Zonation of ground beetles (Coleoptera: Carabidae) and spiders (Araneida) in salt marshes at the North and the Baltic Sea and the impact of the predicted sea level increase

The ground beetles and spiders of two salt marshes at the German Northand Baltic Sea coast were investigated by pitfall traps in 1997 and 1998. Whilethe sites at the North Sea coast are tidal salt marshes, the salt marshes at theBaltic Sea are not influenced by tides. Pitfall traps were installed in agradient from 20 to 150 cm above MHT (mean high tide: 157cm + NN, NN: 500 cm above 0 at Amsterdam gauge) atthe North Sea coast or NN at the Baltic Sea coast at six or sevensampling elevations, each with five replicates. Conductivity, water content, organic substance,frequency or duration of floodings, sand content and pH of the soil weredetermined. The flooding regime is the major factor controlling the zonation ofinvertebrates. Two and three invertebrate assemblages at the North and BalticSea, respectively, were distinguished. These corresponded well with thevegetational zones. The border between the two zones was at 60–80cm above MHT at the North Sea. The three zones at the Baltic Seaextended between 20 and 30 cm, 40 to 80 cm and 100 to150 cm above NN. The elevation of the mean abundance of speciesabove MHT or NN was calculated. A tide simulation experiment resulted in ashifting population and in an increasing activity under a tidal regime aspredicted for the global climate change conditions in 2050. From the actualelevation of the mean abundance, the habitat size of salt marsh species wascalculated for a moderate and worse scenario of global climate change. Habitatreduction becomes highest for species of the lower salt marsh zone. Under worseconditions the gradiental length of habitat will only amount to a maximum of 20m at the slopes of the dikes.     

Données synchorologiques sur la végétation littorale européenne

Four aspects of the synchorology of plant communites along the European coastline are treated: (1) with examples from sand dunes (Agropyreta and Ammophileta) and salt marshes (Puccinellieta maritimae) synvicariance is elucidated; (2) The increase in synvicariance towards the inner sand dunes is discussed as a result of an increasing effect of autochthonous climatic features; (3) with examples from sand dunes and cliffs the concept of synendemism is elucidated; (4) synvicariance at the landscape (geosigmetum) is discussed with examples from the French coastline.

     

Zonation of spiders (Araneae) and carabid beetles (Coleoptera: Carabidae) in island salt marshes at the North Sea coast

The specific communities of spiders and carabid beetles of island salt marsh habitats of the East Frisian Island chain at the German North Sea coast were investigated. During the vegetation periods of 1997 and 1998 three pitfall trapping transects were installed on the islands of Borkum and Wangerooge. Within the salt marshes, transects extended from 0 m to 175 m. Elevation gradients varied between 10 cm and 232 cm above MHT (mean high tide). On Borkum, 35 traps were exposed in two transects, on Wangerooge 25 traps were placed in one transect. Three to five elevations above MHT were investigated per transect, each one with five traps. Highest species numbers were recorded in the higher elevated salt marshes. In contrast, highest activity values were noticed in the medium elevated salt marshes. Within both groups, spiders and carabids, four communities were distinguished by indirect gradient analysis. Indicator species were assigned to the different communities that were mainly assorted to different elevations of the salt marshes. Thus, the communities of both taxa corresponded well to the vegetational formations. The importance of sea level rise for structuring the communities of salt marsh arthropods is discussed. Overall, still great uncertainties exist on how arthropod communities and salt marshes themselves will develop.     

