Uses of American Water-willow (Justicia americana) by Reservoir Fishes and Invertebrates in Lake Conroe, Texas.
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Water-willow (Justicia americana) is popular in fish habitat improvement projects because of its ease of establishment and relative resistance to herbivory by grass carp (Ctenopharyngodon idella). However, the response by the lentic fish community to water-willow establishment has not been well documented. This study uses 9.32m^2 plots of water-willow established by Texas Parks and Wildlife Department in Lake Conroe, Montgomery County, Texas. Three replicates were randomly selected for each category of plant patch diameter within the plot (bare substrate, small, medium, and large) in each of four consecutive seasons. Plots were block netted then electrofished exhaustively to capture fish inside the block net. A 0.5-m diameter plankton net was used to simultaneously collect representative samples for macroinvertebrates in the water column and on plant stems and to calculate patch stem density. A 3.8-liter benthic sediment sample was collected where the plant stems were removed. Macroinvertebrates and fish were identified to the lowest practical taxon to determine assemblage structure. Fish were identified to species, weighed to the nearest gram, and total length was measured to the nearest mm and stomach contents were examined. Fish size composition, relative weight (Wr), and stomach contents were compared for each species across water-willow stand categories and season. Results show that biodiversity and total abundances of both fish and macroinvertebrates within water-willow sites was greater than in un-vegetated control sites. Water-willow patch size and stem density had little impact on sport fish Wr and length frequency distributions.
O'Hanlon, Ryan Christopher (2016). Uses of American Water-willow (Justicia americana) by Reservoir Fishes and Invertebrates in Lake Conroe, Texas.. Master's thesis, Texas A & M University. Available electronically from