The plant food component of the diet at the late Mesolithic (Ertebolle) settlement at Tybrind Vig, Denmark

Tybrind Vig is a late Mesolithic (Ertebølle) coastal settlement, dated to the period 5600–4000 BC. The site has yielded some very important finds associated with fishing activity, probably the best preserved example from the Mesolithic in Europe. Recently analysed botanical samples from submerged cultural deposits have provided evidence for the contribution of plants to the subsistence diet of the inhabitants of Tybrind Vig. The food plant remains are represented by the charred fragments of parenchymatous tissue from roots ofBeta vulgaris ssp.maritima (sea beet), fragments ofQuercus sp. parenchyma (acorn), and shell fragments ofCorylus avellana (hazelnut). The possibility that the grains ofGlyceria fluitans (floating sweet grass) and stems ofPhragmites australis (reed) were collected for food should not be excluded. In addition to the species identified in the charred remains, an abundance of edible plant seeds and fruits were represented in the waterlogged remains, suggesting that a much broader range of food plants was available in the area. These additional foods could have included a large variety of wild berries and other fruits, such asRubus idaeus, R. caesius, Fragaria vesca, Malus sylvestris, Cornus sanguinea, Crataegus monogyna/laevigata, Sorbus aucuparia, Viburnum opulus andRosa spp. Several other plants could have been gathered as green vegetables (Rumex crispus, Urtica dioica andCakile maritima), or could have been utilized for both their greens and seeds (Chenopodium album, Atriplex andScirpus maritimus).     

Effects of long-term fire exclusion on tree species composition and stand structure in an old-growth Pinus palustris (Longleaf pine) forest

Frequent fire is an integral component of longleaf pine ecosystems, creating environmental conditions favoring survival and growth of juvenile pines. This study examined stand structure, species composition, and longleaf pine regeneration in an old-growth tract of longleaf pine forest (Boyd Tract) experiencing long-term (>80 yr) fire exclusion in the Sandhills of North Carolina. Sampling of woody stems (i.e., 2.5 cm diameter at breast height) and tallies of longleaf pine seedlings were carried out in plots established randomly on upland, mesic areas and lowland, xeric areas within the Boyd Tract. Dominant woody species in mesic plots were black oak, hickories, and large, sparse longleaf pines. Xeric plots had high densities of turkey oak with the large longleaf pines, as well as higher frequencies of smaller longleaf stems. These differences between areas were associated with higher clay content of upland soils and higher sand content of lowland soils. Age-class frequency distributions for fire-suppressed longleaf pine following the last wildfire at the Boyd Tract approximately 80 yr ago contrasted sharply with data from an old-growth longleaf tract in southern Georgia (Wade Tract) that has been under a long-term frequent fire regime. Post-burn recruitment for the Boyd Tract wildfire appears to have been initially high on both site types. Longleaf pine recruitment diminished sharply on the mesic site, but remained high for 60 yr on the xeric site. Currently, longleaf pine regeneration is minimal on both site types; several plots contained no seedlings. Sharp contrasts in longleaf pine dominance and stand structure between the Boyd and Wade Tracts demonstrate the importance of large-scale disturbance, especially hurricanes and fire, in shaping the structure and function of longleaf pine ecosystems of the southeastern United States. In particular, long-term exclusion of fire on the Boyd Tract has altered stand structure dramatically by permitting hardwoods to occupy at high densities the characteristically large gaps between longleaf stems that are maintained by fire and other disturbances.     

Studies on the zooplankton community of a shallow lagoon of the Southern Baltic Sea: long-term trends,seasonal changes,and relations with physical and chemical parameters

The Darß-Zingst Lagoon, a coastal inlet of the southern Baltic Sea, was subject to extended monitoring. The biomass data of zooplankton from 1969 to 2001 were used to analyze long-term trends and to correlate zooplankton biomass with abiotic factors. The dominant species in the lagoon were the calanoid copepods Eurytemora affinis and Acartia tonsa, and the rotifer Keratella cochlearis f. tecta. In the long-term trend, two pronounced changes in zooplankton biomass and species composition were observed. They are discussed in connection with a shift in dominance from macrophytes to phytoplankton and the invasion of a polychaet species into the lagoon. Significant relations between zooplankton data and abiotic parameters were found. While temperature, precipitation and NAO winter index correlated positively with copepods and negatively with rotifers, the relationships were inversely for pH-value and duration of ice cover.     

