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

within the literature, we extracted the following information from 104 papers: 1) the year of publication, the duration of the study, and the precise location (latitude/longitude or region), (2) the number of farm dams in the study and the target taxon (if any), and (3) the defined research goals or objectives. To ensure meaningful conclusions, this review focused only on research which fulfilled the aforementioned criteria. 2.1.1 Bias assessment. We performed a comprehensive bias assessment focusing on eco- logical fallacy, confounding variables, data validity and reliability, temporal issues, and geo- graphical boundary generalizations. The goal of this assessment was to critically assess the potential sources of bias and limitations across the 104 papers selected for inclusion. Each of the included papers underwent a thorough bias assessment using the standardised scoring sys- tem provided by the Cochrane Collaboration’s Risk of Bias Tool [42]. This resulted in each study being assigned an overall result ranging from low to high. Notably, for a paper to receive a "high" overall ranking, it is judged to be at high risk of bias in at least one domain, or there may be concerns across multiple domains that substantially lowers confidence in the result. 2.2 Research questions 2.2.1 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)?. We used data collected during the third stage of the review to identify trends in the

farm dam literature. We created five categories (“Study Type”, “Taxon”, “Predictor Variable”, “Response Variable”, and “Location”). For example, the category “Study Type” was broken into groups such as “Observational”, “Interventional”, “Long-term”, “Short-term”, and each article was accordingly assigned one or more of these labels (S1 Appendix). Predictor and response variable categories were comprised of a combination of similar variables measured in each paper e.g., the “Dam characteristics” category included variables related to dam configu- ration such as “Construction design”, “Construction year” and, “Surface area”. We used the R package ggplot2 [43] to create a heatmap of the data, i.e., a matrix where each entry shows a colour corresponding to the prevalence of articles in a given category. Each heatmap was then used to visualise variation across multiple combinations of two of the data categories [Study Type, Response Variable, Predictor Variable, Taxon] to display patterns of associations. All 104 articles were evaluated for: 1) duration of study, 2) number of waterbodies, 3) tar- geted taxonomic groups, and 4) the nature of the sampling methodology, distinguishing between observational and interventional methods. For the examination of global farm dam research over time, survey dates and region were extracted for each study at the level of detail provided by the study and then categorized into year, country, and continent. 2.2.2 Which taxonomic groups are studied and which biodiversity metrics are used to

quantify these groups at farm dams?. We conducted a detailed evaluation of farm dam papers with biodiversity objectives (n = 104) to identify variables influencing patterns of biodi- versity. We read each paper and recorded the ecological response variables measured, for example species richness. Biodiversity can be classified and measured in several ways depend- ing on the landscape, ecosystem, or habitat subject to evaluation [44–47]. We identified and recorded the taxonomic groups and biota examined in each article, encompassing a range from amphibians, birds, and macroinvertebrates to include invasive and predatory species such as fish and crayfish. Articles that focused on more than one group were recorded across all relevant taxa. We also identified and recorded the “biodiversity metric” (e.g., species rich- ness, abundance, and occurrence) used to measure the biota studied. Heatmaps were produced to visualise patterns of association between the groups of biota that articles examined, and the biodiversity metrics used to quantify those groups. PLOS ONE The ecological and biodiversity conservation values of farm dams PLOS ONE | https://doi.org/10.1371/journal.pone.0303504 May 13, 2024 6 / 18