Species richness–phosphorus relationships for lakes and streams worldwide

Abstract

23Aim: We investigated the patterns of autotrophic and heterotrophic relative species 24 richness along a total phosphorus (TP) concentration gradient. The relative species richness -25 TP relationships were calculated separately for four different regions [(sub)tropical, xeric, 26 temperate, and cold] and two types of water bodies (lakes and streams). 27 Location: Global 28Methods: Using data from peer-reviewed articles reporting the occurrence of 29 freshwater species at specific TP concentrations, we determined the species richness along a 30 TP gradient. Using log-logistic regressions, we then estimated the TP concentration at which 31 the potential decrease of relative species richness (RSR) equals 0.5 and the slope at which the 32 decrease occurs (β). The RSR is given as the ratio of species richness to maximized species 33 richness along a TP gradient. 34Results: The RSR of streams generally decreased more rapidly than that of lakes with 35 increasing P, as illustrated by the steeper slope of the log-logistic functions for streams (β lakes 36 < β streams ). Although there was no consistent trend between autotrophs and heterotrophs in the 37 different regions, we found that the TP concentration at which the RSR equals 0.5 was lower 38 in cold regions (0.04 -0.22 mg P/L) than in warmer regions (0.28 -1.29 mg P/L). 39Main conclusions: The log-logistic relationships between RSR and TP concentration 40 vary considerably among regions of the world, between freshwater types (lakes and streams) 41 and between species groups (autotrophs and heterotrophs). This variability may be attributed 42 to differences between the two freshwater types in respect to their species groups and 43 evolutionary patterns, nutrient demand, biogeochemical and hydrologic processes. We were 44 not able to derive log-logistic regressions for all combinations of freshwater type or species 45 type and region [e.g., (sub)tropical lakes]. For other areas, our results can be used to assess 46 the potential impact of phosphorus eutrophication on freshwater biota. 47 3

Modelling spatially explicit impacts from phosphorus emissions in agriculture

“…The response of organisms to increased phosphorus levels was investigated without taking interactions with other stressors into account (Azevedo et al 2013b). In particular, nitrogen has been reported to be equally essential for primary production as phosphorus (Elser et al 2007).…”

“…Impact pathways for depletion of phosphate rocks, a source for phosphorus, exist since a long time (Brentrup et al 2002). The impacts on biodiversity were considered in this study based on recently developed effect factors (Azevedo et al 2013b). But there is currently no methodology available to assess the impacts of phosphorus scarcity on human health as a consequence of limited food production and malnutrition.…”

“…Its persistence in the water bodies is described by spatially explicit fate factors (FF in days; Helmes et al 2012) while the effect factors (EF in m 3 / kg P; Azevedo et al 2013b) describe the potential decrease in relative species richness due to the P concentration in freshwater. The product of the FF and the EF define the characterisation factors (CF in days m 3 / kg crop), and multiplying the CF in turn by the EE results in the impacts (I in days m 3 / kg crop):…”

“…The model implemented in ReCiPe (Goedkoop et al 2013) was recommended by the European Commission (JRC 2011). Helmes et al (2012) calculated global spatially explicit fate factors of P describing its residence time in the aquatic environment which is mainly affected by advection and Azevedo et al (2013b) derived the corresponding effect factors relating P concentration to potential decrease in relative species richness or the potentially not occurring fraction (PNOF, dimensionless) (Azevedo et al 2013a) which can be set equal to the potentially disappeared fraction (PDF) commonly used for assessing impacts on ecosystem quality (Azevedo et al 2014). The product of these fate and effect factors (that is, the characterisation factors) is available at a resolution of 0.5° within the LC-IMPACT project (LC-Impact 2014).…”

GLOBIO-Aquatic, a global model of human impact on the biodiversity of inland aquatic ecosystems

“…Another approach are the ecological assessment methods derived at the European-scale (Moss et al, 2003;Penning et al, 2008;Verdonschot and Nijboer, 2004 and others), which derived indicator species for certain disturbance factors. Azevedo et al (2013) related relative species richness for several biotic groups to total phosphorus concentrations in lakes and streams worldwide. Although methods and indicators differ, these studies also support a decrease of biodiversity at higher nutrient levels.…”