Balancing the nutrient load in Lake Erie is a 'wicked problem'

Lake Erie, known for its rich aquatic life, has been facing some challenges. Interestingly, the current regulations limiting nutrients from agriculture flowing into Lake Erie may be too restrictive for some fish species.

However, these restrictions are anticipated to maintain healthy fisheries until at least mid-century when taking our warming climate into consideration, according to a new study led by the University of Michigan.

Taking action now for the future

“Hitting the target for the future is the right thing to do now,” said Don Scavia, professor emeritus at U-M’s School for Environment and Sustainability. “Even though the proposed limits are too much for now, I don’t think they should be relaxed because it takes a decade or longer to affect change.”

This intriguing study is the result of combined efforts from scientists across the United States and Asia.

The team integrated climate projections, historical fishery data, and innovative mathematical modeling of the lake’s nutrient load. The researchers also looked at an important indicator of water quality – the oxygen levels in the lake’s depths.

Nutrients in Lake Erie

With all of these elements in the mix, the researchers found that the situation is even more complex than one might expect.

Reducing nutrient flows does indeed improve water quality, but this doesn’t automatically translate into a boon for all fish species.

“There are tradeoffs,” said Scavia. He noted that as the planet continues to warm, temperature – not nutrient load – will be the primary influence over Lake Erie’s oxygen levels and other similar ecosystems worldwide.

Solutions for a “wicked problem”

Does this complexity mean we’re in a no-win situation? Not at all. Instead, it simply means that management strategies will need to adapt as conditions change.

Because there isn’t a single, perfect solution for these ecosystems, our approach must remain flexible to accommodate new realities. In the world of land management, this is known as a “wicked problem.”

The nutrients used in fertilizers, while incredibly beneficial for crops, pose a problem when they enter our water systems. They act as a buffet for microorganisms like algae and cyanobacteria, leading to algal blooms in places like Lake Erie, the northern Gulf of Mexico, and Chesapeake Bay.

As these blooms decompose, they create hypoxic, or low-oxygen, conditions that are disastrous for many fish species.

While cyanobacteria thrive in nutrient-rich waters, so do the plankton that provide food for larger fish species.

Balancing nutrients in Lake Erie

Stuart Ludsin, a professor in the Aquatic Ecology Laboratory at Ohio State University (OSU), explained that hypoxia is bad news for lake whitefish that prefer the cold bottom water of Lake Erie.

However, not all fish live in depths where hypoxia is a concern. Yellow perch, for instance, actually benefit from nutrient-rich waters, noted Professor Ludsin.

Currently, nutrient levels in Lake Erie are also beneficial to walleye. Achieving the right balance for both water quality and fish populations is a delicate, moving target.

The goal is not to encourage pollution to support fisheries but rather to find a level of nutrients that can balance water quality goals and support the lake’s suite of fisheries.

Anna Michalak, founding director of Carnegie Science’s Climate and Resilience Hub, suggests that determining this level should involve the system’s managers and stakeholders.

Adaptive tactics to tackle the issue

Michalak, who has been working with Scavia for a decade studying Lake Erie and other aquatic ecosystems, advocates for a systems-level approach. She emphasizes that the optimal choices for one aspect, such as water quality, might come with a cost to another, like fisheries.

According to Professor Dan Obenour of North Carolina (NC) State University, the study provides a template and prior knowledge that can be applied to other systems.

Pointing out that the climate-hypoxia model has proven robust and reliable over long time periods, Professor Obenour reinforces the need for adaptive tactics to tackle this wicked problem.

The role of climate change

Climate change further complicates the web of challenges faced by Lake Erie nutrient limits and similar water systems. Rising global temperatures alter precipitation patterns, increasing the frequency of intense rainfalls that wash more nutrients into bodies of water.

This not only exacerbates the existing nutrient management issues but also demands more dynamic solutions. Scientists are beginning to incorporate climate resilience into their models to predict more accurately how these aquatic systems will change over time.

By understanding and planning for these shifts, policymakers and stakeholders can better devise strategies that preemptively address the changing environmental conditions.

Innovation in environmental policy

Advancements in technology and data analytics are playing pivotal roles in shaping effective environmental policies. By leveraging satellite imagery and real-time sensor data, researchers can monitor nutrient loads and algal blooms with greater precision than ever before.

These innovative tools allow for the rapid assessment of water quality and the development of more targeted mitigation strategies.

As environmental challenges become increasingly complex, the integration of cutting-edge science with proactive policy measures stands to offer a beacon of hope for maintaining Lake Erie’s ecological balance and preserving its invaluable natural resources.

Indeed, determining the best management solutions is a challenging task. Even after reaching a consensus, future changes will require continued reassessments.

The study is published in the journal Proceedings of the National Academy of Sciences.

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