Effects of macroconsumers on benthic communities across a gradient of vegetation loss in tropical karst streams

No effects of macroconsumer exclusion on macroinvertebrate functional composition in Brazilian karst streams along a gradient of riparian forest loss

“…The regional watershed hydrology is characterized by spring-fed, clear-water streams that drain into the Pantanal wetland with complex surface and sub-surface networks of flow-path connectivity and high levels of calcium carbonate (Sallun Filho & Karmann, 2007). The region has experienced increasing rates of land-use change over recent decades, particularly from native forest conversion for monocultures and cattle grazing that can increase soil erosion and nutrient inputs during high-flows (Chiaravalloti et al, 2022;Corrêa et al, 2018Corrêa et al, , 2019Roque et al, 2016;SOS-Pantanal et al, 2017).…”

“…Experimental exclusion of macroconsumers and measurement of physical and chemical parameters were performed in a large 500 m long pool located between upstream and downstream at each sampling site. Concentration of total nitrogen and phosphorous in the study streams measured in June 2015, respectively, ranged between 1.87-0.85 μg/L and 0.179-0.102 μg/L (see Corrêa et al, 2019 in Tables S1, for more details).…”

“…. The additions of riparian resources are important because fish, aquatic insects, decapod crustaceans, and tadpoles often play an important trophic role in consuming and altering these and other benthic food resources (Barnum et al, 2022;Corrêa et al, 2019;Crowl et al, 2001;Usio, 2000).…”

“…Previous empirical research conducted in the Bodoquena Plateau, a karst region in the central west of Brazil bordering the Brazilian Pantanal wetland, demonstrated that aquatic and terrestrial insects responded idiosyncratically to a gradient of riparian vegetation loss among karst streams (Roque et al, 2017). Corrêa et al (2018Corrêa et al ( , 2019 showed that the experimental exclusion of macroconsumers had no detectable effect on the composition of aquatic insects and the stream ecosystem. Here, to supplement previous analyses, we evaluated if the experimental exclusion of macroconsumers along the gradient of vegetation loss affected the benthic macroinvertebrate community structure by FFG using the data from Corrêa et al (2019).…”

“…Corrêa et al (2018Corrêa et al ( , 2019 showed that the experimental exclusion of macroconsumers had no detectable effect on the composition of aquatic insects and the stream ecosystem. Here, to supplement previous analyses, we evaluated if the experimental exclusion of macroconsumers along the gradient of vegetation loss affected the benthic macroinvertebrate community structure by FFG using the data from Corrêa et al (2019). Based on the general expectations that (i) taxa with certain functional traits can be affected by local environmental variables; (ii) the functional structure of the macroinvertebrate communities varies in relation to the land-cover patterns, especially the loss of riparian vegetation (Poff, 1997;Poff et al, 2006;Southwood, 1977;Townsend & Hildrew, 1994;Vannote et al, 1980;Wallace et al, 2015); and (iii) the simultaneous effects of macroconsumers and riparian vegetation control the abundance and distribution of the FFG macroinvertebrates (Espinoza-Toledo et al, 2021), we hypothesized that the effect of macroconsumers on the FFG macroinvertebrate abundance would vary along the riparian vegetation-loss gradient.…”