Geo-politics and freshwater fish introductions: How the Cold War shaped Europe's fish allodiversity

Activities that manipulate ecosystems to support economic activities provide major introduction pathways for non-native species. As such, substantial differences in the socioeconomic conditions between countries could influence how ecosystems are manipulated and thus impact the composition of their communities of non-native species. Here, we compared the influence of freshwater fish aquaculture production and macro-socioeconomic drivers on the freshwater fish allodiversity of Europe between 1970 and 2009. A divergence in the socio-economic conditions of Europe prevailed during much of the latter half of the 20th Century as a result of the Cold War. For example, GDP and GDP per capita were significantly higher in Western bloc countries compared to the Eastern bloc. In this 39 year period, aquaculture production in Eastern bloc countries was dominated by Asian cyprinid fish whereas in Western bloc countries it was dominated by the North American rainbow trout Oncorhynchus mykiss. Analysis of a European database on introduced fish into the wild from aquaculture revealed that in entirety, there were 279 separate freshwater fish introductions in Europe associated with aquaculture (Eastern bloc 118, Western bloc 161), involving 117 species from 32 families. There was relatively low homogeneity in these introduced fishes between the two blocs; only 28 species were introduced into both. Western bloc countries also had significantly more introduced fishes and more introduction events, and less similarity in the introduced fishes between their countries. Aquaculture production was a significant predictor of the number of non-native freshwater fish across all the countries, although additional factors, especially human population size and GDP per capita, were also significant predictors. Thus, aquaculture has been a strong introduction pressure in Europe and provides a reliable predictor of fish allodiversity.     

佳木斯市气侯资源在淡水池塘养殖中的应用及养鱼产量预报方程

通过与佳木斯市水产技术推广站的合作,对淡水养殖中气象指标进行分析,选用气象因子对佳木斯市池塘淡水养鱼建立预报产量模式,达到充分利用气侯资源的目的。     

Detecting climate impacts with oceanic fish and fisheries data

Anthropogenic climate change is affecting the environment of all oceans, modifying ocean circulation, temperature, chemistry and productivity. While evidence for changes in physical signals is often distinct, impacts on fishes inhabiting oceanic systems are not easily identified, and therefore, quantification of responses is less common. Correctly attributing changes associated with a changing climate from other drivers is important for the implementation of effective harvest and management strategies and for addressing associated socio-economic impacts, particularly for countries highly dependent on oceanic resources. Data supporting investigation of responses of oceanic species to climate impacts include fisheries catch, fisheries-independent surveys, and conventional and electronic tagging data. However, there are a number of challenges associated with detecting climatic responses with these data, including (i) data collection costs (ii) small sample sizes (iii) limited time series relative to temporal scales at which environmental variability occurs, (iv) changing fisher and fisheries behavior due to non-climate drivers and (v) changes in population dynamics due to natural climate variability and non-climate drivers. We highlight potential biases and suggest strategies that should be considered when using oceanic fish and fisheries data in the evaluation of climate change impacts. Consideration of these factors is important when assessing variability in exploited species and designing management responses to climate or fisheries threats.     

Shocks to fish production: Identification,trends, and consequences

Sudden disruptions, or shocks, to food production can adversely impact access to and trade of food commodities. Seafood is the most traded food commodity and is globally important to human nutrition. The seafood production and trade system is exposed to a variety of disruptions including fishery collapses, natural disasters, oil spills, policy changes, and aquaculture disease outbreaks, aquafeed resource access and price spikes. The patterns and trends of these shocks to fisheries and aquaculture are poorly characterized and this limits the ability to generalize or predict responses to political, economic, and environmental changes. We applied a statistical shock detection approach to historic fisheries and aquaculture data to identify shocks over the period 1976–2011. A complementary case study approach was used to identify possible key social and political dynamics related to these shocks. The lack of a trend in the frequency or magnitude of the identified shocks and the range of identified causes suggest shocks are a common feature of these systems which occur due to a variety, and often multiple and simultaneous, causes. Shocks occurred most frequently in the Caribbean and Central America, the Middle East and North Africa, and South America, while the largest magnitude shocks occurred in Asia, Europe, and Africa. Shocks also occurred more frequently in aquaculture systems than in capture systems, particularly in recent years. In response to shocks, countries tend to increase imports and experience decreases in supply. The specific combination of changes in trade and supply are context specific, which is highlighted through four case studies. Historical examples of shocks considered in this study can inform policy for responding to shocks and identify potential risks and opportunities to build resilience in the global food system.     

