An in situ video camera for plankton studies:design and preliminary observations

A design for an In sltu v ~d e o camera for plankton observations 1s presented A hght weight alununium rig supports a video camera 1~1th an opposing stroboscope which produces dark field images of plankton >O 3 mm In the present configuration the camera can be used down to 100 n~ and provides video images of 10 to 40x magnificat~on when vlewed on a 1 4 (ca 35 cm) monitor Video recordings iron1 the field show moderate aggregations of small copepods to the subsurface fluorescence maximunl and at times indications of honzontal patchiness The large copepod Calanus finrnarchlcus was found to aggregate 5 m below the fluolescence maximum at night In cornpansons with a traditional WP-2 plankton net, the video camera p ~o v l d e d simllar length frequency distnbutions whlle abundance estimates from video recordings were 10 to 20% hlgher than net estimates It is concluded that the presented video camera offers excellent observations of the pelagic environment at a n affordable cost KEY WORDS.Fine