ALBERT

Description:    The threatened seagrass Halophila johnsonii grows intertidally to 3 m deep in river-influenced and marine-influenced habitats. In this study, environmental parameters and photosynthetic characteristics of H. johnsonii were measured hourly for populations from adjacent riverine and marine habitats under opposite tidal regimes (high tide at midday, low tide at midday). The two populations exhibited habitat-specific diurnal responses, which indicate long-term acclimatization to their different environments. During periods with similar bottom irradiances, effective photochemical efficiencies and chlorophyll concentrations were comparatively greater in the riverine population, indicative of low-light acclimation. In addition, ultraviolet pigment absorbance (340–345 nm) was generally greater in the riverine plants and it generally increased following ebb tides and decreasing salinity, suggesting a stress response. Multivariate analyses indicated that photosynthetic characteristics were most dissimilar when environmental conditions were most dissimilar, i.e., riverine plants when low tide occurred at midday compared to marine plants when high tide occurred at midday. Salinity, photosynthetically active radiation, and optical water quality ( K 0PAR , S CDOM , and a 412 ) were most correlated with variability in photosynthetic characteristics. As there is no significant genetic variation among populations of H. johnsonii , the photosynthetic characteristics of the riverine and marine populations we examined reflect acclimation to their respective habitats through a highly phenoplastic physiology. Content Type Journal Article Pages 1-14 DOI 10.1007/s12237-012-9571-2 Authors Amanda E. Kahn, Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA Jeffrey L. Beal, Florida Fish and Wildlife Conservation Commission, FAU HBOI, 5600 US1, Ft. Pierce, FL 34946, USA Michael J. Durako, Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    Rice cultivation in the Ebro Delta (Catalonia, Spain) has inverted the natural hydrological cycles of coastal lagoons and decreased water salinities for over 150 years. Adjustments in the water management practices—in terms of source and amount of freshwater inputs—have resulted in changes in the diversity, distribution and productivity of submerged angiosperms. Between the 1970s and late 1980s, a massive decline of the aquatic vegetation occurred in the Encanyissada–Clot and Tancada lagoons, but little information on the status is available after the recovery of macrophytes in the 1990s. Here, we evaluate the influence of salinity regimes resulting from current water management practices on the composition, distribution, seasonal abundance and flowering rates of submersed macrophytes, as well as on the occurrence of epiphyte and drift macroalgae blooms in three coastal lagoons. Our results show that Ruppia cirrhosa is the dominant species in the Encanyissada lagoon (185.97 ± 29.74 g DW m −2  year −1 ; 12–27 ‰ salinity) and the only plant species found in the Tancada lagoon (53.26 ± 10.94 g DW m 2  year −1 ; 16–28 ‰ salinity). Flowering of R . cirrhosa (up to 1,011 ± 121 flowers m −2 ) was only observed within the Encanyissada and suggests that mesohaline summer conditions may favor these events. In contrast, low salinities in Clot lagoon (∼3–12 ‰) favor the development of Potamogeton pectinatus (130.53 ± 13.79 g DW m 2  year −1 ) with intersperse R . cirrhosa (8.58 ± 1.71 g DW m −2 ) and mixed stands of P . pectinatus and Najas marina (up to ∼57 g DW m −2  year −1 ) in some reduced areas. The peak biomasses observed during the study are 88 to 95 % lower than maximum values reported in the literature at similar salinities, and there is also little or no recovery in some areas compared to last reports more than 20 years ago. The main management actions to restore the natural diversity and productivity of submersed angiosperms, such as the recovering of the seagrass Zostera noltii , should be the increase of salinity during the period of rice cultivation, by reducing freshwater inputs and increasing flushing connections with the bays. Content Type Journal Article Pages 1-16 DOI 10.1007/s12237-012-9570-3 Authors Patricia Prado, IRTA Aquatic Ecosystems, Ctra. Poble Nou km 5.5, 43540 Sant Carles de la Ràpita, Tarragona, Spain Nuno Caiola, IRTA Aquatic Ecosystems, Ctra. Poble Nou km 5.5, 43540 Sant Carles de la Ràpita, Tarragona, Spain Carles Ibáñez, IRTA Aquatic Ecosystems, Ctra. Poble Nou km 5.5, 43540 Sant Carles de la Ràpita, Tarragona, Spain Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    Tidal freshwater wetlands are complex, species-rich ecosystems located at the interface between tidal estuaries and nontidal rivers. This study conducted on the Patuxent River estuary in Maryland was designed to assess vegetation dynamics over several decades to determine if there were directional changes in the dominant communities. Aerial photographs (1970, 1989, and 2007) documented broad-scale spatial changes in major plant communities. The coverage of areas dominated by Nuphar lutea and Phragmites australis expanded; mixed vegetation and scrub–shrub habitats were essentially unchanged; and Typha and Zizania aquatica communities fluctuated in coverage. Data collected between 1988 and 2010 