Novel facultative anaerobic acidotolerant Telmatospirillum siberiense gen. nov. sp. nov. isolated from mesotrophic fen

Three facultative anaerobic acidotolerant Gram-negative motile spirilla strains designated 26-4b1, 26-2 and K-1 were isolated from mesotrophic Siberian fen as a component of methanogenic consortia. The isolates were found to grow chemoorganotrophically on several organic acids and glucose under anoxic and low oxygen pressure in the dark, tolerant up to 5kPa of oxygen. At low oxygen supply, faint autotrophic growth on the H(2):CO(2) mixture was also observed. All three isolates were able to fix N(2). Major cellular fatty acids were 18:1 omega7c, 17:0 cyclopropane and 16:0. Phylogenetic analyses of the 16S rRNA gene sequences revealed that they formed a deep branch within the family Rhodospirillaceae of the Alphaproteobacteria with the highest similarity of 90.9-92.5% with members of genera Phaeospirillum and Magnetospirillum. Phylogenetic study of nifH (nitrogenase) and cbbL (RuBisCO) amino acid sequence identities confirmed that the new isolates represent a novel group. Based on the phylogenetic analyses and distinct phenotypic characteristics, we are of the opinion that strains 26-4b1, 26-2 and K-1 represent a new species of a novel genus for which the name Telmatospirillum siberiense gen. nov. sp. nov. is proposed.     

Nursery ground value of an endangered wetland to juvenile shrimps

Although urban development impacts wetlands around the world, until now there have been no studies of its effects on coastal wetlands in tropical regions of developed countries such as Australia. In fact the ecological value of such wetlands is poorly understood. This study provides an initial step in evaluating the ecological value of urbanised, tropical coastal wetlands by determining (a) the extent to which a remnant wetland, in a highly urbanised estuary in northern Australia, is used by juvenile commercial penaeid shrimps, and (b) the extent to which the shrimps rely on food chains based on wetland plants versus marine based food chains. Juvenile penaeids were abundant in the 11 wetland pools sampled. Catches included 5 commercial penaeids with two species, Fenneropenaeus merguiensis and Metapenaeus bennetae, comprising half the catch. Densities in the wetland pools were usually substantially higher than in adjacent estuarine habitats. Stable isotope analysis indicated that much of the nutrition of juvenile shrimps was supplied by marine primary producers (phytoplankton, epiphytic and epilithic algae, microphytobenthos, green filamentous algae) however the locally abundant saltmarsh grass Sporobolus virginicus was also a major contributor. In contrast, there was little indication of nutritional support from mangrove carbon. The lack of importance of mangrove carbon is surprising because the catches of F. merguiensis are often closely linked to the area or extent of mangroves, suggesting that aspects of mangrove systems other than the supply of mangrove carbon may determine the distribution of juvenile F. merguiensis.     

陕西省水鸟种群和地理分布研究

水鸟是湿地野生动物中最具代表性的类群,是湿地生态系统的重要组成部分,灵敏并深刻地反映着湿地环境的变迁.2002年以来,省林业厅鸟类调查组对我省的鸟类资源及分布进行了全面系统的调查,结果表明陕西省湿地水鸟有10目20科113种.本文阐明了我省水鸟的种类、地理分布及保护价值,并讨论了陕西湿地水鸟种群现状、面临的威胁和相应的保护对策.     

The impact of Hurricane Ivan on the primary productivity and metabolism of marsh tidal creeks in the NorthCentral Gulf of Mexico

Past research has examined hurricane impacts on marine communities such as seagrass beds, coral reefs, and mangroves, but studies on how hurricanes affect marsh tidal creeks are lacking despite the important ecological roles that marsh tidal creeks have in coastal ecosystems. Here we report on the impact of Hurricane Ivan, which made landfall on September 16, 2004, on the primary productivity and metabolism of six marsh tidal creeks in the NorthCentral Gulf of Mexico. The hurricane did not seem to have any large, lasting impact on nutrient concentrations, primary productivity, metabolism, and chlorophyll a concentration in the water-column of the marsh tidal creeks. In contrast, the hurricane seemed to largely decrease gross primary productivity, net productivity, and chlorophyll a concentration in the sediment of the marsh tidal creeks. The results observed for Hurricane Ivan were coincident with those observed for four other major storms that made landfall close to the study area during 2005, Tropical Storm Arlene and Hurricanes Cindy, Dennis, and Katrina. However, the apparent negative impact of major storms on the sediment of the marsh tidal creeks did not seem to be long-lived and appeared to be dissipated within a few weeks or months after landfall. This suggests that marsh tidal creeks mostly covered with bare sediment are less disturbed by hurricanes than other types of marine communities populated with bottom-attached and/or more rigid organisms, such as seagrass meadows, coral reefs, and mangroves, where hurricane impacts can be larger and last longer.     