镉质量浓度和鱼尺寸对罗非鱼积累和转移镉的影响

为研究尺寸和镉(Cd²⁺)质量浓度对罗非鱼积累和转移水环境中Cd²⁺的影响,用室内培养的方法,选取4种尺寸的罗非鱼,设置不同质量浓度Cd²⁺的暴露试验,分别测定其半致死率、Cd²⁺积累量和对Cd²⁺的转移系数以及罗非鱼的相对增长率.结果表明:不同尺寸的罗非鱼对Cd²⁺的响应不同,其中,幼龄鱼的LC₅₀浓度最低,体长为31.5±3.4 cm的罗非鱼LC₅₀最高;低质量浓度Cd²⁺(0.5 mg/kg)处理下,罗非鱼尺寸不同,相同鱼组织对Cd²⁺的吸收积累量差异显著(P< 0.05),而高质量浓度Cd²⁺处理时,不同尺寸罗非鱼的同一组织对Cd²⁺的积累量无显著性差异;除体长27.4±2.9 cm罗非鱼外,相同尺寸的罗非鱼Cd²⁺转移系数都是低质量浓度显著大于高质量浓度(P< 0.05);高质量浓度Cd²⁺处理对各种尺寸罗非鱼质量增加的抑制率显著高于低质量浓度Cd²⁺处理的抑制率.此外,不同Cd²⁺质量浓度对相同尺寸的罗非鱼也产生不同的影响.因此,罗非鱼的尺寸和Cd²⁺质量浓度都对罗非鱼积累和转移Cd²⁺产生影响.     

Modeling of climate change effects on stream temperatures and fish habitats below dams and near groundwater inputs

A deterministic heat transport model was developed to calculate stream water temperatures downstream of reservoir outlets (tailwaters) and groundwater sources. The model calculates heat exchange between the atmosphere, the water and the sediments and is driven by climate and stream hydrologic parameters. Past and projected climate conditions were used as input to the stream water temperature model. To produce a projected future weather scenario, output from the Columbia University Goddard Institute for Space Studies (GISS) global circulation model (GCM) for a doubling of atmospheric CO₂ were used to adjust past (1955–1979) weather parameters. Stream reach lengths, within which water temperatures are suitable for survival or good growth of 28 fish species, were determined for four selected streams. Several alternative upstream inflow conditions were chosen: Discharges from surface (epilimnion) and bottom (hypolimnion) outlets of reservoirs, and two groundwater inflow scenarios. By applying water temperature criteria for fish survival and good growth (Stefanet al., 1993) to simulated stream temperatures, it was possible to estimate stream lengths with suitable habitat. When simulated suitable habitat was compared to actual fish observations, good agreement was found. For projected climate change, the simulations showed how much of the available stream habitat would be lost. In the examples presented the effect of cold hypolimnetic water release from a reservoir or groundwater discharges is felt as far as 48 km (30 miles) downstream from its source, especially in smaller shaded streams. The impact of climate change on stream temperatures below dams is more pronounced when the water release is from the epilimnion (reservoir surface) rather than the hypolimnion (deep water). Examples used for this study show elimination of coldwater habitat for rainbow trout when the upstream release is from the surface of a reservoir, but only reductions of coldwater habitat when the upstream release is from a reservoir hypolimnion.     

