Tracking change in a human‐dominated landscape: developing conservation guidelines using freshwater fish

• 1. To conserve biodiversity in a human‐dominated landscape, a science‐based inventory and monitoring plan is needed that quantifies existing resources, isolates drivers that maintain natural communities, determines harmful stressors, and links ecological drivers and human stressors. A tactical approach is proposed for conservation planning using freshwater fish at the Cape Cod National Seashore.
• 2. Freshwater fish are well studied and occur across environmental gradients. The lentic systems at the national park are relatively pristine yet are enveloped by a region of high population density. Using fish community data, three steps were taken for tracking anthropogenic impacts in a human dominated landscape. First, fish and potential drivers were sampled intensively along a gradient to determine which fish metrics reflect natural communities and which abiotic and biotic factors structure them. Second, emerging and existing regional human threats were identified. Third, these human threats were linked to the potential drivers that maintain natural communities to identify the most informative metrics to monitor and track change.
• 3. Fish communities, water quality, habitat, and food resources were sampled concurrently in 18 ponds in 1999 and 2000. Three common fish species explained 98% of variation in numbers across systems. Based on ecological relationships, pH, depth, vegetation, prey, and community complexity were determined to maintain biodiversity of freshwater fish communities.
• 4. The primary human threats here included: development‐related, land‐use changes; non‐point source pollution; eutrophication from septic systems; and introduced species that are a byproduct of high human visitation. These are common threats in many rapidly urbanized areas and are likely to have relevance to many sites.
• 5. To track the impact of emerging threats to freshwater ponds related to increased human population, monitoring changes in water quality, vegetated habitat, fish diversity, and trophic interactions are recommended.

Copyright © 2008 John Wiley & Sons, Ltd.     

Classification of guppies’ (Poecilia reticulata) gender by computer vision

Labor costs of guppy growers and breeders are largely those of manual sorting (by strain, quality and gender) and counting fish. In most farms, female and male fish are grown together and sold either separately or together. Sorting fish according to gender is important for marketing as well as for breeding programs, so that a device for sorting and counting fish can potentially reduce production costs and improve quality.

A project aiming to develop sorting and counting technologies for ornamental fish growers included development and testing of image-processing algorithms for sorting guppy fish (Poecilia reticulata) by gender. The algorithms are derived from shape and color differences between female and male guppies. An algorithm for the determination of landmarks on fish contours was developed and found to be accurate in accordance with human judgment, enabling extraction of specific shape and color features of the tail and the body.

The algorithms were applied to three sets of images of guppies of the “Red-Blond” strain. Gender identification accuracy was approximately 90% using shape features, approximately 96% using color features and was slightly improved when both color and shape features were used.

Some of the components used are essential for future development of a computer vision based system for sorting and grading ornamental fish by strain and quality.     

淡水养殖鱼类主要细菌性传染病快速诊断的研究——鱼病诊断箱的应用试验

应用以葡萄球菌Ａ蛋白协同凝集试验（ＳＰＡ－ＣＯＡ）为主要检测手段的鱼病诊断箱，于１９９５￣１９９７年在吉林，辽宁等７省进行现场检测试验。结果，６１个渔场１１个品种的５１６尾病鱼有菌生长的２８５尾，经ＳＰＡ－ＣＯＡ鉴定阳性数为２３９尾，占有菌生长的８３．８６％，１２个渔场５个品种１２１６尾假定健康鱼有菌生长的为２８尾，经ＳＰＡ－ＣＯＡ鉴定阳性数为２２尾，占有菌生长的７８．５７％，认为本诊断箱适用于基     

Experimental infections of a ciliate Tetrahymena pyriformis on ornamental fishes

SUMMARY: Experimental infection of Tetrahymena pyriformis was conducted on ornamental fishes with skin wounded by acetic acid treatment. Among fishes used in this experimental infection, guppy Poecilia reticulata , pristella Pristella maxillaris , neontetra Paracheirodon innesi and cherry barbs Puntius titteya proved to be sensitive to challenge, while medaka Oryzias latipes , dwarf gourami Colisa lalia , goldfish Carassius auratus , platy Xiphophorus maculatus and angelfish Pterophyllum scalare were resistant. In catfish Corydoras aeneus infection was unsuccessful. Exposure to Tetrahymena at ≥100 cells/mL at 25 to 30°C and at pH of 6.0 to 8.0 resulted in the successful infection of some sensitive fish species. Histological and bacteriological observations suggest that deeply destroyed skin tissues from the acid-treated method are the primary factors in successful infection.     

Soil physical fertility, soil structure and rooting conditions after ploughing organically managed grass/clover swards

