Technical, economics and environmental analysis of semi-intensive shrimp (Litopenaeus vannamei) farming in Sonora, Sinaloa and Nayarit states, at the east coast of the Gulf of California, México

In Mexico shrimp pond aquaculture is the main activity and contributes with 45.9% of the total fisheries volume and 74.3% of gross profit generated by the national products, being Sonora, Sinaloa and Nayarit in the east coast of the Gulf of California the states generating around 70% of region gross profit. The main species cultivated is the white shrimp Litopenaeus vannamei, and for this reason academic and government sector devoted much attention in this species, however, still researching on economic feasibility is scarce and needed. In this paper, the technical, economics, production and environment parameters of 80 semi-intensive commercial in these states are analyzed and discussed. The results showed the main external constraints affecting short and long run farm performance. The overall observations pointed out that there is an increase on yield and income when shrimp farms invest in higher quality inputs such as equipment and technology for more efficiency in using water, use of certified post-larvae and better design of farm facility. Nevertheless, further research is needed to adjust shrimp production strategies to specific farm requirement by investing in premium quality inputs. Furthermore, the most serious threat from shrimp aquaculture is the potential effect on water quality and the infrastructure associated, that having more serious effects on the environment, particularly in the coastal wetlands. The economic and the environment care must be driven to lead a more sustainable scenario.     

Spatial analysis of the impact of shrimp culture on the coastal wetlands on the Northern coast of Sinaloa, Mexico

In the Mexican coasts, as in many tropical and subtropical coastal areas, shrimp culture grew exponentially over the last three decades. This process has produced an intense debate on the economic benefits but also about the extent and intensity of the impact of this activity on the coastal ecosystems, particularly the effects of pond construction on mangrove areas and other coastal wetlands. For the Northern coast of Sinaloa (Northwest Mexico), a region where shrimp culture is actively practiced and reproduces most of the shrimp controlled production model in Mexico, a land cover change-detection analysis, with Landsat images, outputs that 75% of the shrimp farming in this region has been built on saltmarshes while less than 1% was constructed on mangrove areas. Through the estimation of landscape metrics for different scenarios (with and without shrimp culture infrastructure), we find that in addition to direct removal of saltmarshes, shrimp aquaculture has significantly modified the spatial patterns of coastal wetlands, retreating wetland borders and fragmenting their patches. These last impacts are mainly related with the development of the linear infrastructure associated with shrimp culture (drainage channels and roads), rather than the construction of the ponds. Present findings and other from similar studies done in Northwest Mexico; allow us to estimate that 60% of shrimp farming in Mexico impacted directly on saltmarshes, contrasting with the 3% of shrimp farms built on mangroves.     

Fluxes and behavior of radium isotopes, barium, and uranium in seven Southeastern US rivers and estuaries

This paper demonstrates the importance of advective transport of water through permeable estuarine and salt marsh sediments. This transport delivers significant quantities of radium and barium to the coastal ocean; and, in some cases may remove significant quantities of uranium. These conclusions are based on repeated analyses of seven river–estuarine systems from North Carolina to Florida. Fluxes of radium and barium from these river systems are shown to be inadequate to balance the dissolved inventories of these elements in the South Atlantic Bight. The strong interactions that occur between surface and subsurface waters as these rivers encounter coastal marshes lead us to consider these river mouths as marsh-dominated in terms of their chemical fluxes to the ocean. Such interactions between the river and coastal marsh must be considered when estimating fluxes of material between the land and ocean.     

GIS for land evaluation for shrimp farming in Haiphong of Vietnam

This study was conducted to identify appropriate sites for shrimp farming development in Haiphong province of Vietnam using geographical information systems (GIS). Thirteen base layers (thematic maps) were grouped into four main land use requisites for aquaculture, namely, (1) potential for pond construction (slope, land use type, soil thickness, elevation), (2) soil quality (soil type, soil texture, soil pH), (3) water availability (distance to sea, and water source), and (4) infrastructure and socio-economical status (population density, distance to roads, local markets, and hatcheries). A constraint layer was used to exclude areas from suitability maps that were not allowed to implement shrimp farming. A series of GIS models was developed to identify and prioritize the most suitable areas for shrimp farming.This study shows that the land evaluation model is useful for identifying suitable areas for shrimp farming and for allocating land for efficient income generation, effective conservation, and sustainable land management. It was estimated that about 31% (2604 ha) of the total land area (8281 ha) in Haiphong was highly suitable for shrimp farming. Since existing shrimp farms cover only 1690 ha of land in the study area, the potential for expanding shrimp farms should take into consideration further political and environmental issues.     