Trade-offs associated with different modeling approaches for assessment of fish and shellfish responses to climate change

Considerable progress has been made in integrating carbon, nutrient, phytoplankton and zooplankton dynamics into global-scale physical climate models. Scientists are exploring ways to extend the resolution of the biosphere within these Earth system models (ESMs) to include impacts on global distribution and abundance of commercially exploited fish and shellfish. This paper compares different methods for modeling fish and shellfish responses to climate change on global and regional scales. Several different modeling approaches are considered including: direct applications of ESM’s, use of ESM output for estimation of shifts in bioclimatic windows, using ESM outputs to force single- and multi-species stock projection models, and using ESM and physical climate model outputs to force regional bio-physical models of varying complexity and mechanistic resolution. We evaluate the utility of each of these modeling approaches in addressing nine key questions relevant to climate change impacts on living marine resources. No single modeling approach was capable of fully addressing each question. A blend of highly mechanistic and less computationally intensive methods is recommended to gain mechanistic insights and to identify model uncertainties.     

Dams on the Mekong River: Lost fish protein and the implications for land and water resources

Proposed dam construction in the Lower Mekong Basin will considerably reduce fish catch and place heightened demands on the resources necessary to replace lost protein and calories. Additional land and water required to replace lost fish protein with livestock products are modelled using land and water footprint methods. Two main scenarios cover projections of these increased demands and enable the specific impact from the main stem dam proposals to be considered in the context of basin-wide hydropower development. Scenario 1 models 11 main stem dams and estimates a 4–7% increase overall in water use for food production, with much higher estimations for countries entirely within the Basin: Cambodia (29–64%) and Laos (12–24%). Land increases run to a 13–27% increase. In scenario 2, covering another 77 dams planned in the Basin by 2030 and reservoir fisheries, projections are much higher: 6–17% for water, and 19–63% for land. These are first estimates of impacts of dam development on fisheries and will be strongly mediated by cultural and economic factors. The results suggest that basic food security is potentially at a high risk of disruption and therefore basin stakeholders should be fully engaged in strategies to offset these impacts.     

Climate change impacts on fish catch in the world fishing grounds

Climate change impacts on fish catch in the major fishing areas in the world oceans using a new method for forecasting of fish catch is presented with probability statements. The data on historical behaviour of surface water temperature and fish catches were analyzed and processed to assess the dynamics of spatial temperature distribution and fish catches for the world oceans. An analysis shows that the species diversity of fish catch does not change significantly with time and hence the total fish catch was used as the main dynamic variables, practically without loss of information about the dynamic properties of the system. A predictor was constructed to predict the dynamics of fish catch for new values of four moments for a future temperature distribution and the predictor’s power was estimated with a probability statement. Based on the predicted temperatures for the years 2000–2100, the fish catches in the Pacific, Atlantic and Indian Oceans have been predicted with a probability statement.     

Impact of intensive fish farming on methane emission in a tropical hydropower reservoir

Fisheries and aquaculture are important sources of food for hundreds of millions of people around the world. World fish production is projected to increase by 15% in the next 10 years, reaching around 200 million tonnes per year. The main driver of this increase will be based on fish farming management in developing countries. In Brazil, fish farming is increasing due to the climate conditions and large supply of water resources, with the production system based on Nile tilapia (Oreochromis niloticus) farming in reservoirs. Inland waters like reservoirs are a natural source of methane (CH₄) to the atmosphere. However, knowledge of the impact from intensive fish production in net cages on CH₄ fluxes is not well known. This paper presents in situ measurements of CH₄ fluxes and dissolved CH₄ (DM) in the Furnas Hydroelectric Reservoir in order to evaluate the impact of fish farming on methane emissions. Measurements were taken in a control area without fish production and three areas with fish farming. The overall mean of diffusive methane flux (DMF) (5.9?±?4.5 mg CH₄ m^?2 day^?1) was significantly lower when compared to the overall mean of bubble methane flux (BMF) (552.9?±?1003.9 mg CH₄ m^?2 day^?1). The DMF and DM were significantly higher in the two areas with fish farming, whereas the BMF was not significantly different. The DMF and DM were correlated to depth and chlorophyll-a. However, the low production of BMF did not allow the comparison with the limnological parameters measured. This case study shows that CH₄ emissions are influenced more by reservoir characteristics than fish production. Further investigation is necessary to assess the impact of fish farming on the greenhouse gas emissions.     

