Seagrass Biodiversity Assessment (SeBA)

Concepts: eDNA, Biodiversity, Conservation

Environmental DNA (eDNA) is a valuable research tool for monitoring protected species in Bermuda. eDNA assessments involve collecting samples from the environment and analysing the DNA which they contain to determine the overall biodiversity of the ecosystem (i.e. which species are present). In the Seagrass Biodiversity Assessment (SeBA), we are applying this technique to determine which species are present in our island’s few remaining seagrass meadows. Local seagrass has experienced a rapid die-off, declining from 5000 acres to nearly total depletion over the last 30 years. In addition to supporting marine species, seagrass also provides essential ecological services for human communities:

• It sequesters carbon to mitigate climate change;

• It filters environmental toxins;

• It retains sediments which helps maintain Bermuda’s crystal clear water.

With efforts underway to restore local seagrass beds, we are searching for tools to help us track changes in these ecological services. In our study, we are focusing on the nursery habitat which seagrass provides for juvenile fish. By painting a picture of the larger seagrass community, we will form a deeper understanding of the health of this ecosystem. We are trialing a new method for collecting fish eDNA by sampling directly from seagrass blades. If successful, our project will provide a method that is less expensive, more feasible and more effective than traditional marine monitoring techniques.

The loss of Bermuda seagrass has galvanised Government and public support for seagrass restoration cages which exclude sea turtles - the primary consumers of seagrass. This approach has achieved significant regrowth of seagrass within cages. Having demonstrated that seagrass acreage can be restored, we must determine if we can also restore the nursery habitat which this seagrass has historically provided for local fish. We propose to track the biodiversity of fish in Bermuda seagrass using eDNA. With lower costs and more expedient results compared to traditional survey methods, eDNA is a powerful tool that will provide valuable information about seagrass habitats in Bermuda.

We are piloting a new method which samples eDNA directly from seagrass blades. To date, researchers have extracted eDNA from water, sponges and marine sediments. By establishing the potential for a new technique which samples eDNA directly from seagrass blades, we will be chartering a protocol for the long-term monitoring of seagrass restoration in Bermuda and making a novel contribution to global marine science. We will collect eDNA from two species of seagrass currently growing in cages at Burt Island in the Great Sound. We will compare our data against a growing genetic library of Bermuda fish species to rapidly gather biodiversity information on these seagrass restoration sites. Using a combination of traditional survey methods, contemporary eDNA methods and our novel eDNA method, we will create a digital archive of our island's seagrass ecosystems which will serve as a baseline for future generations of Bermudian scientists and conservation officers.

The primary objective of this project is to determine if eDNA can be extracted directly from seagrass. The anticipated benefit of achieving this objective is the establishment of a long-term monitoring protocol for assessing the recovery of seagrass in Bermuda.