from permanent plots and transects were used to examine fine-scale changes. Shifts in the importance of some species through time were observed, but there were no directional changes in community species composition. The lack of directional change as measured at a fine scale is characteristic of tidal freshwater wetlands in which variations in the abundance of individual species, especially annuals, are responsible for most short-term change in species composition. Changes in the composition of plant communities are interpreted as responses to variations in vertical accretion, stability of habitat types, invasive plant species, and herbivores. In the future, vegetation changes are likely to occur as a result of the intrusion of brackish water and increased flooding associated with global climate change and sea level rise. This long-term study establishes a baseline from which potential future changes to tidal freshwater wetlands can be better understood. Content Type Journal Article Pages 1-16 DOI 10.1007/s12237-012-9568-x Authors Christopher W. Swarth, Jug Bay Wetlands Sanctuary, 1361 Wrighton Road, Lothian, MD 20711, USA Patricia Delgado, Chesapeake Bay National Estuarine Research Reserve in Maryland, Maryland Department of Natural Resources, 580 Taylor Avenue, E2, Annapolis, MD 21401, USA Dennis F. Whigham, Smithsonian Environmental Research Center, P.O. Box 28, 647 Contees Wharf Road, Edgewater, MD 21037, USA Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    Using the Eddy Covariance (EC) technique, we analyzed temporal variation in net ecosystem CO 2 exchange (NEE) and determined the effects of environmental factors on the balance between ecosystem photosynthesis and respiration in a reed ( Phragmites australis ) wetland in the Yellow River Delta, China. Our results indicated that diurnal and seasonal patterns of NEE and its components (ecosystem respiration ( R eco ), gross primary production (GPP)) varied markedly among months for the growing season (May to October). The cumulative CO 2 emission was 1,657 g CO 2 m −2 , while 2,612 g CO 2 m −2 was approximately accumulated as GPP, which resulted in the reed wetland being a net sink of 956 g CO 2 m −2 . The ratio of R eco to GPP in reed wetland was 0.68, which was close to other temperate wetlands. Soil temperature and soil moisture exerted the primary controls on R eco during the growing season. Daytime NEE values during the growing season were strongly correlated with photosynthetically active radiation. Aboveground biomass showed significant linear relationships with 24-h average NEE, daytime GPP, and R eco , respectively. Thus, we conclude that the coastal wetland acted as a carbon sink during the growing season despite the variations in environmental conditions, and long-term flux measurements over these ecosystems are undoubtedly necessary. Content Type Journal Article Pages 1-13 DOI 10.1007/s12237-012-9572-1 Authors Guangxuan Han, Key Laboratory of Coastal Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Chunhui Road 17, Laishan District, Yantai, Shandong 264003, China Liqiong Yang, Key Laboratory of Coastal Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Chunhui Road 17, Laishan District, Yantai, Shandong 264003, China Junbao Yu, Key Laboratory of Coastal Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Chunhui Road 17, Laishan District, Yantai, Shandong 264003, China Guangmei Wang, Key Laboratory of Coastal Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Chunhui Road 17, Laishan District, Yantai, Shandong 264003, China Peili Mao, Key Laboratory of Coastal Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Chunhui Road 17, Laishan District, Yantai, Shandong 264003, China Yongjun Gao, Department of Earth and Atmospheric Sciences, University of Houston, Houston, 77204-5007 TX, USA Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    Despite excessive growth of macroalgae in estuarine systems, little research has been done to examine the impacts of increased algal biomass that drifts into nearby salt marshes and accumulates on intertidal flats. The accumulation of macroalgal mats and subsequent decomposition-related releases of limiting nutrients may potentially alter marsh communities and impact multiple trophic levels. We conducted a 2-year in situ study, as well as laboratory mesocosm experiments, to determine the fate of these nutrients and any bottom-up impacts from the blooms on the dominant salt marsh plant ( Spartina alterniflora ) and herbivores. Mesocosm results showed that macroalgal decomposition had a positive impact on sediment nitrogen concentrations, as well as S. alterniflora growth rates. In contrast, our in situ results suggested that S. alterniflora growth was hindered by the presence of macroalgal mats. From our results, we suggest that macroalgal accumulation and subsequent release of nitrogen during decomposition may be beneficial in nitrogen limited areas. However, as marshes are becoming increasingly eutrophic, releasing lower marsh plants from nitrogen limitation, this accumulation of macroalgal biomass may hinder S. alterniflora growth through smothering and breakage of culms. As macroalgal blooms are predicted to intensify with rising temperatures and increased eutrophication, the ecological impacts associated with