Open Coast Seagrass Restoration. Can We Do It? Large Scale Seagrass Transplants (original) (raw)
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Modelling seagrass growth and development to evaluate transplanting strategies for restoration
Annals of Botany, 2011
Aims Seagrasses are important marine plants that are under threat globally. Restoration by transplanting vegetative fragments or seedlings into areas where seagrasses have been lost is possible, but long-term trial data are limited. The goal of this study is to use available short-term data to predict long-term outcomes of transplanting seagrass. † Methods A functional -structural plant model of seagrass growth that integrates data collected from short-term trials and experiments is presented. The model was parameterized for the species Posidonia australis, a limited validation of the model against independent data and a sensitivity analysis were conducted and the model was used to conduct a preliminary evaluation of different transplanting strategies. † Key Results The limited validation was successful, and reasonable long-term outcomes could be predicted, based only on short-term data. † Conclusions This approach for modelling seagrass growth and development enables long-term predictions of the outcomes to be made from different strategies for transplanting seagrass, even when empirical long-term data are difficult or impossible to collect. More validation is required to improve confidence in the model's predictions, and inclusion of more mechanism will extend the model's usefulness. Marine restoration represents a novel application of functional -structural plant modelling.
Limited effects of source population identity and number on seagrass transplant performance
PeerJ, 2017
Global declines in coastal foundation species highlight the importance of effective restoration. In this study, we examined the effects of source population identity and diversity (one vs. three sources per plot) on seagrass (Zostera marina) transplant success. The field experiment was replicated at two locations in Massachusetts with adjacent natural Zostera marina beds to test for local adaptation and source diversity effects on shoot density. We also collected morphological and genetic data to characterize variation within and among source populations, and evaluate whether they were related to performance. Transplants grew and expanded until six months post-transplantation, but then steadily declined at both sites. Prior to declines, we observed variation in performance among source populations at one site that was related to morphological traits: the populations with the longest leaves had the highest shoot densities, whereas the population with the shortest leaves performed the...
Restoration Ecology, 2009
Selection of strategies to efficiently utilize limited seed supplies in efforts to restore the seagrass Zostera marina (eelgrass) requires a better understanding of the processes that limit seedling establishment at potential restoration sites. We investigated the effect of seed distribution timing on seedling establishment and tested for interactive effects of seed burial and distribution timing. We also investigated the effect of habitat type on seedling establishment by distributing Z. marina seeds inside and outside of established Ruppia maritima (widgeongrass) patches and examined mechanisms causing habitat differences by manipulating seed position (buried or unburied) and vulnerability to seed predators (unprotected or protected in packets). Seeds distributed on the sediment surface in the summer (July or August) produced fewer seedlings than seeds distributed in fall (October) in five of six trials over 3 years.
Assessing methods for restoration of eelgrass (Zostera marina L.) in a cold temperate region
Journal of Experimental Marine Biology and Ecology, 2016
More than 50% of eelgrass habitats have disappeared from the Swedish NW coast in the last 30 years. Restoration is being proposed to assist recovery but little is known regarding methods suitable under Scandinavian conditions ; e.g. short growing seasons and scouring by ice. In the present study we evaluated different restoration methods using shoots and seeds in a Swedish fjord and assessed if eelgrass could be successfully transplanted between sites with different depth and exposure. The study demonstrates that both shoot-and seed methods can be successfully used to restore eelgrass at this latitude. Survival and growth of unanchored single shoots, transplanted without sediment in shallow habitats (1.0–1.5 m) was very high (N 500% increase in shoot density after 14 months). This restoration method showed 2–3.5 times higher growth rate and was 2–2.5 times faster compared with shoots anchored in the sediment and shoots transplanted in sediment cores, respectively, and is recommended for shallow habitats in Sweden. Growth within deeper habitats (3.0–4.5 m) was substantially lower (40% loss to 50% increase) due to light limitations and high winter mortality. Restoration using seeds distributed from mesh-bags showed very low seedling establishment rates (approximately 1%) making this method less cost-effective than transplanting single shoots in shallow habitats. However, growth of seedlings was high and this method is recommended for deep habitats with soft sediment where shoot transplantation is difficult. Despite dramatic differences in eelgrass morphology between habitats with different depth and exposure, all shoots within a planting site had the same morphology at the end of the study, independent of origin. A baseline genetic survey supported that the observed changes in morphology of transplants were due to a plastic response, suggesting that donor populations do not have to exactly match the morphology of the plants targeted for restoration.
