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1.
The denitrifying woodchip bioreactor is designed to remediate nitrate-rich water, including those produced from aquaculture effluents. Reuse of treated bioreactor outflows in recirculating aquaculture would offer considerable water savings and valuable alkalinity recuperation. However, such bioreactors may leach detrimental wood-bound contaminants, preventing outflow reuse. To determine water reuse potential, woodchip media from two hardwood species (white ash, Fraxinus americana; Norway maple, Acer platanoides) were evaluated for 206 d under a range of operating conditions (start-up, steady-state, reducing conditions, and drying-rewetting cycles) for a spectrum of potentially harmful dissolved contaminants. Aerated outflows also were evaluated for acute and chronic toxicity to the biologically sensitive invertebrate Ceriodaphnia dubia. Dissolved metal leaching subsided within the first few weeks of operation, though initial concentrations of copper and zinc were detected at concentrations of concern. Elevated concentrations of tannins-lignin and total ammonia nitrogen were detected throughout the study and were influenced by operational phase. Acute toxicity was not generally detected, though chronic toxicity was observed during drying-rewetting cycles in the maple outflows. The measured toxicity was not correlated with water chemistry, indicating an additive effect of several toxicants. Overall, significant differences in outflow water quality between ash and maple wood species were negligible. Results indicated that bioreactor outflows may be applicable for aquacultural reuse, though reusing outflows immediately following start-up or restarting after a dry period would not be recommended. 相似文献
2.
通过对贪食迈阿密虫(M. avidus)对4种养殖鱼类组织匀浆液的趋化特性进行研究,以探讨贪食迈阿虫对养殖鱼类的侵染特点。试验结果显示,贪食迈阿密虫对大黄鱼、大菱鲆、黄姑鱼、鲈鱼的眼、脑、脑脊液匀浆液有强烈的趋化效果(P<0.01),对皮肤黏液、鳃、肝、肌肉、肾组织匀浆液的趋化性较弱(P>0.05);对不同鱼类组织匀浆液对贪食迈阿密虫的趋化诱导差异比较结果推测,贪食迈阿密虫对宿主具有一定的选择性。本研究有助于深化贪食迈阿密虫致病性的认识,并为海水养殖鱼类盾纤虫病的预防提供参考资料。 相似文献
3.
Colorado pikeminnow (Ptychocheilus lucius) has been extirpated from a large portion of its historical range in the Colorado River basin, USA. A repatriation effort via stocking of juvenile P. lucius in the San Juan River, NM, CO and UT has resulted in limited recruitment of individuals into an adult population. Understanding biotic and abiotic factors that limit their persistence in the Colorado River basin will be a critical step in providing for their recovery. To elucidate potential recruitment barriers in the San Juan River, we assessed relationships between the numbers of two age classes of P. lucius and prey, competitors and predators collected at a 1.6 km reach scale between 2003 and 2012. We used an information theoretical approach to rank candidate models testing the relative importance of these biotic conditions in predicting the spatial distribution of P. lucius. We found positive relationships between the numbers of P. lucius ≤200 mm total length (TL) collected and catch per unit effort (CPUE) of native prey among reaches. For P. lucius >200 mm TL (individuals that are likely completely piscivorous), we found positive associations between the numbers of P. lucius collected and CPUE of total prey and CPUE of potential non‐native competitors in each reach. Our data suggest size‐specific affinities of P. lucius for native and non‐native prey as well as the potential for negative interactions between P. lucius and non‐native competitors may contribute to limited recruitment of juvenile P. lucius into an adult population in the San Juan River. 相似文献
4.
María F. Ríos Leonardo A. Venerus Paraskevi K. Karachle William D. K. Reid Karim Erzini Konstantinos I. Stergiou David E. Galvn 《Fish and Fisheries》2019,20(2):355-367
The rule of thumb in marine trophodynamics indicates that the bigger an organism, the higher its trophic level (TROPH). This generalization leads to the assumption that fishes increase their TROPH with growth. However, a recent review showed that for many species, TROPH does not increase with body size, suggesting that size‐independent feeding is not rare in marine fishes. Here, we assessed some morphological traits of marine fishes that could potentially be used as indicators for the ability to vary TROPH with body size. Stable isotope values of nitrogen were used as a proxy TROPH. The specific objectives were as follows: (a) to evaluate the relationship between the oral gape and the trophodynamic trend and (b) to quantify the relevance of 11 external morphological traits in determining the size‐based trophodynamics. We used random forest models to identify the morphological traits that would help predict which species would have the potential to increase TROPH with growth and which would have not. The selected traits included the pelvic fin relative position, the dorsal fin shape, total length, and relative mouth size. Our results also showed a marked relationship between the rate of increase in the oral gape and TROPH. The analyses presented here provide the first comprehensive and quantitative review aiming at linking the trophodynamics of marine fishes with external morphological traits. 相似文献
5.
The importance of seagrass beds and mangroves as a juvenile habitat as opposed to other shallow water habitat types is investigated using a single sampling method on four islands in the western Indian Ocean for Cheilinus undulatus, and on one island in the southern Caribbean Sea for Scarus guacamaia. Both species occur on the Red list of threatened species. Juveniles of Cheilinus undulatus were predominantly found on seagrass beds while adults were limited to the coral reef. The presence of seagrass beds resulted in significantly higher densities of the species on coral reefs in front of these habitats, indicating the importance of seagrass beds as a juvenile habitat. For Scarus guacamaia, juveniles were exclusively observed in mangroves while adults only occurred on the coral reef. Adult S. guacamaia occurred on all coral reefs along the sheltered coast of the island containing mangroves, but no relationship with distance to mangroves was observed. This could indicate the importance of mangroves for the occurrence of adults of this species on the scale of an entire island. 相似文献
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7.
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 总被引:2,自引:0,他引:2
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 相似文献
8.
分析生态对策从典型的k-选择类型到典型的r-选择类型的6类共28种淡水鱼类,用逐步判别法对这些鱼类的7项生态参数变量(渐近体长L∞,渐近体重m∞,生长系数K,初次性成熟年龄tm,最大性成熟年龄tmax,瞬时自然死亡率M,种群繁殖力系数Fp)进行挑选。结果表明,在判别鱼类的生态对策类型时,除变量Fp外,其余6项变量作用显著。根据上述28种鱼类的6项入选变量,用Bayes判别法建立生态对策判别函数估计式,并判定南方大口鲶(长江上游)、翘嘴红鱼白(长江下游)、鲥鱼(长江下游)的生态对策类型分别为“偏向k-选择类型”、“偏向r-选择类型”、“属于r-选择类型”。 相似文献
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