| 左涛,黄经献,张传涛,王俊,孙坚强.中国明对虾放流对鱼类生态位的影响.渔业科学进展,2023,44(6):30-39 |
| 中国明对虾放流对鱼类生态位的影响 |
| Effects of Chinese shrimp (Fenneropenaeus chinensis) stock enhancement on the fish niche in a mesocosm |
| 投稿时间：2022-06-14 修订日期：2022-07-08 |
| DOI： |
| 中文关键词: 中国明对虾 放流 鱼类 生态位特征 围隔 |
| 英文关键词: Fenneropenaeus chinensis Stock enhancement Fish Niche characteristics Mesocosm |
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| 中文摘要: |
| 为探究中国明对虾(Fenneropenaeus chinensis)增殖放流对水域内鱼类的影响及其表现形式，采用原位实验生态学方法，在对虾放流河道构建围隔，设置3种虾苗放流量(模拟莱州湾近岸放流5亿尾、7.5亿尾和10亿尾)和无放流处理，经过一个对虾生长季后，比较不同处理围隔中鱼类组成和生态位特征差异。结果显示，4种处理围隔中，回捕对虾数量随放流量增加而增加，但其生物量、平均个体大小和回捕率未随放流量增加而增加；回捕率在放流围隔间差异显著，以5亿尾模拟围隔的值最高；鱼的种类组成相似，可归于杂食性、浮游动物食性和鱼/虾食性。总鱼类和鱼/虾食性的鱼类产出量在围隔间差异不显著，杂食性鱼的产出量以放流围隔较高，浮游动物食性鱼的产出量随对虾放流量增加而减少。鱼种间高生态位重叠(>0.75)配对数随对虾生物量增多而减少。相似性分析显示，放流最多的和无放流围隔的鱼类生态位相异程度最高。综上认为，在实验水体中，放流对虾并不降低鱼类总量产出，但可能会影响不同食性鱼类的相对组成和生态位重叠度，且影响效应随放流量增加更为明显。 |
| 英文摘要: |
| Marine stock enhancement is not only commonly reported to amplify the target species production but also induces some potential threats or effects at multiple ecological levels in the receiving ecosystem. Studies on the interaction between released and naturally occurring organisms are necessary to avoid or minimize the adverse impacts of invasive species from stock enhancement in the receiving system. Chinese shrimp Fenneropenaeus chinensis, are an important stock enhancement species, and in recent years approximately 10 billion have been released annually into the coastal waters of China. Owing to fishing pressure and the ecological complexity of the open sea, the interaction between the released shrimp and native species may be weak and undetectable. Studies on the ecological impacts of such intensive releasing activities are limited. Therefore, in this study, an in-situ mesocosm experiment was carried out to determine if the released shrimp altered the relative composition and niche characteristics of fish, the results of which could serve as a reference to the local risk management of the species stock enhancement. The mesocosm was located in the shrimp-releasing channel of Weihe, Laizhou Bay, from April to September 2019. A cross design of four treatments with three replicates was conducted in the mesocosm. The habitats were homogenized across the replicates by mixing substrates and filtering seawater with a 0.28 cm sieve. The number of individual shrimp larvae released into net enclosures in each of the four treatments were: A) 2 400, B) 1 800, C) 1 200, and O) 0. The treatments were designed to represent the release of 1 billion, 750 million, 500 million, and no shrimp larvae (none-releasing) in the coastal waters of Laizhou Bay, respectively. The released shrimp larvae had an average body length of (1.63±0.18) cm and an average body width of (0.38±0.12) cm. At the end of the experimental period in September, shrimp and fishes were recaptured and their Levin’s niche breadth and overlap indices were examined in each enclosure. Results indicated that within the enclosures of the four treatments, the recapture rates of shrimp ranged from 8.16% to 12.69% and had an average value of 9.87%. The number of recaptured shrimp increased with the number released, and had the highest value in enclosure A. However, the total biomass, average individual mass, and recapture rate of shrimp did not show a similar pattern among enclosures. The recapture rate of shrimp was significantly different among the treatments and had the highest value in enclosure C. The fish species composition was similar across all four treatment enclosures and included six species with three different feeding habits: Omnivores (Konosirus punctatus and Liza haematocheila), zooplanktivores (Thryssa mystax and Sardinella zunasi), and fish/shrimp predators (carnivores) (Acanthogobius sp. and Sparus microcephalus czerskii). Of the fish species, Acanthogobius sp. dominated in all enclosures, while S. m. czerskii occurred in only a few. There was no significant difference in the number and biomass of total fishes and carnivorous fishes among enclosures. There were more omnivorous fishes in the released enclosures A–C, while the number of zooplanktivorous fishes decreased when shrimp were released and had the highest number and biomass in the non-released enclosure O. Moreover, fishes with different feeding habits had variable niche breadths among the four treatment enclosures. Most fish species had a wider niche breadth in enclosures with released shrimp (enclosure A–C) than in enclosure O. Both the fish´s niche overlap indices and the species pairs with high niche overlap (>0.75) decreased in the order non-released enclosure O > released enclosure B >enclosure C >enclosure A. The carnivorous fish Acanthogobius sp. had more pairs with niche overlap indices (>0.75) in the non-released enclosure O than in the other three treatments. A similarity analysis and multidimensional plot indicated that enclosures A and O could be differentiated by the relatively long similarity distance and little overlap area. The results of the experiment suggest that the shrimp recapture efficiency did not increase when shrimp were released. In the waters of the study area, released shrimp could have a positive effect on the total output of both shrimp and fish, especially for omnivorous and carnivorous fishes, as the shrimp could share predation pressure and provide food for them. In addition, the shrimp release may affect the relative composition and niche characteristics of fish by increasing their niche breadth and reducing the overlap between fishes with different feeding habits, and the impacts may be more detectable as the shrimp number increases. |
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