Vegetation composition of a threatened hypersaline lake (Lake Bardawil), North Sinai

Lake Bardawil is the only oligotrophic hypersaline lagoon along theMediterranean coast of Egypt. Its ecological significance is increasing due tothe progressive degradation of comparable wetlands in the region. The aim ofthis study is to analyse the structure and life forms of the vegetation alongthe lake before the execution of the North Sinai Agricultural DevelopmentProject (NSADP) which will threaten the ecosystem of the lake. A data set of150 stands was analysed using multivariate procedures(TWINSPAN, DCA and CCA), to classify the lake's vegetation, and to determinetherelationship between the plant community structure and the environmentalfactors. The classification and ordination resulted in a clear demonstration ofnine vegetation groups associated with four habitat types: submerged seagrasses, salt marshes and sabkhahs, eastern and middle calcareous dunes, andwestern non-calcareous dunes. The first axis of the CCA-ordination separatesthe salt marshes andsabkhahs species from those of the sand dunes along the soil salinity, watertable depth, cations, and pH gradients. CaCO₃ and soil textureshowedhighly significant correlation with the second axis of CCA which was animportant predictor for the psammophytic species distribution. The life formsranged from hydrophytes (sea grasses) to phanerophyteswith the dominance of therophytes and chamaephytes. Geophytes and chamaephytesdominate the saline habitats, while therophytes and hemicryptophytes dominatedthe sandy dunes. Eventhough the eastern section of the lake (Lake Zaraniq) wasdeclared as a RAMSAR site, Lake Bardawil needs urgent management to prevent itspollution by the new land use system.     

1973-2020年黄河三角洲滨海盐沼湿地景观格局演化模式和驱动因素

明晰滨海盐沼湿地景观格局演化模式和驱动因素,有助于制定合理的盐沼湿地修复策略、维护区域生态系统健康和可持续发展。以黄河三角洲滨海盐沼湿地为例,基于Landsat系列卫星影像获取1973—2020年共十个时期土地利用/覆被数据,得出盐沼湿地时空变化及其与周边土地利用/覆被的相互转化;利用改进的景观格局状态与演化识别模型(SEDMS),分析盐沼湿地景观格局演化模式,并利用地理探测器探究其空间分异驱动因素。结果表明：(1)1973—2020年,盐沼湿地面积减少了252.35 km²,空间范围总体向外海迁移且趋于集中。盐沼湿地转出类型主要为草地、养殖池/盐田和耕地,转入类型主要为滩涂未利用地和水体。(2)盐沼湿地景观格局演化模式呈明显的阶段性特征：1973—1995年为动荡期,演化模式以消失和破碎为主导;1995—2010为过渡期,格局演化模式逐渐由消失和破碎为主导转变为扩张为主导;2010年后为稳定期,格局发生演化的区域较少,总体以新增和扩张为主。(3)36%的盐沼湿地出现了多次格局演变模式的转变,滩涂未利用地、耕地对于景观格局演化频数的影响最为显著,人工表面、养殖池/...     

Biotechnological potential of North Sea salt marsh plants—a review of traditional knowledge

Extreme environments are characterised by wide variations in physical factors. Tidal flats and their adjacent salt marshes along the North Sea coast experience this type of variability on a daily, seasonal and annual basis. Plants and animals living in these extreme environments have to adapt to these, at times rapid, changes. This can be done by developing specific physiological responses which often encompass the synthesis of unusual chemicals. A number of salt marsh plants have traditionally been used for medical, nutritional or even industrial purposes. Here, examples are presented for these plants.     

Population biology of salt marsh and sand dune annuals

Annuals represent a significant component of the vegetation of coastal salt marshes and sand dunes. From many points of view, the two habitats might appear to have little in common. Yet both are characterized by episodes of low water potential, marked spatial and temporal heterogeneity and a zonation which, within certain limits, reflects successional change.There are also similarities of distribution. Annuals are dominant usually in the pioneer stages; the Salicornia-dominated low marsh areas are perhaps analogues with strandline ephemeral populations (e.g. Cakile maritima) on the fore-dunes. In mature stages, annuals are associated with small gaps in the matrix of perennials, at least some of these arising from drought or disturbance. Nevertheless populations can reach very high densities.The most striking contrast is phenological; only summer annuals are found on marshes, whereas winter annuals predominate on dunes (except for the strandline). Similarly there is a difference in species richness. Rather few species of annual are typical of marshes while a great many are found on dunes.Properties of the seed bank, survival, reproduction and population regulation are compared in marsh and dune annuals, with special reference to Cakile, Salicornia, Rhinanthus and Vulpia. Interpretations are suggested which take account of environmental predictability and heterogeneity. Finally, the general applicability of simple mathematical models of these populations in the different coastal habitats is considered.Nomenclature follows Clapham, Tutin & Warburg (1981) except where otherwise stated.     

