Organic matter features, degradation and remineralisation at two coastal sites in the Ligurian Sea (NW Mediterranean) differently influenced by anthropogenic forcing

Organic matter (OM) features, degradation and remineralisation were studied in the seawater of a natural coastal site (Marine Protected Area of Portofino) and at an urbanised coastal site (Quarto, Genoa city) of the Ligurian Sea. The accumulation of low trophic value OM and the persistence of phytoplanktonic biomass throughout the year were observed only at the urbanised site. Efficient OM degradation and remineralisation via high-activity (two times higher than at the Portofino site) hydrolytic enzymatic activities (alkaline phosphatase and leucine aminopeptidase) were recorded. This active degradation indicated a generally good resistance of the Quarto system to environmental pressures (coastal inputs and anthropogenic influence). However, the high potential release of recycled inorganic nutrients and the favourable environmental conditions (i.e. higher seawater temperature at the Quarto site and allochthonous inputs), could encourage unpredictable development of the autotrophic fraction, including an already observed dystrophic blooming of toxic microalgae.     

Organic matter characterisation and turnover in the sediment and seawater of a tourist harbour

A survey of a Ligurian tourist harbour was carried out during winter 2006 and summer 2007 in order to study the organic matter (OM) turnover through extracellular enzymatic activity. Seawater and sediments were sampled at six stations, three inside the port boundaries, one outside the port and two in an area influenced by the outflow of a minor river (Boate). The seawater showed OM turnover times similar to other oligo-mesotrophic coastal areas, and low concentrations of chlorophyll-a and inorganic nutrients. The sediments, instead, revealed high OM loads and a predominance of proteolysis. A significant reduction of the OM loads was observed in the outside station, indicating that the OM accumulation was due to the structures and activities of the harbour and to the Boate influence. The OM biotic recycling via enzymatic activity was enhanced especially during summer. Although the carbohydrates were probably highly refractory, their turnover was notably faster, due to glycolytic enzymatic activity that was enhanced more than the proteolytic in both the sediment and in the seawater. This suggested that the removal and recycling of OM were potentially efficient, and prevented the shift to eutrophication of the Rapallo harbour area.     

Geochemical associations and post-depositional mobility of heavy metals in coastal sediments: Loch Etive,Scotland

Surficial sediments of a Scottish sea loch exhibit enrichment profiles for the minor metals Cu, Pb and Zn. ¹³⁷Cs data indicate enrichment during the last 20–40 years of deposition. Variations in the onset of enrichment between sites within the fjord, which have similar accumulation rates, infer that whilst the metal inputs may originally have been of an anthropogenic nature the present distribution of the metals in the sediments is controlled by organic matter diagenesis. These processes are especially important within the sulphate reducing zone. This suggestion is supported by the similar behaviour of the heavy metals and I/C_org ratios in the sediments. Diagenetic recycling of Pb may also explain discrepanceis that were observed between ²¹⁰Pb and ¹³⁷Cs chronologies. The source and diagenetic remobilisation of these elements is discussed with relation to the fate of anthropogenic metals in coastal sediments.     

Anthropogenic factors and habitat complexity influence biodiversity but wave exposure drives species turnover of a subtropical rocky inter‐tidal metacommunity

Coastal ecosystems are complex and species rich, but are vulnerable to degradation from a variety of anthropogenic activities. Nevertheless, information on inter‐tidal community composition in the Caribbean Basin and at other oceanic sites is lacking. Such information is essential to developing a more comprehensive understanding of rocky inter‐tidal systems and their responses to global change. The goals of this study were to determine the relative importance of environmental (wave power density, wave height), habitat (e.g. algal cover, slope, complexity of rock surfaces) and anthropogenic (distance to roads, population density) factors associated with the structure of local assemblages at multiple shore heights and the regional metacommunity of mobile invertebrates on oceanic rocky inter‐tidal habitats. Environmental characteristics associated with habitat complexity (algal cover, rock surface complexity) and human population density were most strongly associated with abundance and biodiversity of invertebrates. Species richness was positively correlated with surface complexity, but abundance was negatively correlated with both surface complexity and per cent algal cover. By contrast, abundance of invertebrates was positively correlated with human population density, and diversity was negatively correlated with human population density. Abundance of invertebrates was greatest in the mid inter‐tidal zone, whereas diversity was greatest in the lower inter‐tidal zone. Metacommunity structure was Gleasonian, but the gradient along which species turnover occurred was correlated with measures of wave exposure, rather than anthropogenic activity. Unlike in previous studies, mostly at mainland sites, human activity primarily altered dominance patterns of communities, while having relatively little effect on species richness or composition.     

