U.S. GLOBEC: Copepod population biology on Georges Bank

Investigator: Charles B. Miller (Oregon State University)

Grant Period: 1 September 1993 - 31 August 1996

Statement of Objectives

The original project summary reads as follows:

It is proposed to participate in the management and data analysis of the GLOBEC Georges Bank Broad Scale Survey. This will include (1) work on the formation and management of the Georges Bank Plankton Technical Group (GBPTG) at Woods Hole, and (2) studies of the population biology of Calanus finmarchicus, Pseudocalanus moultoni, and Pseudocalanus newmani using the very large sample set to be collected by the Broad Scale Survey. I will be a major author of the technical handbook for the GBPTG, and will participate in data development and analysis throughout the Georges Bank Survey. In specific studies of copepods I will use the broad scale survey preserved sample set, plus specially preserved samples and subsamples, to examine aspects of C. finmarchicus and Pseudocalanus spp. life history, growth, and production biology as functions of season, temperature and stratification, location over or off the bank, food availability, and hydrography. I will apply gonad analysis of late copepodites, vitellogenesis staging of females, trithek/quadrithek evaluation of females, stage- and size- frequency analyses, molt phasing of jaws, jaw development facies indicative of diapause and lipid (specifically wax ester/triglyceride) quantification. Goals will include comprehensive estimation of secondary production by C. finmarchicus and Pseudocalanus spp. to allow comparisons among seasons, years, and sites across Georges Bank.

Statement of Work

In Year 1 the PI and project technician (Ms Cheryl Morgan) participated in the May-June 1994 Process Cruise due to the delay of Broad Scale Survey sampling until 1995. Collections were primarily taken and used for a study of storage lipid accumulation in C. finmarchicus. A data report on our lipid results has been prepared and distributed to GLOBEC PI's. A reader of this summary can get a report by writing the PI. I believe it was also scanned onto the World Wide Web. In brief:

In Year 2 the P.I. and Ms Morgan participated in seven cruises of the Georges Bank Broad Scale Survey. The first was a training cruise in November 1994. Others on the survey itself were one cruise in each month from February through July (July cruise departs Woods Hole on 10 July). The PI was chief scientist on the March cruise aboard R/V ENDEAVOR sailing from Rhode Island. In the laboratory ashore we have concentrated on (1) video and Iatroscan analysis of storage lipids in Calanus finmarchicus. Other work has been sample evaluation with emphasis on (2) the fraction of Calanus females with quadrithek antennae (see below), (3) jaw and gonad development staging of Calanus fifth copepodites (C5) as indicators of diapause and immediate maturation. None of the results is ready for distribution or entry in the Georges Bank data base. However, some preliminary results can be reported from each of these studies:

Most of the work from the end of the July cruise until the 1996 Broad Scale Survey begins will be devoted to study of sexual switching and stock division into maturing and diapausing groups at the ends of generations. We will also carry through an ovarian activity analysis for our collection of sorted females which is intended to expand the utility of egg production rate estimates produced by Dr. Jeffery Runge on the Georges Bank Process Study cruises. Our intention to work extensively with Pseudocalanus, as well as Calanus, has run aground on our inability to distinguish the two species known to be living on and around Georges Bank: P. moultoni and P. newmani. We can't even distinguish the adults of either sex on a reliable basis. The small urosomal hairs whose length distinguishes these species are too frequently rubbed off for reliable ecological work based upon them. After substantial effort to acquire a "gestalt" by which the species might be distinguished, we have given up. We await a molecular probe, although that may not allow sufficient counting to be ecologically useful.

The PI and project technician (to be appointed; Ms Morgan intends to quit on 15 August) will participate in all 1996 Georges Bank Broad Scale Survey cruises. We strongly urge NSF and NOAA to sustain the intention to field a Broad Scale Survey in both 1996 and 1997. The continuity of our time series will be extremely valuable to the study of Calanus, as well as to the group effort on cod and haddock. In any case we will continue to work on aspects of later life history in Calanus finmarchicus. We will work on Pseudocalanus biology as opportunities present themselves.

Finally, a peripheral effort is intended to illuminate distributional data for C. finmarchicus adults when it becomes available. This is a study of how copulation is accomplished in Calanus spp. Apart from demonstrations that pheromones are important in copulation, the mechanics are unknown. Using a 1.3 m plankton "Kreisel", the PI and Dr. Atsushi Tsuda of the University of Tokyo have succeeded in observing the male search patterns and mode of approach to females.