Restoration projects require an underpinning of science to maximise success at restoring ecological function. Occasionally wetland restoration objectives focus on clearing intertidal vegetation, including removal of introduced and rapidly expanding native species, such as the expansion of mangrove forests in New Zealand. Typical objectives of these restoration projects addressing mangrove expansion include restoring intertidal sites to historically sand-dominated substrates that are associated with higher societal and cultural values through recreational access, natural character (e.g., viewscape) and enhancement of shellfish resources. Historically, mangrove management occurred with minimal or no monitoring to confirm if these objectives were achieved, and with no consistent approach in terms of restoration methodology or monitoring used across the various management jurisdictions. This paper reviews the monitoring programs associated to date with restoration projects in New Zealand involving mangrove removal, with an aim to outline the key management considerations and environmental measures that should be included in future monitoring programs. Monitoring techniques that should be included in management activities that involve mangrove removals are summarised, highlighting methodologies to document changes in surface topography, sediment characteristics and various biological changes. The monitoring objectives have been categorised in three levels, relative to the complexity of the technique and the cost. We hope that this paper will be useful to any group or organisation around the globe who wish to document the extent and rate of change where mangrove vegetation has been cleared. Better documentation on successes and failures of management actions related to mangrove expansion can inform future management strategies, and prioritise cost-effective actions in locations that are likely to result in successful restoration of ecological function of estuarine habitats.
Coastal regions are complex social-ecological systems (SESs) critically important for their diverse and invaluable services for human well-being. The marked losses of these systems on a global scale has led to proposals for the protection of healthy habitats which, however, have proven to be less than completely successful, thereby necessitating the restoration of impacted habitats. Although the effective delivery of restored ecosystem services or natural capital is determined by governance and management, these important topics have only rarely been examined (and never comparatively so) in the marine literature. Because marine ecological restoration is still very much in its infancy, it is necessary to turn to terrestrial examples for guidance. The present paper reviews the wider, terrestrially-based literature that has developed on the conceptual and practical relationships of governance to ecological restoration, towards an end of importing five lessons from this experience that might prove useful for the sustainable management of marine SESs, particularly in relation to the praxis of marine social-ecological restoration. These lessons are: avoid science/engineering only; instill adaptive management; hybrid governance models work best; establish an experienced advisory committee; and put stakeholders front and centre. Recommended actions needed to adopt these lessons include: assessing the cultural modification of the restoration location; including a social scientist on the restoration team; identifying multiple stakeholders; integrating technical knowledge of experts and local wisdom of residents; and implementing flexibility in governance to facilitate project resilience.
Restoration of native species may be hampered by competition with non-native species. The outcomes of competition are often context-dependent, with one species dominating under some conditions but not others. Where non-natives differ from natives in their ability to tolerate stressful environmental conditions, restoration practitioners may be able to manipulate conditions or strategically locate restoration projects along naturally occurring stress gradients to favor native species. We tested the responses of native oysters and a suite of non-native sessile invertebrate species (mostly soft-bodied organisms) to varying tidal elevations, shoreline types, and distances from source populations. Cover of non-natives was lower at higher tidal elevation and far from adult populations. Native oyster recruitment was also reduced at the high tidal elevation. At this elevation oyster dominance was increased, but abundance was reduced. To test an adaptive management approach, we moved substrates from the low to high tidal elevations. Cover of non-natives had decreased dramatically one year later, while oyster metrics were unaffected or improved compared to those on substrates remaining at the low elevation. Our study indicates that reduction of non-native species abundance, often an explicit goal of restoration, may be achieved by strategic location of restoration units, although abundance of target species may also be reduced, at least over the short term. However, restoration practitioners may be able to increase abundance of target species and reduce non-natives by applying stress differentially over time, with benign conditions during sensitive early life stages, and increasing stress after target organisms become more tolerant.