Restoring Ecological Function to a Submerged Salt Marsh

Impacts of global climate change, such as sea level rise and severe drought, have altered the hydrology of coastal salt marshes resulting in submergence and subsequent degradation of ecosystem function. A potential method of rehabilitating these systems is the addition of sediment‐slurries to increase marsh surface elevation, thus ameliorating effects of excessive inundation. Although this technique is growing in popularity, the restoration of ecological function after sediment addition has received little attention. To determine if sediment subsidized salt marshes are functionally equivalent to natural marshes, we examined above‐ and belowground primary production in replicated restored marshes receiving four levels of sediment addition (29–42 cm North American Vertical Datum of 1988 [NAVD 88]) and in degraded and natural ambient marshes (4–22 cm NAVD 88). Moderate intensities of sediment‐slurry addition, resulting in elevations at the mid to high intertidal zone (29–36 cm NAVD 88), restored ecological function to degraded salt marshes. Sediment additions significantly decreased flood duration and frequency and increased bulk density, resulting in greater soil drainage and redox potential and significantly lower phytotoxic sulfide concentrations. However, ecological function in the restored salt marsh showed a sediment addition threshold that was characterized by a decline in primary productivity in areas of excessive sediment addition and high elevation (>36 cm NAVD 88). Hence, the addition of intermediate levels of sediment to submerging salt marshes increased marsh surface elevation, ameliorated impacts of prolonged inundation, and increased primary productivity. However, too much sediment resulted in diminished ecological function that was equivalent to the submerged or degraded system.     

Nature management in coastal areas of Western Europe

The general environmental characteristics of West European coastal dunes and those of salt marshes are outlined. It is pointed out that the dynamical character of the dune system with its interaction between plants and sand in building and degeneration phases has been known for a much longer period of time than generally believed.As to the salt marshes the special significance is discussed of ungrazed marshes; the majority of the marshes having been under a grazing regime for a long time is elucidated.The distinction between internal management is mentioned, i.e. the measures taken to maintain or improve the qualities of an area, versus external management, i.e. the measures to prevent or counteract negative influences from outside the area.Nomenclature follows Heukels & Van Ooststroom (1977).     

Integrated management of artificially created salt marshes in the Wadden Sea of Schleswig-Holstein, Germany

In the about 10,000 km² large Wadden Sea 353 km² of salt marshes exist. The great majority of these are artificial, i.e. developed through accretion enhancement techniques. Salt marshes in the Wadden Sea have a high coastal defence value as well as ecological significance. High salt marshes in front of sea walls reduce the wave-impact on the dikes and, therewith, the danger of breaching. At the same time, the salt marshes have a high ecological value, e.g., as resting places for migratory birds. In consequence, for coastal defence, salt marshes should be created and/or maintained. For nature protection, natural dynamic processes (incl. erosion) should prevail. To anticipate this possible conflict among coastal defence and environmental administration, in Schleswig-Holstein an interdepartmental working group established a salt marsh management concept. For information of the interested parties and for monitoring of the concept, an integrated salt marsh board was established, consisting of representatives from public administration and local interest groups (NGO's, dike and water boards, municipalities). Five years after implementation of the concept, this board established a first progress report. Although the concept was, in the beginning, met with great scepticism, five years of practical experience demonstrate that it functions well. The salt marshes are stable or growing, i.e. the management measures are successful. As a planning instrument, the concept is unambiguous, i.e. provides clear guidelines on how to manage the salt marshes. Finally, as an instrument of participation, the salt marsh board is valued positively by all members.     

Responses of Salt Marsh Ecosystems to Mosquito Control Management Practices along the Atlantic Coast (U.S.A.)

