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Seagrass are under great stress in the tropical coast of Asia, where Enhalus acoroides is frequently the dominant species with a large food web. Here, we investigate the question of the fine-scale genetic structure of this ecologically important foundation species, subject to severe anthropogenic disturbance in China. The genetic structure will illuminate potential mechanisms for population dynamics and sustainability, which are critical for preservation of biodiversity and for decision-making in management and restoration. We evaluated the fine-scale spatial genetic structure (SGS) and flowering output of E. acoroides, and indirectly estimated the relative importance of sexual versus asexual reproduction for population persistence using spatial autocorrelation analysis. Results reveal high clonal diversity for this species, as predicted from its high sexual reproduction output. The stronger Sp statistic at the ramet-level compared with genet-level indicates that clonality increases the SGS pattern for E. acoroides. Significant SGS at the genet-level may be explained by the aggregated dispersal of seed/pollen cohorts. The estimated gene dispersal variance suggests that dispersal mediated by sexual reproduction is more important than clonal growth in this study area. The ongoing anthropogenic disturbance will negatively affect the mating pattern and the SGS patterns in the future due to massive death of shoots, and less frequency of sexual reproduction. Agência financiadora National Science & Technology Basic Work Program 2015FY110600 National Natural Science Foundation of China 41606182 41730529 Chinese Academy of Sciences XDA13020204 info:eu-repo/semantics/publishedVersion

The Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK model) was developed by the U.S. Environmental Protection Agency to support assessments of health risks to children from exposures to lead (Pb).This study evaluated performance of IEUBK model (v2.0) as it would be typically applied at Superfund sites to predict blood Pb levels (BLLs) in populations of children.The model was evaluated by comparing model predictions of BLLs to 1144 observed BLLs in a population of children at the Bunker Hill Superfund Site for which there were paired estimates of environmental Pb concentrations.Predicted population geometric mean (GM) BLLs (GM: 3.4 µg/dL, 95% CI: 3.3, 3.5) were within 0.3 µg/dL of observed (GM: 3.6 µg/dL, 95% CI: 3.5, 3.8). The model predicted the observed age trend in GM BLLs and explained ~90% of the variance in the observed age-stratified GM BLLs. The mean predicted probability of exceeding 5 µg/dL (PAlthough the more general applicability of these findings to other populations remains to be determined in future studies, our results support applications of the IEUBK model (v2.0) for informing risk-based decisions regarding remediation of soils and mitigation of exposures at Superfund sites where the majority of the exposure unit GM BLLs are expected to be ≤5 µg/dL and where it is desired to limit the predicted probability of exceeding 5 µg/dL to5%.

Biscayne Bay is a shallow subtropical estuary, 225 square miles of water, at the edge of the tropics, located within Dade County, one of the fastest growing counties in the U.S.A. The fragility of this seagrass and mangrove dominated estuary has been demonstrated by repeated destruction of these ecosystems by man's activities, such as dredging, filling, drainage, sewerage, thermal pollution, and others. At the southern end, the U.S. Department of the Interior has recently established the Biscayne Monument, a preserve area where fairly rigit restrictions for man's use of the biota are enforced. At the northern end, intense land development since 1910 along with establishment for artificial islands and causeways, bulkheading, sewerage outfall and other pollutants has altered the ecology greatly. Approximately 1.5 million people inhabit this area. Multiple authorities for regulating use in the bay and its shoreline exist ranging from county to Federal. Many problems of overlapping jurisdiction and enforcement occur. Two symposia to bring together the knowledge of processes occurring m the bay and to delineate a policy for managing the bay were held in March 1976 resulting in the Volume, Biscayne Bay: Past, Present, and Future. Aspects of the ecology of this bay and of the management problems and goals will be discussed.

