We collected fishes and macroinvertebrates seasonally from eight headwater streams in three different drainage basins (the Red, Calcasieu, and Sabine rivers) crossing Peason Ridge Training Area in west-central Louisiana. Peason Ridge is part of the Fort Polk military training facility. We used multivariate analyses to test the effects of physical variables (i.e., current velocity, depth, and substrate), time (seasonal variability), drainage basin, and military training activities on assemblage structure. Tributaries of the Red River had the highest gradient and were predominated by shallow, swift-flowing runs with sandy substrates. Southern tributaries of the Calcasieu and Sabine rivers were of lower stream gradient and contained deep, sluggish runs and pools with large amounts of woody debris and silt. Fish assemblages were structured primarily by military training and drainage basin. Faunal differences among drainage basins probably reflect differences in stream gradient. Fish assemblages in tributaries of the Sabine River were less diverse and showed evidence of historical degradation. Macroinvertebrate assemblages also were structured primarily by military training but had a strong seasonal component related to their short life cycles and high seasonal turnover. In contrast to fishes, macroinvertebrate assemblages were similar among drainages. Because military training was most intense in the Red River basin, its significance in these models probably represents differences in stream gradient among the basins because we found no negative effect on stream biota resulting from current training activities. Rather, historical logging and the resultant siltation coupled with isolation of populations by reservoirs are probable explanations for the changes in fish assemblages in tributaries of the Sabine River.
The coppernose bluegill (CBG) Lepomis macrochirus purpurescens is a bluegill subspecies that is native to Florida. The CBGs and their hybrids are of interest as potential food fish. Our objectives were to (1) develop an osmolality activation curve for CBG sperm, (2) determine suitable cryoprotectants for the cryopreservation of CBG sperm, and (3) demonstrate the ability of cryopreserved CBG sperm to fertilize eggs. Sperm were stripped from mature CBGs (mean Ϯ SD ϭ 113 Ϯ 35 g, n ϭ 10), diluted in Hanks' balanced salt solution (HBSS; osmolality ϭ 300 mosmols/kg), and stored at 4ЊC. An activation curve was generated by exposing the sperm to solutions prepared by serial dilution of HBSS with de-ionized water. The sperm remained inactive at osmolalities above 265 mosmols/kg. Dilution below 115 mosmols/kg was required for complete activation. The motility of sperm stored in these solutions was estimated at 24-h intervals. Stripped sperm motility (mean Ϯ SD) declined from 90 Ϯ 7% initially to 26 Ϯ 11% after 6 d of storage at 4ЊC. Motility of sperm from crushed testes declined from 80 Ϯ 8% at collection to 28 Ϯ 10% at 1 d of storage. By day 5, motility of sperm from crushed testes was 9 Ϯ 9%; no motility was observed at 6 d. Sperm were exposed to 10% concentrations of the cryoprotectants dimethyl acetamide (DMA), dimethyl sulfoxide (DMSO), and methanol (MeOH), and motility was evaluated at 15min intervals for 60 min. Initially, motility was 81 Ϯ 11% for the control sperm. At 60 min, motility was 0% for DMA, 30 Ϯ 24% for DMSO, 78 Ϯ 10% for MeOH, and unchanged for the control. For samples frozen in a controlled-rate freezer (CRF), post-thaw motility was 26 Ϯ 10% for samples with 10% DMSO and 51 Ϯ 18% for
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