Eelgrass restoration by seed maintains genetic diversity: case study from a coastal bay system

Abstract

Genetic diversity is positively associated with plant fitness, stability, and the provision of ecosystem services. Preserving genetic diversity is therefore considered an important component of ecosystem restoration as well as a measure of its success. We examined the genetic diversity of restored Zostera marina meadows in a coastal bay system along the USA mid-Atlantic coast using microsatellite markers to compare donor and recipient meadows. We show that donor meadows in Chesapeake Bay have high genetic diversity and that this diversity is maintained in meadows restored with seeds in the Virginia coastal bays. No evidence of inbreeding depression was detected (F IS −0.2 to 0) in either donor or recipient meadows, which is surprising because high levels of inbreeding were expected following the population contractions that occurred in Chesapeake Bay populations due to disease and heat stress. Additionally, there was no evidence for selection of genotypes at the restoration sites, suggesting that as long as donor sites are chosen carefully, issues that diminish fitness and survival such as heterosis or out-breeding depression can be avoided. A cluster analysis showed that, in addition to the Chesapeake Bay populations that acted as donors, the Virginia coastal bay populations shared a genetic signal with Chincoteague Bay populations, their closest neighbor to the north, suggesting that natural recruitment into the area may be occurring and augmenting restored populations. We hypothesize that the high genetic diversity in seagrasses restored using seeds rather than adult plants confers a greater level of ecosystem resilience to the restored meadows.KEY WORDS: Seagrass · Zostera marina · Restoration · Genetic diversity · Microsatellite DNA Resale or republication not permitted without written consent of the publisher Contribution to the Theme Section 'Eelgrass recovery'OPEN PEN ACCESS CCESS

Restoration recovers population structure and landscape genetic connectivity in a dispersal‐limited ecosystem

“…Many of the Zostera marina populations in southern Chesapeake Bay were decimated by the wasting disease of the 1930s (Orth & Moore 1984) but recovered naturally and have a high genetic diversity (Table 1, Reynolds et al 2012). This is probably due to an abundance of seed from the more northern parts of Chesapeake Bay.…”

“…Recovery in this region is recent (< 15 years), and the young meadows present in this region are either a result of large-scale restoration or natural recruitment. Naturally recruited, restored and source meadows for restoration were included in this survey as well as the previously hypothesized source of natural recruitment (Chincoteague Bay; Harwell & Orth 2002;Reynolds et al 2012) and other representative meadows both north and south of the region. See Table 1 for a summary of sampling sites.…”

“…Methods follow those described in Reynolds et al (2012): DNA was extracted from leaf tissue using DNeasy TM plant extraction kits (Qiagen, Valencia, CA, USA) following manufacturer's instructions. Extracted DNA was amplified at seven polymorphic loci previously described for this species (CT3, GA2, GA3: described by Reusch, Stam & Olsen 1999; and CT17H, CT35, CT19 and CT20: described by Reusch 2000) using standard PCR techniques (Reusch, Stam & Olsen 1999).…”

Numerous mitigation transplants of the eelgrass Zostera marina in southern California shuffle genetic diversity and may promote hybridization with Zostera pacifica

“…A new transplant technique incorporating seeds has been shown to be very promising in Chesapeake Bay, VA Orth and McGlathery, 2012;Reynolds et al, 2012a). In theoretical terms, the result is not surprisinout linkage disequilibrium.…”

INTRODUCTION Eelgrass recovery in the coastal bays of the Virginia Coast Reserve, USA

“…They also identify the depth limit (1.6 m) for eelgrass populations in the coastal bays. Using microsatellite markers, Reynolds et al (2012) show that the high genetic diversity in donor beds from Chesapeake Bay is maintained in meadows restored by seeding in the Virginia coastal bays. found that nitrogen fixation increased as the meadows aged, with older beds fixing almost 3 times more nitrogen than younger meadows and 30 times more than bare sediment.…”