Base and stressed ventilation rates for Leiostomus xanthurus Lacepede and Morone americana (Gmelin) exposed to strobe lights

A biomonitoring system interfaced with a microcomputer was used to monitor ventilation rates for white perch (Morone americana) and spot (Leiostomus x anthurus) under baseline and stressed conditions caused by strobe lights. T ests were conducted on light- and dark-acclimated specimens. These two estu arine species have been found to exhibit avoidance behavior to strobe light s. Potential accommodation to the strobe light stimulus was explored over a 24 h period. The biomonitoring system successfully recorded ventilation ra tes under baseline and stressed conditions. Baseline mean ventilation rates for 0.5 h intervals ranged from 1 count per minute (cpm) to 97 cpm for lig ht-acclimated white perch with an overall mean for 24 h ((x) over bar) of 4 1 cpm. Mean stressed rates ranged from 1 to 100 cpm with an overall mean of 44 cpm. Baseline rates for dark-acclimated white perch ranged from 1 to 79 cpm ((x) over bar = 35 cpm), with stressed rates from 2 to 83 cpm ((x) ove r bar = 30 cpm). Light-acclimated spot had baseline ventilation rates rangi ng from 3 to 146 cpm ((x) over bar = 42 cpm), while stressed rates ranged f rom 2 to 134 cpm ((x) over bar = 36 cpm). Mean baseline rates for dark-accl imated spot ranged from 1 to 94 cpm ((x) over bar = 40 cpm), and stressed r ates ranged from 1 to 72 cpm ((x) over bar = 25 cpm). The difference in ven tilation rates between base and stressed conditions (as absolute values) fo r light-acclimated white perch over the 24 h experiments ranged from 0 to 4 3 cpm ((x) over bar = 11.01 cpm). Dark-acclimated white perch had differenc es ranging from 0 to 78 cpm ((x) over bar = 11.13 cpm). Light-acclimated sp ot had differences ranging from 0 to 101 cpm ((x) over bar = 14.68 cpm). Da rk-acclimated spot had differences ranging from 0 to 70 cpm ((x) over bar = 20.56 cpm). Ventilation rates varied between species and among individuals within a species. Ventilation rates were generally lower for dark-acclimat ed specimens. For both species under all conditions, the base and stressed rates were significantly (P < 0.05) different during the 24 h period. Howev er, dark-acclimated specimens exhibited a more distinct difference than lig ht-acclimated specimens. The lack of accommodation to strobe light and a st ronger reaction under dark conditions indicate that strobe lights continue to offer potential as behavioral guidance systems for these species.