The surficial sediments of Königshafen-variations over the past 50 years

The investigation highlights the untypical nature of the intertidal sediments of the sheltered Königshafen embayment in the north of the island of Sylt. The area is characterized by medium sand, which might be explained by aeolian input from the adjacent dunes. Mudflats and sandy mudflats build up the western part of the bay. Other sandy mudflats, all with a small spatial distribution, are associated with mussel beds. A peculiarity of the sediments in the Königshafen embayment are the gravel and cobbles along the northern shore and parts of the southern shore. These can be interpreted as residual sediments from former stages of the “Ellenbogen” spit. A comparison of the present results with earlier studies by Wohlenberg (1937) and Felix (1981) shows a decline in mudflats and an increasing consolidation of the mud in the period up to 1981. Since 1981 the sediment distribution has not changed, hence this tidal embayment can today be qualified as representing a relatively stable depositional area.     

Historical changes and inventory of macroalgae from Königshafen Bay in the northern Wadden Sea

Knowledge on the distribution, abundance and species richness of intertidal macroalgae occurring on sandy and muddy flats of the German Wadden Sea is still incomplete. We summarize published and unpublished information available on the presence of macroalgae on the tidal flats of Königshafen Bay (island of Sylt, North Sea), one of the more extensively studied areas of the Wadden Sea. A total of 46 green algal species, 36 brown algal species and 26 red algal species has been recorded within the last 120 years on soft and hard substrata of Königshafen Bay (disregarding species found unattached or drifting). Several of these species were only temporarily resident on the tidal flats. Today, at least 35 green, 15 brown and 12 red algal species occur within or close to Königshafen Bay. Significant long-term changes in species abundances have occurred in all three major groups of algae: Since the late 1970s, dense green algal mats dominated byEnteromorpha flexuosa, E. radiata andE. prolifera have occurred regularly on the intertidal flats, whereas a general decrease of brown and red algae has been documented. Two red algal species,Gracilaria verrucosa and its epiphyteCallithamnion corymbosum, were conspicuous members of the macroflora until the middle of this century. Although still present in the 1980s, they have now disappeared completely. On the other hand, the brown algaSargassum muticum has begun to colonize mussel beds. The causal background of long-term changes in the macroalgal flora of Königshafen Bay is discussed. Owing to substantial nomenclatural changes during the last 120 years, a revised species list with authors’ names and synonyms is included.     

Benthic grazers and suspension feeders: Which one assumes the energetic dominance in Königshafen?

Size-frequency histograms of biomass, secondary production, respiration and energy flow of 4 dominant macrobenthic communities of the intertidal bay of Königshafen were analysed and compared. In the shallow sandy flats (Nereis-Corophium-belt [N.C.-belt], seagrass-bed andArenicola-flat) a bimodal size-frequency histogram of biomass, secondary production, respiration and energy flow was found with a first peak formed by individuals within a size range of 0.10 to 0.32 mg ash free dry weight (AFDW). In this size range, the small prosobranchHydrobia ulvae was the dominant species, showing maximal biomass as well as secondary production, respiration and energy flow in the seagrass-bed. The second peak on the size-frequency histogram was formed by the polychaeteNereis diversicolor with individual weights of 10 to 18 mg AFDW in theN.C.-belt, and byArenicola marina with individual weights of 100 to 562 mg AFDW in both of the other sand flats. Biomass, productivity, respiration and energy flow of these polychaetes increased from theNereis-Corophium-belt, to the seagrass-bed, and to theArenicola-flat. Mussel beds surpassed all other communities in biomass and the functional parameters mentioned above. Size-frequency histograms of these parameters were distinctly unimodal with a maximum at an individual size of 562 to 1000 mg AFDW. This size group was dominated by adult specimens ofMytilus edulis. Averaged over the total area, the size-frequency histogram of energy flow of all intertidal flats of Königshafen showed one peak built byHydrobia ulvae and a second one, mainly formed byM. edulis. Assuming that up to 10% of the intertidal area is covered by mussel beds, the maximum of the size-specific energy flow will be formed byMytilus. When only 1% is covered by mussel beds, then the energy flow is dominated byH. ulvae. Both animals represent different trophic types and their dominance in energy flow has consequences for the food web and the carbon flow of the total area. If the energy flow of the macrozoobenthos of Königshafen is dominated byM. edulis, then the primary energy has to be gained from the pelagic primary production and the total ecosystem will be dependent on energy input from the North Sea and deeper parts of the adjacent Wadden Sea. In the case of a dominance ofH. ulvae, the energy flow of Königshafen is mainly based on autochthonous primary production.     

