Survival and Expansion of Mechanically Transplanted Seagrass Sods

Abstract

Although planting seagrass is not technically complex, the ability to plant large areas is limited by the time-consuming nature of manual methods. Additionally, manual methods use small, spatially isolated planting units (PUs; shoot bundles or plugs/cores) that are often highly susceptible to disturbance. The likelihood for harvesting intact apical meristems may be higher with large sods compared to smaller units, thus increasing survival and expansion rates. Here, we examined the survival and expansion of large units (1.5 3 1.2 m) of seagrass transplanted using a mechanized planting boat (Giga Unit Transplant System; GUTS). Twenty-seven units of seagrass (18 Halodule wrightii and 9 Thalassia testudinum) were transplanted and monitored for survival, shoot density, and expansion. After 3 years, 74.1% of the units had survived (66.7% H. wrightii and 88.9% T. testudinum) with 12 H. wrightii units having expanded substantially beyond the bounds of the original PU, merging with adjacent units to form spatially continuous patches of seagrass. High survival rates for T. testudinum should be interpreted in light of concomitant declines in density and lack of significant expansion after 3 years. In its tested configuration, the GUTS was a viable method for transplanting H. wrightii where donor and receiver sites were in close proximity (<2 km; a current limitation of the GUTS design used here). However, based on the reduced density and lack of significant expansion of T. testudinum that has persisted 3 years posttransplant, the GUTS cannot yet be fully recommended for transplanting this species.

The Value of Long‐Term Assessment of Restoration: Support from a Seagrass Investigation

“…Spillover effects of expanding seagrass cover have received little attention previously, although greater than 100% cover at a restoration site was noted by Fonseca et al () (see also Uhrin et al ). Only by following seagrass development over a comparatively long time were spillover effects revealed however.…”

“…Finally, over expanded time intervals, seagrass coverage may extend beyond initial plot demarcations especially if rhizome growth underlies space occupation (Jensen & Bell ). If spillover of seagrass footprints beyond plot dimensions represents production of new seagrass from the restoration effort (Fonseca et al ; Uhrin et al ), it thereby merits inclusion in metrics of newly created habitat. Thus, information documenting any of the aforementioned scenarios contributes to improved assessment of restoration success.…”

Effects of the roots ofCynodon dactylonandSchefflera heptaphyllaon water infiltration rate and soil hydraulic conductivity

“…(). Note that the applied experimental scheme for the tree‐covered soil was consistent with some typical and standardized procedures adopted for ecological restoration and rehabilitation of some infrastructure such as slopes, road embankments and landfill cover systems (Hau and Corlett, ; Urhin et al ., ). The tree‐covered soil was then subjected to natural variation, until the initial suctions recorded at 0.1‐, 0.3‐ and 0.5‐m depths (8, 9 and 15 kPa, respectively) were close to those observed in bare and grass‐covered soil.…”

Species richness accelerates marine ecosystem restoration in the Coral Triangle

“…However, facilitative interactions could benefit restoration early on or in fluctuating or stressful environments (34,61), as demonstrated intraspecifically for a salt marsh species (62). Interspecific facilitation has been proposed to spread predation risk (52) or hasten colonization of a climax target species, i.e., succession could be "compressed" by planting a single nurse or pioneer species (50,(63)(64)(65). However, empirically testing the effect of species richness on restoration trajectories has remained a research gap highly relevant to restoration goals and costs (17, 66) (Results), which is particularly true in the Coral Triangle where much is at stake environmentally and socially.…”