Detoxification mechanisms in shrimp: comparative approach between hydrothermal vent fields and estuarine environments

Hydrothermal vents are extreme deep-sea habitats that, due to their singular features, still intrigue scientific communities. Swift growth rates and profuse biomass of biological communities can be observed, despite of their inherently unstable physical-chemical and toxic conditions, indicating that organisms inhabiting this environment must be well adapted to these inhospitable conditions. The caridean shrimp, Chorocaris chacei, Mirocaris fortunata and Rimicaris exoculata, together with bathymodiolid mussels, dominate the vent fauna along the Mid-Atlantic Ridge (MAR). Crustacean species are widely used as biological indicators of environmental alterations, since they play a key ecological role as planktivorous grazers, epibenthic scavengers or as prey species. The biological consequences of the hydrothermal metal-rich environment in shrimp species are still largely unknown. Therefore, the aim of this study was the determination of the metal levels (Ag, Cd, Cu, Fe, Mn and Zn), metallothioneins (MT) and lipid peroxidation (LPO) in shrimp species collected in Rainbow, Lucky Strike and Menez-Gwen vent sites, in order to evaluate their different adaptation strategies toward metals when compared with two common coastal shrimp species (Palaemon elegans and Palaemonetes varians) from a fairly unpolluted estuarine system in south Portugal (Ria Formosa). Results show significant differences in metal concentrations, MT levels and lipid peroxidation between vent and coastal shrimp and also between shrimp species from the same site. This indicates that biochemical responses in both vent and coastal shrimp are affected not only by the environmental characteristics but also by inter-specific differences. Nevertheless, these responses apparently grant a successful adaptation for the survival in a metal-extreme environment.     

Biogeochemical factors influencing the residence time of microconstituents in a large tidal estuary, Delaware Bay

Generally the large tidal estuaries of the eastern United States, such as Delaware Bay, are characterized by rather high suspended particle concentrations at the landward end and high biological activity at the seaward end. As such, these estuaries can be conceptualized as geochemical and biochemical “reactors” for those processes controlling the transmission of trace elements from fresh to the coastal shelf waters. The efficiency of these reaction processes relative to estuarine flushing will control the residence times of microconstituents in such estuaries.Evidence is drawn from the Delaware estuary to illustrate biogeochemical estuarine reaction processes using salinity distribution data and mass balance calculations. The Delaware retains some of its estuarine trace elements as sedimented estuarine particles, while others are more conservative and largely exported. Those retained by sedimenting processes include trace elements in primarily geochemical (particle reactive) chemistries, while those exported appear recycled by biochemical (nutrient reactive) chemistries. Often, the behavior of trace elements (e.g., Fe, Cd) and nutrients (e.g., PO₄) appear biogeochemically linked. Other examples are drawn from mixing studies to illustrate particle interaction, and benthic flux measurements to illustrate limited diagenetic reflux.The residence time of estuarine microconstituents should depend seasonally on the relative turbidity, flushing rate, and primary production of tidally dominated estuaries such as the Delaware. Thus, residence times of the more biogeochemically reactive microconstituents must be substantially shorter (days to weeks) than the average flushing times of these larger estuaries, while the residence times of the less reactive ones should approach such flushing times (weeks to months). True estuarine residence times of microconstituents can only be modeled after using large data sets averaged over time (season, tides) and space (salinity).     

