Future ocean acidification will be amplified by hypoxia in coastal habitats

Ocean acidification is elicited by anthropogenic carbon dioxide emissions and resulting oceanic uptake of excess CO₂ and might constitute an abiotic stressor powerful enough to alter marine ecosystem structures. For surface waters in gas-exchange equilibrium with the atmosphere, models suggest increases in CO₂ partial pressure (pCO₂) from current values of ca. 390 μatm to ca. 700–1,000 μatm by the end of the century. However, in typically unequilibrated coastal hypoxic regions, much higher pCO₂ values can be expected, as heterotrophic degradation of organic material is necessarily related to the production of CO₂ (i.e., dissolved inorganic carbon). Here, we provide data and estimates that, even under current conditions, maximum pCO₂ values of 1,700–3,200 μatm can easily be reached when all oxygen is consumed at salinities between 35 and 20, respectively. Due to the nonlinear nature of the carbonate system, the approximate doubling of seawater pCO₂ in surface waters due to ocean acidification will most strongly affect coastal hypoxic zones as pCO₂ during hypoxia will increase proportionally: we calculate maximum pCO₂ values of ca. 4,500 μatm at a salinity of 20 (T = 10 °C) and ca. 3,400 μatm at a salinity of 35 (T = 10 °C) when all oxygen is consumed. Upwelling processes can bring these CO₂-enriched waters in contact with shallow water ecosystems and may then affect species performance there as well. We conclude that (1) combined stressor experiments (pCO₂ and pO₂) are largely missing at the moment and that (2) coastal ocean acidification experimental designs need to be closely adjusted to carbonate system variability within the specific habitat. In general, the worldwide spread of coastal hypoxic zones also simultaneously is a spread of CO₂-enriched zones. The magnitude of expected changes in pCO₂ in these regions indicates that coastal systems may be more endangered by future global climate change than previously thought.     

Distribution and mortality of diapause eggs from calanoid copepods in relation to sedimentation regimes

Distribution, abundance and age of diapause eggs from three species of calanoid copepods (in particular from Acartia spp. most likely Acartia tonsa, and Centropages hamatus and less numerous from Temora longicornis) were recorded in sediment profiles by enumerating hatched nauplii from incubated sediment samples. Phytoplankton pigments and ²¹⁰Pb and ¹³⁷Cs analyses indicated that the sedimentation regimes were different between two southern and two northern stations of the island Funen, Denmark. Significant variations in vertical distribution, abundance and mortality of diapause eggs were found between the stations. Dating of the sediment cores suggested a ~70-year maximum age of viable eggs on the northernmost stations, and ~28 year at the southernmost stations. The eggs exhibited a significantly higher mortality rate at the southernmost stations compared with the northernmost, 0.35–0.53 year⁻¹ vs. 0.07–0.08 year⁻¹ with no systematic pattern among species. The differences in abundance, mortality and age of the diapause eggs are suggested to be due to the sediment characteristics in which they are buried.     

Short-term responses of soil chemistry, needle macronutrients and tree growth to clinker dust and fertiliser in a stand of Scots pine

Waste management of clinker dust by spreading it on forest soil was studied in a 25-year-old Scots pine stand on acidic sandy soil. Clinker dust (0.5 kg m?2), fertiliser (N, P, K, Mg, 0.05 kg m?2; N 190 kg ha?1) and untreated soil were applied on 120-m2 plots in four replicates. The fertiliser was included to confirm the nutrient limitation in the stand. Clinker dust increased the soil pH by 1.2 units relative to the pH of 4.6 in the untreated soil by the second year. Soil K and Mg concentrations were larger in the dust and fertiliser treatments. Nutrient diagnostics indicated that needles of untreated trees were deficient in N and K. Fertiliser treatment indicated that the growth of trees was limited by N, since the fertiliser tended to increase needle K, N, N/P, needle dry mass and diameters of stem and shoots. By an auxiliary dataset, no effects of the dust and fertiliser on possible excess of the micronutrient Mn were observed. Clinker dust increased needle K concentration, but due to the N limitation, there was no increase in the growth of stems, branches, shoots and needles. It was concluded that in plots of 120 m2 application of clinker dust at a rate of 0.5 kg m?2 was safe for the 21-year-old Scots pine stand in this trial on an acid nutrient-poor sandy soil during 4 years after the treatment.     