Responses of talitrid amphipods to a gradient of recreational pressure caused by beach urbanization

Demands for public outdoor recreation and urbanization are a potential source of environmental disturbances, particularly on sandy beaches. These habitats have therefore experienced rapid degradation worldwide. Talitrid amphipods, which are common inhabitants of sandy beaches, are probably good indicators of such disturbances. In this study, we evaluated the responses of the two amphipods Talitrus saltator and Atlantorchestoidea brasiliensis to human pressure on Spanish and a Brazilian beach, hypothesizing that disregarding species differences, their population sizes will decline under urbanized conditions. The Barra da Tijuca (Brazil) and Levante (Spain) beaches have mixed landscapes with varying levels of development, and each has a protected area (MPA) adjacent to urbanized sites. Numbers of talitrids as well as visitors were compared among sites on each beach. Talitrids were most abundant at the protected sites. This was true of both beaches, even though temporal patterns of human activity were quite different, with Levante experiencing sharp declines in the number of visitors during its harsh winter. Urbanized sites did not experience high Talitrid densities even during a period of low human pressure. On this basis, T. saltator and A. brasiliensis were considered good indicators of urbanization and recreational activities on sandy beaches. MPAs were found to be very important for the successful conservation of the talitrid populations. A feasible method of managing human pressure and thereby conserving beach biodiversity therefore seems to be the establishment of beach MPAs.     

Threats to sandy beach ecosystems: A review

We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical–biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders.     

Macrobenthic surf zone communities of temperate sandy beaches: spatial and temporal patterns

The spatial and temporal patterns within the surf zone epibenthic assemblages were studied in a coastal fringe of Argentina to determine whether assemblage compositions, abundance, species richness and diversity vary spatially and temporarily. Sampling was conducted seasonally in two sandy beaches over 2 years with a benthic sledge used to collect the fauna in the upper centimeters of soft bottom sediments and the epifauna on the sediment surface. Physical variables were measured in the same coastal sites where biological sampling was conducted. A total of 58 morphospecies were collected. Peracarid crustaceans were the most abundant group. The mysid Pseudobranchiomysis arenae (new genus–new species) (29.73 ± 17.79 ind. per sample) and the isopod Leptoserolis bonaerensis (51.54 ± 22.35 ind. per sample) were the most abundant and common species and were present regularly throughout the sampling period. Differences in the surf zone community composition were found between the beaches; these differences could be related to variation in physical parameters such as sand grain size and wave climate, indicating the possible influence of the morphodynamic state of the beaches on the epibenthic assemblages. A seasonal abundance trend was detected, reflecting the changes in abundance of the two dominant species; the richness pattern was not easily detectable due to the sporadic appearance of non‐resident species in the surf zone, probably due to different causes, including dispersion by entry of water from surrounding areas, littoral currents and storms. The surf zone studied presents a complex and dynamic epibenthic community that appears to be influenced by the morphodynamic state of the beach and the dynamic of non‐resident species.     