Testing alternate ecological approaches to seagrass rehabilitation: links to life‐history traits
Journal of Applied …, 2010
1. Natural resources and ecosystem services provided by the world's major biomes are increasingly threatened by anthropogenic impacts. Rehabilitation is a common approach to recreating and maintaining habitats, but limitations to the success of traditional techniques necessitate new approaches. 2. Almost one-third of the world's productive seagrass meadows have been lost in the past 130 years. Using a combined total of three seagrass species at seven sites over 8 years, we experimentally assessed the performance of multiple rehabilitation methods that utilize fundamentally different ecological approaches. 3. First, traditional methods of transplantation were tested and produced varied survival (0-80%) that was site dependent. Secondly, seedling culture and outplanting produced poor survival (2-9%) but reasonable growth. Finally, a novel method that used sand-filled bags of hessian to overcome limitations of traditional techniques by facilitating recruitment and establishment of seedlings in situ produced recruit densities of 150-350 seedlings m )2 , with long-term survival (up to 38 months) ranging from 0 to 72 individuals m )2 . 4. Results indicate that facilitating seagrass recruitment in situ using hessian bags can provide a new tool to alleviate current limitations to successful rehabilitation (e.g. mobile sediments, investment of time and resources), leading to more successful management and mitigation of contemporary losses. Hessian bags have distinct environmental and economic advantages over other methods tested in that they do not damage existing meadows, are biodegradable, quick to deploy, and cost less per hectare (US$16 737) than the estimated ecosystem value of seagrass meadows (US$27 039 year )1 ). 5. Synthesis and applications. This research demonstrates how exploring alternate ecological approaches to habitat rehabilitation can expand our collective toolbox for successfully re-creating complex and productive ecosystems, and alleviate the destructive side-effects and low success rates of more traditional techniques. Moreover, new methods can offer economic and environmental solutions to the restrictions placed upon managers of natural resources.
Restoration Ecology, 2008
Restoration has become an integral part of coastal management as a result of seagrass habitat loss. We studied restoration of the seagrass (Halodule wrightii) near Tampa Bay, Florida. Experimental plots were established in June 2002 using four planting methods: three manually planted and one mechanically transplanted by boat. Seagrass cover was recorded at high resolution (meter scale) annually through July 2005. Natural seagrass beds were concurrently examined as reference sites. We also evaluated the suitability of a commonly used protocol (Braun-Blanquet scores, BB) for comparing the development of seagrass cover using the planting methods and quantifying spatial patterns of cover over time. Results show that BB scores mirrored conventional measures of seagrass characteristics (i.e., shoot counts and above- and belowground biomass) well when BB scores were either low or very high. However, more caution may be required at intermediate cover scores as judged by comparison of BB scores with direct measurement of seagrass abundance. Significant differences in seagrass cover were detected among planting methods and over time (2002–2005), with manual planting of rubber band units resulting in the highest cover. In contrast, the peat pot and mechanical planting methods developed very low cover. Recovery rates calculated from development of seagrass spatial cover were less than those reported for natural expansion. Importantly, time to baseline recovery may be substantially greater than 3 years and beyond standard monitoring timelines. Prolonged recovery suggests that the rate of service returns, critical for estimating compensatory restoration goals under habitat equivalency analysis, may be severely underestimated.
