Salinity effects on osmoregulation and growth of the euryhaline flounder Paralichthys orbignyanus

The flounder, Paralichthys orbignyanus, is found in coastal and estuarine waters of the Western South Atlantic Ocean. It is being considered for aquaculture due to its high market price and wide tolerance to environmental factors such as salinity, pH, and nitrogenous compounds. The objective of this study was to characterize the ionic and osmotic regulation of P. orbignyanus over the range of its tolerated ambient salinities (0-40‰) and to evaluate the survival and growth in freshwater (0‰) and seawater (30‰) over 90 days. After 15 days of exposure to different salinities (0‰, 10‰, 20‰, 30‰ and 40‰), plasma osmolality and ionic (Na⁺, Cl⁻, K⁺ and Ca²⁺) concentrations slightly increased with salinity. The isosmotic point was estimated as 328.6 mOsm kg⁻¹ H₂O and corresponded to 10.9‰ salinity. After 90 days, survival was similar in freshwater and seawater, but osmo- and ionoregulation was significantly affected in freshwater and flounders reared in this medium showed a lower growth rate than those reared in seawater. Based on the results from this study, P. orbignyanus can be characterized as a marine/estuarine euryhaline teleost capable of hyper/hypo iono- and osmoregulation over the fluctuating salinity regime faced by this species in the environment. Furthermore, results suggest that the lower growth rate exhibited by P. orbignyanus in freshwater could be due, at least partially, to a higher energy expenditure associated to a higher branchial Na⁺, K⁺-ATPase activity in this environment.     

水产养殖用解淀粉芽孢杆菌微胶囊的安全性评价

目的:评价水产养殖用解淀粉芽孢杆菌微胶囊的安全性。方法:参照《GB/T21805-2008化学品藻类生长抑制试验》、《GB/T13266-91水质物质对蚤类(大型蚤)急性毒性测定方法》、《GB/T13267-91水质物质对淡水鱼(斑马鱼)急性毒性测定方法》、《渔药临床试验技术规范》等国家标准及相关法规,观察了解淀粉芽孢杆菌微胶囊对小球藻生长的抑制作用以及对大型蚤、斑马鱼和草鱼的急性毒性,分析了其对养殖水体主要理化因子的影响。结果:解淀粉芽孢杆菌微胶囊在终浓度为0.2～2 000mg/L时对小球藻生长具有促进作用,对小球藻的半数抑制浓度大于2 000mg/L,而且其对大型蚤、斑马鱼和草鱼的半数致死浓度也大于2 000mg/L(或mg/kg体重)。此外,在养殖水体中加入解淀粉芽孢杆菌微胶囊至终浓度为0.2～2 000mg/L后14天内,各浓度组的氨氮含量、硫化物和pH均缓慢下降,仅亚硝酸盐氮含量稍微升高后逐渐缓慢降低,但这些理化因子的变化与解淀粉芽孢杆菌微胶囊的加入量呈负相关关系。结论:解淀粉芽孢杆菌微胶囊实际无毒,对养殖水中氨氮、亚硝酸盐氮、硫化物和pH等理化因子的影响均控制在虾虎鱼仔鱼、黄颡鱼、白斑狗鱼、克氏原螯虾等水产养殖动物的安全浓度范围内,为其在水产养殖中的安全应用提供了重要的科学依据。     

海水网箱养殖对环境的影响

综述了近20年来国内外关于网箱养殖对环境影响的研究动态和成果,包括网箱养殖碳、氮、磷和悬浮物输出造成水体的污染及对沉积物的影响、养殖过程中使用化学药品的污染、养殖鱼类逃逸对渔场生态环境的影响以及外来种、定向育种生物甚至转基因生物养殖所造成的基因污染,以及导致了养殖海区各类生物多样性的改变等,并对海水网箱养殖的可持续发展提出了一些看法和建议。     

Addition of dissolved nitrogen and dissolved organic carbon from wild fish faeces and food around Mediterranean fish farms: Implications for waste-dispersal models