On the displacement of marked pebbles on two coarse-clastic beaches during short fair-weather periods (Marina di Pisa and Portonovo, Italy)

The aim of the investigation was to define the mechanisms of sediment transport in the swash zone of microtidal coarse-clastic beaches in the very short term by evaluating the displacement rates of marked pebbles under low-energy wave conditions. Tests were performed at two sites (Marina di Pisa, Ligurian Sea, and Portonovo, central Adriatic Sea) to check the consistency of the data over a range of different grain sizes. Two recovery campaigns were carried out at both sites, one 6 h and the other 24 h after the injection. During the experiments wave action was at a minimum (wave heights never exceeded 0.3 m). The results show that 20% of pebbles ranging in diameter from 30–90 mm moved significantly (more than 0.5 m) already 6 h after the injection, with some tracers being lost (3%). After 24 h, 40% of the pebbles were significantly displaced and 10% were lost. The preferential downslope movement of tracers, which suggests that coarse sediment movement under low-energy conditions is mainly controlled by gravity processes enhanced by steep beachface slopes, represents the novelty of the results reported here. It would appear that swash processes on low-energy beaches cause a significant rate of pebble displacement through the destabilization induced by wave uprush and backwash. Despite the microtidal range, the position of the mean water level plays a major role in changing the beach level at which swash processes can actually trigger pebble movement. The results of this study show that considerable, and mostly seaward-directed, coarse sediment transport takes place even during short fair-weather periods.     

华南水东湾波控、中等潮差岬湾海滩地形动力分类

海滩地形动力分类在国外的海岸地貌研究中已经被广泛接受。本文使用了华南粤西水东湾切线带、过渡带和遮蔽带海滩连续16个月32次大潮期间同步获取的波浪、潮汐、泥沙和海滩地形数据,分别按照无量纲沉降参数、相对潮差参数和无量纲海湾尺度参数对这一岬湾海滩不同岸段的海滩类型进行了研究,研究发现：（1）水东湾切线带海滩的主要状态为有裂流的低潮台地状态和沙坝型海滩状态,过渡带海滩主要状态是低潮沙坝/裂流海滩和沙坝消散型状态,遮蔽带海滩主要状态是有或无沙坝的消散型状态;（2）海湾不同岸段海滩状态的顺序变化与差异体现了岬湾海滩状态的时空变化性,与现场观测的海滩地形的变化基本一致,说明了对波控中到强潮海滩进行研究时,需要考虑潮汐的影响。同时,本文主要给出了海滩状态研究的一个框架体系,由于海滩不同的状态伴随不同的侵蚀模式,要求我国今后需加强在这一方面研究,以进一步丰富我国海滩地形演变、海滩地形动力过程和海滩防侵蚀的理论基础。     

Macrobenthic zonation patterns along a morphodynamical continuum of macrotidal,low tide bar/rip and ultra-dissipative sandy beaches

The species composition, densities, biomass and zonation patterns of the macrobenthos of sandy beaches are greatly influenced by the morphodynamics and morphology of the beaches. Macrobenthic zonation patterns along a small-scale morphodynamic gradient, comprising eight Belgian beach sites, were investigated. By taking into account the dimensionless fall velocity (Ω) and the relative tidal range, the beach sites were ordered along the gradient from the ultra-dissipative beach type (UD) to the low tide bar/rip beach type (LTBR). The resulting beach state index varied between 1.8 and 4.2 and the beach profiles were related with the beaches' morphodynamic state.In total 35 macrobenthic species, mainly polychaetes and crustaceans, were encountered, varying between 19 and 23 species per beach site. The species composition was quite similar among beach sites, with Scolelepis squamata being abundant at all eight sites. Furthermore, the macrobenthic distribution patterns were mainly related to elevation at all beach sites. Some remarkable difference in metrics, largely related to the beach morphodynamics and the consequent hydrodynamics, were found. At the hydrodynamically benign and consequently macrobenthos-rich UD beaches, the highest macrobenthic densities and biomass occurred on the upper beach, while at the hydrodynamically harsh and thus macrobenthos-poor LTBR beaches, the maximum densities and biomass occurred lower on the beach. Species, typically occurring on the upper UD beaches, such as Eurydice pulchra, S. squamata, and Bathyporeia sarsi, were restricted to the sub-optimal middle and lower beach zone at LTBR beaches. Only Bathyporeia pilosa was found on the upper beach of both UD and LTBR beaches. The more robust polychaete Ophelia rathkei and the interstitial polychaete Hesionides arenaria were exclusively found in the hydrodynamically harsh conditions of the middle LTBR beach zone.     

