Our inspiration derives from our region: Thessaly, Greece.

From the early dawn of civilization, freshwater sources played a vital role in the rise of cities and communities. The ancient Greeks soon realized the value of the rivers and began worshiping them. According to Greek mythology Pineios was a Thessalian River God, a child of Oceanus and Tethys1. Since Thessaly is known for its agricultural activities, Pinios River and Lake Karla are essential water bodies for regional development, playing a catalytic role in local biodiversity, financial stability, and social structure.

Figure 1. Map of Thessaly2

Lake Karla and Pineios river are notable for their high biodiversity as they host many species of fish (13 species) and birds (180 species), including some extremely rare, which has earned these aquatic surfaces a place on the list of Natura 2000 protected areas3.

Figure 2. The biodiversity of the local freshwater ecosystems in Thessaly.

However, nowadays these water bodies are under qualitative and quantitative degradation due to the pollution pressures usually associated with the increased use of fertilizers, pesticides and sewage disposal coming from the Plain of Thessaly. For years, an unpleasant odor from the river and a blue-green hue in the lake have been disregarded by the local authorities. After researching scientific literature, our team found out that several reports indicate the lake's "poor ecological condition" due to intense anthropogenic eutrophication.

Phenomenon of eutrophication

Globally, eutrophication of wetlands remains the largest water quality challenge. 30–40% of lakes and reservoirs worldwide are affected by anthropogenic eutrophication4. Eutrophication refers to the phenomenon in which excess nitrogen (N), phosphorus (P), and other inorganic nutrients enter a body of water such as a lake, reservoir, or river. Phosphorus is often the main cause of eutrophication, since 80% of eutrophication in freshwaters is restricted by phosphorus, and 10% is related to nitrogen5. Eventually, cyanobacteria over-proliferate in the water, ensuing in the consumption of dissolved oxygen (DO). Additionally, the cyanobacteria produce chlorophyll-a (Chl-a) and cyanotoxins, resulting in water quality degradation and the death of fish and other aquatic organisms. Eutrophication has severe, universal consequences on water quality, public health, and more notably biodiversity loss, financial stability, and climate change.

Figure 3. Brief explanation of the eutrophication phenomenon

Biodiversity loss

By definition, biodiversity describes the enormous variety of life on Earth. Specifically, it refers to all species in one region or ecosystem, including plants, bacteria, animals, and humans. Biodiversity is vital in supporting ecosystem services and activities which are essential for the health and sustainability of our communities. As mentioned before, eutrophication leads to changes in the availability of light and certain nutrients to an ecosystem, causing alterations in the species composition, as the more tolerant species survive and finally biodiversity loss occurs. This situation poses a threat to the billions of organisms around the world who rely on rivers, lakes, and tributaries for food and water. Since 1970, 83% of freshwater species and 30% of freshwater ecosystems have been lost6. Wetlands are a combination of natural habitats. They are complex ecosystems and provide benefits in fisheries, livestock, forest timber, recreation and environmental education. Freshwater biodiversity is dramatically dwindling: Wetlands are disappearing 3 times more quickly than forests globally.

Global scale

Freshwater ecosystems, covering less than 1% of Earth's surface, are home to 10% of all species and ⅓ of vertebrate species7. These habitats also support about 700 birds, 17.800 fishes, 5700 dragonflies, 250 turtles, 1600 crabs, and an estimated 70 species of freshwater-adapted mammals8. Among freshwater species, endemism rates are remarkably high. For example, more than half of the fish species evaluated for the world's freshwater ecoregions were restricted to a single ecoregion9.

Figure 4. World Map with Endangered species due to Eutrophication

Pantanal

Location: Brazil, Bolivia, Paraguay

Endangered Species: Hyacinth Macaw (Anodorhynchus Hyacinthinus), Pantanal Jaguar (Panthera Onca)

Baltic Sea

Location: Northern Europe, Central Europe, Eastern Europe

Endangered Species: Gull-Billed Tern (Gelochelidon nilotica)

Lake Baikal

Location: Southern Siberia, Russia

Endangered Species: Baikal Seal (Pusa Sibirica)

Great Lakes

Location: Canada, United States

Endangered species: L.Erie Water Snake (Nerodia sipedon insularum), Red Knot (Calidris Canutus Rufa)

Lake Victoria

Location: Burundi, Kenya, Rwanda, Tanzania, Uganda

Endangered species: Singida tilapia (Oreochromis esculentus)

Lake Karla

Location: Thessaly, Greece

Endangered Species: Thessalogovius (Knipowitschia thessala)

Local scale

Greece is known to be one of the richest European and Mediterranean biodiverse countries, with many endemic species of plants, animals, and important habitats. An International Union for Conservation of Nature's (IUCN) report indicates that 43% of all freshwater fishes in Greece are under threat due to pollution and water mismanagement10.

Wetlands are habitats for rare species of flora and fauna and provide benefits in fisheries, livestock, forest timber, recreation and environmental education. Lake Karla and Pineios River are significant wetlands in Greece, due to the rich variety of plant and animal life that thrived there.

Climate Change and Financial Costs

Global scale

As mentioned before, the impact of our project is expanding globally, as local water quality protection has global economic implications. The financial consequence of eutrophication is indicated by the climate damages which it causes. The estimated present value of the global climate change costs of CH4 emissions from eutrophic lakes and reservoirs by 2050 range from $7.5 to $81 trillion12. By eliminating eutrophication in a local waterbody, the amount of CH4 greenhouse gas released into the atmosphere is decreased. As a result, protecting local waters could contribute to climate change mitigation and provide trillions of dollars in benefits13.