Temperature Dependent Depuration of Norovirus GII and Tulane Virus from Oysters (Crassostrea gigas)

Raw oysters are considered a culinary delicacy but are frequently the culprit in food-borne norovirus (NoV) infections. As commercial depuration procedures are currently unable to efficiently eliminate NoV from oysters, an optimisation of the process should be considered. This study addresses the ability of elevated water temperatures to enhance the elimination of NoV and Tulane virus (TuV) from Pacific oysters (Crassostrea gigas). Both viruses were experimentally bioaccumulated in oysters, which were thereafter depurated at 12 °C and 17 °C for 4 weeks. Infectious TuV and viral RNA were monitored weekly for 28 days by TCID₅₀ and (PMAxx-) RT-qPCR, respectively. TuV RNA was more persistent than NoV and decreased by?<?0.5 log₁₀ after 14 days, while NoV reductions were already?>?1.0 log₁₀ at this time. For RT-qPCR there was no detectable benefit of elevated water temperatures or PMAxx for either virus (p?>?0.05). TuV TCID₅₀ decreased steadily, and reductions were significantly different between the two temperatures (p?<?0.001). This was most evident on days 14 and 21 when reductions at 17 °C were 1.3–1.7 log₁₀ higher than at 12 °C. After 3 weeks, reductions?>?3.0 log₁₀ were observed at 17 °C, while at 12 °C reductions did not exceed 1.9 log₁₀. The length of depuration also had an influence on virus numbers. TuV reductions increased from?<?1.0 log₁₀ after seven days to?>?4.0 log₁₀ after 4 weeks. This implies that an extension of the depuration period to more than seven days, possibly in combination with elevated water temperatures, may be beneficial for the inactivation and removal of viral pathogens.

     

Monitoring contaminants from oil production at sea by measuring gill EROD activity in Atlantic cod (Gadus morhua)

An ex vivo gill EROD assay was applied in Atlantic cod (Gadus morhua) as a biomarker for waterborne CYP1A-inducing compounds derived from oil production at sea. Exposure to nominal concentrations of 1 ppm or 10 ppm North Sea crude oil in a static water system for 24 h caused a concentration-dependent gill EROD induction. Further, exposure of cod for 14 days to environmentally relevant concentrations of produced water (PW, diluted 1:200 or 1:1000) from a platform in the North Sea using a flow-through system resulted in a concentration-dependent induction of gill EROD. Crude oil (0.2 ppm) from the same oil field also proved to induce EROD. Finally, gill EROD activity in cod caged for 6 weeks at 500-10 000 m from two platforms outside Norway was measured. The activities in these fish were very low and did not differ from those in fish caged at reference sites.     

Long-term geochemical evolution of the near field repository: insights from reactive transport modelling and experimental evidences

The KBS-3 underground nuclear waste repository concept designed by the Swedish Nuclear Fuel and Waste Management Co. (SKB) includes a bentonite buffer barrier surrounding the copper canisters and the iron insert where spent nuclear fuel will be placed. Bentonite is also part of the backfill material used to seal the access and deposition tunnels of the repository. The bentonite barrier has three main safety functions: to ensure the physical stability of the canister, to retard the intrusion of groundwater to the canisters, and in case of canister failure, to retard the migration of radionuclides to the geosphere. Laboratory experiments (< 10 years long) have provided evidence of the control exerted by accessory minerals and clay surfaces on the pore water chemistry. The evolution of the pore water chemistry will be a primordial factor on the long-term stability of the bentonite barrier, which is a key issue in the safety assessments of the KBS-3 concept.In this work we aim to study the long-term geochemical evolution of bentonite and its pore water in the evolving geochemical environment due to climate change. In order to do this, reactive transport simulations are used to predict the interaction between groundwater and bentonite which is simulated following two different pathways: (1) groundwater flow through the backfill in the deposition tunnels, eventually reaching the top of the deposition hole, and (2) direct connection between groundwater and bentonite rings through fractures in the granite crosscutting the deposition hole. The influence of changes in climate has been tested using three different waters interacting with the bentonite: present-day groundwater, water derived from ice melting, and deep-seated brine. Two commercial bentonites have been considered as buffer material, MX-80 and Deponit CA-N, and one natural clay (Friedland type) for the backfill. They show differences in the composition of the exchangeable cations and in the accessory mineral content. Results from the simulations indicate that pore water chemistry is controlled by the equilibrium with the accessory minerals, especially carbonates. pH is buffered by precipitation/dissolution of calcite and dolomite, when present. The equilibrium of these minerals is deeply influenced by gypsum dissolution and cation exchange reactions in the smectite interlayer. If carbonate minerals are initially absent in bentonite, pH is then controlled by surface acidity reactions in the hydroxyl groups at the edge sites of the clay fraction, although its buffering capacity is not as strong as the equilibrium with carbonate minerals. The redox capacity of the bentonite pore water system is mainly controlled by Fe(II)-bearing minerals (pyrite and siderite). Changes in the groundwater composition lead to variations in the cation exchange occupancy, and dissolution–precipitation of carbonate minerals and gypsum. The most significant changes in the evolution of the system are predicted when ice-melting water, which is highly diluted and alkaline, enters into the system. In this case, the dissolution of carbonate minerals is enhanced, increasing pH in the bentonite pore water. Moreover, a rapid change in the population of exchange sites in the smectite is expected due to the replacement of Na for Ca.     

