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

of the state of the scientific literature focussed specifically on the use of farm dams and the relationships between their structure, condition, management, and their value for biodiver- sity conservation. The development of an effective conservation strategy for human-made habitats requires the examination of appropriate sampling methodologies, study duration and size, taxonomic group coverage, publication year and the country in which the study was conducted. Studies with longer durations can provide insight into the effects of ecologi- cal dynamics over time while a larger sample size may provide more statistically robust results [38,39]. The inclusion of a wide range of taxonomic groups in a study allows for a more comprehensive understanding of ecological dynamics [39]. Publication year is a potential indicator of the most recent developments in the field and whether the research takes those into account [40]. Knowledge about the country where the study was conducted can illuminate the framework of local culture, social, economic and political factors which may influence the local conservation strategies. It is important to consider these factors to develop more informed and effective conservation strategies to address the challenges facing conservation in human-made habitats. This study aims to critically examine research on farm dams to identify themes that may assist in the development of policies and programs in support of biodiversity. In conducting this review, our goals were to: quantify the literature investigating biodiversity in farm dams,

highlight the major knowledge gaps in biodiversity in farm dams, and identify possible ave- nues to overcome these gaps. We asked the following questions to guide our review: 1. What are the characteristics of conservation-focused research on farm dams (e.g., sample size, study duration, taxonomic group coverage, publication year, and country of study)? 2. Which taxonomic groups are studied, and which biodiversity metrics are used to quantify these groups at farm dams? 3. What are the ecological variables used to predict the biodiversity values of farm dams (e.g., vegetation cover, and water quality)? 2. Methods 2.1 Multi-stage process–empirical review Adhering to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we conducted a systematic review of the farm dam literature using a three-stage process (Fig 1). The first stage involved using the databases “Clarivate Web of Science” and “Scopus” to search for peer-reviewed publications that measured ecological variables on farm dams. In each database, we adapted the search to account for syntax differences and include any words shown in Table 1 representing a farm-related context (e.g., TITLE-ABS-KEY- WORD (farm* OR agriculture*) with the words shown in Table 1 representing a waterbody (e.g., TITLE-ABS-KEY (dam* OR pond* OR tank*). The two search engines grouped the arti- cles into research areas, enabling us to exclude articles from fields which were not relevant for the purpose of our study, such as aquaculture and hydropower. Studies with an ecological

objective that addressed agricultural production, water quality, vegetation or biodiversity were retained. The search was run on September 19th, 2023, and identified a total of 7,995 papers that met our search criteria. For the second stage of the review, two independent researchers, distinct from the team of co-authors, alongside the author, screened the titles and abstracts of 7,995 articles with the R statistical language program “revtools” [41], identifying articles focused on biodiversity objec- tives in farm dams (Table 2). PLOS ONE The ecological and biodiversity conservation values of farm dams PLOS ONE | https://doi.org/10.1371/journal.pone.0303504 May 13, 2024 3 / 18