Evaluation of Seagrass Planting and Monitoring Techniques: Implications for Assessing Restoration Success and Habitat Equivalency

Abstract

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 (BraunBlanquet 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)(2003)(2004)(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.

Addition of juvenile oysters fails to enhance oyster reef development in Pamlico Sound

“…Management restoration efforts are usually limited by management sche mes that lead to unsustainable harvesting practices, the amount of money allocated for restoration, and the complexity of ecological processes. Managers and stakeholders should invest in experiments that test whether recruitment is limited before artificially augmenting natural recruitment, a strategy commonly used to restore other biogenic habitats such as seagrass meadows (Bell et al 2008, Orth et al 2012) and coral reefs (Clark & Edwards 1995). As habitat restoration efforts increase, restoration techniques need to be firmly grounded in experimental ecology so that invested resources are maximized based on the spatial and temporal dynamics of recruitment and overall restoration goals.…”

Recovery trajectories during state change from bare sediment to eelgrass dominance

“…Evans & Short (2005) showed that functional equivalence (with reference to natural meadows) of habitat structure based on shoot density, canopy height, and leaf area index was achieved after 3 yr, which is the typical time frame for monitoring programs (Evans & Short 2005). Other studies of restoration by transplanting have also shown similarly fast recovery of habitat structure and specific faunal communities (Fonseca et al 1996a,b, Leschen et al 2010), but Bell et al (2008) found that percent cover of transplanted Halodule wrightii took more than 3 yr to reach 100% coverage equivalent to reference areas. Though perhaps slower to recover, an obvious advantage of the seeding technique we used is the large area that can be restored (>1700 ha in this study after 9 yr; ).…”

“…Assessing the time to achieve functional equivalence of restored areas ideally involves reference sites that are of similar scale, located in similar conditions, and within close proximity (Addy 1947, Palmer et al 1997, Craft et al 2003, Simenstad et al 2006, Bell et al 2008, Fonseca 2011). These requirements were not possible to find for the restored Zostera marina meadows in the Virginia coastal bays; we initially followed Z. marina meadows in Chesapeake Bay and in southern-most coastal bay near the mouth of Chesapeake Bay.…”

“…Metrics in restored habitats are generally compared with natural, reference meadows, although the selection of suitable reference sites by which to judge appropriate restoration endpoints can be problematic, especially in degraded habitats or in areas where seagrass loss is widespread. Assessment of functional trajectories describing the development of ecological functions over time can be used to assess when functional equivalency is reached in seagrass restoration projects (Craft et al 2003, Evans & Short 2005, Bell et al 2008). Our study is the first to monitor long-term (9 yr) trajectories of recovery in seagrass meadows following restoration by seeding.…”

Using Habitat Equivalency Analysis to Assess the Cost Effectiveness of Restoration Outcomes in Four Institutional Contexts

“…This amount was then to be used for restoration actions in order to produce ecosystem services for the population as a whole, as mentioned in the Oil Pollution Act (OPA). The implementation of this method quickly faced two main challenges: it was very costly to collect information on preferences regarding both environmental damages and environmental restoration projects, and the CVM was heavily debated in the community of economists (Bateman and Willis 1999;Arrow 1993;Arrow et al 1993;Kahneman and Ritov 1994;Kahneman et al 1999) and strongly contested by the polluters. 3 The result of these problems was that, at the end of the 90 s, these monetary valuations were less and less accepted by the court of justice as estimates of the non-market impacts of environmental pollution (Thompson 2002).…”