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A Diverse Makeup

Marine invertebrates that live on the ocean bottom are organisms that have complex life cycles. They spend their adult life moving, at best, only very small distances. Many reproduce by releasing sperm and eggs into the water where fertilization occurs and embryos are produced. As the microscopic larvae develop, they get carried by currents and eventually (if they don’t starve, get eaten, or transported away from suitable areas)
return to the ocean bottom and attach themselves in the parental habitat.

A bit of a biology lesson, but one with great importance, especially when considering the overall health of the world’s oceans. Biodiversity is important to the ocean’s overall balance. Because the marine environment and its components are interconnected, loss of a species can have far-reaching and long-lasting impacts.

Dalhousie’s Dr. Anna Metaxas is one of about 65 researchers (Dalhousie has 10 in all) from 15 universities who makeup the Canadian Healthy Ocean Network (CHONe). The network addresses a pressing need for scientific data to ensure proper conservation
and the sustainable use of Canada’s ocean resources.

Metaxas leads the “Population Connectivity” theme which examines the role of dispersal of early life stages in diversity patterns and in population resilience to disturbances. She is specifically considering the role of larval dispersal in maintaining existing populations of marine invertebrates and repopulating extirpated ones.

“We are removing species at a far faster rate than natural selection would. We have a role to protect marine species, not drive them to extinction,” says Metaxas, who also earned her PhD from Dalhousie’s Biology Department. “In order to protect them, we must first understand how these organisms maintain their populations.”

For example, marine protected areas may prove ineffective if the life cycle complexity of the invertebrate species is not taken into consideration. “You might close a certain area to fishing, but in fact it may not be an area that serves as a source of recruits.”

Studying invertebrate dispersal and connectivity will provide baseline information against which future changes in the oceans can be monitored and understood. This is critical to the sustainable management of the country’s ocean biodiversity resources.

Reproduced from
OutFront Magazine: Research that Matters
Fall/Winter 2009/10 - vol. 4 no. 1