Consumption of benthic fauna by carnivorous birds in the Wadden Sea

Consumption by carnivorous birds was estimated for the Sylt-Rømø tidal inlet in the northern part of the Wadden Sea, as well as the subarea Königshafen, a small, tidal bay. The bird community of the Sylt-Rømø Wadden Sea was dominated by Dunlin (35% of all birds counted), Eider (9%), Oystercatcher (8%), Knot (8%), and Shelduck (7%). The community in the Königshafen was dominated by Eider (20%), Knot (17%), Bar-tailed Godwit (17%), Dunlin (13%), and Oystercatcher (8%). Annual consumption was estimated at 3.4 g AFDW · m^?2 · year^?1 for the entire Sylt-Rømø Wadden Sea and 19.2 g AFDW · m^?2 · year^?1 for the Königshafen. Restricting the calculations to the intertidal area resulted in a consumption of 8.7 g AFDW · m^?2 · year^?1 for the Sylt-Rømø Wadden Sea and 17.6 g AFDW · m^?2 · year^?1 for the Königshafen. In the two areas, consumption was dominated by the Eider with 37% and 60% of the total consumption, respectively. In comparison to the western parts of the Wadden Sea the seasonal pattern of consumption as well as species composition differed, most probably as an effect of different climatic conditions, whereas annual consumption on intertidal flats seems to be in the same order of magnitude. On average, 15–25% of the mean annual macrozoobenthic biomass seems to be taken by carnivorous birds in the Wadden Sea, which is in the same order of magnitude as in other northern temperate estuarine areas.     

Germination and anchorage ofEnteromorpha spp. in sediments of the Wadden Sea

Large quantities of filamentous green algae (Enteromorpha spp.) have regularly occurred on muddy and sandy tidal flats in Königshafen, on the island of Sylt (North Sea), since 1979 — covering the sediments in thick mats during the summer months. While spores ofEnteromorpha were encountered in both mud and sand, germling formation was restricted to sand. However, mud snails (Hydrobia ulvae Pennant) were overgrown with smallEnteromorpha filaments in both habitats, about 50% of them at a muddy site and 20% at a sandy one. Filaments, several cm in length and still adhering to the snails, became tangled into clusters. At the sandy site, with abundantArenicola marina L., these clusters slid into the feeding funnels of lugworm burrows; the importance of this secondary anchorage is demonstrated by a field experiment. We suggest that the primary and secondary attachment ofEnteromorpha filaments provided by benthic fauna is an essential step in the development of green algal mats on sedimentary tidal flats.     

Long-term changes of intertidal and subtidal sediment compositions in a tidal basin in the northern Wadden Sea (SE North Sea)

Wadden Sea tidal flats are highly dynamic regarding the spatial distribution and the grain size composition of their sediments. From 2003 to 2006 surface sediments have been surveyed in an intertidal and a subtidal area within the tidal inlet Königshafen (south-eastern North Sea, northern Wadden Sea, island of Sylt) with the goal to gain information on short-term development trends in the grain size composition. The average grain size (Mean) becomes finer in the sheltered part of the intertidal survey area whereas a coarsening tendency can be observed in the more exposed part of the intertidal and especially in the subtidal survey area. The trend of the most frequent grain size (first Mode) shows the same spatial distribution pattern but is far less distinct. Thus, the changing Mean must be related to an increase in the deposition of fines in the sheltered part of the intertidal Königshafen as well as a general removal of fine-grained material in the exposed intertidal and subtidal Königshafen. In order to see long-term trends the surveys of 2003–2006 were compared to earlier studies conducted in 1932/1933, 1981 and 1989. A significant depletion of mud can be observed in the entire survey area. It is concluded that primarily changed hydrodynamics that may accompany ongoing climate change are responsible for this. However, the loss of fine-grained sediments is additionally amplified by a reduced vegetation cover and coastal protection measures.     