The European Water Framework Directive requires a good ecological potential for heavily modified water bodies. This standard has not been reached for most large estuaries by 2015. Management plans for estuaries fall short in linking implementations between restoration measures and underlying spatial analyses. The distribution of emergent macrophytes – as an indicator of habitat quality – is here used to assess the ecological potential. Emergent macrophytes are capable of settling on gentle tidal flats where hydrodynamic stress is comparatively low. Analyzing their habitats based on spatial data, we set up species distribution models with ‘elevation relative to mean high water’, ‘mean bank slope’, and ‘length of bottom friction’ from shallow water up to the vegetation belt as key predictors representing hydrodynamic stress. Effects of restoration scenarios on habitats were assessed applying these models. Our findings endorse species distribution models as crucial spatial planning tools for implementing restoration measures in modified estuaries.
Coastal “blue carbon,” (carbon sequestered in salt marsh, mangroves, and seagrasses) is a newly recognized benefit. The National Oceanic and Atmospheric Administration (NOAA), with partners, has been exploring and developing new policy opportunities for coastal conservation using the climate benefits of these ecosystems. We detail NOAA's efforts (federal and international, market and non-market) to leverage blue carbon for coastal conservation including: (1) how blue carbon is or could be incorporated into U.S. federal policies (both existing and new policy activities); (2) market-based policy solutions including the development of a Verified Carbon Standard methodology for carbon credits for wetland restoration and two landscape assessments of the climate mitigation benefits of watershed-scale restoration; and (3) international efforts to build a North American community of practice for blue carbon science and policy with the Commission for Environmental Cooperation, Canada, and Mexico, and an assessment of where blue carbon can be incorporated into international policy frameworks (including the Intergovernmental Panel on Climate Change (IPCC) Wetlands Supplement and the United Nations Framework Convention on Climate Change (UNFCCC)). Protecting coastal carbon leads to co-benefits including resilience to storms and erosion, and fishery benefits, thus blue carbon is a “triple win” for climate mitigation, adaptation, and conservation.
With accelerating degradation of coastal environment worldwide, restoration has been elevated as a global strategy to enhance the functioning and social services of coastal ecosystems. While many developing countries suffer from intense coastal degradation, current understanding of the science and practice of their coastal restorations is extremely limited. Based on analysis of > 1000 restoration projects, we provide the first synthesis of China's coastal restorations. We show that China's coastal restoration has recently entered a rapidly developing stage, with an increasing number of restoration projects carried out in multiple types of coastal ecosystems. While long-term, national-level restorations enforced by the government appear promising for some coastal ecosystems, especially mangroves, restorations of many other coastal ecosystems, such as salt marshes, seagrasses and coral reefs, have been much less implemented, likely due to under-appreciation of their ecosystem services values. Furthermore, the planning, techniques, research/assessment, and participation models underlying current restorations remain largely inadequate for restoration to effectively halt rapid coastal degradation. To promote success, we propose a framework where paradigms in current restorations from planning to implementation and assessment are transformed in multiple ways. Our study has broad implications for coastal environmental management policies and practices, and should inform sustainable development of coupled human-ocean systems in many countries.
The enhanced key-food-web offshore restoration technique by wall roughening is proposed in this approach. Three kinds of wall roughening, i.e. artificial reefs, hard slope roughing and the integration of artificial reefs and hard slope roughing are applied to enhance the original key-food-web offshore restoration technique. The effects of ecological rehabilitation of the proposed enhanced key-food-web offshore restoration technique are predicted by the models of Ecopath model and ocean health index. The results indicate that the ecological rehabilitation of the enhanced key-food-web offshore restoration technique with different wall roughening is better than that of the original one. Among them, the enhanced key-food-web offshore restoration technique with the integration of artificial reefs and hard slope roughing is the best. After using it, the restored offshore ecosystem is the most mature, and the ocean health index is increased to 87.1 or 87.3 with respect to the case of 2% or 0.57% artificial reef for the conservative or optimistic analysis.