Leaching of ammonium (NH₄⁺) and dissolved organic carbon (DOC) from food pellets used at three fish farms in the Mediterranean Sea and the faeces of four different species of farm-associated wild fish (Trachurus mediterraneus, Mugil cephalus, Trachinotus ovatus and Boops boops) were determined. They were placed in seawater and agitated slowly (5 cm s^− 1) to reflect natural conditions during their fall to the sediment. Two temperatures were tested, 25 °C and 15 °C, to assess the influence of seasons on leaching rates. Leaching from fish faeces was generally higher compared to food pellets. T. mediterraneus faeces leached more NH₄⁺ and DOC than M. cephalus, T. ovatus and B. boops. The results showed that there is an important addition of NH₄⁺ and DOC to the water column during sinking of the faeces and that this is species-dependent. Water turbulence and faeces composition seemed to have a higher influence than temperature on the leaching process. Due to the high abundance and biomass of farm-associated fish in the Mediterranean and their capacity to remove waste, they appear to be an important component for models that predict the impact of aquaculture. Large biomasses of wild fish at fish farms may reduce the impact on benthic systems but increase the nitrogen and carbon loads into the water column, affecting the pelagic system and modifying the spatial dispersion of wastes.     

Impact categories for life cycle assessment research of seafood production systems: Review and prospectus

Goal, Scope and Background In face of continued declines in global fisheries landings and concurrent rapid aquaculture development, the sustainability of seafood production is of increasing concern. Life Cycle Assessment (LCA) offers a convenient means of quantifying the impacts associated with many of the energetic and material inputs and outputs in these industries. However, the relevant but limited suite of impact categories currently used in most LCA research fails to capture a number of important environmental and social burdens unique to fisheries and aquaculture. This article reviews the impact categories used in published LCA research of seafood production to date, reports on a number of methodological innovations, and discusses the challenges to and opportunities for further impact category developments. Main Features The range of environmental and socio-economic impacts associated with fisheries and aquaculture production are introduced, and both the commonly used and innovative impact categories employed in published LCA research of seafood production are discussed. Methodological innovations reported in agricultural LCAs are also reviewed for possible applications to seafood LCA research. Challenges and options for including additional environmental and socioeconomic impact categories are explored. Results A review of published LCA research in fisheries and aquaculture indicates the frequent use of traditional environmental impact categories as well as a number of interesting departures from the standard suite of categories employed in LCA studies in other sectors. Notable examples include the modeling of benthic impacts, by-catch, emissions from anti-fouling paints, and the use of Net Primary Productivity appropriation to characterize biotic resource use. Socio-economic impacts have not been quantified, nor does a generally accepted methodology for their consideration exist. However, a number of potential frameworks for the integration of such impacts into LCA have been proposed. Discussion LCA analyses of fisheries and aquaculture call attention to an important range of environmental interactions that are usually not considered in discussions of sustainability in the seafood sector. These include energy use, biotic resource use, and the toxicity of anti-fouling paints. However, certain important impacts are also currently overlooked in such research. While prospects clearly exist for improving and expanding on recent additions to environmental impact categories, the nature of the LCA framework may preclude treatment of some of these impacts. Socio-economic impact categories have only been described in a qualitative manner. Despite a number of challenges, significant opportunities exist to quantify several important socio-economic impacts. Conclusion The limited but increasing volume of LCA research of industrial fisheries and aquaculture indicates a growing interest in the use of LCA methodology to understand and improve the sustainability performance of seafood production systems. Recent impact category innovations, and the potential for further impact category developments that account for several of the unique interactions characteristic of fisheries and aquaculture will significantly improve the usefulness of LCA in this context, although quantitative analysis of certain types of impacts may remain beyond the scope of the LCA framework. The desirability of incorporating socio-economic impacts is clear, but such integration will require considerable methodological development. Recommendations and Perspectives While the quantity of published LCA research for seafood production systems is clearly increasing, the influence this research will have on the ground remains to be seen. In part, this will depend on the ability of LCA researchers to advance methodological innovations that enable consideration of a broader range of impacts specific to seafood production. It will also depend on the ability of researchers to communicate with a broader audience than the currently narrow LCA community.     