Stable musselMytilus edulis beds in the Wadden Sea—They’re just for the birds

Predation by eiders, oystercatchers and herring gulls on natural mussel bedsMytilus edulis was studied in the Königshafen, a sheltered bay in the Wadden Sea. About 15 ha (2.5%) of the Königshafen were covered with mussel patches of a biomass of about 1300 g AFDW m^?2. The biomass on the mussel beds was dominated by old mussels and found to be constant over several years. Birds annually removed 30% of the standing stock. Eiders were by far the most important predators and consumed 346 g AFDW m^?2, followed by oystercatchers with 28 g AFDW m^?2 and herring gulls with 3.6 g AFDW m^?2. Birds consumed a substantial part of the annual production of the mussel beds which was estimated from literature data to be approx. 500 to 600 g AFDW m^?2. As other predators were absent, the production of the mussels was sufficient to sustain the high predation rate by birds. Stable mussel beds form a short and efficient link between primary production and bird predation which is unusual for the Wadden Sea, where the main part of primary food supply is thought to be unavailable for higher trophic levels.     

A comparison of summer nutrient data obtained in Königshafen Bay (North Sea,German Bight) during two investigation periods: 1979–1983 and 1990–1992

A comparison of summer nutrients obtained during the investigation periods 1979–1983 and 1990–1992 was made, to elucidate whether or not changes have occurred in Königshafen Bay during the last decade. In both the flood current as well as in the ebb current, concentrations of silicate, phosphate, nitrite and nitrate have decreased. Ammonia, however, has increased by a factor of two in the flood current waters, but was similar in both investigation periods in the ebb current waters. In addition, a significant increase of salinity has been observed. The differences between flood and ebb current median nutrient concentrations suggest that the bay was a source of nutrients during the 1979–1983 period, exporting large amounts of silicate, nitrite and ammonia with the ebb current. Today, the bay appears to be more a sink than a source of nutrients. Export rates of silicate and nitrite are greatly reduced and phosphate and ammonia are imported nowadays. Nitrate fluxes were in balance during both periods. Reasons for the observed changes are discussed.     

Mobile dunes and eroding salt marshes

The paper deals with general outlines of salt marsh and dune vegetation in the Ellenbogen and Listland area on Sylt (Schleswig-Holstein, FRG). The composition of current salt marsh vegetation is considered to be mainly the result of a long-lasting process of tidal inundation, grazing, and a permanent influence of groundwater seepage from the surrounding dunes. The lower salt marsh communities have shown constancy for 67 years, due to the effect of heavy grazing. The mid-upper salt marsh communities demonstrated a succession from aPuccinellia maritima-dominated community of the lower marsh to aJuncus gerardii-dominated community of the mid-upper salt marsh, which may be due to the transport of sand — over a short time — on the surface of the marsh. The area covered by plant communities of annuals below Mean High Water (MHW) seemed to diminish. Salt marsh soils, especially of the mid-upper marsh, indicate sandy layers resulting from sand drift of the dunes. Dry and wet successional series of the dunes in the Listland/Ellenbogen area both show grassy stages shifting to dwarf shrubs as final stages. White primary dunes can only be found on the accreting shoreline of the Ellenbogen, which is also grazed by sheep; vegetation cover therefore remains dominated by grasses, mosses and lichens. Three mobile dunes (as the most prominent features of this landscape) have been left unaffected by seeding and planting by local authorities. Grazing is considered to be an inadequate tool in nature conservation as long as natural processes are to prevail in the landscape as major determinants.     

