Malone stares at his computer screen as if he could see the past recaptured. When he first arrived in Bay country, he could not have foreseen that he would become interim President of UMCES after Morris' tragic death in 1988 at the age of forty-nine. That he would become the Director of the Horn Point Laboratory in 1990 — a position he held for 12 years. That he would step down from that post to work on an integrated observing and prediction system for the oceans, here on the 12th floor of this high-rise office outside Washington, D.C.

When he first came to the Bay, Malone spent time on the water. He and his colleagues — like Michael Kemp from UMCES and Tom Jones from Salisbury State University — motored back and forth across the Bay every week on the 25-foot research vessel Osprey. They ran a zig-zag course from the Eastern Shore to the Western Shore as they worked their way from the Bay bridge at Kent Island down to the mouth of the Patuxent River. Their zig-zags were deliberate. The measurements they took were meant to provide a new dimension for understanding how the Bay works.

In contrast to prior research on the Bay that focused on changes occurring along the axis of the main stem, this effort focused on shifts that occur laterally from shore to shore. Their work showed that water sloshes back and forth between the Eastern and Western shores as water flows up and down the main axis. This led to the discovery that nutrients and oxygen-depleted bottom water from the main channel can slop into shallow waters, stimulating phytoplankton production and causing fish kills during the summer.

Filling the gaps in ocean observing systems, researcher Tom Malone takes time from his post at the University of Maryland Center for Environmental Science to build a national program. Widely known for detailing links between nutrients, algae, and oxygen, he now works with the Intergovernmental Oceanographic Commission to integrate observing and prediction systems. Photograph by Skip Brown.

Their work got a major boost in 1985, when federal funds came through for a five-year research initiative to determine why bottom waters in the Bay lose oxygen (become anoxic) during the summer. Managers and others wanted to know what determines the timing and extent of that anoxic zone. The program, administered by the National Oceanic and Atmospheric Administration and the Sea Grant programs of Maryland and Virginia, directed researchers to study the very processes that intrigued Malone and his colleagues. Precisely what mechanisms drive the disappearance of oxygen during the summer months? How much of this is natural and how much is manmade? Is it getting worse and, if so, why?

The results of this work were captured in a landmark book, Oxygen Dynamics in the Chesapeake Bay (see "A Classic Text," below right). Among other findings, the study determined that most of the Bay's nutrient load comes during the winter and spring when river flows and runoff from the land are high — and long before the seasonal onset of oxygen depletion in bottom waters of the Bay. Come spring, as water temperatures and sunlight increase, algae production kicks into high gear. As the waters warm, algae soak up light, drink in nutrients, and bloom.

This spring bloom is nothing new — it's been going on for thousands of years. But because so many nutrients now wash into the Bay from human sources — some six to eight times the amount of nitrogen of pre-Colonial times — the amount of biomass that accumulates during the spring is enormous. It exceeds the capacity of the Bay's herbivores — everything from oysters to menhaden to copepods — to eat it. Most of this algal biomass sinks to the bottom. There bacteria populations explode as they metabolize this organic matter, a process that sucks oxygen from the water.

Malone and his colleagues were able to show that summer anoxia is related to the accumulation of phytoplankton in the Bay during winter and spring (when grazing rates by herbivores are low). They showed that the amount of biomass that accumulates depends on the size of the nutrient load. The bigger the nutrient load, the bigger the spring bloom. Says Malone, "That makes estuaries like Chesapeake Bay particularly sensitive to human activities in their watersheds."

Meanwhile, all through the warmer months, more nutrients enter the Bay and those that came in during winter and spring recycle. All summer algae bloom, fall to the bottom, and decay. As they break down, they release more nutrients to feed more algae blooms.

Malone and his fellow scientists found that the Bay and its rivers had become a remarkably efficient algae factory.

This page was last modified September 15, 2018