Method for the quantitative evaluation of ecosystem services in coastal regions

Wetlands, tidal flats, seaweed beds, and coral reefs are valuable not only as habitats for many species, but also as places where people interact with the sea. Unfortunately, these areas have declined in recent years, so environmental improvement projects to conserve and restore them are being carried out across the world. In this study, we propose a method for quantifying ecosystem services, that is, useful for the proper maintenance and management of artificial tidal flats, a type of environmental improvement project. With this method, a conceptual model of the relationship between each service and related environmental factors in natural and social systems was created, and the relationships between services and environmental factors were clarified. The state of the environmental factors affecting each service was quantified, and the state of those factors was reflected in the evaluation value of the service. As a result, the method can identify which environmental factors need to be improved and if the goal is to increase the value of the targeted tidal flat. The method demonstrates an effective approach in environmental conservation for the restoration and preservation of coastal areas.

119 targeted in this study, it would generally be desirable to use more target tidal flats to reduce the 120 deviation of the service scores.

121
SN is an artificial biological symbiotic port structure in Tokyo Bay ( 132 The scope of the tidal flat evaluation comprised the area from the water-land interface to the 133 intertidal zone (i.e., the area shallower than the low water level). The water-land interface was 134 delineated by embankments or structures abutting the landward side of tidal flats.

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The Manuscript to be reviewed 166 The present status x i is normalized by the reference point with Equation (2): 168 where X i is the present status value for service i and X i,R is the reference point. Any X i value 169 beyond 2 from the mean was determined to be an outlying observation and was not used in the 170 calculations. Halpern 198 where T i is the trend for service i (see Section 2.4), β is the relative importance of the trend 199 versus PR (pressure and resilience) scores, and PR i is the PR score for service i (see Section 2.6).

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A positive sustainability score means that the service will improve under present conditions, 217 and a negative one means that the service will decline under present conditions. We can look for 280 As an index of environmental education for water front use, we used the number of visitors for 281 the purpose of environmental education and related activities (SI 4). As an index of research for 282 water front use, we used the number of published papers and reports (SI 5).

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As an index of historical designation as special sites for sense of place, we used the numbers 284 of festivals and of faith-related buildings (SI 6). As an index of places for everyday rest and 285 relaxation for sense of place, we developed a rest and relaxation index relative to the total hours 286 of everyday use that was adjusted for the user's stated level of conscious awareness of the value 287 of the sites for walks, rest and relaxation, and other similar uses (SI 7).

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As an index of suspended material removal for water quality regulation, we used the bivalve 289 water filtration volume (SI 8). As an index of organic matter decomposition for water quality 290 regulation, we used the COD purification amount (calculated from the production/biomass ratio) Manuscript to be reviewed 291 by benthic organisms (SI 9). As an index of carbon storage for water quality regulation, we used 292 the carbon fixation in benthic organisms and sediment (0-10 cm in depth) (SI 10).

293
As an index of degree of diversity for biological diversity, we used the Shannon-Wiener 294 diversity index (H') for the entire study area (SI 11). Finally, as an index of rare species for 295 biological diversity, we used the number of threatened species adjusted by category of threatened 296 status (SI 12). 336 Although SN had a high service score, its sustainability score was negative (-41%), indicating 337 that this service will decay under the present condition. To suppress this decay, countermeasures 338 need to be taken in the categories of anoxic water, blue tide, ground stability, predatory or 339 competitive species, and protection of species, all of which had negative PR scores (Fig. S3).
340 Although the service score of UK was low (5.3), its sustainability score was positive (+17%), so 341 the present status can be maintained in the present environmental condition. UK is located in an 342 area with good water quality and has been established for more than 30 years, so there is no need 343 for countermeasures against the water environment and instability of the ground just after 344 construction. The service scores of TR and OR (4.0 and 5.6) were not high, but the sustainability Manuscript to be reviewed 507 our results allow consideration of countermeasures to improve individual services, but that is not 508 sufficient to improve the comprehensive evaluation of services of tidal flats. Incorporating trade-509 off relationships and a weighting of services is necessary to be able to consider which services 510 would be most effective for taking countermeasures.

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It is conceivable that the weight of the effect of the environmental factors also differs. At 512 present, the PR scores were all weighted the same, but we need to consider weighting these 513 scores as well. In addition, we assumed a qualitative PR score to be half that of a quantitative PR 546 where T i is the trend score, T i-U is the upper limit of the 95% CI, T i-L is the lower limit of the 95% 547 CI, t i is the slope of the regression line, and se i is the standard error of the slope.

548
We estimated CIs for likely near-term future status and service scores for food provision, 549 coastal protection, environmental education, research, suspended material removal, organic 550 matter decomposition, carbon storage, degree of diversity, and rare species for which likely near-551 term future status were calculated based on past data (Fig. 5). The other services (recreation, 552 historical designation as special sites, and places for everyday rest and relaxation) were not 553 included because there was no past data and trends were not estimated.

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For food provision, suspended material removal, organic matter decomposition, and degree 555 of diversity, whose service scores depend on biomass, the error was large in SN. It has been less 556 than 10 years since SN was constructed, and biomass in the area may still be in transition. In 557 addition, SN is located in a port with poor water quality, and environmental impacts such as 558 anoxic water and blue tide often occur and the habitat environment is unstable. In contrast, the 559 error for rare species was greater for the natural tidal flats. This occurred because, in the natural 560 tidal flats, the annual differences in the number of rare species observed was large, whereas in    Manuscript to be reviewed Services, indices of services provided, definitions of spatial and temporal range, and key index unit of tidal flats and tidal flat ecosystems.
The services and indices are described in more detail in the SI. 1 Note: A "-" indicates the tidal flat was omitted from the analysis, usually because the service did 2 not apply in that tidal flat.