Recycling of aquaculture wastewater using charcoal based constructed wetlands

Abstract

The competitive demand for water makes it a scarce resource for agricultural use. This necessitates wastewater reuse for irrigation and any other agricultural purpose, especially in developing countries where treatment of wastewaters is not a priority. The aim of this study was to evaluate the performance of a charcoal-based constructed wetland (CBCW) in treating aquaculture wastewater. Aquaculture wastewater from a Research Fishpond Farm was treated in a CBCW planted with Sacciolepsis africana and Commelina cyannae for 5?days retention time. Raw wastewater and the treated wastewater from the constructed wetland (CW) was sampled and the physicochemical parameters determined. The performance of the CW in treating aquaculture wastewater was conducted. The result showed that the CBCW was capable of removing 50% TSS, 88% COD, 93% BOD_5, and 100% nitrate nitrogen. The pH and DO of the wastewater before treatment and after treatment ranged from 6.68 to 6.91 and 4.13 to 6.30?mg/l, respectively. Thus, CWs have great potential for the treatment of aquaculture wastewater and prevention of environmental degradation through wastewater treatment, thereby solving the problem of water scarcity for agriculture for optimum food production.     

Changes in the immune response and metabolic fingerprint of the mussel, Mytilus edulis (Linnaeus) in response to lowered salinity and physical stress

Mussels, such as Mytilus edulis, are common keystone species on open coasts and in estuaries and are frequently used in environmental monitoring programmes. Mussels experience a wide range of environmental conditions at these locations, including rapid changes in salinity and physical disturbance (both natural and from aquaculture practices).This paper addressed the hypothesis that reduced salinity will lower mussel blood immune function and influence mussel blood metabolic responses, and that this will in turn increase the susceptibility of mussels to other stresses such as physical disturbance. To test these hypotheses, experiments were conducted in controlled laboratory tank conditions and mussel blood was analysed using a combination of metabolic fingerprinting with FT-IR and immunological assay techniques.Reducing seawater salinity to half that of normal caused a significant reduction in several measures of immune function, including the concentration of haemocytes, percentage of eosinophilic haemocytes and phagocytosis. Mechanical shaking of mussels for 10 min caused a reduction in the level of respiratory burst activity. However, there was no evidence of additive or interactive effects of lowered salinity with shaking on the immune response. Analysis of mussel blood metabolic fingerprints revealed differences in response to half salinity (vs. full salinity) but there were no detectable effects of shaking. Increasing frequency and magnitude of flood events at coastal sites due to climate change could lead to longer, and more frequent, periods of reduced salinity. The potential impact on the immune function of this keystone species within or near estuaries could have knock-on effects on the wider ecosystem including altered nutrient cycling, changes in biodiversity and aquaculture production.     

Strong seasonality of Bonamia sp. infection and induced Crassostrea ariakensis mortality in Bogue and Masonboro Sounds, North Carolina, USA

Asian oyster Crassostrea ariakensis is being considered for introduction to Atlantic coastal waters of the USA. Successful aquaculture of this species will depend partly on mitigating impacts by Bonamia sp., a parasite that has caused high C. ariakensis mortality south of Virginia. To better understand the biology of this parasite and identify strategies for management, we evaluated its seasonal pattern of infection in C. ariakensis at two North Carolina, USA, locations in 2005. Small (<50 mm) triploid C. ariakensis were deployed to upwellers on Bogue Sound in late spring (May), summer (July), early fall (September), late fall (November), and early winter (December) 2005; and two field sites on Masonboro Sound in September 2005. Oyster growth and mortality were evaluated biweekly at Bogue Sound, and weekly at Masonboro, with Bonamia sp. prevalence evaluated using parasite-specific PCR. We used histology to confirm infections in PCR-positive oysters. Bonamia sp. appeared in the late spring Bogue Sound deployment when temperatures approached 25 degrees C, six weeks post-deployment. Summer- and early fall-deployed oysters displayed Bonamia sp. infections after 3-4 weeks. Bonamia sp. prevalences were 75% in Bogue Sound, and 60% in Masonboro. While oyster mortality reached 100% in late spring and summer deployments, early fall deployments showed reduced (17-82%) mortality. Late fall and early winter deployments, made at temperatures <20 degrees C, developed no Bonamia sp. infections at all. Seasonal Bonamia sp. cycling, therefore, is influenced greatly by temperature. Avoiding peak seasonal Bonamia sp. activity will be essential for culturing C. ariakensis in Bonamia sp.-enzootic waters.     