Open marsh water management (OMWM) of salt marshes modifies grid‐ditched marshes by creating permanent ponds and radial ditches in the high marsh that reduce mosquito production and enhance fish predation on mosquitoes. It is preferable to using pesticides to control salt marsh mosquito production and is commonly presented as a restoration or habitat enhancement tool for grid‐ditched salt marshes. Monitoring of nekton, vegetation, groundwater level, soil salinity, and bird communities before and after OMWM at 11 (six treatment and five reference sites) Atlantic Coast (U.S.A.) salt marshes revealed high variability within and among differing OMWM techniques (ditch‐plugging, reengineering of sill ditches, and the creation of ponds and radial ditches). At three marshes, the dominant nekton shifted from fish (primarily Fundulidae species) to shrimp (Palaemonidae species) after manipulations and shrimp density increased at other treatment sites. Vegetation changed at only two sites, one with construction equipment impacts (not desired) and one with a decrease in woody vegetation along existing ditches (desired). One marsh had lower groundwater level and soil salinity, and bird use, although variable, was often unrelated to OMWM manipulations. The potential effects of OMWM manipulations on non‐target salt marsh resources need to be carefully considered by resource planners when managing marshes for mosquito control.     

Ecophysiological adaptations of coastal halophytes from foredunes and salt marshes

Ecophysiological strategies of coastal halophytes from foredunes and salt marshes are discussed. A comparison is made of the factors that limit growth in salt marshes and sand dunes. In salt marshes, zonation and succession are primarily governed by variation in soil salinity, which strongly depends on inundation with seawater. Results are described of experiments which aim at separating salinity and inundation effects on growth, osmotic and mineral relations in a comparison of salt-marsh halophytes. The growth response of plants cannot simply be correlated (and causally explained) with the concentration of Na, Cl, and K in the tissues. Also, the compatible osmotic solutes proline and methylated quaternary ammonium compounds may accumulate both in species with a positive response to increased salinity and in species with a growth reduction under seawater inundation. More likely inadequate adaptation of the plants water potential with these components is partly the cause of retarded growth. Disfunctioning of the plant in this respect may be at three levels: (a) total water potential of the plant, (b) (loss) of turgor pressure potential; (c) regulation at the cellular level. The ecological importance of some factors in seawater other than sodium chloride is considered. In coastal sand dunes airborne rather than soil salinity limits plant growth, together with the effects of abrasion, sand accretion, drought and the poor nutrient status of the dune sand. Adaptations of sand-dune species to these factors may consist of: large seeds with storage tissue germinating in the dark and seedling growth enough to emerge through the accreted sand. Aerial parts must be resistant to mechanical damage (high wind speed and abrasion), possibly by a sclerophyllous and tough structure. Efficient nutrient uptake, translocation and retranslocation seem to help survive sand-dune species in a nutrient-poor rooting medium.     

Drainage and Elevation as Factors in the Restoration of Salt Marsh in Britain

Intertidal restoration through realignment of flood defenses has become an important component of the U.K. coastal and estuarine management strategy. Although experimentation with recent deliberate breaches is in progress, the long‐term prognosis for salt marsh restoration can be investigated at a number of sites around Essex, southeast England where salt marshes have been reactivated (unmanaged restoration) by storm events over past centuries. These historically reactivated marshes possess higher creek densities than their natural marsh counterparts. Both geomorphology and sedimentology determine the hydrology of natural and restored salt marshes. Elevation relative to the tidal frame is known to be the primary determinant of vegetation colonization and succession. Yet vegetation surveys and geotechnical analysis at a natural marsh, where areas with good drainage exist in close proximity to areas of locally hindered drainage at the same elevation, revealed a significant inverse relationship between water saturation in the root zone and the abundance of Atriplex portulacoides, normally the physiognomic dominant on upper salt marsh in the region. Elsewhere in Essex natural and restored marshes are typified by very high sediment water contents, and this is reflected in low abundance of A. portulacoides. After a century of reestablishment no significant difference could be discerned between the vegetation composition of the storm‐reactivated marshes and their natural marsh counterparts. We conclude that vegetation composition may be restored within a century of dike breaching, but this vegetation does not provide a reliable indicator of ecological functions related to creek structure.     