Market access,population density,and socioeconomic development explain diversity and functional group biomass of coral reef fish assemblages

There is overwhelming evidence that many local-scale human activities (e.g. fishing) have a deleterious effect on coral reef fish assemblages. Our understanding of how broad social phenomena (e.g. socioeconomic development) affect the diversity and function of coral reef fish assemblages however, is still poor. Here, we use structural equation models to reveal how human population density, socioeconomic development, and market access affect fishing pressure and coral cover to, in turn, explain the diversity and biomass of key functional groups of reef fish assemblages within Solomon Islands. Fishing pressure is predominantly driven by both market access and local population density, and has a clear negative effect on the diversity and function of coral reef fishes. The strong positive effect of market access on fishing pressure makes clear the importance of understanding social-ecological linkages in the context of increasingly connected societies. This study highlights the need to address broad social phenomena rather than focusing on proximate threats such as fishing pressure, to ensure the continued flow of coral reef goods and services in this time of rapid global social and environmental change.     

Can marine fisheries and aquaculture meet fish demand from a growing human population in a changing climate?

Expansion in the world's human population and economic development will increase future demand for fish products. As global fisheries yield is constrained by ecosystems productivity and management effectiveness, per capita fish consumption can only be maintained or increased if aquaculture makes an increasing contribution to the volume and stability of global fish supplies. Here, we use predictions of changes in global and regional climate (according to IPCC emissions scenario A1B), marine ecosystem and fisheries production estimates from high resolution regional models, human population size estimates from United Nations prospects, fishmeal and oil price estimations, and projections of the technological development in aquaculture feed technology, to investigate the feasibility of sustaining current and increased per capita fish consumption rates in 2050. We conclude that meeting current and larger consumption rates is feasible, despite a growing population and the impacts of climate change on potential fisheries production, but only if fish resources are managed sustainably and the animal feeds industry reduces its reliance on wild fish. Ineffective fisheries management and rising fishmeal prices driven by greater demand could, however, compromise future aquaculture production and the availability of fish products.     

Use of a reservoir water quality model to simulate global climate change effects on fish habitat

A case study was conducted on the potential impacts of climate change on fish habitat in a southeastern reservoir. A reservoir water quality model and one year of baseline meteorologic, hydrologic, and inflow water quality input were used to simulate current reservoir water quality. Total adult striped bass habitat, defined by specific quantitative temperature and dissolved oxygen criteria, was simulated. Daily reservoir volumes with optimal, suboptimal, and unsuitable temperature and DO were predicted for the year. Output from recent runs of atmospheric general circulation models (GCMs), in which atmospheric carbon dioxide concentrations have been doubled, was then used to adjust the baseline inputs to the water quality model. New sets of input data were created for two grid cells for each of three GCMs. All six climate scenarios are predicted to cause overall declines in the available summer striped bass habitat, mostly due to lake water temperatures exceeding striped bass tolerance levels. These predictions are believed to result from the consensus among GCM scenarios that air temperatures and humidity will rise, and the sensitivity of the reservoir model to these parameters. The reservoir model was found to be a promising tool for examining potential climate-change impacts. Some of the assumptions required to apply GCM output to the reservoir model, however, illustrate the problems in using large-scale gridcell output to assess small-scale impacts.     

Predicting the impact of climate change on the spatial pattern of freshwater fish yield capability in eastern Canadian lakes

Equations of fish yield in lakes as a function of mean annual air temperature have been published for lake whitefish, northern pike, and walleye. Using the contouring and modelling features of a geographic information system (Tydac Technologies' SPANS), we prepared maps of (i) species distribution, (ii) mean annual air temperature, and (iii) temperature increases predicted by the Goddard Institute for Space Studies' global climate model (GISS-GCM). We combined these maps with the yield equations for the three study species to form a regional model predicting the spatial distribution of yield capability in eastern Canada with and without climate change. The GISS-GCM predicts temperature increases of 2.5 to 7.7 °C (mean = 4.5 °C) in eastern Canada, midway between the values predicted by two other GCMs considered. The regional model predicts a substantial spatial re-distribution of fishery capabilities. Areas now supporting high yields become marginal and areas at the margin of, or outside, the current species range become optimal. Without efforts to prevent temperature increases or large artificial efforts to redistribute preferred fish species, Canadian freshwater fisheries will suffer major disruptions given the temperature increases predicted by the GISS-GCM.     

