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Title: Recording fathometer techniques for hydrilla distribution and biomass studies
Authors: University of Florida. Institute of Food and Agricultural Sciences.
United States. Army. Corps of Engineers. Jacksonville District.
Aquatic Plant Control Research Program (U.S.)
Shireman, J. V.
Macéina, Michael J. (Michael John), 1954-
Keywords: Aquatic plants
Aquatic plant control
Biological control
Lake Baldwin
Lake Orange
Lake Pearl
White amur
Grass carp
Hydrilla verticillata
Plant density
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Miscellaneous Paper
Abstract: Quantitative vegetation parameters are presented to calculate hydrilla cover and biomass. It is recommended that several of these parameters be utilized to describe hydrilla relationships in a lake. Predictive equations were formulated for the three study lakes and it was concluded that the independent values taken for biomass did not indicate similar relationships in each lake. Differences in subsurface light intensity, water chemistry, and substrate types may cause differences in hydrilla growth patterns which are not detectable with the fathometer. Plant density appears to be a major variable in determining plant biomass using fathometer tracing characteristics. Further investigations to determine the relationship of plant density at various depth intervals and different bodies of water should be incorporated into the current equations to improve predictive capabilities. Studies were conducted to document temporal changes in white amur and native fish populations and aquatic plant distribution associated with the introduction of white amur. White amur capture techniques including electroshocking, block netting, gill netting, and haul seining were investigated in Lake Baldwin. Although white amur were collected by all methods, none was considered effective. Two distinct white amur size classes were evident. Hydrilla consumption rates were determined for Lake Baldwin white amur. Effective control was obtained with 185 kg fish per ha of hydrilla. Native fish were collected with both block nets and electrofishing gear. Small forage fish were dominant and harvestable sport fish composed a small percentage of total fish biomass. The data, however, indicate that Lake Baldwin has a harvestable bass population of 30.5 kg/ha. Condition factor analysis of largemouth bass, bluegill, and redear sunfish indicates that condition values are lower than the national average and are related, to some extent, to the amount of hydrilla present.
Appears in Collections:Miscellaneous Paper

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