Effects ofFucus vesiculosus covering intertidal mussel beds in the Wadden Sea

The brown algaFucus vesiculosus formamytili (Nienburg) Nienhuis covered about 70% of mussel bed (Mytilus edulis) surface area in the lower intertidal zone of Königshafen, a sheltered sandy bay near the island of Sylt in the North Sea. Mean biomass in dense patches was 584 g ash-free dry weight m^?2 in summer. On experimental mussel beds, fucoid cover enhanced mud accumulation and decreased mussel density. The position of mussels underneath algal canopy was mainly endobenthic (87% of mussels with >1/3 of shell sunk into mud). In the absence of fucoids, mussels generated epibenthic garlands (81% of mussels with <1/3 of shell buried in mud). Mussel density underneath fucoid cover was 40 to 73% of mussel density without algae. On natural beds, barnacles (Balanidae), periwinkles (Littorina littorea) and crabs (particularly juveniles ofCarcinus maenas) were significantly less abundant in the presence of fucoids, presumably because most of the mussels were covered with sediment, whereas in the absence of fucoids, epibenthic mussel clumps provided substratum as well as interstitial hiding places. The endobenthic macrofauna showed little difference between covered and uncovered mussel beds. On the other hand, grazing herbivores — the flat periwinkleLittorina mariae, the isopodJaera albifrons and the amphipodsGammarus spp. — were more abundant at equivalent sites with fucoid cover. The patchy growth ofFucus vesiculosus on mussel beds in the intertidal Wadden Sea affects mussels and their epibionts negatively, but supports various herbivores and increases overall benthic diversity.     

The long-term development of urban vegetation in Helsinki, Finland: A pollen diagram from Töölönlahti

A core from Töölönlahti, a bay close to the central business district of Helsinki, the capital of Finland, was analysed for its pollen stratigraphy. The extrapolated age-depth curve based on¹³⁷Cs dating, sphaeroidal carbonaceous particle analysis and historical data suggests that the core goes back to the 17th or early 18th century. Four local pollen assemblage zones (LPAZ) were identified. Detrended correspondence analysis was used to detect the main phases of change represented by these zones. The basal LPAZ indicates that the vegetation was characterized by forest dominated byPinus sylvestris andPicea abies during the early history of the city of Helsinki and that human impact remained relatively minor until the end of the 19th century. A drastic change in vegetation took place at the turn of the 19/20th century when bothPinus andPicea declined rapidly while pollen values of several anthropogenic indicators rose. These changes were synchronous with the rapid expansion of population and urban area in Helsinki. Rarefaction analysis shows that palynological richness was highest during the early phase of increased human impact but then started to fall. During the 20th century the main vegetational trend has been the proliferation of introduced park trees. Palynological richness has decreased.     

不同沙源供给条件下柽柳灌丛与沙堆形态的互馈关系——以策勒绿洲沙漠过渡带为例

以塔克拉玛干沙漠南缘策勒绿洲—沙漠过渡带为研究区域,根据沙源供给丰富程度的明显差异,在固定沙地、半固定沙地、半流动沙地和流动沙地随机选择100个相对独立的柽柳灌丛沙堆,对每个沙堆形态进行测量,并对沙堆上的柽柳灌丛进行调查,分析研究不同沙源供给条件下柽柳灌丛形态特征和沙堆形态变化及其相互关系。结果表明:(1)在4种沙源供给条件下,柽柳灌丛高度相对稳定,灌丛长度、宽度、树冠投影面积、总枝条数、新枝率、基部新枝率和生物量随着沙源供给丰富度的增加而相应增加。(2)随沙源供给丰富度的增加沙堆尺度显著增大,外形向着沿风向拉长的不对称圆丘状发展,风影沙尾轮廓逐渐清晰。沙堆形态参数间存在良好的相关性,其中长度与宽度协同增长,回归曲线在流动沙地为二次函数关系,在其它3种沙地呈线性相关;底面积与高度表现为良好的二次函数关系;底面积与体积间存在显著的线性关系。(3)柽柳灌丛形态参数与沙堆形态参数间存在良好的相关性。其中树冠面积与沙堆体积间为显著线性关系,而树冠大小又与总枝条数以及新枝率密切相关,柽柳灌丛沙堆的适应机理应归于不断增加的沙源供给而产生的风积沙埋对柽柳灌丛生长的促进作用及灌丛与沙堆间的互馈效应。该区域柽柳沙包的形成以一定灌幅的存在为前提,可以判定是土地退化的产物,其中半流动沙地生境相对于其他沙地正处于急速退化中。     

Drifting meio- and macrobenthic invertebrates on tidal flats in Königshafen: A review