Assessment of potential risk for fish consumption by population in the Baltic Sea area where chemical weapon was dumped

Chemical weapon dumped after World War II in the Baltic Sea continues to be of a great concern of the public and population of the countries adjoining the area of dumping. One of such areas is part of the water area in the vicinity of the island of Bornholm. In 2007–2008, within the frameworks of the EU MERCW project “Modelling the Environmental Risks Related to Sea-Dumped Chemical Weapons” the area was researched during the expedition and potential effect of the dumped chemical weapon on the Baltic Sea ecosystem was studied. The major objective of this paper is to assess the risk for the population from consuming the fish caught in the area of chemical weapon dumping near Bornholm. The risk assessment for the population consuming the fish contaminated by arsenic compounds was conducted. It is demonstrated that the level of the risk for the human population taking in arsenic is of such a value that (in accordance with the carcinogen risk classification) the decision-makers are recommended to take measures for its reducing.     

Climate modulation of fish populations: the role of the Western Mediterranean Oscillation (WeMO) in sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) production in the north-western Mediterranean

This study investigates the connections between climate fluctuations and sardine and anchovy production in the NW Mediterranean, taking the Western Mediterranean Oscillation index (WeMOi) as an indicator of climate variability. The basic working hypothesis is that sardine and anchovy productivity is influenced by the WeMOi, a proxy for the local environmental conditions such as sea surface temperature (SST) and river runoff. Sardine and anchovy landings (1974–2009) in the Catalan Coast and landings per unit of effort (LPUE) were used as proxy for recruitment. The results demonstrated a clear link between climate fluctuations and sardine and anchovy production. Positive WeMOi values were significantly correlated with low SST, high river runoff and high LPUE, that is, with better-than-average recruitment of sardine and anchovy. Conversely, negative WeMOi values were associated with high SST, low river runoff and low LPUE. During the negative WeMOi phases (such as that at the end of the analyzed period), environmental conditions are unfavourable for the overall biological productivity in the NW Mediterranean and would decrease the survival, growth, condition and reproduction of sardine and anchovy during their life cycle. Despite the evidences on the appropriateness of the NAOi as an indicator of the climate in Europe and its impact on some biological variables, we suggest that using a regional index, such as the WeMOi, can provide a more accurate representation of the environmental conditions affecting small pelagic fish production in the NW Mediterranean.     

棉花生育模拟模型及生产管理决策系统研究进展

简要叙述了国内外棉花生长发育模拟模型，棉花专家系统和棉花生产管理决策系统的发展，重点介绍了美国的GOSSYM模拟模型和我国的COTGROW模拟模型等最成功的研究成果。     

雾与能见度数值预报诊断SW方案和FSL方案改进的研究及评估

为了提高雾与能见度的预报水平,对业务上常用的两种能见度诊断方案,即Stoelinga and Warner（SW）方案与Forecast Systems Laboratory（FSL）方案的改进进行预报试验,SW方案基于Gultepe方案考虑了液态水粒子数浓度对能见度的影响,FSL改进方案中利用了递减平均法对公式中用到的温度与露点温度进行订正,并用其重新计算公式中的相对湿度。基于山东省气象科学研究所逐时更新循环（hourly update cycle,HUC）业务模式输出结果,从2015—2016年选取10次雾天气过程,并详细分析了2015年11月13—14日这次雾天气过程的预报结果,比较了改进前后各方案对雾与能见度的预报效果,结果显示：在模式预报的雨水含量占总液态含水量比例较大的预报时效,改进后的SW方案对雾与能见度预报效果优于原始方案,在模式预报液态含水量接近0的预报时效,改进前后的SW方案对雾与能见度的预报效果相当;利用订正的温度与露点温度重新计算相对湿度,其平均绝对误差（mean absolute error,MAE）降低明显的预报时段,改进后的FSL方案对雾与能见度的预报效果大大提升。将两种改进后的方案相融合并进行预报试验,结果显示,综合对能见度与雾的预报效果,Combined Visibility（CVIS）方案要优于其他两种改进方案。