Hot and Cold> UM scientist uses sky-high technology to predict ebb, flow of ocean life

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Who would have thought you’d have to go into space to understand life in the ocean?

But that incongruity becomes evident in the swirling, multi-color satellite image of the Gulf of Maine on Andrew Thomas’ computer screen.

Thomas, a biological oceanographer and associate professor at the School of Marine Sciences at the University of Maine, is using satellite infrared readings of surface water to discover how temperatures affect organisms in the Gulf.

His newest line of research, not surprisingly, is with lobsters, a study he is doing in conjunction with Robert Steneck, a professor of oceanography at the university, and Lewis Incze, a scientist at Bigelow Laboratory for Ocean Sciences in Boothbay Harbor.

Preliminary findings from the Penobscot Bay suggest that satellite data measuring surface water temperatures could be used to predict the rate at which lobster larvae settle to the bottom of the ocean. Surface water temperature is believed to play a large part in how and when the baby lobsters settle and grow into adulthood in six to eight years.

While nothing can be done about altering the ocean’s temperature, understanding a link between surface temperature and lobster propagation could help the industry in predicting harvests and micromanaging the gulf’s stock.

Satellite imagery of ocean temperatures is a relatively new area of study, coming into its own only in the early 1980s, Thomas said. Meteorologists had seen the possibilities of tracking weather via satellite in the late 1960s and began measuring cloud temperatures.

Oceanographers began wondering if the science could be applied to the ocean surface as well as clouds. But the practical application of the new “satellite oceanography” was slow in developing.

“The data is quite complex, quite bulky,” Thomas said. That requires computer programs that parse and interpret a vast amount of digital data, technology that is relatively new. The data is then converted into images on a map of the gulf, with gradations of color representing different degrees of temperature.

“I’m a very visually oriented guy,” Thomas said. “So even though I really like biology, I’ve been pulled into satellite technology.”

Four times each 24 hours a satellite belonging to the National Oceanic and Atmospheric Administration passes over the Gulf of Maine scanning for temperatures. And during each of those arcs the satellite dish atop Libby Hall at the Orono campus downloads over a billion digital bytes of data.

It’s a quantum leap from the old method of measurement: get in a boat, motor to a given point, drop in a thermometer, write down the temperature, move to the next point. Obviously, simultaneous measurements are not possible with this method, which means a snapshot of the gulf’s temperature is incomplete.

Not so with satellite imaging. “There are not enough people in this field to analyze all this data,” Thomas said.

The question underpinning most of Thomas’ scientific queries is straightforward: Can we monitor the ocean and see how its changing temperatures, or variability, affect biological life?

“Fishermen will often tell you, `Things are different this year,’ but there’s never been a way of quantifying those perceptions,” Thomas said.

Although NOAA and NASA had been archiving satellite data on the Gulf of Maine for years, no one had actually analyzed it, Thomas said. When he joined the faculty three years ago, the university encouraged him to undertake the project because “it’s in our back yard.”

Thomas now has high-quality data for 1985 through 1997, and he and graduate students continue to process information daily.

That data has shown that temperatures in the gulf vary from year to year by 1 to 2 degrees Celsius. Warm currents from the south and cooler currents from north generally meet along the bottom half of the Maine coast, but the division shifts from year to year. Anomalous patches of cool or warm water sometimes show up for extended periods.

Thomas is participating in the Penobscot Bay Marine Resources Collaborative, which began in 1996 and brought together nine research and marine resource organizations for a thorough surface-to-bottom study of Penobscot Bay.

Thomas is working directly with Steneck and Incze, the lobster scientists, to investigate whether surface temperatures could be used as a predictor for lobster populations. Over his years of research, Steneck has maintained counts of lobster larvae that have settled to the bay’s floor. The number of larvae found in any given area, in any given year, varied.

According to Steneck, scientists believe that surface water temperatures directly affect the rate of lobster settlement to the floor. When the upper six inches of water is cool — which is where the babies live after birth — fewer make it to the floor. It is believed warmer temperatures increase the settlement rate.

Over the years of his research, Steneck has taken population samples during different years at various sites in the bay. Thomas matched three year’s of Steneck’s samples with the pinpoint satellite data of the same sites.

Preliminary data show that in 1994, a year in which Steneck found high rates of settlement, the surface water was warmer than average, according to satellite readings. Conversely, surface waters were cooler than average in 1996, and settlement was weak.

“But three years is not enough to really say anything,” Thomas cautioned. “It’s pointing to something but we need more data.”

“We’re actually getting pretty good at predicting harvest by looking at settlement,” Steneck said. “What Andy’s doing is pushing the envelope to tell where you’ll have good settlement in the first place.”

The satellite readings could eventually be a valuable link in accurately forecasting how many mature lobsters could be harvested in any given area. Thomas likens it to weather forecasting: “We can’t change the weather, but it sure helps to know when a hurricane is coming.”

For the past three years Thomas has also handled the satellite-image portion of a New England-based project studying toxic algae blooms in the Gulf of Maine, specifically Alexandrium tamarensis, which causes red tides. When the algae proliferate near shore, they emit a toxin that contaminates clams and mussels, prompting harvest restrictions for large sections of tidal flats.

The project has already made a significant discovery when it learned that toxic algae exist not only near the coast line, but also quite far out at sea.

Red tides occur less frequently in the Penobscot Bay area than to the areas north and south, Thomas said. He and others are now investigating what part surface temperature variability might play in this anomaly.

“My personal hope is that the linkages between the red tide and satellite pictures will be a quick, easy way to predict when red tide is coming to the shore,” he said.