Salinity shapes food webs in lakes: a study of 24 lakes in a semiarid region, xingjian north west china

NICOLAS VIDAL; JINLEY YU; MARÍA FLORENCIA GUTIERREZ; FRANCO TEIXEIRA DE MELLO; ÜLKÜ NIHAN TAVSANOGLU; AYE IDIL ÇAKIROGLU; HE HU; MARIANA MEERHOFF; ZHENGWEN LIU; ERIK JEPPESEN

Maringá

Congreso; XV Congresso Brasileiro de Limnologia; 2015

Sociedad Brasilera de Limnología

A runoff reduction and higher evaporation rates are projected toward 2050 for arid and semiarid regions of the world; resulting in a reduction of water level and salinization of inland waters. Besides natural processes of catchment erosion, human activities such as irrigation of crops may also increase salinization. Reduction of biodiversity in freshwater systems is the most common reported effect of salinization, which may have implications for food web structure and likely for the ecosystem functioning. The objective of the study was to analyze the effect of salinity on the community and food web structure in 24 lakes along a wide salinity gradient, from freshwater (0.5 gL-1) to hypersaline lakes (115 gL-1) in a semiarid region in North West China. Fish, zooplankton and macroinvertebrate communities were sampled for structure and stable isotopes analysis during July 2014. Base on the stable isotope data we calculated the food web Layman metrics: total area (TA), nitrogen range (NR), carbon range (CR), centroid distance (CD), mean nearest neighbor distance (MNND) and standard deviation of the nearest neighbor distance (SDNND) and also trophic position for each community and for entire food web. We found a significant decline in the number of taxa of all communities analyzed and a reduction of the food web complexity with the increase of salinity. Accordingly, the metrics used to describe the entire lake food web, all of them were negatively related with salinity, however, when we examined the food web of each sampled community, the effect was not significant, implying that despite of the community species reduction this was not reflected at the trophic diversity. The potential negative impacts of salinity increase under a global change scenario are discussed.