The relative influence of nutrients and habitat on stream metabolism in agricultural streams

Abstract

Stream metabolism was measured in 33 streams across a gradient of nutrient concentrations in four agricultural areas of the USA to determine the relative influence of nutrient concentrations and habitat on primary production (GPP) and respiration reach. When data for all study areas were combined, there were no statistically significant relations between gross primary production or community respiration and any of the independent variables. However, significant regression models were developed for three study areas for GPP (r 2 = 0.79-0.91) and CR-24 (r 2 = 0.76-0.77). Various forms of nutrients (total phosphorus and area-weighted total nitrogen loading) were significant for predicting GPP in two study areas, with habitat variables important in seven significant models. Important physical variables included light availability, precipitation, basin area, and in-stream habitat cover. Both benthic and seston chlorophyll were not found to be important explanatory variables in any of the models; however, benthic ash-free dry weight was important in two models for GPP.

Agricultural Best Management Practice Abundance and Location does not Influence Stream Ecosystem Function or Water Quality in the Summer Season

“…The average metabolic rates of the 12 streams in our study exhibited a range of 0.88-35. . Although the maximum rates of GPP and ER from our study sites are almost two-fold higher than rates from Bernot et al [46] and Frankforter et al [47], this difference may be attributed to the shallow (mean = 0.14 m) and relatively slow moving (mean = 0.05 m/s) streams assessed in our study. Shallow depths are associated with increased light availability and associated primary production at the streambed in all areas of the stream [48].…”

Generalized Linear Models to Identify Key Hydromorphological and Chemical Variables Determining the Occurrence of Macroinvertebrates in the Guayas River Basin (Ecuador)

“…Anthropogenic alteration of flow regimes, such as dam constructions, can affect aquatic organisms since they cannot tolerate rapid changes in flow [4]. Agricultural areas often show nutrient enrichment in rivers [4,5], which can increase the biomass of algae. This condition will consequently cause a decrease of oxygen levels in the water and alter the habitat of aquatic organisms [5].…”

“…Agricultural areas often show nutrient enrichment in rivers [4,5], which can increase the biomass of algae. This condition will consequently cause a decrease of oxygen levels in the water and alter the habitat of aquatic organisms [5]. Moreover, disturbed areas also show higher nutrient transport in the rivers compared to forested watersheds [6].…”

Water Quality Degradation of Krivaja Watercourse

“…Biološki i biohemijski procesi su u ovakvim eutrofnim ekosistemima veoma intenzivni što često kao posledicu ima smanjivanje količine rastvorenog kiseonika, a na kraju i preovlađivanje anaerobnih nad aerobnim procesima. Naročito je nepovoljna interakcija ovakvog stanja sa povišenom temperaturom vode tokom letnjih meseci kada u stajaćim i sporotekućim vodenim ekosistemima eutrofikacija može biti veoma ubrzana (Chambers et al, 2006;Frankforter et al, 2010;Yu et al, 2012). Uznapredovali procesi eutrofikacije se negativno odražavaju na kvalitet i upotrebljivost vode ali imaju i druge ekološke, meliorativne i hidrotehničke efekte kao što su: remećenje uslova tečenja vode u vodotoku, povećanje hidrauličkih otpora, smanjenje propusne moći, nagomilavanje plivajuće, flotantne, vegetacije u zoni vodoprivrednih objekata što izaziva teškoće i zastoj u njihovom radu, itd.…”