Aquatic Plants and Greenhouse Gases: A Surprising Connection

Recent research sheds light on an unexpected player in the battle against climate change: aquatic plant communities. From floating plants to submerged vegetation, these organisms can significantly influence greenhouse gas emissions in shallow freshwater bodies.

As we grapple with the escalating consequences of climate change, it's crucial to recognize that nearly half of the world's methane emissions originate from aquatic environments, such as wetlands, ponds, and shallow lakes. Methane is alarmingly potent—over 28 times more impactful than carbon dioxide over a century.

The Power of Plant Management

Meredith Theus, a doctoral student and lead author of the study published on August 5 in *Aquatic Botany*, believes that effective management of these aquatic ecosystems could mitigate greenhouse gas emissions. "Many water bodies are actively managed according to public preference, often prioritizing aesthetics over ecological health," Theus explained.

By adjusting the management of water plants, communities could play a vital role in climate change mitigation.

Field Experiments Reveal Surprising Results

To explore this, Theus conducted a summer field experiment at Cornell Experimental Ponds Facility, setting up controlled environments with different plant combinations: submerged plants, a mix of submerged and floating species (like duckweed), and phytoplankton.

Contrary to expectations, the treatment with submerged and floating plants showcased high concentrations of carbon dioxide and methane but didn't correspond with the expected fluxes of gases escaping into the atmosphere. This contradiction raises intriguing questions about the dynamics of greenhouse gas emissions in aquatic ecosystems.

Duckweed: The Unseen Barrier?

One hypothesis for this anomaly relates to the behavior of duckweed. While these tiny plants may seem insignificant, they can form a dense surface cover that might trap gases. Previous research suggests that ponds entirely covered in duckweed can actually harbor the highest methane levels, as the plant acts almost like a lid, stifling gas release.

However, researchers noted that measurements were not taken daily, so rapid fluctuations in gas emissions during weather changes may have gone unrecorded.

A Complex Ecosystem Awaits Exploration

The study's findings highlight the complexity of pond ecosystems. Duckweed's roots host specialized bacteria called methanotrophs, which consume methane, suggesting that the plant community structure could greatly influence emissions that remain hidden from immediate observation.

Theus emphasizes the importance of understanding these interactions, stating, "How we manage plant types and assemblages in ponds may have profound effects on emissions that we currently overlook."

Future Research on the Horizon

With backing from significant institutions like the Cornell Atkinson Center for Sustainability and the National Science Foundation, this research prompts a deeper investigation into the relationship between aquatic plant diversity and greenhouse gas dynamics.

As scientists delve into these fascinating aquatic systems, the potential for using plant management as a tool for combating climate change has never seemed more within reach.