The Newsletter of the Center for Ocean Sciences Education Excellence - Mid-Atlantic (COSEE-MA)

North's Lab
Adapted from Erica Goldman, “A Model Scientist,” Chesapeake Quarterly, Maryland Sea Grant. (http://www.mdsg.umd.edu/CQ/V04N3/main.html)

On a warm June day beneath the waters of the Choptank River on Maryland's Eastern Shore, oysters on one of the river's last remaining reefs begin to spawn. The male's shell parts slightly and a white thread of sperm issues forth from the gap in a steady stream. Nearby, a female oyster raises her shell and brings it down with a sudden clap, a pulse of whitish eggs puffing out. She claps again. Pretty soon, neighboring oysters join in, clapping their shells in unison, turning the water milky white with maybe billions of eggs and sperm. A single female may release as many as 25 million eggs during a single spawn.

Photo Credit: Rob Honer

When the clapping subsides, the clouds disperse. The now-fertilized eggs divide again and again. Soon they sprout hairlike cilia and begin a microscopic journey. If the larvae survive tides, currents, let alone a score of predators, they will change shape and begin to make active decisions about where to swim. After two weeks, these tiny animals will begin to scout out an oyster reef on which to attach permanently and transform into adults.

How far will the larvae travel? How many will find an oyster bar on which to settle and begin adult life? How many will die before reaching one? With millions of larvae no larger than a pencil dot, answers to these questions lie beyond the reach of the human eye.

So how can one follow larvae on this unseen journey, a task critical to predict whether oyster populations can once again thrive in the Chesapeake Bay? Mathematical models may be able to take over where the eye leaves off, translating years of laboratory and field observations into equations that account for the major forces at work — currents, tides, and larval behavior.

With a few deft keystrokes, scientist Elizabeth North calls up a schematic map of the Choptank River on her computer screen — now she fills it with clouds of blue dots, simulated oyster larvae spread throughout the river. Small irregular shapes on the map represent oyster reefs, settlement targets where larvae will begin life as adults.

Photo Credit: Rob Honer

A "settle or die" oyster drama will play out over and over again on her computer as North, a biologist and mathematical modeler, runs model simulation after simulation. From her quiet, uncluttered office on the shores of the real Choptank River, at the University of Maryland Center for Environmental Science (UMCES) Horn Point Laboratory (HPL), North first gives the blue dots the behavioral traits of the native oyster, Crassostrea virginica, derived from published data accumulated over years of scientific study and recent laboratory experiments. Dr. North’s research is an integral component to the Center for Ocean Science Education Excellence, Mid-Atlantic (COSEE MA) teacher professional development workshop, “Taking the Pulse of the Ocean”, which explores the inter-relationship of coastal and ocean movement with climate and weather, transport of sea organisms and pollutants through the eyes of ocean observing systems.

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About the Scientist

Elizabeth North received her B.A. degree in 1991 from Swarthmore College in Religion, M. S. degree in 1996 from Johns Hopkins University School of Continuing Studies, Interdisciplinary Science Studies, concentration in Environmental Science, and her Ph.D. in 2001 from University of Maryland College Park, Marine-Estuarine-Environmental Science, specialization in Fisheries Science. North’s research interests include Biological-physical interactions, circulation and particle trajectory modeling, fish larvae and zooplankton ecology, fisheries population variability, estuarine and coastal physical oceanography. For more information, visit Dr. North's webpage at http://northweb.hpl.umces.edu/

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Scientists' Toolbox

For More Information:

Maryland DNR's Oyster InFocus
www.dnr.state.md.us/dnrnews/infocus/oysters.asp

Maryland Sea Grant Oyster Node
www.mdsg.umd.edu/oysters/

National Academy of Sciences Report on C. ariakensis
www.nap.edu/books/0309090520/html/

Chesapeake Bay Program Scientific and Technical Advisory Committee information on C. ariakensis
www.chesapeake.org/stac/ariakensis.html
www.chesapeake.org/stac/stacpubs.html

Spawning Stripers on Demand: Basic Research - Real World Uses
http://www.mdsg.umd.edu/MarineNotes/Sep-Oct98/index.html

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Related Education/Outreach Resources

Animations of model simulations
http://northweb.hpl.umces.edu/videos_animations/BITMAX.htm

This issue's Data Discovery activity (below) is based on the presentation “Striped bass scales and life-history tales: fish and physics in Chesapeake Bay”. An abbreviated version of the talk is available on the web at: http://northweb.hpl.umces.edu/education_outreach/education_outreach.htm

Striped Bass Fact Page
http://www.dnr.state.md.us/fisheries/education/rockfish/rockfish.html

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Data Discovery

Each issue of The Pulse brings you a Data Discovery - an educational activity that incorporates the use of real data relevant to the featured research. Based on the “Data Tips” found on The Bridge education web site (www.vims.edu/bridge), each Data Discovery challenges the user to employ inquiry and critical thinking skills to interpret and apply scientific data in a meaningful context.

This issue’s Data Discovery is a web-based activity that uses information on striped bass habitat preferences and water temperature and dissolved oxygen to understand where striped bass can be found in Chesapeake Bay. Users are asked to answer a series of questions about the potential location of striped bass by following links to monitoring programs and observing systems for recent information on physical conditions in Chesapeake Bay.

Click here to access this activity: Where could the stripers be?

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