Littoral macroinvertebrates are an integral component of lake food webs, but their productivity may be affected by shoreline alteration. We hypothesized that human modification of lake shores simplifies habitat diversity, which, in turn, affects littoral macroinvertebrate production and patterns of depth–production relationships. Furthermore, we expected that lakeshore modification would favor nonnative species, potentially compensating for negative effects of lakeshore modification on production of native taxa. To test these ideas, we estimated benthic macroinvertebrate production in the upper littoral, middle littoral, and profundal zones of a large lowland lake (Lake Scharmützelsee) in Northeast Germany. We collected samples between April and November 2011 along depth transects established at both natural and modified shorelines. We found that production in the upper littoral zone was significantly lower at beaches than natural shores or marinas, but no difference existed between natural shorelines and marinas. The substantially lower production at beaches was correlated with lower habitat diversity, resulting from a lack of macrophytes. Additionally, production declined with increasing water depth at natural shores and marinas, but at beaches, production was highest in the middle littoral zone. Production of native taxa was lower at marinas than at natural shorelines, but production of nonnative species offset these declines. The increased productivity of nonnative species in upper littoral habitats at modified shorelines demonstrates that shoreline development has compromised the function of the littoral zone in Lake Scharmützelsee. Extrapolating depth- and habitat-specific production estimates to the entire lake showed that 33% of whole-lake benthic secondary production occurred in the upper littoral zone, even though this depth zone comprised only 7% of total lake area. Additionally, we estimated that completely replacing natural habitats with beaches would reduce whole-lake benthic secondary production by 24%. Our results highlight the crucial role of the littoral zone for whole-lake ecosystem functioning and the high susceptibility of littoral benthic secondary production to lakeshore modification by human activities.
& Brauns, M.
(2018). Lakeshore Modification Reduces Secondary Production of Macroinvertebrates In Littoral But Not Deeper Zones. Freshwater Science, 37 (4), 845-856.