Figure 10.Green House Gases emissions from eutrophic lakes.12

Local scale

The regional economy of Thessaly depends strongly on agricultural activities and the water of River Pineios is used primarily for irrigation of fields. Regenerating the river’s ecosystem is very important for our local community because, as the region of Thessaly relies entirely on agricultural income, the conservation of the river contributes to the financial support of the region. Sustainable utilization of water generates multiple benefits for society, such as recreational activities and tourism, supporting the local economy.

Management of eutrophication nowadays faces several challenges. The first is the global and local lack of monitoring data in eutrophic freshwaters. As most satellite monitoring systems are for coastal areas, monitoring of eutrophication levels in freshwater is inadequate. Furthermore, eutrophication-specific indicators such as microcystins, a class of toxins produced by cyanobacteria in eutrophic ecosystems, are not yet detectable. The second is the use of unsustainable methods for water bioremediation. Chemical interventions such as the use of copper sulfate (CuSO4), herbicides, and algaecide or CuSO4 as a systematic and empirical way to eliminate or manage phytoplankton blooms are typical examples. In addition, the sediment dredging approach exposes hazardous compounds that degrade the sediment ecosystem. To that end, allow us to introduce Navanthus.

Navanthus: A monitoring and phytoremediation system in eutrophicated water bodies

With project Navanthus, our team aims to implement a universal monitoring and phytoremediation approach in eutrophicated waters. Multiple sensors will be placed on top of a Remotely-Controlled (RC) Boat, monitoring and evaluating the ecological status of the water body. Wherever our data indicate critical levels of eutrophication, a Constructed Floating Wetland (CFW) will be implemented. The CFW will be made of mycelium, an environmentally friendly material, and it will carry genetically engineered Phragmites australis plants. The plant roots will be submerged in the water and once they detect microcystins via a novel synthetic riboswitch, they will enhance the expression of Pi transporters on the root cells, resulting in enhanced phosphate uptake and storage. The aboveground part of the plants will be harvested and converted into fertilizers.

Figure 11. Project Navanthus.

Monitoring system

An innovative component of our project will be the construction of a Remotely-Controlled (RC) Boat, which will sense and monitor eutrophication levels concerning the waterbody we operate in. Specifically, it will contain multiple sensors directly related to the phenomenon of eutrophication. These include a pH sensor, a dissolved oxygen (DO) sensor, a temperature sensor, and a GPS sensor to provide localization of pollution at each specific spot inside the operating water body. Through these sensors, we aim to develop a database that, through machine learning, will accurately predict the existence and concentration of the toxin Microcystin-LR inside the water body. The real time data received from the monitoring device, will be transmitted to a cloud service and will be available for the research community to build upon and advance scientific research concerning eutrophication.

Figure 12. Monitoring System.

Bioremediation

Constructed Floating Wetland

Wherever our data indicate critical levels of eutrophication, a Constructed Floating Wetland (CFW) will be implemented. The CFW will be made of mycelium, an environmentally friendly material, and it will carry genetically engineered Phragmites Australis plants.

Engineered Plants

The plant Phragmites australis, is considered native in freshwater ecosystems, hence its placement in the CFW will not disturb the biodiversity of the, already affected, aquatic ecosystem. According to the design, at the bottom part of the wetland, the roots of Phragmites australis will be submerged in the water, while the upper shoot system will stand over a thin layer of soil, needed for the support of the plants. However, the Phragmites australis plants in the CFW will be genetically engineered, to have an extra property in their root system: in the presence of microcystins the plants will absorb more inorganic phosphorus by their roots and store it in their shoots and leaves, hence decreasing the levels of Pi in the eutrophic water. Specifically, a novel riboswitch with a particular aptamer that recognizes microcystins will detect these specific cyanotoxins. In the presence of microcystins, the riboswitch will suppress the Tet-Repressor (Tet-R) protein, which is the next part of our system. TetR's inhibition will lead to the optimal overexpression of the PHT1 protein family's Pi transporters, leading to increased Pi uptake by the roots. The shoots and leaves of the plants will eventually be harvested and converted into fertilizer.

Figure 13. Constructed Floating Wetland illustration

With the current global energy crisis, it is more important than ever to reduce consumption. Environmental protection is vital to this year's project. Therefore, we believed from the beginning of our study that it was essential to follow to a standard model of environmentally responsible sustainable development. Circular economy is a production and consumption model that incorporates sharing, reusing, repairing, and recycling existing resources and goods14. Circularity attempts to solve widespread and ongoing global challenges, including climate change, biodiversity loss, waste, and pollution. The three principles of a circular economy are: the elimination of waste and pollution; the circulation of products and materials; and the regeneration of nature. As Navanthus was built using biodegradable materials and aiming at the bioremediation of water bodies, not only a zero environmental footprint will be achieved during the implementation of the project but also, in the long run, a positive effect on the environment will be observed because of bioremediation. Furthermore, following the implementation of our proposal, we intend to recycle the resources and convert them into marketable products from a circularity perspective. The recyclable components of our project are the hull of the remote-controlled boat, the mycelium, and the genetically modified plants. Both the mycelium platform and genetically modified plants have the potential to produce biomass via the process of composting. This biomass will be utilized to generate energy in the case of the mycelium, and it will be used to generate fertilizer in the case of the genetically modified plant which has stored phosphorus.