Field Sampling/Technology Working Group Report

Chairman: Rick Pieper
Rapporteur: Ed Cohen

A key aspect of the discussions of the Field Sampling/Technology Working Group was the importance of recognizing that after an initial period of intensive ship based survey work (i.e., for sea truth) time series data from moored instruments could largely replace ship surveys. There are data to suggest that time series from moored arrays will maintain the ability to detect and assess population changes while being much less intensive of both capital and labor than large scale ship surveys. It was felt that moored instruments could provide both short term high resolution data and longer time scale records indicative of global change.

The organization of the sampling and technology section followed largely from the deliberations of the zooplankton group. The zooplankton group's plan for proposed research is composed of Mesoscale Surveys, Process Studies and Moored Instruments for time series measurements. The areas discussed by covered technology (extant, almost ready and necessary but non-existent) for surveys, rates and moorings.

9.6.1 Mesoscale surveys

Available gear for assessing the distribution and abundance of zooplankton and fish include MOCNESS, bug counter, acoustic (multifrequency, dual beam and acoustic doppler current profilers (ADCP)), silhouette photography and image analysis, and sonar for fish schools. Further development of optical systems for assessing distribution and abundance and feeding interactions (e.g., "critter cam") was highlighted as a fruitful area for further development.

The group felt that additional development of biotechnology for marine science was necessary. A primary area of interest was biotechnology related to assessing feeding rates and identifying food items. Another area for biotechnological applications is the use of genetic markers in stock structure and in studying "survivors" in recruitment studies. Physical oceanographic instrumentation of interest for mesoscale surveys included acoustic Doppler current profilers (ADCP) and CTD arrays in conjunction with fluorometers, transmissometers, light and other optical sensors.

9.6.2 Moorings

Most of the discussion centered on technology related to moorings, because of the great potential for moorings in time series measurements. The types of instruments envisioned encompassed hydrographic, biooptical, bioacoustic, and passive and active biological samplers.

Existing instruments include CTDs with fluorometers and transmissometers, the moored dual beam echosounder (BIOSPAR), which has been tested in a lake, and ADCPs.

In the "almost ready" category the group considered the usefulness of bioacoustic instruments including multifrequency acoustics, a "bug counter", low frequency acoustics for fish schools, multi-element split beam acoustics and broad band acoustics. Some of these instruments already exist but are not yet available for deployment on a mooring. Optical instrumentation and video image analysis are two areas where significant gains could be realized. Another area of interest were active samplers on moorings. This could include a programmable plankton pump and tidally driven samplers for plankton and moored egg samplers.

An area of potentially great usefulness is the development of 3D acoustic imaging (which could be deployed on a mooring or as part of a survey or process study). A system called "Fish TV" (FTV) is in the early stages of development.

9.6.3 Process Studies

There was very little instrumentation specific to process cruises, i.e., most of the instruments have already been mentioned in conjunction with surveys and moorings. There are, however, areas where new technology and methods are sorely needed, particularly with respect to rate measurements, e.g., egg production, development, growth and mortality of all stages. There is also the necessity for the development of Lagrangian drifters. Particularly acute is the need for "smart drifters" that can be programmed to mimic the diel vertical migration of fish larvae or zooplankton. The development of MOCNESS systems which include acoustics, optics and "bug counters" is also an area for further development.

The Working Group felt that satellite and other remote sensing methods (e.g., AVHRR and CZCS) should be an integral part of any GLOBEC field program. The possibility of using side scan sonar and submersibles for investigations of the benthic boundary layer and benthic pelagic coupling is desirable.

Benthic specialists on the Working Group made a special request for new technology using fluorescent or other tags for real time identification and enumeration of meroplankton.

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