产业与环境：丹麦展望

近20-30年来,很多国家引进了综合性环境保护法律.然而,人们逐渐认识到,在进行具体技术调控的同时,也需要意识上和管理原则上的改变.为帮助各公司在公司层次上减少、评估、监测和控制环境影响,已经开发了各种环境管理技术.本文根据对丹麦公司的一次调查,论述了下列问题:这些技术是如何在工业中采用的?以及发生态度上的变化了吗?     

Seaweed sex pheromones and their degradation products frequently suppress amphipod feeding but rarely suppress sea urchin feeding

Summary. A diverse group of brown seaweeds produce bouquets of C₁₁ metabolites, some of which act as pheromones that cue gamete release or attract sperm to eggs following release. We demonstrate that these C₁₁ metabolites and their degradation products also frequently and strongly deter feeding by the herbivorous amphipod Ampithoe longimana, but rarely by the herbivorous sea urchin Arbacia punctulata. Across the range of concentrations tested, seven of twelve C₁₁ metabolites or mixtures that we tested deterred feeding by the amphipod, but only two of eleven deterred the sea urchin. For those compounds where we could rigorously contrast the magnitude of deterrence against the amphipod with the magnitude of deterrence against the urchin, the amphipod was deterred significantly more than the urchin by five of six metabolites. Thus, C₁₁ compounds were more frequently and more strongly deterrent to the amphipod than to the sea urchin. These findings for C₁₁ metabolites conflict with previous investigations, where other classes of seaweed chemical defenses have been shown to deter feeding by large mobile herbivores like urchins and fishes but to be relatively ineffective against mesograzers, especially the species of amphipod that we used here. Our results suggest that C₁₁ metabolites are unusual among the known seaweed chemical defenses in that they are especially effective against mesograzers, which often consume seaweed spores, zygotes, and juveniles. The high concentrations of C₁₁ metabolites in brown algal eggs could allow these defenses to be especially important in defending gametes, zygotes, or young sporelings from herbivorous mesograzers. Received 26 February 1998; accepted 9 April 1998.     

Spawning behaviour and sex hormone levels in adult and precocious brown trout (Salmo trutta L.) males and the effect of anosmia

Summary. In the present experiment the behaviour and endocrine status of males of the brown trout, Salmo trutta L., (Salmoniformes: Salmonidae) were studied when males were kept in a stream tank with a nest digging female. Groups of mature adult males and precocious intact or anosmic male parr were placed with the nesting female so that the group resembled a natural spawning situation with big anadromous fish acting as dominant males and precocious parr acting as “sneakers”. A control experiment was also run with only males without a female present. In intact parr there were significant positive correlations between the per cent of the total observation time spent with a female, milt volume, and plasma concentration of 17α, 20β-dihydroxy-4-pregnen-3-one. Anosmic parr had significantly lower volumes of strippable milt and gonadal steroid hormone levels compared with intact parr. However, no differences were found in the control experiment. Significantly fewer anosmic parr attended and courted the nesting female and those anosmic fish that attended the female had significantly lower plasma levels of gonadal hormones. Intact parr also displayed a greater number of agonistic acts against other parr without any difference in fighting ability. No differences in aggression occured in the control experiment. In adult males together with a female, post-experimental gonadal steroid hormone levels were higher than pre-experimental levels. Positive correlations between aggression and androgen hormone levels were observed in adult males. No differences in plasma hormone levels were observed between adult males and intact precocious males. The results show that olfactory occlusion results in low steroid hormone levels and milt volumes in precocious males placed in a spawning situation. The courting behaviour was also affected by anosmia. Odours from the nesting female may have caused the enhanced plasma hormone levels and stimulated the males to attend the female. Received 15 May 1997; accepted 29 June 1997.