Plathelminth abundance in North Sea salt marshes: environmental instability causes high diversity

Although supralittoral salt marshes are habitats of high environmental instability, the meiofauna is rich in species and abundance is high. The community structure of free-living Plathelminthes (Turbellaria) in these salt marshes is described. On an average, 104 individuals are found below an area of 10 cm². The average species density in ungrazed salt marshes is 11.3 below 10 cm² and 45.2 below 100 cm², indicating strong small-scale heterogenity. The faunal similarity between sediment and the corresponding above-ground vegetation is higher than between adjacent sample sites. Species prefer distinct ranges of salinity. In the lower part of the supralittoral salt marshes, the annual fluctuations of salinity are strongest and highly unpredictable. This region is richest in plathelminth species and abundance; diversity is highest, and the faunal composition of parallel samples is quite similar. In the upper part of the supralittoral salt marshes, the annual variability of salinity is lower, plathelminths are poor in species diversity and abundance. Parallel samples often have no species in common. Thus, those salt marsh regions with the most unstable environment are inhabited by the most diverse species assemblage. Compared to other littoral zones of the North Sea, however, plathelminth diversity in salt marshes is low. The observed plathelminth diversity pattern can apparently be explained by the dynamic equilibrium model (Huston, 1979).     

Holocene salt marsh plant communities in the North Adriatic coastal plain (Italy) as reflected by pollen, non-pollen palynomorphs and plant macrofossil analyses

In this work we investigate the development of a salt marsh environment during the Holocene marine transgression in the North Adriatic coast (North Italy) near the pre-Roman and Roman towns of Cittanova and Concordia Sagittaria. Pollen, plant macrofossils, non-pollen palynomorphs (NPPs) and foraminifers are analysed in cores and archaeological excavations to indicate the development of salt marsh plant communities. Other independent proxies (foraminifers, plant macrofossils, molluscs) confirm the ecological interpretation based on pollen records. The relevance of NPPs as indicators of salt marsh environment is evaluated. Linings of foraminifers are the most frequent NPP type, recorded in 85% of the brackish sediments. They may tentatively be referred to the genus Ammonia, a very common benthonic genus in the present lagoons of the North Adriatic Sea. Radiocarbon dates available from previous work allow the salt marsh development to be dated in the sector from the east of the Lagoon of Venice to the Lagoon of Caorle. Near Cittanova, salt marshes developed before 6700 yrs cal. b.p. At Concordia Sagittaria, the first evidence dates from ca. 6700 yrs cal. b.p. and a phase of freshwater conditions is recorded in the sediments of ca. 4500 yrs cal. b.p.     

Coastal vegetation on the Western, Southern, and Eastern coasts of South Korea

We used the Braun-Blanquet method to study the vegetation of coastal wetlands in South Korea. Three habitat types were found, i.e., salt marshes, salt swamps, and sand dunes. These plant communities were classified as: 1) two groups (five associations each) in the salt marshes that comprised either annual herbaceous halophytes (ClassThero-Salicornietea), or biennial/perennial herbaceous species (ClassAsteretea tripolii); 2) one group in the salt swamps consisting of five hydrophilous halo-tolerant associations (ClassPhragmitetea); and 3) three groups in the sand dunes, including one association of annual herbaceous halophytes (ClassSalsoletea komarovii), seven associations of herbaceous perennial halophytes (ClassGlehnietea littoralis), and one association of shrub perennial halophytes (ClassVrticetea rotundifoliae). These three habitat types accounted for the majority of the six main classifications of coastal vegetation distributed in South Korea.     