Many benthic species have been recorded to occur in the water column above the tidal flats in Königshafen. They were either passively suspended from the sediment or performed active migrations. Concerning both number of species and organisms, active migrations were more important. The causes for these migrations range from (1) individual escape from a sudden threat such as predator attack, over (2) group evasion of local subpopulations to avoid environmental deterioration, to (3) habitat changing of entire populations. The temporal scales involved range from seconds to seasons, and the spatial scales from cm to km. Such changes of distribution patterns have been demonstrated in juvenile molluscs and in meiofaunal copepods and plathelminths. Since migrations may interfere with many kinds of population studies in the field, new methods and concepts need to be developed to avoid and overcome pittalls. As a precaution, the migration potential of benthic species should be taken into account in any field study including population parameters.     

沙障对流动沙丘区地表节肢动物分布及多样性的影响

沙障作为人工固沙植被恢复与保护绿洲和道路安全的一种手段,可以有效阻止沙丘移动,改变流动沙丘地表生态水文过程,进而影响节肢动物多样性及营养结构及功能变化。鉴于此,选取临泽县中部沙带为研究区,利用陷阱法系统调查了生物、物理沙障和流动沙丘区沙丘不同部位地表节肢动物分布及多样性。研究结果表明,沙障营建强烈影响了流动沙丘区地表节肢动物组成,生物和物理沙障区地表节肢动物的活动密度、物种丰富度及多样性均显著高于流动沙丘区,捕食性和其它食性节肢动物较植食性节肢动物对沙障营建的响应更为敏感。沙障还改变了沙丘地表节肢动物的分布规律,生物和物理沙障区地表节肢动物的活动密度从沙丘底部到顶部依次增加,而流动沙丘区地表节肢动物主要分布在沙丘中下部。谢氏宽漠王和尖尾东鳖甲在流动沙丘区主要分布沙丘的中下部,沙障营建导致沙丘顶部谢氏宽漠王和尖尾东鳖甲的活动密度大幅提高。此外,研究还发现生物和物理沙障对地表节肢动物的影响不同,生物沙障区地表节肢动物活动密度显著高于物理沙障区,捕食性和东鳖甲属等其它食性节肢动物的活动密度在生物沙障区均高于物理沙障区。总之,沙障营建及类型差异强烈影响地表节肢动物的分布及多样性,它通过资源上行效应和土壤物理环境的改变提高了地表节肢动物的多样性及营养结构,从而影响了土壤生态系统结构及功能变化过程。     

Phenols: a review of their history and development as antimicrobial agents.

Phenols were first isolated in crude form at the end of the eighteenth century. Pure phenol was isolated in 1834 and its structure proved in 1842. In 1860 Küchenmeister first used phenol as a wound dressing in Germany. Lister was to use it in his classical experiments in antiseptic surgery. Substituted phenols, and to some extent phenol itself, are still in use today as antiseptics, disinfectants and preservatives.     

Turnover of postlarval bivalves in sediments of tidal flats in Königshafen (German Wadden sea)

After larval settlement, juvenile bivalves may rapidly re-enter the water column and attain secondary dispersal by byssus-drifting. In order to estimate the quantitative importance of byssus-drifting, the abundance of drifters in the water column, their re-entry into the sediment, and their density in the ambient sediment were measured simultaneously over 3 months on a tidal flat in Königshafen near the Island of Sylt in the North Sea. Turnover of juvenile clamsMacoma balthica and cocklesCerastoderma edule was more than once per week in summer, showing strong short-term variability because of semi-lunar rhythms of drifting activity. While there is currently no evidence for active habitat selection in settlingM. balthica andC. edule larvae, it is suggested that habitat selection occurs following postlarval migrations.     