Seagrass longevity up to 47 years in well-restored, well-sited seagrass restorations are demonstrated from 253 trials at 83 regional sites in tropical and subtropical portions of three oceans (Atlantic, Pacific, Indian Oceans). These trials include over 3.04 million planted units into 306.3 ha. Approximately 12% of the total global tropical restored seagrass by Van Katwijk, Thorhaug et al. (2016) calculations from 1786 trials are included. Almost all projects herein reviewed persisted since date of planting except several cases with harsh anthropogenic impact or forceful natural events in first post-planting months. The oldest tropical/subtropical restoration continually observed is 47 yrs, many are 35 yrs. An array of observed and/or measured restored services accompanied these. This review may provide informational background for government resource managers, legislators, scientists, and citizens concerning tropical/subtropical seagrass longevity. This data from these trials may substantiate future seagrass restoration investments. Public outreach, national & regional government training,and outreach occurred, needing continuation.

Climate Change solutions include CO2 extraction from atmosphere and water with burial by living habitats in sediment/soil. Nowhere on the planet are blue carbon plants which carry out massive carbon extraction and permanent burial more intensely concentrated than in SE Asia. For the first time we make a national and total inventory of data to date for “blue carbon” buried from mangroves and seagrass and delineate the constraints. For an area across Southeast Asia of approximately 12,000,000 km2, supporting mangrove forests (5,116,032 ha) and seagrass meadows (6,744,529 ha), we analyzed the region's current blue carbon stocks. This estimate was achieved by integrating the sum of estuarine in situ carbon stock measurements with the extent of mangroves and seagrass across each nation, then summed for the region. We found that mangroves ecosystems regionally supported the greater amount of organic carbon (3095.19Tg Corg in 1st meter) over that of seagrass (1683.97 Tg Corg in 1st meter), with corresponding stock densities ranging from 15 to 2205 Mg ha−1 and 31.3 to 2450 Mg ha−1 respectively, a likely underestimate for entire carbon including sediment depths. The largest carbon stocks are found within Indonesia, followed by the Philippines, Papua New Guinea, Myanmar, Malaysia, Thailand, Tropical China, Viet-Nam, and Cambodia. Compared to the blue carbon hotspot of tropical/subtropical Gulf of Mexico's total carbon stock (480.48 Tg Corg), Southeast Asia's greater mangrove–seagrass stock density appears a more intense Blue Carbon hotspot (4778.66 Tg Corg). All regional Southeast Asian nation states should assist in superior preservation and habitat restoration plus similar measures in the USA & Mexico for the Gulf of Mexico, as apparently these form two of the largest tropical carbon sinks within coastal waters. We hypothesize it is SE Asia's regionally unique oceanic–geologic conditions, placed squarely within the tropics, which are largely responsible for this blue carbon hotspot, that is, consistently high ambient light levels and year-long warm temperatures, together with consistently strong inflow of dissolved carbon dioxide and upwelling of nutrients across the shallow geological plates.

Managing seagrass and mangrove can be enhanced through carbon valued payment incentives schemes. Success will depend on the accuracy and extent of the carbon stock mitigation and accessible methods of monitoring and marking changes. In a relatively closed socioecological Southeast Asian lagoon we estimated the value of total organic carbon stocks (TOC) of both seagrass and mangroves. Mitigation corrections were also made for black carbon (BC) and calcareous inorganic carbon equivalents (PICequiv), and their sediment dry bulk density (DBD) tested as a cost effective means of both estimating those stock concepts and possible impacts outside their parameter confidence intervals. Overall, seagrass and mangroves TOC densities across the lower lagoon ranged from 15.3±4.3 and 124.3±21.1 Mg C ha-1respectively, 175.2±46.9 and 103.2±19.0 Mg C ha-1for seagrass and 355.0±24.8 and 350.3±35.2 Mg C ha-1) for mangroves across the two upper lagoon branches. Only mangrove biomass made significant additional contributions ranging from 178.5±62.3 to 120.7±94.8 Mg C ha-1for lower and upper regions respectively. The difference between the lagoons total seagrass and mangroves TOC stocks (5.98±0.69 and 390±33.22 GgC respectively) was further amplified by the lagoons’ larger mangrove area. When corrected for BC and PICequiv, the carbon stock mitigation was only reduced by a moderate 14.2%. Across the lagoon the sedimentary DBD showed strong (R2= 0.85,P< 0.001) to moderate (R2= 0.67,P< 0.001) linear correlations with seagrass and mangrove [TOC] respectively, moderate correlations with seagrass [PIC] (R2= 0.6,P< 0.001), but an invariant and relatively constant response to mangrove [PIC] (2.7 kg m-3± 0.07). Valuations as CO2ewas worth on average 0.44 million US$ y-1over 20 years; less than the total income of the indigenous users as potential custodians (1.8 and 7.4 million US$ y-1). Implications of this valuation was discussed.