饲料中添加芽孢杆菌组分对凡纳滨对虾幼虾生长、能量代谢和抗WSSV能力的影响

以凡纳滨对虾(Litopnnaus vannamei)幼虾为实验动物,在其基础饲料中分别添加芽孢杆菌(Bacillus sp.)胞外蛋白粗提物(1.0%,胞外蛋白组)、胞内多糖粗提物(1.0%,胞内多糖组),以基础饲料为对照组饲料,进行为期28d的养殖实验,探讨芽孢杆菌胞外蛋白和胞内多糖粗提物对幼虾生长、能量代谢及抗病能力的影响。研究表明,芽孢杆菌2种粗提物对凡纳滨对虾的生长和成活率影响不显著(P>0.05)。饲喂2种粗提物影响了凡纳滨对虾肝胰腺和肌肉中能量代谢相关酶活力。胞外蛋白组肝胰腺中磷酸果糖激酶(PFK)、乳酸脱氢酶(LDH)活力在养殖实验前期显著高于对照组(P<0.05),而肌肉中PFK、LDH活力显著低于对照组(P<0.05);胞内多糖组肝胰腺中己糖激酶(HK)活力及肌肉中PFK、LDH活力显著低于对照组(P<0.05)。饲喂2种粗提物均显著提高了凡纳滨对虾肌肉中琥珀酸脱氢酶(SDH)活力和肝胰腺中电子传递系统(ETS)活力(P<0.05),胞外蛋白粗提物对肝胰腺中的SDH活力也有显著的提高作用(P<0.05)。饲喂2种粗提物显著降低了凡纳滨对虾肝胰腺及肌肉组织中脂肪酸合酶(FAS)含量(P<0.05)。此外,饲喂2种粗提物均会显著提高凡纳滨对虾肠道蛋白酶活力(P<0.05),而胞外蛋白粗提物使凡纳滨对虾肠道脂肪酶活力显著降低(P<0.05)。白斑综合征病毒(WSSV)感染后,与对照组相比,胞外蛋白组和胞内多糖组凡纳滨对虾半致死时间分别延长了26.19%和7.14%。根据以上结果推测,芽苞杆菌2种粗提物能够影响凡纳滨对虾能量代谢水平并提高其抗WSSV能力,且二者之间密切相关。     

Group farming for sustainable aquaculture

Sustainable farming is a critical issue in aquaculture development. The concept is well understood but the issue is that of methodology for implementing it. It is well recognized that fragmented holdings have been a major constraint in the implementation of farming practices by small-scale farmers. In India 80 per cent of the shrimp production comes from small and marginal holdings which follow different systems of production, including the traditional `pokkali’ farms of Kerala state, improved traditional farming, and scientific methods. Group farming, which was highly successful in paddy farming, was tested among small-scale shrimp farmers practicing paddy and shrimp farming in rotation in a cluster of `pokkali’ fields in Kerala. The model served as an effective extension intervention to educate farmers on sustainability while helping them to improve their farming practices. The farmers, including women, could be equipped with the technology for farming not only shrimp but also finfish, crab and aquaculture feed production by strengthening the farmer–extensionist–researcher–political–administrative linkages. The work was done during 1993–1996 at the Central Marine Fisheries Research Institute, Cochin, India. The study formed a part of the action research project on empowerment of rural communities through extension.     

Exposure of grass shrimp to sediments receiving highway runoff: Effects on reproduction and DNA

A grass shrimp bioassay was carried out on sediments from three estuarine stations which were different distances from a highway storm drain. Total polycyclic aromatic hydrocarbon (PAH) concentrations were 29, 1.5 and 0.1 μg/g sediment at stations A (next to drain), B (100 m from drain) and C (500 m from drain), respectively. Lower embryo production and embryo hatching rates and a higher level of DNA strand breaks (comet assay) were observed in grass shrimp exposed to stations A and B sediments. There appeared to be an association between reproduction abnormalities and increased DNA strand breaks as a result of grass shrimp exposure to estuarine sediments receiving highway runoff.     

Distribution and bioturbation effects of the tropical alpheid shrimp Alpheus macellarius in sediments impacted by milkfish farming

