How do natural changes in flow magnitude affect fish abundance and diversity in temperate regions? A systematic review protocol

We conducted a systematic review on the impacts of natural causes of variation or changes in flow magnitude (resulting from climatic variability and broad‐scale drivers such as climate‐induced change) on fish abundance and biomass in temperate regions. Following our systematic review protocol (Birnie‐Gauvin et al., 2021), we examined commercially published and grey literature originally identified during a recent systematic map process (Rytwinski et al., 2020) and a systematic search update. Articles were screened using an a priori eligibility criteria, with consistency checks performed at the title and abstract, and full text screening stages. All eligible articles were assessed for study validity. A narrative synthesis included all available evidence (300 studies from 219 articles), and meta‐analyses (1863 datasets from 193 studies) were conducted where appropriate. Most studies were conducted in the United States (65%) on genera in the Salmonidae and Leuciscidae families (29% and 28%, respectively), and mainly investigated variation in flow magnitude, followed by droughts and floods. We found that fish abundance and biomass responses to changes in natural flow magnitude were mainly negative, but analyses do not support clear generalizable signals across all contexts (e.g. types of changes in flow magnitude, taxa, locations). When exploring reasons for heterogeneity in effect sizes, we found a detectable effect of intervention type on average fish abundance within the first year of the natural change in flow magnitude, with floods and droughts associated with overall negative responses. However, these patterns were more variable when considering between‐year variation or specific taxonomic responses. Our results suggest that while immediate responses were more apparent and relatively consistent within specific types of natural events, fish populations may recover after such events (i.e. ≥2 years post‐natural event); however, most studies were short in duration (<2 years) and longer‐term effects were more variable and may be context dependent. To improve our understanding of species‐specific and population‐level effects, as well as time‐lags in fish responses to natural changes in flow regimes, standardized, long‐term continuous monitoring both before and after a change in flow magnitude are needed to address knowledge gaps. Studies that focus on systems outside North America are recommended.

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Section: Introductionmentioning

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How do natural changes in flow magnitude affect fish abundance and biomass in temperate regions? A systematic review

Rytwinski

Lin

Harper

et al. 2023

How do natural changes in flow magnitude affect fish abundance and diversity in temperate regions? A systematic review protocol

Birnie‐Gauvin

Rytwinski

Harper

et al. 2021

Self Cite

1. Natural flow regimes play important roles in maintaining the ecological integrity and diversity of aquatic ecosystems. Wildlife has adapted over time to the natural dynamics of their environment, including changes in flow regimes. Changes in flow, including changes in magnitude, frequency, duration, timing and rate of change, may affect the physical characteristics of aquatic habitats, access to habitats, food availability, population dynamics and community composition.2. Given the importance of natural flow regimes for fish, it is necessary to understand the extent to which natural flow regimes alter fish abundance and diversity. Here we present a protocol for a systematic review that will estimate how fish abundance and diversity are affected by natural variation (resulting from climatic variability and broad-scale drivers such as climate-induced change) in flow.3. This systematic review will use evidence published before 2016 that was identified in a recent systematic mapping exercise on the broader topic of flow regime change impacts (both natural and anthropogenic) on direct outcomes of freshwater or estuarine fish productivity. An updated English language search will be performed using six bibliographic databases, Google Scholar and networking tools to include commercially published and grey literature that has been published after 2016. Eligibility screening will be conducted at two stages: title and abstract, and full-text. We will include all studies that evaluate the effect of natural changes in flow magnitude on fish abundance (broadly defined to also capture density and biomass metrics) and species diversity (broadly defined to also capture species richness and composition metrics). Any freshwater or estuarine fish species in temperate regions will be considered. 4. Included eligible studies will be assessed for study validity. We will extract information on study characteristics, intervention/comparator details, measured outcomesThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

What is the effectiveness of methods for eradicating or controlling abundance and biomass of invasive aquatic plants in Canada? A systematic review protocol

Harper,

Rytwinski,

Irvine

et al. 2024

Invasive freshwater aquatic plants can have adverse ecological effects on the systems to which they are introduced, changing ecosystem function, threatening native plant species and causing billions of dollars in damage to infrastructure. Additionally, once established, invasive aquatic plants are often difficult to eradicate or control. Given the importance of managing invasive aquatic plants, and the high associated economic costs of doing so, it is essential to determine the relative effectiveness of different control methods. Here, we present a protocol for a systematic review that will estimate the effectiveness of various biological, chemical, habitat manipulations and/or manual/mechanical methods for eradicating or controlling invasive plant abundance and biomass. This systematic review will use published and grey literature, without date restriction, that determines the effectiveness of invasive plant control methods. English‐language searches will be performed using five bibliographic databases, Google Scholar, and networking tools to find relevant literature. Eligibility screening will be conducted at two stages: (1) title and abstract and (2) full text. Studies that evaluate the effectiveness of methods for controlling the abundance or biomass or eradicating invasive plants will be included. A list of plant species currently, or potentially, in Canadian freshwater systems and of management concern will be considered. Included studies will undergo critical appraisal of internal study validity. We will extract information on study characteristics, intervention and comparator details, measured outcomes (abundance and biomass, broadly defined) and effect modifiers (e.g., plant growth pattern or timing of treatments). A narrative synthesis will be used to describe the quantity and characteristics of the evidence base, while quantitative synthesis (i.e., meta‐analysis) will be conducted to estimate an overall mean and variance of effect when sufficient numbers of similar studies are available.