Among medusae, only the narcomedusae, coronates and 

 Deepstaria were restricted as groups to deeper water. There was 

 evidence of vertical migration in narcomedusae, but not in the 

 other mesopelagic medusae. Both physonect and calycophoran 

 siphonophores were widely distributed as groups, although 

 Apolemia and the unknown red physonects were seen only below 

 700 m. Many surface-living lobate and cestid ctenophores were 

 found to be eurybathyal in distribution, but the truly 

 mesopelagic genera, including red cyddipids, were seen only below 

 300 m. Larson et al. (1988a) report a broadly similar vertical 

 distribution for gelatinous organisms in waters off New England. 

 They rarely saw medusae above 600 m, but found siphonophores and 

 ctenophores to be widely distributed. Two unidentified species 

 of pigmented cydippid ctenophores, perhaps like the ones we 

 collected, were seen only below 550 m. 



The abundance of crustaceans seen from a submersible is 

 always affected by their attraction to the lights. However, 

 estimates of depth distribution based on shallowest and deepest 

 sightings are probably fairly reliable. We found a clear pattern 

 of diel vertical migration for the euphausiids and sergestids, 

 but amphipods and copepods were patchily distributed day and 

 night . 



Although we were unable to conduct experiments in attraction 

 and aggregation from the midwater platform, observations from the 

 submersible showed that the time-course of attraction to a light 

 source can be quantified and expressed in the same way as 

 attraction to bait (St. Marie and Hargrave, 1987). During the 

 second and third years of this project, we plan to make more use 

 of moored lights and baits in midwater to study the dynamics of 

 attraction and aggregation. 



The distribution of the "red fauna" between about 700 m to 

 the bottom at 900 m was the most distinct discontinuity we 

 observed. With representatives from all the zooplankton taxa, 

 this group does not appear to migrate, and is presumably limited 

 to this depth range by one or more common factors. The red-to- 

 brown pigmentation suggests that obscurity in the blue-green 

 ambience of bioluminescence is of primary importance to this 

 entire community. 



Our field work in 1987 has confirmed our belief that in-situ 

 observation and documentation is essential to understand 

 mesopelagic animals and the processes which bind them into a 

 community. With further field time in the oceanic environment we 

 hope to develop more specific models of the distribution, trophic 

 roles and behavioral patterns of the midwater zooplankton and 

 micronekton. 



303 