these changes need to be continuously monitored in order to preserve these fragile ecosystems. Content Type Journal Article Pages 1-12 DOI 10.1007/s12237-012-9565-0 Authors Christine Newton, Marine Science Center, Northeastern University, 430 Nahant Road, Nahant, MA 01908, USA Carol Thornber, Department of Biological Sciences, College of Environmental Life Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    This research investigates the dynamics of the axial tidal flow and residual circulation at the lower Guadiana Estuary, south Portugal, a narrow mesotidal estuary with low freshwater inputs. Current data were collected near the deepest part of the channel for 21 months and across the channel during two (spring and neap) tidal cycles. Results indicate that at the deep channel, depth-averaged currents are stronger and longer during the ebb at spring and during the flood at neap, resulting in opposite water transport directions at a fortnightly time scale. The net water transport across the entire channel is up-estuary at spring and down-estuary at neap, i.e., opposite to the one at the deep channel. At spring tide, when the estuary is considered to be well mixed, the observed pattern of circulation (outflow in the deep channel, inflow over the shoals) results from the combination of the Stokes transport and compensating return flow, which varies laterally with the bathymetry. At neap tide (in particular for those of lowest amplitude each month), inflows at the deep channel are consistently associated with the development of gravitational circulation. Comparisons with previous studies suggest that the baroclinic pressure gradient (rather than internal tidal asymmetries) is the main driver of the residual water transport. Our observations also indicate that the flushing out of the water accumulated up-estuary (at spring) may also produce strong unidirectional barotropic outflow across the entire channel around neap tide. Content Type Journal Article Pages 1-14 DOI 10.1007/s12237-012-9566-z Authors Erwan Garel, CIMA (Centre for Marine and Environmental Research), Universidade do Algarve, Edifício 7, Campus de Gambelas, 8005-139 Faro, Portugal Óscar Ferreira, CIMA (Centre for Marine and Environmental Research), Universidade do Algarve, Edifício 7, Campus de Gambelas, 8005-139 Faro, Portugal Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    We investigated spatial and temporal changes in spectral irradiance, phytoplankton community composition, and primary productivity in North Inlet Estuary, South Carolina, USA. High concentrations of colored dissolved organic matter (CDOM) were responsible for up to 84 % of the attenuation of photosynthetically available radiation (PAR). Green-yellow wavelengths were the predominant colors of light available at the two sampling sites: Clam Bank Creek and Oyster Landing. Vertical attenuation coefficients of PAR were 0.7–2.1 m −1 with corresponding euphotic zone depths of 1.5–6.7 m. Phytoplankton biomass (as chlorophyll a [chl a ]) varied seasonally with a summer maximum of 16 μg chl a l −1 and a winter minimum of 1.4 μg chl a l −1 . The phytoplankton community consisted mainly of diatoms, prasinophytes, cryptophytes and haptophytes, with diatoms and prasinophytes accounting for up to 67 % of total chl a . Changes in phytoplankton community composition showed strongest correlations with temperature. Light-saturated chl a -specific rates of photosynthesis and daily primary productivity varied with season and ranged from 1.6 to 14 mg C (mg chl a ) −1  h −1 (32–803 mg C m −3  day −1 ). Calculated daily rates added up to an annual carbon fixation rate of 84 g C m −3  year −1 . Overall, changes in phytoplankton community composition and primary productivity in North Inlet showed a strong dependence on temperature, with PAR and spectral irradiance playing a relatively minor role due to short residence times, strong tidal forcing and vertical mixing. Content Type Journal Article Pages 1-18 DOI 10.1007/s12237-012-9567-y Authors Evelyn Lawrenz, Marine Science Program, University of South Carolina, Columbia, SC 29208, USA Erik M. Smith, Belle W. Baruch Institute for Marine and Coastal Sciences, University of South Carolina, Georgetown, SC 29442, USA Tammi L. Richardson, Marine Science Program, University of South Carolina, Columbia, SC 29208, USA Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    This study examined the genetic diversity and composition of 15 populations of Zostera japonica in the Hii River system, Japan. Genetic and genotypic diversity were consistently higher in populations in the Ohashi River than those in Lake Nakaumi, and the local tidal movements may explain the observed patterns of genetic diversity. Pairwise fixation index values among the populations in Lake Nakaumi were higher than among those in the Ohashi River, even though the ranges of the distances among the populations in the two locations were almost the same. The gene flow from the Ohashi River populations was important for some populations in Lake Nakaumi. The low genotypic diversity and gene flow in Lake Nakaumi seemed similar to those of marginal populations. If this low genotypic diversity and genetic differentiation were partly caused by human activities, the promotion of gene flow should be taken