中国重点海水浴场中粪肠球菌和主要肠道病毒的调查研究

本文调查了中国十大典型海水浴场,旨在监测人类肠道病毒在海水浴场的发生情况,并且找出表面海水中肠道病毒的存在与传统的粪便污染指示物一粪大肠菌群是否存在关系,如果存在,是什么关系。分别采用常规的平板计数法和RT-PCR技术对粪大肠菌群和人类致病性的主要肠道病毒（甲肝病毒、轮状病毒、脊髓灰质炎病毒）进行了检测。结果显示,在2...     

Deep-sea terrigenous organic carbon transfer and accumulation: Impact of sea-level variations and sedimentation processes off the Ogooue River (Gabon)

Sedimentary, isotopic and bulk geochemical proxies measured in sediment samples of five gravity cores collected in the distal part of the Ogooue turbidite system (around 4000 m-depth) were used to develop a conceptual model to describe the accumulation of terrigenous organic matter (OM) during the last 200,000 yrs BP in the eastern part of the Gulf of Guinea. This model takes into account the influence of the different depositional processes (turbiditic vs hemipelagic sedimentation), geomorphological features and sea-level variations.Total organic carbon (TOC) and the stable organic carbon isotopes of the OM (δ¹³C) variability follow the highstand/lowstand (interglacial/glacial) cyclicity with a very low accumulation rate of terrigenous OM during periods of high sea-level and higher accumulation rate during period of low sea-level. A sea-level of 80–120 m below present day seems to favor the transfer of terrigenous sediments to the deep offshore environment through the turbidite system and thanks to the connection of the canyons heads with the river system presently located at the shelf edge at −120 m water depth.In this system, terrigenous OM matter delivered by the river accumulate in the sediments via two main processes. Indeed, a part of the terrigenous OM settles in combination with the finest particles forming hemipelagites, while another part, formed of very well preserved land plant debris, is transported and deposited far offshore with turbidity currents. The proportion of terrigenous OM accumulated due to turbidity currents is important as it can represent more than 70% of the carbon accumulated during sea-level lowstand. Moreover, terrigenous OM seems to preferentially accumulate in the levees and the lobes of the system notably due to the higher frequency of organic-rich turbidites.This study demonstrates that gravity flows, influenced by the sea-level variations, can significantly affect the terrigenous OM budget of the deep offshore Atlantic margins and that channel-levee complexes as well as turbidite lobes can be regarded as good sink for terrestrial organic carbon. These processes should be taken into consideration in the context of source rocks exploration but also for the estimation of the general carbon accumulation in ocean sediment.     

The rates of organic matter destruction in the central part of the Arctic Basin

The intensity of the processes of organic matter (OM) destruction in the deep-water part of the Arctic Basin is considered in terms of the activities of hydrolytic enzymes (alkaline phosphatase and proteases) and of redox enzymes of the electron transport system (ETS). High concentrations of mineral phosphorus are shown to cause low phosphatase activity (0.000–0.005 μM P/l h). The average time of the phosphate recycling amounted to about 240 h. The ranges of the total and specific activity of protease are 0.000–0.192 mg of azocasein/(l h) and 0.00–3.57 mg of azocasein/h mg of protein, respectively. It is found that the microplankton production of exo- and endopeptidase in the Arctic Basin is controlled by the concentration of nitrates in the water. The values of the total and the specific activities of the ETS enzymes vary within 0.27–8.96 μl O₂/(l h) and 8.4–583 μl O₂/mg of protein h, respectively. It is shown that the maximum values of the total activities of the hydrolytic and redox enzymes are characteristic for the photic layer. The vertical fluxes of organic carbon from the photic layer, being calculated by the activity of the ETS enzymes, amounted to 220–600 g of C_org/year m². The presence of ice intensifies the redox processes by factors of 2–15.     

