Eligibility criteria | Exclusion criteria |
---|---|
Population (unit of study)a | |
Lotic fresh waters anywhere in the world Mesocosms made to mimic lotic freshwater systems | Lentic or non-fresh waters (wetlands, lakes, reservoirs, ponds, oceans, estuaries) |
Exposure (environmental variable to which population is exposed) | |
Exposure to total nitrogen (TN) or total phosphorus (TP) measured as concentration (e.g., mg/L) | Exposure only to other nutrients, or nitrogen and phosphorus not reported as TN or TP |
Comparators (control or alternative intervention) | |
Comparison to sites or treatments with lower or higher levels of TN or TP across a gradient Comparison to control group (no or background TN or TP) or to lower or higher levels of TN or TP in experimental studies | Studies of single sites (without sampling across time) or those without comparison to lower or higher levels of TN or TP |
Outcomes (eligible outcomes resulting from exposure) | |
Concentration of benthic or sestonic chlorophyll a, measured as mass per area or volume (e.g., µg/cm2, mg/m2, µg/L) | Studies examining only TN or TP with no data on biological responses Studies examining other biological effects |
Study type | |
Experimental studies in mesocosms or field sites Field-based, observational studies | Studies examining only TN or TP with no data on biological responses Studies examining only biological effects other than chlorophyll a |
Publications (types of sources used) | |
Study must contain original data Study must contain sufficient detail on methodology to assess study validity | Articles with no original data (e.g., editorials, reviews) Articles without sufficient information to evaluate pertinent relationships (chlorophyll a response to TN or TP) or study validity (e.g., methodology) Retracted articles |