MOTION BEHAVIOR OF NAUPLII AND EARLY COPEPODID STAGES OF MARINE PLANKTONIC COPEPODS

The goal of this study was to quantify periods of activity and velocit ies of late naupliar and early copepodid stages of planktonic copepods occurring regularly on the southeastern continental shelf of the USA. We obtained quantitative information on eight species, including adul t females of Oithona plumifera. All studies were conducted at food con centrations near or above satiation levels. Activities ranged from 0.8 5% (adult females of O.plumifera) to 100% of time (nauplii and copepod ids of various calanoid species). Motion velocities (excluding escape motion) covered more than one order of magnitude: from 0.39 mm s(-1) f or nauplii of Temora stylifera to 5.24 mm s(-1) for nauplii of Oncaea mediterranea. Ranges of activities of species range from occasional fo r early juveniles to adult females of O.plumifera to 100% for the same range of T.stylifera, the latter creating a feeding current from N II I onwards the former not at all. Of notable interest is Centropages ve lificatus which moves intermittently as a late nauplius, continuously as an early copepodid and intermittently as an adult. All observed cal anoid late nauplii and copepodids move in three dimensions, excluding copepodids of the shelfbreak/oceanic Paracalanus aculeatus. The result s indicate not only significant differences in motion behavior between cyclopoids and calanoids, but also between calanoid species. Yet, som e calanoid species show little ontogenetic changes at all.