Evaluation of the viability of Posidonia oceanica transplants associated with a marina expansion
Botanica Marina, 2000
In March 2005, a preliminary Posidonia oceanica transplantation was carried out as a restoration measure prior to enlargement of a marina. Seagrass sods of approximately 1 m 2 surface area and 40 cm depth (including rhizome and sediment) were cut free from the area expected to be impacted by harbor expansion. These fragments were transferred to nearby areas lacking P. oceanica, viz. in bare areas within the nearest meadows and at the same depth as the donor site (;10 m). The present work was carried out with the aim of evaluating the feasibility of this technique through estimating the vitality of transferred plants (measured as density and cover) for comparison with plants from a nearby meadow with similar conditions. There was a high level of mortality among transplants and a considerable degradation of the shoots that remained alive at the time of the sampling. When results were expressed in terms of global density, the rate of survival of transplanted shoots decreased to 15% (50 vs. 361 shoots m -2 of meadow in transplant and control plots, respectively). These results indicate that transplant techniques for P. oceanica on a large scale are not feasible.
Marine Pollution Bulletin, 2009
Large-scale losses of seagrass beds have been reported for decades and lead to numerous restoration programs. From worldwide scientific literature and 20 years of seagrass restoration research in the Wadden Sea, we review and evaluate the traditional guidelines and propose new guidelines for seagrass restoration. Habitat and donor selection are crucial: large differences in survival were found among habitats and among donor populations. The need to preferably transplant in historically confirmed seagrass habitats, and to collect donor material from comparable habitats, were underlined by our results. The importance of sufficient genetic variation of donor material and prevention of genetic isolation by distance was reviewed. The spreading of risks among transplantation sites, which differed in habitat characteristics (or among replicate sites), was positively evaluated. The importance of ecosystem engineering was shown in two ways: seagrass self-facilitation and facilitation by shellfish reefs. Seagrass self-facilitative properties may require a large transplantation scale or additional measures.
Aquatic Botany, 1997
Using a technique we call the 'horizontal rhizome method', we recently transplanted 2.52 ha of eelgrass in the Great Bay Estuary, New Hampshire, to mitigate for port expansion impacts to an existing eelgrass population. The project represents the largest, most northerly eelgrass transplanting ever attempted on the east coast of the United States. For our revised method, we created a planting unit (PU) by overlapping the rhizomes of two eelgrass shoots in opposite directions and securing them horizontally into the sediment with a bamboo staple. A variation of the bare-root technique, the horizontal rhizome method reduces the number of plants required by up to 80%, has less impact on the donor site, and provides survival rates that equal or exceed that of other methods. One-year survival rates at three subtidal transplant sites were 75-95% for 1993 transplants, and were 98-99% at four of the five subtidal sites planted in 1994. One-year survival rates varied tremendously; low percent survivals resulted from ice damage at all intertidal sites and animal disturbance at some subtidal sites. We found that intertidal transplanting in this tidally dynamic estuary was not successful (sites had 0-15% survival). Sea ice damage, in conjunction with tidal action, caused this lack of success, although natural intertidal eelgrass beds occur both up-and down-estuary of our transplant sites. At the less successful subtidal sites, low survival rates of 1-5% resulted from disturbance of newly transplanted shoots by crabs and clam worms. Overall survival rates for subtidally transplanted eelgrass using the horizontal rhizome method equalled or exceeded those reported for other methods. Shoot density at one transplant site (234 shoots m 2 _+ SE 52.0) exceeded that of the control site (162 shoots m -2 ___ 20.6) within 1 yr of transplanting. Shoot density at all subtidal transplant sites surpassed that of the control site (100 shoots m 2 _+ 11.6) within 2 yr. The horizontal rhizome method is a successful, minimum-impact * Corresponding author. 0304-3770/97/$17.00 © 1997 Elsevier Science B.V. All rights reserved. Pll S0304-3770(97)00034-X 2 R.C. Davis, F.T. Short~Aquatic Botany 59 (1997) 1 15 technique for large scale eelgrass transplanting efforts in a northern New England cold water environment. © 1997 Elsevier Science B.V.