Spawning habitat characteristics of lithophilic fish - using experimental approaches to inform river restoration

在一个以人为压力为特征的快速变化的世界中，有关环境变化对生物多样性影响的知识至关重要。河道内的河流生境退化，往往是由于过多的细沉积物污染造成的，是最常见和得到广泛研究的淡水退化形式之一，细沉积物造成产卵基质质量恶化，这与全球淡水生物多样性下降有关。尽管如此，关于许多物种的环境耐受性，特别是在其早期发育期间的环境耐受性的知识仍然有限。这是特别真实的嗜石（基板产卵）鱼类。虽然存在关于细沉积物含量（“细粉”）对某些鲑科鱼类产卵成功的影响的文献，但关于细粉和其他环境参数对其他典型非鲑科鱼类产卵的变化的影响的知识仍然有限，尽管它们在许多欧洲河流中具有生态、娱乐和社会经济重要性。这已经超越了我们对鱼类生态学的理解，如果没有更好地了解河流鱼卵和仔鱼对产卵基质特性和可变非生物参数的耐受性，我们不知道原位产卵栖息地是否有利于成功繁殖。这也意味着我们目前没有任何容易量化或可转移的方法来衡量河流恢复活动的成功（或失败）与物种特定的环境参数或阈值。此外，由于缺乏具体目标、监测后评价和/或考虑到为具体沉积问题提供背景的景观过程，一些河流恢复项目的成功有限。因此，研究，利用强大的实验设计是必不可少的了解因素，有助于成功的产卵栖息地恢复。因此，该项目旨在增加我们对一些研究不足但在生态，娱乐和经济上重要的淡水鱼类的环境耐受性的了解。此外，还将在自然环境中评估目标物种（包括倒刺鲃、小鳞鲑、褐鳟鱼、萨尔莫、灰鲸）的产卵生境、巢穴特征和自然补充水平。该项目还将调查如何改善退化的生境以提高繁殖成功率。研究将涉及在实地和实验室环境中获取实验数据。该项目将涉及一个跨学科的方法，包括以下要素：（1）利用环境署在其位于Calverton（英国伯明翰郡）的国家孵化场的循环水产养殖系统进行实验室实验，以量化一种或多种研究不足的嗜石动物的卵和幼虫的环境耐受性。可以随时间监测羽化幼虫的健身生理学和/或行为，以评估早期发育期间条件的遗留影响。(2)对产卵生境、巢的特点和目标鱼种的补充情况进行多河流研究，以便更好地了解鱼类在不同河流的何处、如何以及如何成功产卵。(3)通过野外试验研究了几种常用的产卵基质恢复技术的生态和物理效应。

In a rapidly changing world characterised by acute anthropogenic pressures, knowledge regarding the effects of environmental change on biodiversity is of key importance. Within-channel degradation of riverine habitats, often through excess fine sediment pollution, is amongst the most common and widely studied forms of freshwater degradation, with deterioration in spawning substrate quality through fine sedimentation associated with global declines in freshwater biodiversity. Despite this, knowledge regarding the environmental tolerances of many species, particularly during their early development, remains limited. This is particularly true for lithophilic (substrate spawning) fishes. Whilst a body of literature on the influence of fine sediment content ("fines") on the spawning success of some salmonid fishes exists, knowledge of the effects of fines and the variability of other environmental parameters on the spawning of other, typically non-salmonid species, remains limited, despite their ecological, recreational and socio-economic importance in many European rivers. This has consequences which transcend our understanding of fish ecology and without better understanding of the tolerances of river fish eggs and larvae to spawning substrate characteristics and variable abiotic parameters, we do not know whether in-situ spawning habitats are conducive to successful reproduction. This also means we do not currently have any readily quantifiable or transferable method of gauging the success (or failure) of river restoration activities in relation to species-specific environmental parameters or thresholds. In addition, some river restoration projects are limited in their success due to a lack of specific objectives, post-monitoring evaluation and/or consideration of landscape processes that provide the context for specific sedimentation problems. Thus, studies that utilise robust experimental designs are essential for understanding the factors that contribute to successful spawning habitat restoration. This project therefore aims to increase our understanding of the environmental tolerances of some poorly studied yet ecologically, recreationally and economically important freshwater fishes. Further, spawning habitat, nest characteristics and levels of natural recruitment of target species (including Barbel Barbus barbus, Chub Squalius cephalus, Brown Trout Salmo Trutta, Grayling Thymallus thymallus) will be assessed in the natural environment. The project will also investigate how degraded habitats might be improved to increase reproductive success.The research will involve the acquisition of experimental data in field and laboratory settings. The project will involve an interdisciplinary approach comprising the following elements: (1) laboratory experiments utilising the Environment Agency recirculating aquaculture systems at their national hatchery in Calverton (Nottinghamshire, UK) to quantify environmental tolerances of eggs and larvae of one or more poorly studied lithophiles. Fitness physiology and/ or behaviour of emerged larvae may be monitored through time to assess legacy effects of conditions during early development. (2) A multi-river study of the spawning habitats, nest characteristics and recruitment of target species to develop better understanding of where, how and how successfully fish spawn in different rivers. (3) Field experiments to investigate the ecological and physical effects of some commonly applied spawning substrate restoration techniques.