Limnologists collect and analyze samples of surface water, wastewater and groundwater throughout Iowa. This requires examining the physical, chemical and biological characteristics and processes of aquatic systems and their watersheds. The data from their work is used to assess long-term trends in water quality throughout the state.
Staff are based in both the Hygienic Laboratory's Coralville and Ankeny facilities. They devote most of their time to sampling Iowa's surface waters (usually rivers and streams) and evaluating both water quality and the impact of human activity. The environmental specialists in the Limnology section are among the very few taxonomic experts in the Midwest who identify, describe and classify organisms.
- Limnology staff collected and analyzed monthly samples from 76 ambient stream sites. This was significant because nitrogen-containing herbicides, and chloroacetanilide parent compounds and their environmentally persistent ethane sulfonic acid (ESA)/ oxanillic acid (OXA) degradates were added to the analysis this year.
- During the year, staff developed the ability to identify the family chironomidae ("midges," small flies whose larval and pupal stages are mainly aquatic) to genus and species. This rather complicated procedure requires the removal and identification of morphological (form and structure) characteristics of the organism's head capsule, and is only performed by a limited number of biologists in the Midwest. The resulting data is a valuable resource to the Iowa Department of Natural Resources as it seeks to develop statewide biological criteria to aid in determining, maintaining and improving water quality in Iowa.
- The Limnology section completed approximately 80 statewide bioassessments. These assessments generally require several staff members per site to complete the sampling of water, fish and benthic macroinvertebrates, and a comprehensive physical habitat assessment.
- Sampling selected coldwater streams in northeast Iowa and warm water streams in south central Iowa for nutrient analysis proved a considerable workload that was completed by the section. Three streams in northeast Iowa and three streams in the Rathbun watershed in south central Iowa were sampled twice monthly for nutrient parameters (nitrogen and phosphorus forms), pore water analytes and stream flow. Continuous monitoring of temperature and dissolved oxygen using data loggers was also required for these stream sites. A full bioassessment was completed at each site in addition to the nutrient monitoring activities.
Overall sample load in the Limnology section increased 3.4 percent from fiscal year 2012 to fiscal year 2013. The number of samples for identification of aquatic organisms to the lowest practical taxon increased by 68.5 percent.