The Genetic Component of Seagrass Restoration: What We Know and the Way Forwards

Abstract

Seagrasses are marine flowering plants providing key ecological services and functions in coasts and estuaries across the globe. Increased environmental changes fueled by human activities are affecting their existence, compromising natural habitats and ecosystems’ biodiversity and functioning. In this context, restoration of disturbed seagrass environments has become a worldwide priority to reverse ecosystem degradation and to recover ecosystem functionality and associated services. Despite the proven importance of genetic research to perform successful restoration projects, this aspect has often been overlooked in seagrass restoration. Here, we aimed to provide a comprehensive perspective of genetic aspects related to seagrass restoration. To this end, we first reviewed the importance of studying the genetic diversity and population structure of target seagrass populations; then, we discussed the pros and cons of different approaches used to restore and/or reinforce degraded populations. In general, the collection of genetic information and the development of connectivity maps are critical steps for any seagrass restoration activity. Traditionally, the selection of donor population preferred the use of local gene pools, thought to be the best adapted to current conditions. However, in the face of rapid ocean changes, alternative approaches such as the use of climate-adjusted or admixture genotypes might provide more sustainable options to secure the survival of restored meadows. Also, we discussed different transplantation strategies applied in seagrasses and emphasized the importance of long-term seagrass monitoring in restoration. The newly developed information on epigenetics as well as the application of assisted evolution strategies were also explored. Finally, a view of legal and ethical issues related to national and international restoration management is included, highlighting improvements and potential new directions to integrate with the genetic assessment. We concluded that a good restoration effort should incorporate: (1) a good understanding of the genetic structure of both donors and populations being restored; (2) the analysis of local environmental conditions and disturbances that affect the site to be restored; (3) the analysis of local adaptation constraints influencing the performances of donor populations and native plants; (4) the integration of distribution/connectivity maps with genetic information and environmental factors relative to the target seagrass populations; (5) the planning of long-term monitoring programs to assess the performance of the restored populations. The inclusion of epigenetic knowledge and the development of assisted evolution programs are strongly hoped for the future.

Wetland Restoration with Hydrophytes: A Review

“…The use of resistant genotypes (to herbivores and salinity, for example) in hydrophyte restoration, as it is proposed for seagrasses [ 115 ], might be an approach for improving the extant genetic baselines of natural populations and for enhancing the resilience of the restored population to present and future stressors (e.g., climate change). The selection of more tolerant genotypes to improve restoration success could be performed by growing wild specimens under controlled conditions, but resistant genotypes can also be produced with a lower level of intervention through the use of priming/hardening methods [ 116 ].…”

“…Not only ecology but also microbiology, soil and genetic sciences are necessary to improve the success of revegetation with hydrophytes, because they can provide new insights into why revegetation fails. The inclusion of an “epigenetic restoration and conservation” perspective together with a genetic one is also desirable as has been suggested for seagrass restoration [ 115 ]. Many papers lack precise data on the speed and efficiency of colonization of the wetlands by the different species, and this information is very valuable for wetland restoration practices with hydrophytes elsewhere.…”

Rewilding the Sea with Domesticated Seagrass

“…Genetic selection focusing on certain desirable traits has, to our knowledge, only recently started to become considered in scientific restoration literature, particularly in the context of climate change (van Oppen et al 2015 , Coleman and Goold 2019 , Gaitan-Espitia and Hobday 2021 , Pazzaglia et al 2021 ). Genetic selection for certain traits can be desirable to enhance success in environmentally altered environments.…”

“…In seagrasses, an example would be the trait for heat resistance in areas such as Chesapeake Bay, Florida, in the United States, and Shark Bay, in Australia, which have regularly experienced lethal summer heat or heat waves in recent years (Lefcheck et al 2017 , Carlson et al 2018 , Strydom et al 2020 ). Donor material could be sourced from populations experiencing environmental conditions as projected in the near future for the transplantations site (Pazzaglia et al 2021 ). Selection may also focus on preferred traits to deliver ecosystem services or ecosystem goods, such as a large biomass or high seed production.…”

Assessing Population Genetic Status for Designing Plant Translocations

“…If the introduced gene pool is too genetically differentiated from the natural pool or if the propagated transplants originate from several genetically differentiated sources, founders may be maladapted, and outbreeding depression may be found in the outcrossed progeny as a result of a breakdown of the coadapted genes (Edmands, 2007;Bowles et al, 2015;Barmentlo et al, 2018). Therefore, carefully preparing the translocation is essential for optimizing the success in achieving genetically and demographically viable populations (Godefroid et al, 2016a;Commander et al, 2018) and optimizing population resilience to changing environmental conditions (Sgrò et al, 2011;Borrell et al, 2019;Pazzaglia et al, 2021). Several features have to be taken into account in designing the translocation.…”