Spatiotemporal distributions and environmental drivers of diversity and community structure of nosZ-type denitrifiers and anammox bacteria in sediments of the Bohai Sea and North Yellow Sea,China

Denitrification and anammox processes are major nitrogen removal processes in coastal ecosystems. However, the spatiotemporal dynamics and driving factors of the diversity and community structure of involved functional bacteria have not been well illustrated in coastal environments, especially in human-dominated ecosystems. In this study, we investigated the distributions of denitrifiers and anammox bacteria in the eutrophic Bohai Sea and the northern Yellow Sea of China in May and November of 2012 by constructing clone libraries employing nosZ and 16S rRNA gene biomarkers. The diversity of nosZ-denitrifier was much higher at the coastal sites compared with the central sites, but not significant among basins or seasons. Alphaproteobacteria were predominant and prevalent in the sediments, whereas Betaproteobacteria primarily occurred at the site near the Huanghe (Yellow) River estuary. Anammox bacteria Candidatus Scalindua was predominant in the sediments, and besides, Candidatus Brocadia and Candidatus Kuenenia were also detected at the site near the Huanghe River estuary that received strong riverine and anthropogenic impacts. Salinity was the most important in structuring communities of nosZ-denitrifier and anammox bacteria. Additionally, anthropogenic perturbations (e.g. nitrogen overloading and consequent high primary productivity, and heavy metal discharges) contributed significantly to shaping community structures of denitrifier and anammox bacteria, suggesting that anthropogenic activities would influence and even change the ecological function of coastal ecosystems.     

Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): A study supported by a citizen science project

The accumulation of large and small plastic debris is a problem throughout the world's oceans and coastlines. Abundances and types of small plastic debris have only been reported for some isolated beaches in the SE Pacific, but these data are insufficient to evaluate the situation in this region. The citizen science project "National Sampling of Small Plastic Debris” was supported by schoolchildren from all over Chile who documented the distribution and abundance of small plastic debris on Chilean beaches. Thirty-nine schools and nearly 1000 students from continental Chile and Easter Island participated in the activity. To validate the data obtained by the students, all samples were recounted in the laboratory. The results of the present study showed that the students were able to follow the instructions and generate reliable data. The average abundance obtained was 27 small plastic pieces per m² for the continental coast of Chile, but the samples from Easter Island had extraordinarily higher abundances (>800 items per m²). The abundance of small plastic debris on the continental coast could be associated with coastal urban centers and their economic activities. The high abundance found on Easter Island can be explained mainly by the transport of plastic debris via the surface currents in the South Pacific Subtropical Gyre, resulting in the accumulation of small plastic debris on the beaches of the island. This first report of the widespread distribution and abundance of small plastic debris on Chilean beaches underscores the need to extend plastic debris research to ecological aspects of the problem and to improve waste management.     

Whether human-induced activities could change the gradient pattern of coastal land use along the sea-land direction: a case study in Manila Bay,Philippines

Increasing intense human activities have largely changed the coastal landscape and caused many environmental issues. However, whether human-induced activities could change the coastal land use gradient pattern, an important coastal zonal characteristic along the sea–land direction, remains unclear. Manila Bay was selected as the study area in this work. According to the distance of the land use and land cover(LULC) to the coastline, we clustered the typical coastal land use sequence patterns(CLU...     

