The ecological and biodiversity conservation values of farm dams: A systematic review

for various aquatic species. Additionally, our findings indicate a notable focus among research- ers on exploring the impact of physical characteristics and management practices of dams on biodiversity. We found species richness and abundance to be among the frequently used response variables across ecological studies, with water quality and vegetation being com- monly used predictor variables. Our risk of bias assessment also revealed a noteworthy propor- tion of studies exhibiting a "high" risk of bias. This highlights the need for improved methodological rigor and transparency in future research to ensure reliable evidence for effec- tive conservation strategies.Ecological studies vary in length depending on the research ques- tion, the study design and the duration of the ecological phenomena being studied. This has resulted in a body of literature ranging from a few days to many decades. Most of the studies within our review collected data over periods of less than two years. These short-term studies are important for providing snapshot results; however, long-term studies provide valuable insights into the dynamics and processes of ecosystems over extended periods of time, identi- fying patterns, trends, and fluctuations that may not be apparent in short term studies to be identified [49]. More funding for long-term ecological studies is required to sustain long-term data collection, equipment, and personnel costs, provide access to new advances in technology, prepare for unforeseen disruptions and leverage the importance of long-term data in conserva-

tion and management decisions [50]. We identified trends in the geographic and temporal distribution of research on farm dams. For example, there is a growing focus on understanding the ecological and conservation implications of farm dams, with the number of studies on the biodiversity values of farm dams increasing significantly in recent years. However, the location of studies revealed that most research has been conducted in more affluent regions, such as Europe (n = 45), potentially resulting in a biased understanding of the global ecological importance of farm dams. Further- more, the research highlights unique regional conservation and management challenges, such as the presence of non-native species [51], construction configuration and different hydrologi- cal regimes [52]. This information can not only highlight regions that require additional research efforts but identify opportunities for collaboration between conservation research groups in these different regions. Integration of production and biodiversity conservation is increasingly recommended as a management approach to improve the sustainability of agricultural systems [53]. However, we found only a small number of studies examined how agricultural outcomes (e.g., livestock use) were influenced by the physical characteristics of dams, such as the influence of vegetation cover on water quality. Furthermore, only one article, a review [54], considered both conserva- tion and production outcomes. The limited number of studies considering both biodiversity

and production values of farm dams highlights the need for more research across disciplines and the need to engage landholders to co-design and test interventions that enhance both pro- duction and biodiversity values. One way to address this shortcoming could be to prioritize funding schemes that emphasize collaboration between ecological and agricultural researchers as well as landholders and managers. Ecological research on farm dams has predominantly focused on the physical characteris- tics of dams and the surrounding landscape. Vegetation and water quality can be relatively eas- ily measured, manipulated, and recorded and are widely known to contribute to biodiversity. Larger dam size and higher vegetation cover and complexity are important predictors of biodi- versity, while water quality is crucial for both biodiversity and production outcomes [55]. However, highly vegetated dams are sometimes perceived as a hindrance to agricultural pro- duction [16] and improving water quality can involve trade-offs such as increased labour and potential water loss from evaporation through changes in the chemical composition and sur- face tension of water [56,57]. PLOS ONE The ecological and biodiversity conservation values of farm dams PLOS ONE | https://doi.org/10.1371/journal.pone.0303504 May 13, 2024 11 / 18