagui tissues were Fe > Zn > Mn > Cu > Cr > Cd and (iii) C. montagui showed higher bioaccumulation factors for Fe and Cd than for Cu, Mn and Zn in all seasons. Regarding the metal concentrations accumulated in C. montagui tissues during each season of 2011, the ecological quality classifications of the NW coast of Portugal varied from “Class I–Unpolluted” to “Class III–Remarkably Polluted”.     

Wind-related resuspension of sediments in the Peel-Harvey Estuarine System

Resuspension of bottom sediments accounted for 69–92% of mean deposition rates (11·6–69·3 gm^?2 day^?1) measured at 5 sites in the Peel-Harvey Estuarine System, Western Australia. Deposition rates at all but one of the sites were found to be correlated (P<0·05) with a function of wind combining a fetch factor with the number of hours of winds greater than 5 ms^?1 weighted by the third power of wind velocity. The exception was the only site with a cover of benthic algae (Cladophora) during the study. Wind-related resuspension greatly affects the forms and amounts of productivity in this system.     

Methane in the Sevastopol coastal area, Black Sea

Concentrations of dissolved methane in seawater and bottom sediments, as well as of methane emanating from gas seeps were measured at 18 stations including several small bays in the Sevastopol coastal area (Black Sea) during 2007–2008. Methane concentrations in surface waters ranged from 10 to 2,970 nmol l^?1, and correlated well with values recorded for sediments. Methane concentrations in the water column were influenced by water depth, as well as by air and water temperatures. In the spring and summer of 2008, in situ CH₄ saturation relative to air was in the range of 970–71,900%. Maximum saturation was in summer. CH₄ fluxes to the atmosphere from the Sevastopol coastal area were estimated to vary from 190 to 1,550 μmol m^?2 day^?1. Gas bubbles escaping from the seepages contained about 57 vol% methane. Radiocarbon dating of the methane revealed an age not exceeding 150 years, implying a biogenic origin.     

In situ sampling reveals rapid uptake and depuration of polycyclic aromatic hydrocarbons by surf clams (Paphies subtriangulata) affected by the Rena oil spill

ABSTRACT

To investigate the uptake and depuration of polycyclic aromatic hydrocarbons associated with the Rena oil spill we sampled the surf clam Paphies subtriangulata at two open coast locations (6?km apart) just prior to oil coming ashore (7 October 2011), then at 1–3 week intervals for the next 4 months. Total polycyclic aromatic hydrocarbons (tPAH) increased at both sites from 1 to 96–124?µg?kg^?1 (wet weight) by 18 October before declining to low levels (<4?µg?kg^?1) by February 2012. Ongoing sampling throughout 2012–2014 included three additional sites to the north east (up to 30?km away) and a site 5?km to the south east revealing tPAH levels generally <10?µg?kg^?1 except in October 2013 where levels ranged between 39–45?µg?kg^?1 at all sites. A comparison of PAH component profiles with oil-contaminated beach sediment indicated that the high levels observed in surf clams between October–December 2011 were clearly associated with the Rena spill. However, the October 2013 peak had a PAH profile inconsistent with weathered Rena oil, suggesting an alternative source of contamination. Our results highlight the potential for P. subtriangulata as a PAH monitoring tool but recognise more study is needed to better quantify baseline levels and uptake and depuration dynamics.