砾石海滩的沉积和形态动力特征

天然砾石海滩的物质主要来源于河流输入，海岸侵蚀，海底侵蚀，沿岸输送，人类活动及冰川搬运等，砾石海滩在地貌上表现出明显的分带性，海滩坡度的大小随物源和动力条件发生变化，砾石的磨蚀速率与岩性及周围沉积物粒度组成有关，人工砾石海滩建设可借鉴天然砾石海滩的形成和演化过程，合理地设计物质组成，砾石形状和大小，以便能更快地使人工海滩达到平衡状态并维持海滩的稳定性。     

Mercury distribution in ancient and modern sediment of northeastern Bering Sea

Reconnaissance sampling of surface and subsurface sediment to a maximum depth of 80 m below the sea floor shows that typical values of 0.03 p.p.m. and anomalies of 0.2–1.3 p.p.m. mercury have been present in northeastern Bering Sea since Early Pliocene time. Values are highest in modern beach (maximum 1.3 and mean 0.22 p.p.m. Hg) and nearshore subsurface gravels (maximum 0.6 and mean 0.06 p.p.m. Hg) along the highly mineralized Seward Peninsula and in clayey silt rich in organic matter (maximum 0.16 and mean 0.10 p.p.m. Hg) throughout the region. Although gold mining may be partly responsible for high mercury levels in the modern beach near Nome, Alaska (maximum 0.45 p.p.m.), equally high or greater concentrations of mercury occur in buried Pleistocene sediments immediately offshore (maximum 0.6 p.p.m.) and in modern unpolluted beach sediments at Bluff (maximum 1.3 p.p.m.); this suggests that the contamination effects of mining may be no greater than natural concentration processes in the Seward Peninsula region. The mercury content of offshore surface sediment, even adjacent to mercury-rich beaches, corresponds to that of unpolluted marine and fresh-water sediment elsewhere. The normal values that prevail offshore may be attributable to entrapment of mercury-bearing heavy minerals on beaches near sources and/or dilution effects of offshore sedimentation. The few minor anomalies offshore occur in glacial drift derived from mercury source regions of Chukotka (Siberia) and Seward Peninsula; Pleistocene shoreline processes have reworked the drift to concentrate the heavy metals.The distribution pattern of mercury indicates that particulate mercury-bearing minerals have not been widely dispersed from onland deposits in quantities sufficient to increase mercury levels above normal in offshore sediments of Bering Sea; however, it shows that natural sedimentary processes can concentrate this mercury in beaches of the coastal zone where there already is concern because of potential pollution from man's activities.     

Assessing the response of sandy-beach macrobenthos to recreation and the ecological status of the beach ecosystem at Liandao,China

Sandy beaches, prime recreational assets that attract more people than other types of shorelines, are the main assets underpinning many coastal economies and developments. However, the intense stressors to the ecology of sandy beaches caused by recreational activities are generally underestimated or ignored. This study was the first to emphasize the ecological characteristics of recreational beaches in China and assess the response of macrobenthos at Liandao Beach, a typical sandy beach in the central part of China. Using the Before/During/After/Control/Impact (BDACI) method, differences in multiple variables (species richness, mean density, diversity) between a heavily recreationally impacted transect (TrH/Impact) and a less-impacted transect (TrL/Control) in different impact periods (Before, During & After) were applied to assess the response of sandy-beach macrobenthos to recreation and tourism. Meanwhile, a comparison between the macrobenthos conditions of the studied beach and reference conditions calculating from historical data of similar beaches with little recreation and tourism disturbances was carried out. Furthermore, the quality control chart approach was used to detect in detail the macrobenthos stable state and yearly response to recreational activities. The results showed that recreation and tourism posed a serious threat to the beach ecosystem; macrobenthos on the studied beach were seriously disturbed by recreational activities, and their variations were highly negatively related to the human recreational level. After monthly recreational impacts, the macrobenthos decreased sharply and recovered with difficulty during 1 year. Over the long-term, the macrobenthos had a sharp decreasing trend, which indicated that the ecological environment of the beach was highly disturbed. Conservation measures for recreational beaches are very challenging because of the economic value and popularity of sandy beaches as recreational sites. However, practicable conservation measures could be implemented that prevent or slow ecological degradation. A number of management and conservation suggestions are put forward, such as the establishment of the ecological carrying capacity of Liandao Beach in terms of direct recreational use, creation of themed exhibitions related to the beach macrobenthos and beach ecosystem and dissemination of this knowledge to visitors, implementation of spatial zoning of beach use, visitor management and environmental education.