The impact of milkfish fish pens on the distribution of the alpheid shrimp Alpheus macellarius was studied in the Bolinao area, Philippines. In addition, the impact of the alpheid shrimp on sediment biogeochemistry, including organic matter mineralization, nutrient and sulfur cycling was compared in sediments affected and unaffected by fish farming. The fish farming activity had negative impact on the distribution of shrimps by reducing the abundance up to 60% in the vicinity of the net pens, and to almost absence inside the net pens. At a farm site abandoned seven month prior to sampling the abundance of shrimps was still low and sediment pools of reduced sulfur high, indicating a slow benthic recovery. The shrimp had large physical impact on the sediments, and the mineralization rates were stimulated by the presence of the shrimp in pristine sediments, whereas the fish farm impacted sites showed high mineralization rates both in sediments with and without the presence of the shrimp suggesting that the organic matter enrichment stimulated the mineralization in these low-organic sediments, whereas the shrimp had less impact. Sulfate reduction rates and in particular pools of sulfides increased in the farm impacted sediments, and sulfate reduction was an important process for organic matter mineralization (>67%) in all sediments. Although the shrimp had minor effect on the organic matter mineralization and nutrient fluxes in the farm impacted sediments, they appeared to increase the oxidation of sulfides by increasing the zone of oxidized surface sediment and thereby improving the sediment conditions for recolonization after fish farming has ceased.     

Exploring the implications of tidal farms deployment for wetland-birds habitats in a highly protected estuary

Next generation turbines can be installed to exploit tidal energy resource in estuaries. However, the ecological implications of such deployments remain unknown. Accordingly, this study is focused on the impact of tidal farms on intertidal areas and associated waterbird habitats in estuaries. A numerical model simulates the hydrodynamic conditions of the Solway Firth, comprising one of the most extensive intertidal zones in the UK. The effects of tidal farms with different turbine densities have been evaluated in terms of changes to the areas of habitat for wetland bird species of conservation importance. The results suggest that any habitat loss may be minor and that in some cases there may be an increase (also small) in the area of important habitat. The percentage change in intertidal areas is also considerably lower than that expected to result from tidal barrages of similar capacities, implying the potential for tidal farms to present an alternative solution for exploiting tidal energy in highly protected areas. The changes in the extent of intertidal habitat are not proportional to the energy dissipated by the tidal farm. Therefore a range of tidal farm designs should be evaluated in order to optimise installed capacity while minimising habitat loss. However, the site-dependency of the impacts and the complex responses to change of estuarine ecosystems reinforce the requirement for detailed studies to be undertaken for each specific location and array configuration. The methodology presented here is appropriate for such assessments as it can be applied to different locations and turbine types.     

The impact of river flooding and high flow on the demersal fish assemblages of the freshwater-dominated Great Fish Estuary,South Africa

Freshwater inflow has a strong impact on the biological, chemical and physical characteristics of estuaries, which in turn affect the distribution and abundance of estuarine organisms. Increased climatic variability associated with climate change is predicated to modify precipitation patterns, which will likely intensify floods in estuaries. The demersal fish assemblage of the freshwater-dominated Great Fish Estuary, South Africa, was sampled using beam trawls, monthly, from December 2013 to November 2014. The first six months of the study were characterised by river flooding and high flow, with estuarine conditions found only in the mouth region; this was followed by six months of intermediate flow, with estuarine conditions recorded up to 10 km from the mouth. River flooding and subsequent reduced salinity resulted in a decrease in species richness and abundances of fishes in the estuary, with only two estuarine species (Glossogobius callidus and Psammogobius knysnaensis) and one marine migrant (Solea turbynei) recorded following river flooding (201 m³ s^?1), in January 2014. The greatest species richness and abundances among both marine and estuarine fishes were recorded during intermediate flow conditions. We conclude that although freshwater inflow into estuaries is important for the nursery function of these systems, flooding—especially in freshwater-dominated estuaries—may cause a temporary decline in the abundance of most marine and estuarine fish species, including important bentho-pelagic marine migrant fishery species, such as Argyrosomus japonicus and Pomadasys commersonnii.     

Shrimp farming in coastal Brazil: Reasons for market failure and sustainability challenges

In Brazil, farm shrimp production has remained constant over the last five years but exports have fallen sharply and almost all production is now consumed domestically. This situation exists despite adequate water resources, available labour and climatic conditions which allow three production cycles per year. This paper is based on an assessment of the shrimp industry at a critical time when exports had reached their maximum level and were about to fall precipitously. It examines the reasons for the shrimp export market failure and discusses sustainability challenges for the future. Data were collected through interviews with hatchery, farm and processing plant managers and other stakeholders in Rio Grande do Norte state, the largest Brazilian farmed shrimp producer. It was found that market failure was the result of inadequate industry planning, inappropriate public policy and a lack of coordinated actions among the various shrimp producers and stakeholders. The research demonstrates that sustainable Brazilian shrimp farming will require technological and management improvements, institutional changes and an appropriate environmental and social framework.     

