He Takes to the Water:
Marine Ecologist Mark Butler is Busy Protecting Lobsters, Crabs, Sponges and Coral

By Jim Raper

Old Dominion University marine ecologist Mark Butler likes to retell the story he has heard many times from his parents. As a toddler, he came face-to-spray with the Atlantic Ocean for the first time when his family moved from Ohio to Florida. “I had never seen the sea before, but they tell me that I ran straightaway to the water and jumped in.”

Pretty regularly ever since, he has been repeating the feat, often wearing scuba gear in order to study coastal marine life such as crustaceans and sponges. “I am one of those odd fellows who always knew what he wanted to do,” Butler says. “Where it comes from, I don’t know, but it’s always been there.”

His interest in good stewardship of coastal marine environments led him to Florida State University, where he received his Ph.D. in biological sciences. He began a research program there investigating the ways that marine life is affected by human activities. Since joining the ODU faculty almost 20 years ago, he has always had at least one foot in the water around the Keys and in the Caribbean. He rents a home and keeps a truck, boats and mobile lab in the Florida Keys because he is down there so often. He usually has half a dozen ODU graduate students in tow and sometimes is joined by his wife and 15-year-old son, Quint. They call their compound “ODU South.”

Butler has long been interested in the effect that humans have on tropical sea ecosystems through fishing, coastal development and pollution. He is especially interested in how these influence reproduction processes, recruitment (that is, the ecology of young organisms), and the condition of nursery habitats that sustain coastal marine species. For decades he has studied marine ecosystems from Florida to New Zealand.

Marine-Life Research Weighs Global Warming
More recently, he has begun investigations of how young marine life responds to global warming. Together, his many research projects keep the tall, rangy marine biologist busy.

In the spring of 2008 he was working on five funded projects, including a new $2.4 million grant from the National Science Foundation and National Institutes of Health that allows him for the first time to study something local – a disease infecting blue crabs of the mid-Atlantic. He also was taking part in a $12 million World Bank Global Environmental Fund initiative aimed at conservation of coral reefs and building the marine stewardship capacity of developing countries.

“Rarely have I focused on one project at a time,” he says. “I typically have multiple balls in the air.”

Butler is working on the five-year blue crab project with his longtime collaborator, Jeffrey Shields, a professor at the Virginia Institute of Marine Science. The research, which is taking place in small coastal estuaries of the Delmarva Peninsula, focuses on the effects of environmental change and fishing pressures on outbreaks of the pathogenic parasite Hematodinium, which can be especially deadly to young blue crabs.

Key goals of the project are to define the roles that salinity levels—which can be affected by climate change—and fishing levels play in Hematodinium epidemics. Over-harvesting of adult crabs, which are more resistant to the parasite, increases the relative abundance of the more susceptible juvenile crabs and may alter the natural dynamics of this infectious disease, Butler says. “The effect of fishing pressure on disease has received little attention, which is surprising given the increasing reports of disease in marine populations that experience significant exploitation.”

Chris Platsoucas, dean of the College of Sciences, lauds the scope and importance of Butler’s work. “His research involving infectious disease, such as with blue crabs and Hematodinium, certainly deserves the external funding and recognition that it is getting.”

Coral Reef Study Keyed to Connectivity
For the coral reef project off Mexico, Belize and Honduras, Butler is part of a working group studying “Connectivity and Large-Scale Ecological Processes,” in short, how the planktonic larvae of coral reef-dwelling animals are dispersed and in turn influence the replenishment of coral reefs perhaps as far away as thousands of miles. That word, connectivity, is particularly apt in Butler’s case, he says. “What really drives my hodge-podge of research interests is simply my curiosity in so many aspects of marine ecosystems, understanding how all the parts work together.”

Coral reefs, which compose the world’s richest repository of marine biodiversity, are obvious subjects for connectivity research because with so many life forms—from corals, to fish, to lobsters—the full range of larval life histories and behaviors that affect dispersal distances, and thus the connectivity of species among reefs, is on display. To further complicate matters, the peculiar traits of those life forms and the swirling sea currents that transport them, react to environmental change—to warmer water, higher salinity or pollutants, for example. So scientists may know that coral reefs are in deep distress worldwide and that larval connectivity is key for their survival, but they are not sure of the origins or destinations of each reef’s life-sustaining larvae, nor how to cobble together a remedy for these iconic, but rapidly deteriorating ecosystems.

Butler’s connectivity assignment for the World Bank project centers on a species with one of the longest plankton-dwelling larval stages in the Caribbean and one that supports the most important fishery in the region—the Caribbean spiny lobster. He has been studying lobsters for years and fondly calls them “my lab rats.” Once hatched from clusters of orange eggs carried beneath a female lobster’s tail, the lobster’s tiny, spider-like larvae are carried on ocean currents for nearly a year, eventually returning to settle in shallow, coastal nursery areas often far from home. “Lobsters, indeed most marine animals, aren’t like chickens. Their planktonic larvae can potentially move across great distances, and so are a lot more like windblown seeds than the young of barnyard animals. Traditionally, it’s been thought that lobsters in the Caribbean were one large population—one big mixing bowl of widely dispersing larvae. But we’re finding that the larvae don’t float passively and this greatly affects where and how far they travel.” The larvae of lobsters and fish, for example, can move up and down in the water column, where currents move at different speeds and directions at various depths. So by making minor navigation adjustments in response to light and chemical cues, the larvae can control to some extent where they travel.

