Please join the Great Lakes Center for a seminar presented by Dr. Knut Mehler from the Desert Research Institute, NV. The seminar is titled “Understanding effects of changes in land use, environmental parameters, and habitat characteristics on the benthic macroinvertebrates in the Walker River, Nevada” and will be held on Wednesday, December 4th from 3:00 to 4:00 pm in the Classroom Building, Room B309.
The Walker River, NV, has been undergoing dramatic alterations over the past decades due to groundwater withdrawal, water diversion and changes in land use. Natural and anthropogenic changes in land use result in nutrient fluxes to the system which may be affecting the benthic macroinvertebrate (BMI) community composition and benthic food web dynamics by altering the availability of chemical key elements and by changing the habitat characteristics.
Two approaches were used to better understand effects of habitat characteristics and longitudinal changes in land use on BMI’s in the Walker River. Firstly, food web theory through elemental imbalance between food sources and consumers is used to explain whether the impact of human activities can be identified using BMI’s and their food sources. This is done by understanding where and when consumers may be limited by essential elements which in turn are reflected by consumer diversity, both in terms of taxonomic richness and functional feeding group (FFG) variety. Secondly, we analyzed benthic communities, the river environment, and their seasonal and inter-annual shifts using biotic indices, indicator species analysis and canonical correspondence analysis.
While the elemental composition of BMI was related to taxonomic identity and feeding mode, the elemental composition of their potential diet was explained by the percentage of urban and agricultural areas, and forested land in the watershed. Consumer-resource imbalances indicate that certain species and FFG’s may be more prone to changes in the region and it is suggested that they can be used as bio-indicators. The community composition of BMI’s changed along the gradient of environments and was positively correlated to substratum and stream width, and negatively correlated with stream temperature, total suspended solids and organic pollutants.
Results from this study imply that an increase in discharge and a reduction of water temperature and nutrients would improve river conditions and concomitantly benefit the diversity of aquatic communities. It is also suggested that further studies should be dedicated to the area to identify river reaches that are more vulnerable to ecosystem degradation, before setting restoration goals.
Dr. Mehler is a candidate for the Research Scientist position to work on a project “Investigating Lake Sturgeon habitat use, feeding ecology and benthic resource availability in the lower Niagara River” funded by the Ecological Greenway Fund for 2014-2017.
