The world’s oceans are home to complex ecosystems, many of which have come under threat because of environmental changes and human activity. In this article, we explore major threats to ocean health. We explore ways that genetic sequencing technologies are opening the door to new research and conservation strategies.
Researching Threats to Ocean Health
Combatting Plastic Pollution
Macro and microplastics are dangerous threats to ocean ecosystems. Macroplastics can be ingested by fish, birds, and other animals. When these larger plastics break down, microplastics (smaller than 5 mm) can be ingested by a wider variety of animals, from whales to plankton. For fish, these small pieces can interfere with the function of their gills.
Estimating the total amount of plastic in the world’s oceans is an incredibly difficult task. In 2020, the number of plastic particles in the oceans was estimated at between 82 and 358 trillion. Scientists have yet to develop a reliable way to remove microplastics from the ocean.
Some researchers have turned to insect bacteria for their ability to degrade plastic structures. Whether it is bacteria from wax moth larvae breaking down polyethylene or mealworms successfully ingesting and using Nylon 11 as a carbon source, some research projects have found ways to successfully break down plastics. In these studies, genetic sequencing was used to identify bacterial strains and understand changes in bacterial content after the introduction of plastics, respectively.
Other projects have looked at bacterial isolates from Mangrove sediment, algae enzymes, and fungi from 11 different classes. With viable solutions for degradation, the next steps would be developing large-scale processes for waste management.
Monitoring Invasive Species
Ocean temperature changes have made it possible for species to survive in non-native environments. Invasion genetics recognizes the importance of monitoring the spread of these species and any negative impacts on the environment.
On the US East Coast, for example, warmer temperatures have made it possible for the Caribbean green porcelain crab to spread as far as central North Carolina. Morphological and genetic sequencing over a four year period allowed researchers to track the spread of this species.
Genomics technologies are also used to evaluate the differences between native and non-native species, as in a 2017 study on gammarids. With genetic data, researchers better understood the divergence of species within the family, as well as what genetic mechanisms make for successful versus unsuccessful invader species.
When native species interbreed with non-native species, genetic technologies can also detect those hybridizations and the degree of genetic exchange. A major goal of invasion genetics is to identify vectors of species spread. For marine life, that is often via human activities like global shipping routes. A genetic-level understanding of these species is an important step in developing mitigation strategies.
Detecting Unsustainable Fishing Practices
In some instances, illegally captured fish is deliberately substituted and mislabeled to allow for its sale. This can be difficult to detect without genetic sequencing technology, because the fish is then butchered in a way that removes visual identifying features.
In this 2022 Chilean study, researchers used DNA barcoding technology to investigate fish sold at a swordfish market. Results showed that 8.52% of swordfish samples were actually species of shark considered endangered or vulnerable. Developing cost-effective testing to identify fish species is an important key to enforcing conservation legislation.
Conserving Coral Reef Communities
Coral reefs are at the center of high-profile conservation efforts. Reefs provide habitat for many species of marine animals, and are linked to the health of nearby plant and animal communities.
Reef communities are vulnerable to changes in ocean temperatures and pollution. Researchers have used genetic data to compare diversity in coral reef communities. Results from this 2008 study indicated that marine protected areas (MPAs) can create differing pockets of biodiversity. It also indicates that some coral species are more vulnerable to environmental threats than others.
Genetic studies have also been used to monitor fish populations across MPAs. By analyzing SNPs, scientists were able to determine that the ideal spacing between MPAs for the yellowhead Jawfish is 8.3 kilometers. At a distance of greater than 50 kilometers between MPAs, dispersal is dramatically reduced. This study showed the value of SNP analysis for determining ideal MPA spacing for any fish species.
More recent studies have used population genomics data to create polygenic risk scoring for coral bleaching. This research has provided valuable insight into coral species’ tolerance to heat changes and bleaching, as well as the degree to which this tolerance is heritable. Genetic markers have even provided a path forward for crossbreeding of species to create more heat-tolerant coral communities.
The symbiotic relationship between coral and algae species is an important marker of coral success. Algae live in coral tissues and create organic compounds via photosynthesis. These compounds are used by the coral for energy. In return, algae receive a stable environment and energy released by coral polyps.
During coral bleaching, algae are expelled from the coral tissues. This resource loss deprives coral of a major source of energy, making it more vulnerable to death and disease.
Researchers have identified unique transcriptomic factors that make these symbiotic relationships possible, including upregulated genes and decreased metabolic activity. Lab-grown, heat-resistant algae have also been successful in increasing coral tolerance to heat. In a 2020 study out of Australia, 10 lab-grown algal species were more tolerant to increased water temperatures. Three of these species successfully decreased the risk of coral bleaching in host species. Analysis found several down-regulated genes in these heat-exposed algal species, which could be helpful for future conservation efforts.
Genetic research is a powerful tool in ocean conservation, offering invaluable insights and innovative solutions to address the challenges facing marine ecosystems. Through the study of genetic diversity, population dynamics, and evolutionary processes, researchers can unravel marine biodiversity and devise targeted conservation strategies.
Advances in molecular techniques like DNA barcoding, genomics, and population genetics expand the scope and effectiveness of genetic research in ocean conservation. As efforts to protect marine ecosystems continue, we can expect to see genetic research play a critical role in developing effective, informed strategies for safeguarding these communities.