Soil pH and species diversity in coastal dunes

Soil pH was measured at two different spatial scales in coastal dunes on Norderney, North Sea, and in Mecklenburg-Vorpommern, Baltic Sea, Germany. Relationships between the variability in soil pH, species richness and species diversity are presented. Species richness and diversity were highest in grey dunes, where soil pH was at intermediate levels; both variables were lower in yellow and brown dunes. The variability in pH increased with increasing species diversity and also with scale. Overall, soil pH variability decreased with increasing vegetation cover. The lowest pH heterogeneity was found in heath dominated by Empetrum nigrum L. and grey dunes dominated by Campylopus introflexus (Hedw.) Brid. Increasing abundance of dominant species and decreasing species diversity of vegetation apparently reduces soil heterogeneity. Decreasing species diversity of vegetation is likely to explain decreasing variability in soil pH.     

Freshwater wetlands: fertile grounds for the invasive Phragmites australis in a climate change context

Climate change will likely affect flooding regimes, which have a large influence on the functioning of freshwater riparian wetlands. Low water levels predicted for several fluvial systems make wetlands especially vulnerable to the spread of invaders, such as the common reed (Phragmites australis), one of the most invasive species in North America. We developed a model to map the distribution of potential germination grounds of the common reed in freshwater wetlands of the St. Lawrence River (Québec, Canada) under current climate conditions and used this model to predict their future distribution under two climate change scenarios simulated for 2050. We gathered historical and recent (remote sensing) data on the distribution of common reed stands for model calibration and validation purposes, then determined the parameters controlling the species establishment by seed. A two‐dimensional model and the identified parameters were used to simulate the current (2010) and future (2050) distribution of germination grounds. Common reed stands are not widespread along the St. Lawrence River (212 ha), but our model suggests that current climate conditions are already conducive to considerable further expansion (>16,000 ha). Climate change may also exacerbate the expansion, particularly if river water levels drop, which will expose large bare areas propitious to seed germination. This phenomenon may be particularly important in one sector of the river, where existing common reed stands could increase their areas by a factor of 100, potentially creating the most extensive reedbed complex in North America. After colonizing salt and brackishwater marshes, the common reed could considerably expand into the freshwater marshes of North America which cover several million hectares. The effects of common reed expansion on biodiversity are difficult to predict, but likely to be highly deleterious given the competitiveness of the invader and the biological richness of freshwater wetlands.     

Multi-scale segregations and edaphic determinants of marsh plant communities in a western Pacific estuary

Whether and how the roles of environmental factors in producing vegetation patterns in coastal marshes vary with spatial scale is not well understood. We investigated the relationship between plant communities and edaphic factors in the Yangtze estuary at three spatial scales. Plant communities and edaphic factors were quantified at high and low tidal levels in both freshwater and salt marshes. Canonical correspondence analyses were conducted to examine the relationship between plant communities and edaphic factors at the landscape scale (freshwater vs. salt marsh), the zonation scale (high vs. low tidal level) and the patch scale (dominant vs. other species). Soil salinity, moisture content, pH, bulk density, and organic carbon could well explain segregations of plants at the landscape and zonation scales. However, the same factors exhibited only very weak relationships to plant communities at the patch scale. These results suggest that plant communities in the Yangtze estuary are segregated at different spatial scales by different environmental factors. As spatial scale is often not explicitly addressed investigating community assembly rules, our study underscores the importance of scaling for an improved understanding of community organization in coastal wetlands.     

Untersuchungen zum Vorkommen von Myxobakterien in von Meerwasser beeinflußten Substraten unter besonderer Berücksichtigung der Insel Helgoland

Representatives of the family Myxococcaceae,Myxococcus fulvus andM. virescens as well asArchangium gephyra could be isolated from marine sediments (depth range 5–58 m), collected near the island of Helgoland (North Sea); dunes and rudiments of salt marshes additionally yieldedM. coralloides and the rare speciesMelittangium licenicola andM. boletus (Cystobacteriaceae). In soil samples from the island,M. fulvus, M. virescens, M. coralloides, A. gephyra, Cystobacter fuscus andStigmatella erecta were found. These results were confirmed by data, obtained from the coastal zone of the island of Amrum and marine sediments from various regions. On the other hand samples from shallow fresh water (depth range 0.3–1 m) proved to be richer in species. It is assumed that the myxobacteria found in marine sediments occur as resting cells.