Essential role of seaweed cultivation in integrated multi-trophic aquaculture farms for global expansion of mariculture: an analysis

Ecologically friendly aquaculture crops, such as seaweeds, herbivores, omnivores, and detritivores can be cultured using relatively less of our limited natural resources and produce relatively less pollution. They also top FAO’s estimates of aquaculture crops for the 21st century. These crops already comprise nearly 90% of global aquaculture tonnage, >90% of all aquaculture production in China and >60% of production even in North America. Consumers prefer them, most likely due to their low prices. Production costs of organisms low on the food chain are low due to the ability of these organisms to efficiently utilize low-cost, mostly plant-based diets and to recycle their own waste. Thus, ecologically friendly aquaculture is not a dream but a dominant global reality. The less ecologically-friendly aquaculture of salmon, sea bream, fed shrimp, among others, has attracted public opposition to aquaculture, but these crops totaled approximately only 10% of global production in 2004. The profitability of industrialized monocultures of these crops is threatened further by rising costs of energy and feed, environmental regulation compliance, disease, and public opposition. Current monoculture practices and perceptions intrinsic to the aquaculture industry can be turned around into a vision of sustained profitable expansion of carnivores production with trophically lower organisms in ecologically-balanced aquaculture farms. This category of aquaculture, which is the modern intensive form of polyculture practiced in Asia, feeds the waste of carnivore culture to lower trophic level organisms, primarily algae and mollusks. Species are selected based on their ecological functions in addition to their economic potential. Ecologically-balanced farms turn the costly treatment of carnivore waste outside the farm to a revenue-generating process of biofiltration, conversion, and resource recovery into plant and mollusk crops inside the farm. In doing so, they solve several of the major problems faced by modern aquaculture. The aquaculture industry can protect its own interests – and reap major benefits – by understanding the importance of ecological balance, the potential of seaweeds as components in feeds, and the importance of the culture and R&D of low trophic level organisms. The industry should also accept the relevance of environmental, social, and image aspects of aquaculture to its success. Governments have the tools to reward multi-trophic farms with seaweeds by means of tax credits and nutrient credits and to penalize unbalanced monoculture approaches by means of ‘polluter pays’ fines, thereby providing the multi-trophic farms with a significant economic advantage. Such measures have been discussed, but their implementation has been slow.     

Identification of protein components from the mature ovary of the sea urchin Evechinus chloroticus (Echinodermata: Echinoidea)

The gonads of sea urchins are a high value seafood product, with considerable research being undertaken worldwide on the development of sea urchin aquaculture. As the best prices are obtained for specific gonad attributes, research has also focused on the development of artificial diets that enhance gonad quality and quantity. Total protein has been used as a measure of gonad quality; yet no studies to date have applied proteomics technology to diet development. Here we use a MudPIT and 2-DE approach to describe the major proteins in mature ovaries of a New Zealand sea urchin Evechinus chloroticus. This tissue, which is a target seafood product, contained 138 proteins that were identified from the recently completed sea urchin genome (Strongylocentrotus purpuratus) with high confidence. The majority of these proteins had general functions, with only 12 related to ovarian reproductive function. Eighteen proteins were located on the 2-DE; four of these were directly identified from S. purpuratus protein sequences. In combination this paper shows that the genome resources of S. purpuratus can be used to identify proteins in sea urchins from different families; describes the proteome of E. chloroticus mature ovary; and, provides proteomic tools for analysis of gonads from other edible sea urchins.