Seagrass are under great stress in the tropical coast of Asia, where Enhalus acoroides is frequently the dominant species with a large food web. Here, we investigate the question of the fine‐scale genetic structure of this ecologically important foundation species, subject to severe anthropogenic disturbance in China. The genetic structure will illuminate potential mechanisms for population dynamics and sustainability, which are critical for preservation of biodiversity and for decision‐making in management and restoration. We evaluated the fine‐scale spatial genetic structure (SGS) and flowering output of E. acoroides, and indirectly estimated the relative importance of sexual versus asexual reproduction for population persistence using spatial autocorrelation analysis. Results reveal high clonal diversity for this species, as predicted from its high sexual reproduction output. The stronger Sp statistic at the ramet‐level compared with genet‐level indicates that clonality increases the SGS pattern for E. acoroides. Significant SGS at the genet‐level may be explained by the aggregated dispersal of seed/pollen cohorts. The estimated gene dispersal variance suggests that dispersal mediated by sexual reproduction is more important than clonal growth in this study area. The ongoing anthropogenic disturbance will negatively affect the mating pattern and the SGS patterns in the future due to massive death of shoots, and less frequency of sexual reproduction.

The Gulf of Mexico blue carbon habitats (mangroves, seagrass, and salt marshes) form an important North American blue carbon hot spot. These habitats cover 2,161,446 ha and grow profusely in estuaries that occupy 38,000 km2 to store substantial sedimentary organic carbon of 480.48 Tg C. New investigations around GoM for Mexican mangroves, Louisiana salt marshes and seagrasses motivated our integration of buried organic carbon to elucidate a new estimate of GoM blue carbon stocks. Factors creating this include: large GoM watersheds enriching carbon slowly flowing through shallow estuarine habitats with long residence times; fewer SE Mexican hurricanes allowing enhanced carbon storage; mangrove carbon productivity enhanced by warm southern basin winter temperatures; large Preservation reserves amongst high anthropogenic development. The dominant total GoM mangrove blue carbon stock 196.88 Tg from total mangrove extent 650,482 ha is highlighted from new Mexican data. Mexican mangrove organic carbon stock is 112.74 Tg (1st sediment meter) plus USA 84.14 Tg. Mexican mangroves vary greatly in storage, total carbon depositional depths and in sediment age (to 3500 y). We report Mexican mangrove's conservative storage fraction for the normally-compared top meter, whereas the full storage depth estimates ranging above 366.78 Tg (high productivity in very deep sediment along the central Veracruz/Tabasco coast) are not reflected in our reported estimates. Seagrasses stock of 184.1 Tg C organic is derived from 972,327 ha areal extent (in 1st meter). The Louisiana marshes form the heart of GoM salt marsh carbon storage 99.5 Tg (in 1st meter), followed by lesser stocks in Florida, Texas, finally Mexico derived from salt marsh extent totaling 650,482 ha. Constraints on the partial estuarine fluxes given for this new data are discussed as well as widespread anthropogenic destruction of the GoM blue carbon. A new North American comparison of our GoM blue carbon stocks versus Atlantic coastal blue carbon stock estimates is presented.

