Challenge 5: Engineering Ecological Resilience in Nearshore and Coastal Areas

## THE PROBLEM

Coastal Ecosystems—coral reefs, mangrove forests, and coastal wetlands—are facing constant pressures, coupled with chance events, that threaten their survival. They face the stress of human development, including pollution from industrial and agricultural activity, pressures from tourism, and destructive resource extraction, which are magnified by the effects of climate change, including rising sea levels, increased storm energy, and acidification. Due to these stressors, the critical ecological functions of these habitats continue to be lost at alarming rates. How can we improve the capacity of these systems to respond to stochastic perturbations, in the face of increasing deterministic pressures?

## THE CHALLENGE

Engineer resilience of nearshore & coastal ecosystems (coastal wetlands, mangroves, and coral reefs) against greater perturbations of stress, reduce & reverse proximate stressors, and restore degraded habitats through science, technology, and innovation. Specifically, this challenge seeks innovations that:

1. Enhance ecological resilience to perturbation and accelerate adaptation to global climate change and local stressors through molecular and microbiological engineering;

2. Identify, reduce, and reverse proximate drivers for habitat degradation and destruction through new financial and infrastructure innovations;

3. Restore degraded coral reefs, coastal wetlands, and mangroves through ecological engineering.

## PROBLEM STATEMENT

Coral reefs, mangrove forests, and coastal wetlands represent some of the most biologically diverse and productive habitats on earth. Coastal wetlands (which include salt marshes, sea grass beds, and mangrove swamps) provide critical habitat to wildlife, filter out pollutants, and serve as nurseries for fisheries. Coral reefs similarly provide habitat, spawning, and nurseries to multiple fish species and are immense warehouses of biological diversity. Coral reefs support more species per unit area than any other marine environment, including about 4,000 species of fish, 800 species of hard corals and hundreds of other species, with perhaps an even greater number of species yet to be discovered. These three coastal habitats are critical to humans as well. They offer food and livelihoods, provide coastal armament, store carbon, assist with nutrient cycling, provide important geophysical regulatory services and harbor novel pharmaceutical compounds that have provided treatments for cancer, HIV, and malaria.

However, these ecosystems are in danger due to human activities that are intense and increasing; 50% of salt marshes, 35% of mangroves, and 29% of sea grasses have been either lost or degraded worldwide. More than 60% of the world’s reefs are under immediate and direct threat, and tropical reefs have already lost more than half of their reef-building corals over the last 30 years. Reefs are threatened by coastal development and habitat destruction, watershed-based pollution, marine pollution, and overfishing and destructive fishing through the use of explosives and cyanide. Thirty-five percent of mangroves have been lost due to clearance for aquaculture or agriculture, overharvest for firewood and construction, and pollution. Global climate change further stresses these ecosystems, exacerbating local threats through changes in sea level, ocean temperature, ocean circulation, and acidity.

There is great concern that the high rates, magnitudes, and complexity of environmental change—including habitat degradation, pollutants, resource use, and climate change—are overwhelming the intrinsic capacity of corals, wetlands, and mangroves to adapt and survive. Although it is important to address the root causes of changing climate, it is also prudent to explore the potential to augment the capacity of reef and coastal organisms to tolerate stress and to facilitate recovery after disturbances. For all these ecosystems, the ability to understand the rate and drivers of change and reverse them, to adapt to changes under way, and to restore already degraded habitats is critical to ensuring long-term persistence.

## EMERGING SOLUTIONS

**Reducing & Reversing Stressors**. Attempts to conserve coastal habitats will be insufficient without understanding the state of the ecosystems and their health at scale, radically reducing existing stressors on these ecosystems, and incentivizing habitat protection over destruction. There are a number of new techniques that can be scaled to map, measure, and monitor the state of coastal and nearshore ecosystems. XL Catlin Seaview Survey provides systematically collected, high-definition imagery to monitor reefs globally, and shares the data through its public website, providing 134,759 abundance records of 2,367 fish taxa from 1,879 sites in coral and rocky reefs distributed worldwide. Future attempts will use citizen science to help analyze data. There are numerous off-the-shelf (e.g., Deep Trekker) or do-it-yourself (OpenROV) underwater rovers capable of visually photographing and monitoring the ocean. Satellites are capable of mapping and monitoring coral reefs, like NOAA’s Coral Reef Watch, but for a closer look at the corals, higher resolution satellites or aerial photography is needed, from 1—40 meters. Nanosatellites, such as those deployed by Planet Labs, allow for global capabilities to monitor the status of ecosystems, including mangrove forests, on a daily basis and are emerging as potentially less expensive sources of remote imagery. Citizen science and advanced big data analytics can help analyze the terabytes of data generated by these systems.

Once baselines are established, we may use financial innovations including wetland banks, carbon markets through “blue” carbon sinks, and conservation finance to incentivize the protection of coastal habitats from further degradation, and incentivize the restoration of degraded habitats. **Green infrastructure** can reduce primary sources of ocean pollution, such as non-point source pollution (runoff). Pollutants in runoff include motor oil, trash, pet waste, fertilizers, pesticides, and dirt, all of which can harm marine life. Runoff can be diverted from the ocean through green infrastructure, or low impact development, like capturing rainwater in green roofs, bioswales, rain gardens, and other engineered permeable surfaces such as permeable pavement. However, adopting these designs on a large scale requires incentives to lower barriers, coupled with advances in technology to lower the cost of adoption.

**Engineering Ecological Resilience & Accelerating Adaptation:** Examples of engineering ecological resilience in corals have included accelerated evolution of resilient characteristics, acclimatization, transplantation of resilient populations, and active modification of the community composition of coral-associated microbes. Synthetic biology’s gene editing breakthroughs (CRSPR) now allows for the programming of the very assembly and instructions for life, potentially increasing the speed by which species may adapt to changes in ocean temperatures, acidity, and salinity.

**Advancing Restoration:** Restoration of coral reefs and mangroves has involved direct interventions in rebuilding the ecosystems. Structural interventions that are in use and emerging include using novel materials to create scaffolding on which corals can form. One approach is through Biorock technology, which induces coral polyp settling via electrical impulses. As electric currents pass through salt water, calcium carbonate combines with magnesium, chloride, and hydroxyl ions around the cathode, forming a substance similar to natural reef substrates.