Effective management of soil structure and organic matter are essential in organic cropping to ensure good rooting conditions and to optimize the production of mineralized N and thus minimize greenhouse gas emissions. We investigated how mid‐winter or early spring ploughing and three grazing duration treatments prior to ploughing influenced soil structure, soil organic matter and plant root growth under the first spring barley crop after a grass–clover ley. The experiment was carried out over two seasons. We also studied the soil under first‐year oats in a long‐term rotations experiment where 2 or 3 years of arable crops followed 3 or 4 years of grass. Pore size distribution and pore continuity, bulk density, particulate (light fraction) organic matter, readily oxidizable organic matter (ROM), aggregate size distribution and root length densities were measured. Macroporosity appeared to be the best indicator of soil physical fertility; it was sensitive to changes in soil structure arising from compaction and root growth. This, along with visual examination, revealed the loosening resulting from ploughing. The generally favourable macroporosity amongst small, stable aggregates reduced the likelihood of development of anaerobism. Macroporosity and aggregate size can be estimated from visual examination of the soil, a method that offers the advantage of being quick and of sampling a large volume. The content of ROM was high 6.1–6.4 g 100 g^?1 whole soil. However, particulates formed only a small fraction (6–9%) of the ROM. Despite the favourable ROM and structure, the soil was susceptible to compaction damage during seedbed preparation in wet soil after ploughing which reduced grain yield in some plots. Grazing by sheep before ploughing and date of ploughing had minor effects on soil quality. Grazing for 2 months prior to ploughing increased root length density in the upper topsoil in the following arable crop, possibly because of the higher quality of the animal and grass–clover residues. Conservation of soil quality was related more to secondary tillage and sowing operations after ploughing than to duration and timing of grazing.     

未来气温和降水变化对山西冬小麦产量的影响

【目的】冬小麦是山西省重要的粮食作物，气候变化对冬小麦产量影响显著。利用模型模拟评估气候变化对山西省冬小麦产量的影响，为山西省冬小麦种植规划提供重要科学依据。【方法】利用山西省 2017—2018 年气象资料和 2018 年县级冬小麦产量数据，采用 DNDC 区域模拟方法，对山西省冬小麦种植区单产进行模拟和验证；模拟未来 8 种气候变化情景（温度上升 1、2℃，降水减少 20%、10% 以及温度和降水耦合）对冬小麦产量产生的影响。【结果】DNDC 模型可以较好模拟出山西省冬小麦产量整体水平（4 335.6 kg/hm2），总体平均误差为 4.63%，空间上的模拟误差主要由于山西省地形和气候差异导致。【结论】未来气候变化背景下，不同程度的增温对产量的影响不一，在温度平均升高 1℃情况下，山西省冬小麦单产下降 4.60%，而气温上升 2℃情景下，单产增加 16.44%；降水减少 10% 和 20% 情景下，产量均降低，说明水分依然是制约冬小麦产量的重要因子；但在增温和降水减少的耦合作用下产量增加 7.41%~15.84%。未来还需根据山西省种植特点，从轮作角度评估气候变化对农业的影响。     

Spatial integration of freshwater fish markets in the Northern Baltic Sea area

Freshwater fish species and Baltic salmon (Salmo salar) are important to small-scale fisheries in Finland and Sweden. The formerly local markets for these species have expanded as trade has been opened up to international competition. In this study we use cointegration analysis to test the spatial integration of freshwater fish markets in Finland and between Finland and Sweden. The analysed fish species are salmon, perch (Perca fluviatilis), pikeperch (Sander lucioperca), European whitefish (Goregonus lavaretus) and pike (Exos lucius), and the data covers ex-vessel prices from 1993 or 1995 to 2004. We found that the regional prices in Finland were cointegrated. This indicates that the prices are determined on a single market in Finland. Moreover, the study suggests that Finnish and Swedish markets in Baltic salmon, whitefish, pikeperch and perch were partially integrated, while integration of pike markets could not be found. The political implication is that an essential part of the local small-scale fisheries’ operational environment is determined outside the national borders.     

史氏鲟(Acipenser schrenckii)鱼肉的营养价值

本文对史氏鲟鱼肉的氨基酸及脂肪酸组成进行检测,证实史氏鲟鱼肉蛋白质中的两种限制氨基酸赖氨酸和含硫氨基酸的评分分别为163、123,必需氨基酸指数为108,远远高于FAO模式的理想蛋白;精氨酸含量为62.62mg/g,占氨基酸总量的6.51%;支链氨基酸含量为162.94mg/g,与芳香氨基酸的比值为3.52,是一种具有保肝功效、有利于促进儿童生长发育的营养价值较高的蛋白质;其脂肪酸组成的营养价值比大部分的海、淡水鱼低.     

Priority habitats for the conservation of large river fish in the Ganges river basin

• 1. Three classes of habitat used by groups of fish species classified as conservation and management priorities were developed for the Gerua River (also known as the Girwa River, Karnali River) in the Ganges river basin. This river is large (mean annual discharge ca 1500 m³ s^?1, up to 900 m wide), surrounded by protected lands of India and Nepal, and upstream of major diversions and river alterations.
• 2. Fish and habitat sampling was conducted at 45 sites from 2000 to 2003. Data were analysed for 2172 fish of 14 species. Species and life stages found occupying a statistically distinct subset of the river habitats were grouped to identify classes of river habitat for conservation.
• 3. Most species and life‐stage groups specialized on specific habitat conditions revealed by multivariate analyses of variance and a principal component analysis. The most numerous and diverse group (six species, 15 life stages) was associated with deep depositional habitats with sandy substrate. Two species covering three life stages were primarily oriented to erosional habitat marked by fast current velocity with pebble and cobble substrate. A third group of three species of adults and juveniles were intermediate in habitat use.
• 4. River conservation for fish faunas should maintain both erosional and depositional channel habitats with depths, substrates, and current velocity inclusive of the ranges reported. The erosional and depositional nature of the key habitats requires that rivers be maintained with flows capable of channel‐forming functions.

Copyright © 2006 John Wiley & Sons, Ltd.