into account in conserving the populations in Lake Nakaumi. Content Type Journal Article Pages 1-8 DOI 10.1007/s12237-012-9564-1 Authors Yoshikuni Hodoki, Research Center for Coastal Lagoon Environments, Shimane University, 1060 Nishi-kawatsu, Matsue, 690-8504 Japan Kako Ohbayashi, Research Center for Coastal Lagoon Environments, Shimane University, 1060 Nishi-kawatsu, Matsue, 690-8504 Japan Norio Tanaka, Tsukuba Botanical Garden, National Museum of Nature and Science, 4-1-1, Amakubo, Tsukuba, 305-0005 Japan Hidenobu Kunii, Research Center for Coastal Lagoon Environments, Shimane University, 1060 Nishi-kawatsu, Matsue, 690-8504 Japan Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    Four months of daily nutrient and radon (a natural groundwater tracer) observations at the outlet of a heavily drained coastal wetland illustrated how episodic floods and diffuse groundwater seepage influence the biogeochemistry of a sub-tropical estuary (Richmond River, New South Wales, Australia). Our observations downstream of the Tuckean Swamp (an acid sulphate soil floodplain) covered a dry stage, a flood triggered by a 213-mm rain event and a post-flood stage when surface water chemistry was dominated by groundwater discharge. Significant correlations were found between radon and ammonium and N/P ratios and between radon and dissolved organic nitrogen (DON) during the post-flood stage. While the flood lasted for 14 % of the time of the surface water time series, it accounted for 18 % of NH 4 , 32 % of NO x , 66 % of DON, 58 % of PO 4 and 55 % of dissolved organic phosphorus (DOP) catchment exports. Over the 4-month study period, groundwater fluxes of 35.0, 3.6, 36.3, 0.5 and 0.7 mmol m −2  day −1 for NH 4 , NO x , DON, PO 4 and DOP, respectively, were estimated. The groundwater contribution to the total surface water catchment exports was nearly 100 % for ammonium, and 〈20 % for the other nutrients. Post-flood groundwater seepage shifted the system from a DON to a dissolved inorganic N-dominated system and doubled N/P ratios in surface waters. We hypothesise that the Richmond River Estuary N/P ratios may reflect a widespread trend of tidal rivers and estuaries becoming more groundwater-dominated and phosphorus-limited as coastal wetlands are drained for agriculture, grazing and development. Content Type Journal Article Pages 1-18 DOI 10.1007/s12237-012-9561-4 Authors Isaac R. Santos, Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia Jason de Weys, Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia Douglas R. Tait, Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia Bradley D. Eyre, Centre for Coastal Biogeochemistry, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723

Description:    We investigated whether within wetland environmental conditions or surrounding land cover measured at multiple scales were more influential in structuring regional vegetation patterns in estuarine tidal wetlands in the Pacific Northwest, USA. Surrounding land cover was characterized at the 100, 250, and 1,000 m, and watershed buffer scales. Vegetation communities were characterized by high species richness, lack of monotypic zonation, and paucity of invasive species. The number of species per site ranged between 4 and 20 (mean ± standard deviation = 10.2 ± 3.1). Sites supported a high richness (mean richness of native species 8.7 ± 2.8) and abundance of native macrophytes (mean relative abundance 85 % ± 19 %). Vegetation assemblages were dominated by a mix of grasses, sedges, and herbs with Sarcocornia pacifica and Distichlis spicata being common at sites in the oceanic zone of the estuary and Carex lyngbyei and Agrostis stolonifera being common at the fresher sites throughout the study area. The vegetation community was most strongly correlated with salinity and land cover within close proximity to the study site and less so with land cover variables at the watershed scale. Total species richness and richness of native species were negatively correlated with the amount of wetland in the buffer at all scales, while abundance of invasive species was significantly correlated to within wetland factors, including salinity and dissolved phosphorus concentrations. Landscape factors related to anthropogenic disturbances were only important at the 100-m buffer scale, with anthropogenic disturbances further from the wetland not being influential in shaping the vegetation assemblage. Our research suggests that the traditional paradigms of tidal wetland vegetation structure and environmental determinants developed in east coast US tidal wetlands might not hold true for Pacific Northwest wetlands due to their unique chemical and physical factors, necessitating further detailed study of these systems. Content Type Journal Article Pages 1-13 DOI 10.1007/s12237-012-9569-9 Authors Christine L. Weilhoefer, Pacific Coast Ecology Branch, US EPA, 2111 SE Marine Science Drive, Newport, OR 97365, USA Walter G. Nelson, Pacific Coast Ecology Branch, US EPA, 2111 SE Marine Science Drive, Newport, OR 97365, USA Patrick Clinton, Pacific Coast Ecology Branch, US EPA, 2111 SE Marine Science Drive, Newport, OR 97365, USA David M. Beugli, Dynamac Corporation, 200 SW 35th St., Corvallis, OR 97333, USA Journal Estuaries and Coasts Online ISSN 1559-2731 Print ISSN 1559-2723