behavioral responses to pollutants would represent a potentially significant 
field of study; however, devising a means to easily record and rapidly quantify 
swimming and other responses of small larvae has limited efforts in this 
direction (8, 12, 17, 24). 
Development of the Bugsystem at this laboratory has provided the 
technology to rapidly analyze the swimming patterns of large sample numbers 
of organisms of a wide size range (Wilson & Greaves, this volume, report 17). 
With this potential we are presently investigating the use of behavioral 
bioassays for marine larvae. The following results represent initial studies using 
larvae of common barnacle species. 
EXPERIMENTAL 
The spontaneous locomotory activity for second stage nauplii of four 
barnacle species ( Balanus amphitrite amphitrite, B. improvisus, B. venustus, 
Chthamalus fragilis ) was investigated. Of primary concern in this initial study 
was the mean linear velocity (MLV) of sample groups and changes in MLV 
induced by water temperature, light regime, and 24 hour exposure to sublethal 
copper levels. 
Source of Larvae 
Second stage Balanus nauplii used in all experiments were released from 
adult barnacles maintained at 20 ± 2°C, constant illumination in 30-32°/oo, 1 
p fdtered seawater from Narragansett Bay. Balanus amphitrite and B. 
improvisus were initially collected near Georgetown, South Carolina, and 
maintained under the above laboratory conditions 2-12 weeks prior to larval 
release. B. venustus adults were collected in Narragansett Bay; adults released 
larvae within two weeks after capture. Chthamalus fragilis nauplii, also from 
Narragansett Bay, were obtained from ripe egg masses incubated for 24 hours 
at 20°C. In some copper experiments, stage II nauplii were reared to later 
stages on a mixed algal diet of Tetraselmis suecia and Thalassiosira pseudonana . 
Methods of maintaining laboratory populations of barnacles and rearing of 
nauplii are further described by Lang (13, 14). 
Video Recording 
To obtain video tapes of swimming patterns for Bugwatcher analyses, ca.30 
nauplii were placed in 25 ml beakers with a water depth of about 10 mm. The 
beaker with nauplii was put within a cylindrical flat black metal lenshood (light 
shield) attached to a 72 mm diameter #25 deep red glass filter (Figure 18-1). 
This complex was centered upon a Wild M-5 dark Field illumination stage Fitted 
with an “800 nm” interference filter and 22 mm diameter diaphram (Figure 
274 