Seagrasses comprise a substantive North American and Caribbean Sea blue carbon sink. Yet fine-scale estimates of seagrass carbon stocks, fluxes from anthropogenic disturbances, and potential gains in sedimentary carbon from seagrass restoration are lacking for most of the Western Hemisphere. To begin to fill this knowledge gap in the subtropics and tropics, we quantified organic carbon (Corg) stocks, losses, and gains from restorations at 8 previously-disturbed seagrass sites around the Gulf of Mexico (GoM) (n=128 cores). Mean natural seagrass Corg stocks were 25.7±6.7MgCorgha-1 around the GoM, while mean Corg stocks at adjacent barren sites that had previously hosted seagrass were 17.8MgCorgha-1. Restored seagrass beds contained a mean of 38.7±13.1MgCorgha-1. Mean Corg losses differed by anthropogenic impact type, but averaged 20.98±7.14MgCorgha-1. Corg gains from seagrass restoration averaged 20.96±8.59Mgha-1. These results, when combined with the similarity between natural and restored Corg content, highlight the potential of seagrass restoration for mitigating seagrass Corg losses from prior impact events. Our GoM basin-wide estimates of natural Corg totaled ~36.4Tg for the 947,327ha for the USA-GoM. Including Mexico, the total basin contained an estimated 37.2-37.5Tg Corg. Regional US-GoM losses totaled 21.69Tg Corg. Corg losses differed significantly among anthropogenic impacts. Yet, seagrass restoration appears to be an important climate change mitigation strategy that could be implemented elsewhere throughout the tropics and subtropics.

M.M. van Katwijk et al., In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in. From our world-wide meta-analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and natural causes. Proximity to and recovery of donor beds were positively correlated with trial performance. Planting techniques can influence restoration success. The meta-analysis shows that both trial survival and seagrass population growth rate in trials that survived are positively affected by the number of plants or seeds initially transplanted. This relationship between restoration scale and restoration success was not related to trial characteristics of the initial restoration. The majority of the seagrass restoration trials have been very small, which may explain the low overall trial survival rate (i.e. estimated 37%). Successful regrowth of the foundation seagrass species appears to require crossing a minimum threshold of reintroduced individuals. Our study provides the first global field evidence for the requirement of a critical mass for recovery, which may also hold for other foundation species showing strong positive feedback to a dynamic environment. Synthesis and applications. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large-scale planting increases trial survival - large numbers ensure the spread of risks, which is needed to overcome high natural variability. Secondly, a large-scale trial increases population growth rate by enhancing self-sustaining feedback, which is generally found in foundation species in stressful environments such as seagrass beds. Thus, by careful site selection and applying appropriate techniques, spreading of risks and enhancing self-sustaining feedback in concert increase success of seagrass restoration. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large-scale planting increases trial survival - large numbers ensure the spread of risks, which is needed to overcome high natural variability. Secondly, a large-scale trial increases population growth rate by enhancing self-sustaining feedback, which is generally found in foundation species in stressful environments such as seagrass beds. Thus, by careful site selection and applying appropriate techniques, spreading of risks and enhancing self-sustaining feedback in concert increase success of seagrass restoration. Journal of Applied Ecology, A.T. was funded by Greater Caribbean Energy and Environment Foundation grants. N.M. was supported by a Gledden Fellowship from the Institute of Advanced Studies of the University of Western Australia. N.M. C.M.D and A.C. were supported by Biomares contract number LIFE06 NAT/PT/000192. N.M. and C.M.D. were supported by Opera (FP7, contract number 308393). C.P. and the Cornell Cooperative Extension Marine Program are funded in part by County Executive Steve Bellone and the Suffolk County Legislature, Hauppauge, New York. E.B. and C.L. were funded by University of Pisa (Lardicci 308/ex60%2010). M.L.C and G.A.K were supported by ARC Linkage Grants (LP130100155, LP0454138)

