Submitted to: Agricultural Research Service Publication
Publication Type: Other
Publication Acceptance Date: 1/27/2012
Publication Date: 1/27/2012
Citation: Smiley, P.C., Allred, B.J. 2012. Influence of wetland type, hydrology, and wetland destruction on aquatic communities within wetland reservoir subirrigation systems in northwestern Ohio. Agricultural Research Service Publication. Technical Report #ECO-2012-1. Interpretive Summary: A novel agricultural water recycling system (i.e., WRSIS - wetland reservoir subirrigation system) implemented in the Midwestern United States results in the creation of two types of agricultural wetlands (WRSIS treatment wetlands and storage reservoirs). Yet, WRSIS design and management guidelines currently focus on water quality and/or subirrigation strategies for agricultural production and design and management criteria for ecological benefits are lacking. We examined the influence of wetland type, hydrology, and wetland destruction on aquatic communities within WRSIS in northwestern Ohio. Differences in physical habitat, amphibian abundance, and species composition between WRIS wetlands and reservoirs suggest the potential for WRSIS wetlands to provide habitat for different suite of aquatic vertebrates than the reservoirs. Annual and daily hydrology measurements suggest that it is feasible to alter the hydrology of WRSIS wetlands. Reductions in fish abundance following draw downs within WRSIS wetlands suggest planned draw downs will be effective in eliminating fishes from WRSIS wetlands and may promote amphibian colonization. Predicted changes in aquatic communities following wetland destruction suggest that WRSIS with treatment wetlands having amphibians may be severely impacted by wetland destruction than WRSIS with fish dominated treatment wetlands. We used this information and developed design and management criteria for these small treatment wetlands that will improve the ability of this water recycling system to provide habitat for aquatic vertebrates that have been impacted by wetland destruction as a result of agriculture. This information can be used by state, federal, and private agencies involved with creating agricultural wetlands to assist them meeting their conservation and restoration goals.
Technical Abstract: Establishment of an agricultural water recycling system known as the wetland reservoir subirrigation system (WRSIS) results in the creation of two different types of wetlands adjacent to agricultural fields. Each WRSIS consists of one treatment wetland designed to process agricultural contaminants (WRSIS wetlands) and one storage wetland for holding subirrigation water (WRSIS reservoirs). Previous WRSIS related research focused on the filtration ability and development of aquatic plants within WRSIS wetlands. The fauna of the storage wetlands and how their aquatic community structure compares with treatment wetlands is unknown. We sampled physical habitat, water chemistry, aquatic vertebrates (i.e., fishes, amphibians, reptiles) from WRSIS treatment and storage wetlands within three WRSIS in northwestern Ohio from 2006 to 2009. Our objectives were to address the following research questions: 1) Is there a difference in aquatic habitat, water chemistry, and aquatic communities between wetland types created by WRSIS?; 2) Does hydrology differ among the three WRSIS treatment wetlands?; 3) What is the impact of water level draw downs on aquatic communities in the treatment wetlands?; and 4) What is impact of destroying treatment wetlands on overall species diversity and community structure of aquatic vertebrates within WRSIS? Mean water depths and water surface area were greater in storage wetlands than treatment wetlands. Turbidity and total phosphorus were the only water chemistry variables that differed between wetland types. Turbidity and total phosphorus were greater in treatment wetlands than storage wetlands. Percent amphibians were greater in treatment wetlands than storage wetlands and species composition differed between wetland types. Annual and daily hydrology measurements indicate that the temporal variability in hydrology differed among the three treatement wetlands. Draw downs within treatment wetlands were observed to influence aquatic community structure and reduce fish abundance, but the degree of influence of draw downs appeared to be altered by management actions that facilitate fish colonization. Our assessment of the impacts of wetland destruction indicated that decreases in species richness, decreases in amphibian occurrence, and changes in species composition occurred only within WRSIS with treatment wetlands dominated by amphibians, but no differences occurred within the fish dominated WRSIS. Our results provide information that can be used to develop design and management criteria for WRSIS that will improve the ability of this agricultural water recycling system to provide habitat for aquatic vertebrates within agricultural landscapes.