Macroinvertebrate relationships with water temperature and water flow in subtropical monsoon streams of Central China: implications for climate change

Abstract

Effects of global climate change on freshwaters are still poorly known, particularly in systems where they interact with other environmental variables. Using data from a subtropical monsoon stream in Central China, we assessed the relationships between a macroinvertebrate community and variations in temperature and water flow. We then used these data to assess potential changes under different climate change scenarios. Winter macroinvertebrate abundance and richness decreased with increasing water temperature during the last six years. However, effects of climate on biotic metrics in summer were less clear. Partially constrained ordination revealed that variations in community composition could not be explained clearly by individual climatic variables, but total dissolved solids and total nitrogen were more important. Over the period 1978-2008, average annual air temperature in the study area increased by 0.6 degrees C, whereas total annual water flow declined. Projections suggest that further winter warming of 1 degrees C could decrease the macroinvertebrate abundance and richness by 11.1 % and 6.0 %, respectively. One unit increase in the smoothed sea surface temperature (SSST) during winter could increase the abundance and richness by 38.2 % and 21.1 %, respectively. With further global change effects likely in future, our data highlight the importance of the conservation of mountainous streams in the upper Yangtze River.