Fishermen Hurt by Lobster Disease
Nutrients, sediments and pollutants, on the other hand, are simply at the mercy of moving water. It will take a very sophisticated model, therefore, to replicate the hydrodynamic and demographic factors that create a spiny lobster ecosystem. Understanding these complex relationships on large, ocean basin scales are matters for computer modeling that would otherwise be brain busters. As it happens, Butler has a knack for designing experiments whose data can be merged into simulation models. Along with marine ecology, he teaches a biostatistics class at ODU.

While Butler and two colleagues from the University of Miami, Robert Cowen and Claire Paris, are studying spiny lobster connectivity using modeling, others in the World Bank project are applying molecular genetics, chemical tags and even tiny magnetic beads to study the dispersal of corals and fishes. Indeed, one goal of the World Bank Connectivity project is the development of advanced tools to better measure demographic connectivity in all sorts of species all over the world.

A third project under way for Butler involves Caribbean spiny lobsters and a virus called PaV1, which kills enough juvenile lobsters each year to take a bite out of the valuable industry that markets the delectable crustacean. Butler and Shields have been awarded two NSF grants over the past seven years for a continuous study of how factors related to ecology, fishing and the lobsters’ behavior influence the infectious disease in the species.

Similar to the way that Hematodinium outbreaks can strike blue crabs after heavy fishing removes a major portion of the adult population, the PaV1 infections may rise along with fishing pressures. Also, water management in the Everglades and environmental changes can start a chain reaction that promotes PaV1. Butler says large sponges he has studied off the Florida Keys can fall victim to blooms of phytoplankton due to changes to their environment, and, as it turns out, this is bad for lobsters. The sponges are like apartment buildings for juvenile spiny lobsters. As sponges die, more and more juveniles must crowd into the sponges that are still living, and the lobsters’ tighter quarters hastens the spread of the infectious PaV1. “We sometimes say that the loss of sponges creates a rural-to-urban shift in lobster living,” he explained. (See sidebar.)

Balancing Act in the Everglades
Yet another related study in which Butler is involved, and has been on and off for 15 years, is for the South Florida Water Management District. They oversee a large conservation project, the Comprehensive Everglades Restoration Project, which essentially involves “replumbing” of the Everglades—work that is supposed to return the Everglades to a more pristine state— but may have some negative impact on spiny lobsters. The conservation work is changing drainage patterns out of the Everglades, back to those before the turn of the century, before humans cut channels and drained the Everglades for flood control, farming and urban use. The restoration plan will shunt large quantities of freshwater back into the sea at places where this hasn’t happened in many decades. Some of those points now serve as spiny lobster nurseries and, again, this can stress populations of the young creatures. In this case, what is good for the ecosystem as a whole is likely to be detrimental to lobsters and the lobster fishery.

The ecological connectivity among species and ecosystems, complicated processes that in various forms drive his zeal for research, can yield counter-intuitive results, Butler maintains. That’s why we need science; that’s why we need experiments and statistical analysis, he adds.

He uses fishermen to make his point. “Fishermen are wonderful observers of the natural world. They have a vested interest in it. But they’re not scientists and therefore not trained in making connections between cause and effect—what you observe and what is causing it. Often they will get the effect right but the process wrong. Our field and laboratory experiments are necessary to understand processes such as disease transmission, then we build ecological models to pull all the information together to address ecological problems at scales larger than experiments allow. That’s where science comes in.”

Unexpected Product of Lobster Studies Makes Media Stars of Researchers
Connect-the-dots investigations, the kind that appeal to ODU marine biologist Mark Butler, can lead to unexpected findings and even the limelight.

Caribbean spiny lobsters have been a research focus for him for more than a decade, and he has found how a virus called PaV1 can take a toll on the juvenile populations of the lobster, especially when the infections are spurred on by environmental degradation.

Fishermen who trade in the crustacean complain about the virus and the losses it causes them, but Butler and his research colleagues noticed that the highly infectious disease didn’t kill nearly as many lobsters as might be expected. The creatures are highly sociable, thus susceptible to passing the disease among themselves, but only about 7 percent of any given population would die.

Were some lobsters immune? Did behavioral characteristics help some avoid infection?

Enter an ODU postdoctoral researcher, Donald Behringer, who was working with Butler off the coast of Florida. He noticed what seemed like a quarantine habit among the young lobsters; healthy lobsters would shun others that were infected. Several months of tests in open waters and in controlled labs proved that the quarantining did, indeed, happen and that the healthy lobsters could somehow tell which to shun even before symptoms were exhibited. The findings were the first ever to show that creatures in the wild shun neighbors of the same species that have contracted an infectious disease.

“That was sheer serendipity,” Butler says of the discovery, which happened in 2006. He, Behringer and collaborator Jeffrey Shields of the Virginia Institute of Marine Science wrote articles about the quarantining for the prestigious journal Nature, as well as for other scientific publications. Those spawned a literal blitz of publicity for the researchers, with the New York Times, Washington Post and Science magazine’s Science Now Daily News Web page leading the charge.

(Behringer is now on the faculty at the University of Florida. The researchers have since shown that healthy lobsters detect the infection in others by chemical means.)