Soil types with different texture affects development of Rhizoctonia root rot of wheat seedlings

The effect of different soil textures, sandy (97.5% sand, 1.6% silt, 0.9% clay), loamy sand (77% sand, 11% silt, 12% clay) and a sandy clay loam (69% sand, 7% silt, 24% clay), on root rot of wheat caused by Rhizoctonia solani Kühn Anastomosis Group (AG) 8 was studied under glasshouse conditions. The reduction in root and shoot biomass following inoculation with AG-8 was greater in sand than in loamy sand or sandy clay loam. Dry root weight of wheat in the sand, loamy sand and sandy clay loam soils infested with AG-8 was 91%, 55% and 28% less than in control uninfested soils. There was greater moisture retention in the loamy sand and sandy clay loam soils as compared to the sand in the upper 10–20 cm. Root penetration resistance was greater in loamy sand and sandy clay loam than in sand. Root growth in the uninfested soil column was faster in the sand than in the loamy sand and sandy clay loam soils, the roots in the sandy soil being thinner than in the other two soils. Radial spread of the pathogen in these soils in seedling trays was twice as fast in the sand in comparison to the loamy sand which in turn was more than twice that in the sandy clay loam soil. There was no evidence that differences among soils in pathogenicity or soil spread of the pathogen was related to their nutrient status. This behaviour may be related to the severity of the disease in fields with sandy soils as compared to those with loam or clay soils. This revised version was published online in June 2006 with corrections to the Cover Date.     

Transitions in sandflat biota since the 1930s: effects of sea-level rise,eutrophication and biological globalization in the tidal bay Königshafen,northern Wadden Sea

Conspicuous macrozoobenthos and vegetation of intertidal sandflats in Königshafen (Island of Sylt, SE North Sea) were mapped in 1932, 1988 and 2008. Higher water levels since the 1930s with a concomitant increase in tidal dynamics are assumed to have weakened sediment stability. This dissolved the distinctly banded macrobenthic zonation of the 1930s. Near high water level, cyanobacterial mats with associated beetles, belts of the mudshrimp Corophium volutator and the seagrass Zostera noltii have vanished, while the range of the lugworm Arenicola marina has extended towards the shore. Near low water level, sandy elevations have become permanently submerged because a tidal creek has widened its bed. In 1988, extensive green algal mats and the almost complete absence of seagrass are attributed to peak eutrophication. This partially reversed until 2008. The mussel Mytilus edulis had strongly extended its beds along the creek in 1988. These were taken over by introduced Pacific oysters Crassostrea gigas in 2008. Also in 2008, the cordgrass Spartina anglica, another introduced species, grew into large tussocks where cyanobacterial mats and a Corophium-belt had been mapped in the 1930s. Former benthic patterns may have little chance of resurrection by conventional nature protection because these small-scale shifts represent responses to regional and global change.     

雅鲁藏布江山南宽谷风沙化土地土壤养分和粒度特征

在雅鲁藏布江山南宽谷区,选择流动沙地、平缓沙砾地、半固定沙地、固定沙地和覆沙河滩地等类型样地,研究了不同深度(0—10 cm、10—20 cm和20—40 cm)土壤层的养分状况和粒度特征,探讨了风沙运动对土壤粒度组成和养分含量的影响。结果表明:1)风沙化土地土壤pH值呈中性、碱性和强碱性,土壤有机质和全氮含量均很低,但全磷和全钾均很高。土壤粒度组成表现为砂粒含量(53.83%—95.93%)>粉粒(3.3%—40.5%)>粘粒(0.77%—5.68%)。2)粘粒和粉粒含量均以覆沙河滩地(分别为4.02%和27.95%)最大、半固定沙地(分别为1.35%和5.27%)最小。粘粒含量表现为覆沙河滩地>固定沙地(2.98%)>河滩流动沙地(2.89%)>平缓沙砾地(1.69%)>河岸流动沙地(1.54%)>山坡流动沙地(1.49%)>半固定沙地。不同类型沙地粉粒含量的大小顺序与粘粒含量相似,仅在山坡流动沙地和河岸流动沙地的大小顺序有所差别。砂粒含量以半固定沙地(为93.40%)最大、覆沙河滩地最小(68.05%)。不同类型沙地的砂粒含量与粉粒含量的大小顺序正好相反。3)土壤养分含量与粘粒、粉粒、极细砂粒和细砂粒等细沙物质的相关性较强,与中砂粒、粗砂粒和极粗砂粒等粗沙物质呈负相关或相关性较弱。其中,粘粒和极细砂粒含量的增加对土壤养分的增加贡献较大。流动沙丘随风沙运动而不断往复摆动的现象和土壤细颗粒的迁移和损失,对不同类型沙地和沙丘部位的土壤养分状况及其再分配过程产生较大影响。