Science Wednesday: Protecting Ocean Meadows

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

“Amber waves of grain” conjures up images of vast expanses of grassland across middle America. In contrast, can you picture meadows of seagrasses covering broad areas of the seafloor?

image of underwater seagrassSeagrasses are underwater marine flowering plants that have long, narrow leaves. Because they photosynthesize, seagrasses must grow in shallow water where light penetrates. Most of the light required for these plants disappears below 30 feet.

Florida alone has about a half-million acres of seagrass meadow.

Seagrasses provide essential “ecological services,” such as reducing erosion, improving water quality, and supplying refuge and food for aquatic animals. They are vital to commercial and recreational fisheries that are a major part of a coastal community’s economy.

Unfortunately, the health of seagrass meadows has been compromised in many places due to pollution from land-based activities. Excess nutrients from fertilizers and wastewater cause algal blooms which deprive seagrasses and aquatic organisms of essential oxygen. In addition, over-fishing, over-crabbing, and other harvesting practices change the ecological balance within seagrass meadows, leading to shifts in both plant and animal populations.

My PhD thesis brings me to the shallow waters off Bermuda where I am measuring the simultaneous effects of heavy grazing and excess nutrients on the overall health of seagrass pastures. Seagrasses here are being eaten (grazed) by green turtles and parrotfish while fertilizer runoff is also affecting them.

My main focus is to understand how grazers with different feeding strategies—where and how they feed—control the effects of nutrient pollution. I am working in both the laboratory and the field to manipulate and measure nutrient levels.

A conservationist at heart, I constantly seek to educate others about how human actions can either positively or negatively impact the physical environment. My research looking at the indirect effects of local fishing practices and wastewater treatment on seagrass ecosystems has pressing applications for coastal conservation and management worldwide.

About the author: Kim Holzer is a Ph.D. student in the Department of Environmental Sciences at the University of Virginia. Funding for her research is provided by a 2007 EPA Science to Achieve Results (STAR) Graduate Research Fellowship. Kim expects to graduate in the spring of 2011 and continue working as a scientist in environmental protection.