**Underwater Gardening: A Daring Initiative to Revive Eelgrass Along the East Coast**
In the shallow depths of Pleasant Bay, located within the Cape Cod National Seashore in Massachusetts, a bold underwater gardening initiative is in progress. Led by seagrass ecologist Alyssa Novak and a diverse team of researchers, this project aims to revitalize eelgrass meadows—vital aquatic environments that are swiftly disappearing due to climate change and human interference. The endeavor utilizes a unique strategy called “assisted migration,” which aims to enhance the resilience of eelgrass populations in response to increasing sea surface temperatures.
### The Urgent Challenge for Eelgrass Meadows
Eelgrass, the predominant variety of seagrass on the East Coast of the United States, is essential for marine ecosystems. Its meadows serve as habitats for numerous species, such as horseshoe crabs, seahorses, and commercially valuable fish like Atlantic cod and scallops. Beyond its ecological roles, eelgrass also safeguards shorelines from erosion, purifies contaminants from water, and sequesters large quantities of carbon, making it crucial in the fight against climate change.
Nonetheless, these underwater ecosystems are facing a crisis. Years of dredging, nutrient pollution from agricultural runoff, and wastewater have resulted in algal blooms and sediment buildup, obstructing the sunlight required for eelgrass photosynthesis. Escalating sea temperatures, fueled by climate change, have further complicated the situation. Eelgrass flourishes in water temperatures ranging from 60° to 68°F; however, recent marine heatwaves have raised temperatures above 82°F in certain regions, leading to significant die-offs.
The Nature Conservancy reports that some eelgrass meadows in the western Atlantic have shrunk by over 90% in the past century. Worldwide, the United Nations Environment Program estimates that 7% of seagrass habitats vanish annually, with more than 20 of the globe’s 72 seagrass species experiencing decline.
### An Innovative Approach: Assisted Migration
To address these troubling developments, Novak and her team are at the forefront of implementing assisted migration for marine flora—a tactic previously utilized for terrestrial species like cottonwoods and corals. This strategy focuses on identifying eelgrass populations that show greater heat tolerance and relocating them to areas where local populations are under duress. By introducing genetically resilient plants, the team aims to enhance the survival prospects for eelgrass meadows facing increasing temperatures.
“We’re attempting to identify heat-tolerant individuals along the East Coast and relocate them to regions where populations are threatened by rising sea surface temperatures,” Novak stated.
### The Common Garden Initiative
The restoration endeavor revolves around a scientific procedure known as the “common garden experiment.” This method entails planting eelgrass seeds from diverse regions in various locations to analyze how they adapt to new environmental conditions. The objective is to pinpoint genetic characteristics that enable certain populations to withstand heat, low light, and other stressors more effectively.
In 2022, The Nature Conservancy organized a gathering of specialists in seagrasses, corals, forestry, and plant genetics to examine how insights from different ecosystems could be leveraged for eelgrass restoration. Motivated by successful trials with Fremont cottonwoods in Arizona, the team resolved to implement the common garden strategy with eelgrass.
In the past year, researchers collected eelgrass seeds from sites as far north as Maine and as far south as North Carolina. These seeds were subsequently planted in experimental plots at national parks along the East Coast, including Cape Cod National Seashore, Fire Island National Seashore in New York, and Assateague Island in Maryland.
### Interregional Collaboration
The coordinated initiative, named HEAT (Helping Eelgrass Adapt to Temperature), signifies a noteworthy shift in how scientists approach restoration efforts. Historically, academic research has been compartmentalized, with limited inter-state collaboration. However, the pressing nature of the eelgrass crisis has encouraged a collaborative spirit.
“We’re a team,” Novak remarked. “We’re focused on saving the eelgrass and prioritizing the health of this ecosystem.”
The team has also commenced sharing seeds and genetic data to optimize their chances for success. For instance, Novak dispatched eelgrass samples from Massachusetts to the University of North Carolina Wilmington, where researchers are investigating the plants’ DNA to locate genetic indicators of resilience. This knowledge will assist in future restoration initiatives, enabling scientists to align specific seed populations with the environmental conditions of diverse sites.
### The Significance of Eelgrass
Eelgrass meadows are frequently referred to as the “forests of the sea” due to their ecological value. They offer nutrition and shelter for marine organisms, support commercial fisheries, and serve as natural water purifiers. Moreover, eelgrass acts as an effective carbon sink, sequestering carbon at a rate up to 35 times faster than tropical rainforests. Each acre of eelgrass has the capacity to counteract the carbon emissions from a vehicle driving nearly 4,000 miles a year.
However, when eelgrass meadows are compromised, the carbon stored within their roots and sediments is released.
