World Ocean Census - Extract 1 - The light zone and the dark zone
4 December 2009
First amazing extract from The World Ocean Census: A global survey of marine life: The Light zone and The Dark zone
The Light Zone
Drifters and Swimmers
The foundation of life on land is the photosynthetic activity of plant life. Similarly, the foundation of ocean life is the photosynthetic activity of “plants” in the sea: phytoplankton, photosynthetic bacteria and algae. Phytoplankton, comprising almost 95 percent of total marine productivity, live in the top 200 meters (660 feet) of the global ocean, where they find the sunlight needed to photosynthesize. Phytoplankton are consumed by diverse populations of zooplankton, which are dominated by species of crustaceans called copepods. The Census of Marine Zooplankton (CMarZ) is attempting a global-scale analysis of all marine zooplankton species, using new and emerging technologies that include molecular, optical and acoustical imaging, and remote detection.
The light zone is also home to large swimming animals that travel across ocean basins. Scientists are learning about these animals through tagging and real-time tracking. A Census field project, Tagging of Pacific Predators (TOPP), is working with marine animals to create a view of the vast open-ocean habitats as seen by the animals themselves. The travels of top predators are especially intriguing. TOPP scientists have tagged 23 species – more than 2,000 animals – from albatross to albacore tuna to elephant seals and squid.
The Dark Zone: Mid-waters and Bottom Waters
The challenge of investigating the dark zone – water below 200 meters (660 feet) – was undertaken by the multinational group of researchers who formed the Mid-Atlantic Ridge Ecosystems Project (MAR-ECO). Their goal was to explore and understand the distribution, abundance and trophic (food) relationships of the organisms inhabiting the middle and deep waters of the mid-oceanic North Atlantic.
A multidisciplinary trans-Atlantic team of researchers has used ships and submersibles to carry out investigations between Iceland and the Azores. One two-month investigation in mid-2004 along the mid-Atlantic Ridge was the most comprehensive survey of this realm to date, both qualitatively and quantitatively. Sampling yielded 45 to 50 squid species (two potentially new to science) and 80,000 fish specimens, many of which are thought to be new to science, or at least new to the North Atlantic. The team is leading efforts to extend this new technology to other ocean basins.
Text and images reprinted with permission from World Ocean Census: A Global Survey of Marine Life by Darlene Trew Crist, Gail Scowcroft and James M. Harding Jr., Firefly Books, 2009