Environmental consequence analyses of fish farm emissions related to different scales and exemplified by data from the Baltic--a review

The aim of this work is to review studies to evaluate how emissions from fish cage farms cause eutrophication effects in marine environments. The focus is on four different scales: (i) the conditions at the site of the farm, (ii) the local scale related to the coastal area where the farm is situated, (iii) the regional scale encompassing many coastal areas and (iv) the international scale including several regional coastal areas. The aim is to evaluate the role of nutrient emissions from fish farms in a general way, but all selected examples come from the Baltic Sea. An important part of this evaluation concerns the method to define the boundaries of a given coastal area. If this is done arbitrarily, one would obtain arbitrary results in the environmental consequence analysis. In this work, the boundary lines between the coast and the sea are drawn using GIS methods (geographical information systems) according to the topographical bottleneck method, which opens a way to determine many fundamental characteristics in the context of mass balance calculations. In mass balance modelling, the fluxes from the fish farm should be compared to other fluxes to, within and from coastal areas. Results collected in this study show that: (1) at the smallest scale (<1 ha), the "footprint" expressing the impact areas of fish cage farm often corresponds to the size of a "football field" (50-100 m) if the annual fish production is about 50 ton, (2) at the local scale (1 ha to 100 km2), there exists a simple load diagram (effect-load-sensitivity) to relate the environmental response and effects from a specific load from a fish cage farm. This makes it possible to obtain a first estimate of the maximum allowable fish production in a specific coastal area, (3) at the regional scale (100-10,000 km2), it is possible to create negative nutrient fluxes, i.e., use fish farming as a method to reduce the nutrient loading to the sea. The breaking point is to use more than about 1.1 g wet weight regionally caught wild fish per gram feed for the cultivated fish, and (4) at the international scale (>10,000 km2) related to the Baltic Proper, the contribution from fish farms to the overall nutrient fluxes are very small. We have also given two case-studies at the local scale where the impact of the fish farm emissions are greatest and the idea is to identify coastal areas unsuitable and suitable for fish cage farms and the reasons why. It should also be stressed that the results presented here are exemplified using emissions from fish farms, but that the underlying principles to evaluate the ecosystem effects of nutrient discharges from point source emissions are valid in a wider and more general perspective.     

Input of metals to the North Atlantic from two large Canadian estuaries

The freshwater discharge from the Gulf of St. Lawrence and Hudson Bay accounts for more than 80% of the total freshwater discharge from eastern Canada and approximately 70% of the total discharge from the eastern seaboard of North America, from Baffin Island to Florida. If the Gulf of Mexico is included, the Gulf of St. Lawrence/Hudson Bay discharge is still more than half of the total.Both the Gulf of St. Lawrence and Hudson Bay have some distinctly estuarine characteristics and discharges of metals can be estimated using estuarine models. For Al, Mn, Fe, Co, Ni, Cu and Zn, the distributions can be described by simple, highly significant relationships with salinity. These regressions can be used in conjunction with knowledge of water discharges to estimate net metal inputs to the North Atlantic from these two systems.Most of the discharge from the Gulf of St. Lawrence flows along the Scotian Shelf to the Gulf of Maine. Metal-salinity relationships can also be used to estimate metal transports through this region for some metals. The applicability of this estuarine model, however, tends to break down as the oceanography becomes more complex and metal distributions are determined more by oceanic rather than estuarine processes.     