Spectral reflectance of three Western Atlantic subtropical/tropical dominant benthic seagrasses (Thalassia testudinum, Halodule wrightii and Syringodium filiforme) measured in the laboratory by UNIspec Spectral Analysis system over 400-1000 nm are compared to five Western Atlantic dominant benthic and intertidal algae (Fucus vesiculosus, Ulva lactuca, Halimeda incrassata, Udotea flabellum and Penicillus capitatus). Thalassia spectra are also compared to previously studied forest species, showing that the spectral reflectance signature of Thalassia was of the same general shape as forest species, but of lesser peak height (18% vs 28-50%) in the 750-759 nm range. For marine plants, near-infrared reflectance of Thalassia, Syringodium and Halodule was intermediate (18%) between the ubiquitous green alga Ulva (15%) and the temperate brown alga, Fucus (27%). The brown alga had a unique spectral signature in the first difference spectrum (three secondary peaks at differing spectral values than the other species' secondary peaks). Comparisons between Halodule, Syringodium and Thalassia near-infrared peaks and Halimeda (58%), Penicillus (29%) and Udotea (42%), subtropical/tropical algae, were also carried out. Halimeda differed most from the other green algae in terms of numerous oscillations from 450 to 700 nm seen in the first difference spectrum. The three seagrasses were similar in spectral reflectance curve shape to one another but differed somewhat in peak height. The first difference spectrum was helpful in pointing out subtle differences among the species and between algae and seagrass. Spectral reflectance data such as those presented here appear potentially useful for remote sensing of shallow habitats, and may additionally be used to monitor their health.

Massive anthropogenic changes in estuarine salinities, from manipulations of freshwater flows, are again occurring through governmental projects ‘‘correcting’’ past freshwater alterations. The downstream effects of increased freshwater on seagrass meadows, a major fisheries and ecosystem habitat, are not clear. Spectral responses to low salinities were quantitatively delimited for the important habitat seagrass Thalassia testudinum utilizing spectral reflectance measurements for the first time (non-invasive sampling). Over a range of salinities (32‐16 parts per thousand sea salts [ppt] for 24 h) and spectra (308‐1138 nm), Thalassia specimens showed statistically significant differences in spectral values (P , 0.05) between treatments at normal (32 ppt) and 50% reduced (16 ppt) seawater. Mature blades yellowed at low salinities. Reflectance changes at 525 nm and 650‐680 nm at low salinities suggested changes in xanthophylls and chlorophylls. Four indices were also used to characterize the reflectance spectra to delineate the effect of the salinity changes: (1) The normalized difference vegetation index (NDVI) for mature blades reduced at 16 ppt from that at 32 ppt. (2) The chlorophyll normalized difference index (Chl NDI) suggested chlorophyll content decreases in response to reduced salinity. (3) The structure independent pigment index (SIPI), higher in mature blades at 16 ppt than new blades, indicates a higher carotenoid : chlorophyll ratio in mature blades. (4) The photochemical reflectance index (PRI) suggested a lower photochemical efficiency at lower salinities. The main low-salinity effect on Thalassia physiology delineated herein is likely through changes in pigmentation (decreases in chlorophyll and changes in xanthophyll cycle epoxidation).

The Laguna Madre in Corpus Christi, Texas has a great deal of petroleum and natural gas activity while housing a national seashore. The area is a flyway for a wide array of bird species, as well as heavily fished. Historically, the laguna had a series of infrastructure modifications, gas and oil rigs, and real estate development. In the process of placing a drilling rig, a winter storm blew the vessel with the rig off a narrow channel. To remove the vessel, other vessels had to be called. A 35-acre accident occurred. In mitigation, 75 acres of the seagrass Halodule wrightii was planted in three areas: (1) a 15-acre dredge island where a portion of the island was scraped down from upland-spoil deposit to −2 ft mlw; (2) a mile-long channel where seagrasses were restored from −7 to 10 ft mlw to −3 to ft mlw; and (3) a persistently barren site for decades (scraped by another petroleum company's vessel) was restored in the shallows while holes were filled in and seagrass planted on top. The fill throughout was from the scraping from the dredge islands. The fill was transmitted several miles by a new device. Planting of Halodule plugs proceeded from March to July 1999. Within 3 months, the shallow sites had been covered with the restored Halodule,. Endangered species of roseate spoonbills, brown pelicans, great white herons and other wading and fishing birds were regularly feeding at two sites. The deeper sites had heavy fish populations return to the area, fished by man, seagulls and pelicans. Despite a direct hit by Hurricane Bret in 1999, lateral growth at all depths was deemed governmentally satisfactory. This same procedure with seagrasses is recommended for after-effects of estuarine oil spill cleanup, and mitigation banks of seagrasses are recommended for construction or operations mitigation.