Inclusion 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 (relevant 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 quality | –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 quality (e.g. methodology); –Retracted articles |