基于目标框架法的辽河口湿地生态脆弱性评估

河口滨海湿地生态服务功能突出,生境脆弱易损,研究其生态脆弱性对滨海湿地生态环境保护与管理具有重要意义。本文以辽河口滨海湿地为例,基于“干扰-敏感-恢复”评估框架,选取17个指标,构建滨海湿地生态脆弱性评价指标体系,以GIS技术为支撑,综合运用插值法、综合指数法,探究辽河口滨海湿地生态脆弱性空间分布特征,分析生态脆弱性变化的影响因素。结果表明:入海河口污染、河口地区人类开发活动和自然淤涨对河口滨海湿地生态脆弱性的影响较为突出;2014年辽河口滨海湿地生态脆弱性总体态势良好,区域生态脆弱性指数为1.67,整体处于不脆弱状态;空间上,辽河口滨海湿地生态脆弱性表现为中部高于四周,由入海河口向外逐步减弱的格局特征。     

海马人工养殖的研究

介绍海马的生态习性和试养经验,强调对仔稚鱼期投喂适口性好、营养全面的鲜活浮游甲壳类动物可促进其生长、发育,增强抗病能力,提高成活率。提出与沿海对虾育苗场、养殖场相结合,建立海马苗种供应基地和养殖技术咨询服务中心,推动海马人工养殖业发展。     

Local effects of blue mussels around turbine foundations in an ecosystem model of Nysted off-shore wind farm, Denmark

The development of off-shore wind farms along the coastline of north-west Europe is rapidly increasing; it is therefore important to study how this will affect the marine environment. The present study modelled the growth and feed-backs of blue mussels in natural beds and on turbine foundations in an off-shore wind farm (OWF) located in a shallow coastal ecosystem by coupling a dynamic energy budget (DEB) model to a small-scale 3D hydrodynamic–biogeochemical model. The model results showed that blue mussels located higher up in the water column on turbine pillars achieved a 7–18 times higher biomass than those located on the scour protection because the former experience an enhanced advective food supply. Secondly, the high biomasses of blue mussels on foundations created local ‘hot spots’ of biological activity and changed ecosystem dynamics due to their feed-backs e.g. ingestion of microplankton and copepods, excretion of ammonium and egestion of faecal pellets. The model results were supported by field measurements around foundations of Chl a concentrations and biomasses of the fauna community. Our study emphasised that OWFs seem to be particularly favourable for blue mussels in the western Baltic Sea and that the functioning of the OWFs as artificial reef ecosystems depends upon how the blue mussels interact with their local pelagic and benthic environment.     

Spatial management measures for disease mitigation as practiced in Scottish aquaculture

Aquaculture is an increasingly important economic activity in coastal waters. The fluid environment means spatial management is an important tool for protecting fish health. Scottish aquaculture (largely Atlantic salmon) uses a range of different types of area to group farms for different management or reporting purposes related to fish health. Farm Management Areas are defined by local knowledge and used by industry for co-operation among groups of farms, including in the management of sea lice. Disease Management Areas, defined using a simple but robust model, are used by the Scottish Government for control of notifiable diseases. Particle dispersal models are used to assess areas affected by treatment residue around farms, and to manage maximum allowable area biomass for environmental protection. Sophisticated models of sea lice transport have been developed to help inform management of this key parasite. Large regional areas are used for a variety of purposes, such as a policy presumption against new farms covering the entire east and north coasts of Scotland, and five reporting areas for official production statistics. Scottish aquatic environments are shared by many interest groups and spatial management is proving essential for sustainable development by aquaculture and other users.     

Geological consequences of the Saemangeum Dyke, mid-west coast of korea: A review

The Saemangeum Dyke is located in an estuarine setting, regulated in a complicated manner by a macrotidal regime, rivers, and winter monsoon. Accordingly, the constructed dyke resulted in a variety of artificial changes in geological characteristics in the estuary and its vicinity. To investigate those dyke-induced changes, the KORDI (Korea Ocean Research and Development Institute) performed sedimentological and sediment-dynamical observations from 2002 to 2010. On the basis of the KORDI results, the major geological changes and associated dynamical processes are reviewed. Five phenomena, among others, are focused on: depositional-channel creation; gap-related erosion; forced movements of surface sands; tidal-flat growth inside the dyke; and blanketing of mud over the sandy seafloor. These phenomena were unforeseen before the dyke construction, and reflect that the dyke could cause both erosion and deposition on an estuarine scale. The investigations conclude that the sediments in the dyke-influenced region were derived from the two rivers, Mangyeong and Dongjin, of the estuary. This is completely contrary to the offshore origin proposed before the dyke construction. As a result, the review supports the proposal that a thorough geological investigation and rational forecast is necessary prior to dyke construction to avoid economic loss and a fractious environmental debate.