Installation of plankton nets on the remotely operated vehicle ROPOS

Most invertebrate organisms that live on the bottom of the ocean, such as mussels, worms, crabs, sea urchins, and sponges, have complex life cycles. As adults, they live and feed on the bottom, but as embryos they develop into larvae in the water column, where they may spend periods of few hours to months, dispersing by currents. After they mature, larvae move near the bottom, attach to it and, following a sequence of morphological and physiological changes, turn into juveniles. These juveniles look, and live on the bottom, like young adults. The number of new recruits that return to the adult populations greatly depends on the number of larval survivors. In the described research programs, we try to understand the factors that affect larval survival and dispersal in all habitats, including the deep-sea. One measure that we need to collect is the abundance of larvae in the habitat of interest, typically very near the ocean bottom (within 5 m). In the deep-sea, the best way to sample the near-bottom habitat with accurate reference to biological and geological features is by using submersible remotely operated vehicles, such as the Canadian owned and operated ROPOS. Given their low abundance in deep-sea environments, the most effective sampling tool for collecting sufficiently large numbers of larvae is by towing nets that filter large volumes of water in short periods of time. In this proposal, we are requesting funds to install a system of plankon nets on ROPOS. With this equipment, we can sample larvae from near-bottom, deep-sea habitats regardless of topography and in reference to specific features on the ocean floor.