The Impact of the September 2023 Great Floods on Coastal Underwater Wildlife in Thessaly, Greece, and the Transition from Rocks to Mud Substrate

​Introduction:
In September 2023, Thessaly, Greece, witnessed unprecedented floods that not only reshaped its terrestrial landscape but also had a profound impact on the coastal underwater ecosystems. This article explores the aftermath of the great floods, examining the transition from a rocky substrate to mud and evaluating the consequences for marine species. Additionally, it delves into the essential steps needed for future wildlife research and how individuals can contribute to the understanding and preservation of these fragile ecosystems.

The Before Picture:
Before the floods, the coastal underwater environment of Thessaly boasted a diverse and thriving ecosystem. Rocks provided a sturdy substrate, offering habitat for various marine organisms such as algae, mollusks, crustaceans, and small fish. The rocky surfaces were not only a source of shelter but also a platform for the attachment of sessile organisms like barnacles and corals. It was a vibrant and balanced underwater community.

The Flood Impact:
The massive floods in September 2023, triggered by intense rainfall and natural factors, left a lasting imprint on the coastal underwater landscape of Thessaly. The force of the floodwaters eroded the rocky substrate, dislodging rocks and reshaping the seabed. The once stable and rocky environment gave way to a softer, more malleable substrate sand and soil/mud.

Shift to Mud Substrate:
As the floodwaters receded, a layer of sediment settled on the seabed, transforming the once rocky substrate into a muddy environment. This shift had significant implications for the underwater flora and fauna of Thessaly. The mud substrate presented new challenges and opportunities for marine life that had adapted to the previous rocky environment.

Impact on Marine Flora:
The transition from rocks to mud had a notable impact on marine flora. Algae, accustomed to attaching to rocky surfaces, faced challenges in securing themselves to the muddy substrate. While some algae species adapted to the new conditions, others struggled to establish themselves, leading to shifts in the underwater plant life and impacting overall biodiversity.

Changes in Fauna Distribution:
The alteration of the substrate triggered a redistribution of marine fauna. Species adapted to rocky surfaces had to adjust to the softer mud substrate. Mobile organisms such as crabs and certain fish navigated the change more effectively, while sessile organisms like barnacles faced challenges in finding suitable attachment points.

Adaptations and Challenges:
The underwater wildlife system in Thessaly showcased remarkable adaptability. Some species evolved to exploit the new opportunities presented by the mud, while others faced challenges in finding suitable habitats and food sources. The delicate balance of predator-prey relationships and competition for resources underwent a period of adjustment as the ecosystem sought a new equilibrium.

Examples of Species Impact:

Endangered Species:
a. Barnacles and Corals: Sessile organisms like barnacles and certain coral species that rely on rocky surfaces for attachment may face challenges in the mud. Reduced attachment points and difficulty obtaining nutrients from the sediment could endanger these species.

b. Rock-dwelling Fish Species: Fish adapted to rocky habitats may find it difficult to adjust, affecting populations and the local food web.

c. Certain Algae Species: Algae specialized for rocky surfaces may struggle to establish themselves on the muddy substrate, impacting herbivores dependent on them for food.

Thriving Species:
a. Crabs and Burrowing Organisms: Mobile species may thrive in the mud, utilizing the soft sediment for burrowing and shelter.

b. Opportunistic Algae and Seagrasses: Some algae and seagrass species adaptable to different substrates may thrive in the nutrient-rich mud.

c. Generalist Fish Species: Fish species with flexible habitat preferences may adapt more easily to the shift, experiencing population increases.

Migration and Colonization:
a. Migratory Species: Changes in migration patterns may occur as species move to areas with more suitable substrates, impacting regional biodiversity.

b. Colonization by New Species: The mud substrate may attract new species adapted to such environments, contributing to overall ecosystem resilience and diversity.

What Needs to Be Done Tomorrow:
Understanding the evolving dynamics of Thessaly's underwater ecosystems is crucial for effective conservation and management strategies. Tomorrow's wildlife research should focus on:

1. Monitoring and Assessment: Implementing regular monitoring programs to track changes in the underwater environment, species distribution, and ecosystem health.
2. Species-specific Studies: Conducting in-depth studies on vulnerable and thriving species to better comprehend their adaptive mechanisms and vulnerabilities.
3. Ecosystem Modeling: Developing predictive models to anticipate future changes in the underwater ecosystem and assess the potential impact on marine life.
4. Community Engagement: Involving local communities in citizen science initiatives, raising awareness about the importance of preserving coastal biodiversity, and gathering valuable data.
5. Conservation Initiatives: Implementing conservation initiatives to protect endangered species and promote the recovery of ecosystems, including the restoration of natural habitats.

How You Can Contribute:
Individuals can play a crucial role in supporting ongoing research and conservation efforts:

1. Participate in Citizen Science: Join local or online citizen science projects to contribute observations and data on marine life in Thessaly. Anyone will be able to participate in Summer Camp in the area to record every marine species underwater from the beginning and to compare to past data we have from the past.
2. Educate Yourself and Others: Stay informed about coastal ecosystems, the impacts of floods, and ongoing conservation efforts. Share your knowledge with friends, family, and community members.
3. Support Conservation Organizations: Contribute to or volunteer with organizations dedicated to marine conservation in Greece. Your support can aid in research, habitat restoration, and education.
4. Practice Sustainable Living: Reduce your ecological footprint by making environmentally conscious choices in your daily life. Conserve water, reduce plastic usage, and support sustainable fisheries practices.
5. Advocate for Policy Changes: Advocate for policies that prioritize the protection and sustainable management of coastal ecosystems. Engage with local authorities and policymakers to promote responsible environmental practices.