Over the years, the Mondego estuary has undergone various anthropogenic impacts. One of the most serious was the closing of the communication between the two arms of the system (north and south), in the 1990s, which promoted eutrophication and a consequent water quality decline in the south arm. Several mitigation measures were subsequently implemented, in particular the re-establishing of the communication between the two arms in 2006, increasing water flow and reducing water residence time in the south arm. The present study aimed to evaluate the impact of management measures on the ecological and conservation condition of the Mondego estuary, through a longitudinal assessment of the structure and composition of the fish communities over a decade. The Mondego fish community showed important modifications over the years, in terms of structure, ecological quality and conservation value. The fish community status improved following the reconnection of both arms. In the south arm those changes appear to be more evident than in the other estuarine areas, where an inverse pattern was observed in the last few years. A redistribution of the fish species within the system may have been responsible for those unexpected alterations in the north arm and upstream area.
Most marine habitats have unique soundscapes and, among other potential ecological consequences, the larvae of many fish and invertebrates use habitat-specific sounds to locate appropriate settlement habitat. Anthropogenic stressors have degraded coastal ecosystems worldwide, but the effects of this degradation on the sounds emanating from deteriorated habitats are largely undocumented, as is the effectiveness of habitat restoration in reestablishing natural soundscapes. In this study, we investigated how ambient sound emanating from three near-shore, tropical habitats (subtidal mangrove prop-root habitat, seagrass, and sponge-dominated hard-bottom) in the Florida Keys, Florida (USA) varied with time-of-day and lunar phase. We also examined whether the destruction of sponge communities in hard-bottom habitats struck by cyanobacteria blooms alters the soundscape of that habitat, and if restoration of sponge communities can reestablish natural underwater soundscapes. Soundscapes of each habitat were examined using several acoustic metrics, including spectral analysis and counts of fish calls and snapping shrimp snaps. Mangrove, healthy hard-bottom, and restored hard-bottom habitats had higher soundscape spectra levels than seagrass and degraded hard-bottom whether at noon or dusk during new or full moons. Low-frequency sounds, most likely fish calls in the ~ 300 Hz frequency range, were most prevalent in mangroves during dusk full moons. There were also higher numbers of snapping shrimp snaps in mangrove, healthy hard-bottom, and restored hard-bottom habitats than in degraded hard-bottom and seagrass beds, especially during the prominent dusk snapping shrimp chorus. Our results demonstrate that near-shore tropical habitats have unique soundscapes that are diminished by habitat degradation, but can be reestablished by habitat restoration, at least in the case of sponge-dominated hard-bottom.
Mangrove restoration projects, aimed at restoring important values of mangrove forests after degradation, often fail because hydrological conditions are disregarded. We present a simple, but robust methodology to determine hydrological suitability for mangrove species, which can guide restoration practice. In 15 natural and 8 disturbed sites (i.e. disused shrimp ponds) in three case study regions in south-east Asia, water levels were measured and vegetation species composition was determined. Using an existing hydrological classification for mangroves, sites were classified into hydrological classes, based on duration of inundation, and vegetation classes, based on occurrence of mangrove species. For the natural sites hydrological and vegetation classes were similar, showing clear distribution of mangrove species from wet to dry sites. Application of the classification to disturbed sites showed that in some locations hydrological conditions had been restored enough for mangrove vegetation to establish, in some locations hydrological conditions were suitable for various mangrove species but vegetation had not established naturally, and in some locations hydrological conditions were too wet for any mangrove species (natural or planted) to grow. We quantified the effect that removal of obstructions such as dams would have on the hydrology and found that failure of planting at one site could have been prevented. The hydrological classification needs relatively little data, i.e. water levels for a period of only one lunar tidal cycle without additional measurements, and uncertainties in the measurements and analysis are relatively small. For the study locations, the application of the hydrological classification gave important information about how to restore the hydrology to suitable conditions to improve natural regeneration or to plant mangrove species, which could not have been obtained by estimating elevation only. Based on this research a number of recommendations are given to improve the effectiveness of mangrove restoration projects.