How does behaviour underpin the impact of invasive tilapia on native fish?

入侵物种对淡水群落结构产生巨大影响，是生物多样性丧失的主要来源。与入侵潜力相关的生理、形态和生活史特征已被广泛研究。然而，入侵物种和本地物种如何通过行为相互作用却很少被记录，特别是在观察行为有问题的水生栖息地。作为一种经济实惠的动物蛋白来源，使用尼罗罗非鱼的水产养殖在整个热带地区呈指数级增长;然而，其传播与野生种群在其原生范围外建立以及随后对原生鱼类组合的负面影响有关。许多这些负面影响被假设为介导的行为：尼罗罗非鱼被认为是竞争性地排除本地鱼类的庇护所（暴露本地鱼类更大的捕食风险），竞争本地鱼类的食物，和他们的觅食行为减少大型藻类丰度和增加水浊度。尽管这些影响有一些证据，例如来自行为实验室研究的证据，但观察和量化它们在自然系统中发生的程度仍然是难以捉摸的。该项目将在坦桑尼亚的中型生态系统和实地使用配备水下摄像机的人工避难所，以前所未有的细节量化尼罗河罗非鱼（热带淡水生态系统中越来越成问题的入侵物种）与本地慈鲷鱼物种之间的相互作用。

Invasive species have a huge impact on the structure of freshwater communities and are a major source of biodiversity loss. Physiological, morphological and life history traits that are associated with invasive potential have been studied extensively. How invasive and native species interact through behaviour, however, has rarely been documented, particularly in aquatic habitats where observing behaviour is problematic. Aquaculture using Nile tilapia Oreochromis niloticus is growing exponentially throughout the tropics as an affordable source of animal protein; however, its spread is associated with feral populations becoming established outside its native range and subsequent negative effects on native fish assemblages. Many of these negative effects are hypothesised to be mediated by behaviour: Nile tilapia are believed to competitively exclude native fish from shelters (exposing native fish to greater predation risk), outcompete native fish for food, and their foraging behaviour reduces macrophyte algae abundance and increases water turbidity. Despite some evidence of these effects, e.g. from behavioural laboratory studies, observing and quantifying the extent to which they occur in natural systems has remained elusive. This project will use artificial shelters equipped with underwater cameras in mesocosms and at field sites in Tanzania to quantify in unprecedented detail the interactions between Nile tilapia, an increasingly problematic invasive species in tropical freshwater ecosystems, and native cichlid fish species.