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 Unear 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 

 ix filtered 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 

 naupUi 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 v/ith 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 

 vidth an "800 nm" interference filter and 22 mm diameter diaphram (Figure 



274 



