Scientists rarely distinguish between the unknown and unknowable because the pursuit of either creates new knowledge, and possibilities are more inspirational than limitations. Yet more than a decade after the United Nations Conference on Environment and Development in Rio and the Convention on Biodiversity , marine biodiversity scientists who gathered recently to discuss what is known, unknown and unknowable acknowledged that they will never be able to catalogue all of its species, just as nations cannot catalogue all of their citizens. The goal of attaining a complete understanding the roles and interactions of these species, both in terms of the natural and human economies of the planet, is even further out of reach. But we could (and should) know much more than we do.

Some of the limits have been technical - we have sensors that can measure temperature, salinity, currents and depth but automated biological sensors are largely limited to measuring chlorophyll. These limitations are disappearing, as the tools of genomics are applied in the ocean and the tools of informatics are developed to analyze complex assemblages of data. Some habitats, like the deep sea and open ocean, are simply difficult and thus expensive to reach. And the complexity of the webs of ocean life make prediction far more difficult than is commonly realized - predicting the weather is a far less daunting task.

Others obstacles have more to do with the sociology of science than the science itself. High tech routinely trumps basic natural history, and people who know how to identify and classify organisms are almost as endangered as many of the creatures they study. Surely, this must be the reason why our catalogue of stars in the universe is more complete than our catalogue of species on planet Earth (or more accurately, planet Ocean).

Unfortunately, the fate of life on our planet depends far more on what we know and do with that knowledge than does the fate of the stars. We have been slow to appreciate this for ocean life. Turtles hover on the brink of extinction, yet we only now are beginning to know where they go once they leave the beach. Coral reefs have declined dramatically over the last two decades worldwide, but our only estimates for the total number of species on reefs vary between one and ten million and are based on extrapolations from the numbers of insects in tropical rainforests and from counts from a tropical aquarium in Baltimore! Ongoing attempts to create a database for all of the oceans (e.g. the Census of Marine Life) will play an essential role in filling the knowledge gaps that plague our ability to document and cope with the threats to ocean life, but they are just beginning.

"A stitch in time saves nine" vs. "I'll cross that bridge when I come to it": why do we apply the precautionary principle when considering the structural viability of designs for bridges, but fail to do so when the viability of ecosystems is at stake? Underlying our tendency to gamble on nature's resiliency is our fundamental ignorance not only about the biology, but also about the economic costs and benefits of taking vs. postponing action. When contemplating setting aside a marine protected area, we rapidly calculate the short-term costs to fishers affected by the action, but often lack information to fill in the other parts of the equation, such as the long-term benefits that healthy oceans provide. We want our accountants to be "clean", but still care little if they are "green".

When faced with a problem of enormous complexity and scope, people's reactions range from apathy to activism. Most activists are born young, but many generations have passed since major social movements completely captured the passions of the young. As marine scientists who have personally seen the massive changes that have occurred in the oceans, we are partly to blame. Fisheries and with them entire ecosystems are collapsing worldwide, yet the public continues to believe that oil pollution is the greatest threat to life in the oceans. To most policy-makers, biodiversity, if it means anything at all, is about tropical rainforests, not their ocean equivalent, the coral reefs, which are equally threatened. We are also partially to blame as educators, living within the ivory tower and disparaging the efforts of students to work on real-world problems. Potential Gandhi's and Martin Luther King's of the ocean are all around us - we need to answer your emails, give you the tools needed to solve problems, and reward you for doing what we have failed to do ourselves.

      - Nancy Knowlton

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Marine Biodiversity in the Present: The Known, Unknown & Unknowable
December 6-9, 2002; Scripps Institution of Oceanography, La Jolla, California