Phosphorus removal in small constructed wetlands dominated by submersed aquatic vegetation in South Florida, USA

Aims: Free-surface flow-constructed wetland is a powerful means forthe reduction of contaminants from agricultural runoff. Wetlandsdominated by submerged aquatic vegetations (SAVs) may take upnutrients, particularly phosphorus (P), from surface flow withhigh efficiency. The objective of this study was to assess Premoval performance by the SAV community under high and lowP concentrations. Methods: Weekly or biweekly inflow and outflow water samples were collectedfrom four small constructed wetlands (test cells) planted withSAV in South Florida, USA, between September 1999 and September2001. These test cells were divided into two groups, with thenorth test cells receiving a higher inflow total phosphorus(TP) concentration (average = 75 µg l^–1) than thesouth test cells receiving a lower TP concentration (average= 23 µg l^–1). Limerock (LR) berms were installedin two of these test cells to allow an evaluation of the efficiencyof this physical barrier to enhance wetland performance. Important findings: North test cells displayed high TP removal of 60% while theremoval efficiency of the south test cells was only 20%. Solublereactive phosphorus concentrations in both north and south testcells were sequestered down to near-detection limit. High removalefficiencies for particulate phosphorus were also observed inthe north test cells. The LR berms at the two test cells werefound to be associated with decreases of an average TP removalof 2 µg l^–1. Outflow TP concentration did not increasewith inflow TP concentration, but increased with nominal hydraulicloading rates. Findings from this study demonstrated high Premoval from inflow water containing high TP concentration bythe SAV wetland and the importance of hydraulic regime to wetlandperformance.     

Burial disturbance leads to facilitation among coastal dune plants

There is growing evidence that interactions among plants can be facilitative as well as competitive, but knowledge of how disturbances influence these interactions and how they vary with species diversity is lacking. We manipulated plant density, species diversity (richness), and a burial disturbance in a controlled, complete factorial experiment to test theories about the relationships among species interactions, disturbance, and richness. The hypotheses tested were 1) burial disturbance reduces plant performance at all levels of density and richness, 2) burial disturbance can cause net plant interactions to become more facilitative, and 3) facilitation increases with species richness. Burial decreased plant survival by 60% and biomass by 50%, supporting the hypothesis that burial reduces plant performance. In the control (unburied) treatment, there was no difference in proportion survival or per plant biomass between low and high density plots, meaning that neither competition nor facilitation was detected. In the buried treatment, however, high density plots had significantly greater survival and greater per plant biomass than the low density plots, indicating net facilitative interactions. Thus facilitation occurred in the buried treatment and not in the unburied control plots, supporting the hypothesis that facilitation increases with increasing disturbance severity. The hypothesis that facilitation increases with increasing species richness was not supported. Richness did not affect survival or biomass, and there was no richness by burial treatment interaction, indicating that richness did not influence the response of the community to burial. The influence of the disturbance on plant interactions was thus consistent across levels of richness, increasing the generality of the relationship between disturbance and facilitation.     

Sensitivity of US Gulf of Mexico coastal marsh vegetation to crude oil: Comparison of greenhouse and field responses

Greenhouse and field studies were conducted to evaluate the effect of crude oil on selected US Gulf of Mexico coastal marsh species. Species showed different levels of sensitivity to oiling between greenhouse and field conditions. In greenhouse studies, two crude oils were used: South Louisiana crude oil (SLC) and Arabian Medium crude oil (AMC). The majority of Spartina patens plants died within one month following oiling with little or no recovery after three months. Panicum hemitomon and Spartina alterniflora were also adversely affected by oiling under greenhouse conditions but to a lesser extent than S. patens. The SLC or AMC oiling led to biomass reductions in S. alterniflora and S. patens. The dry biomass was not affected by oiling in P. hemitomon, Sagittaria lancifolia, Typha latifolia, and Scirpus olneyi. Results showed that S. patens plants were more sensitive to SLC as compared to AMC oil. Gross CO₂-C fixation data collected in the greenhouse indicated no differences in recovery among species across oiling treatments for S. lancifolia, S. olneyi, and T. latifolia. Field studies with S. alterniflora, S. patens and S. lancifolia demonstrated initial sensitivity of these species to oiling, and recovery following oiling with SLC. Our data also showed that caution must be employed whenever results from greenhouse studies are extrapolated to predict oil impact on vegetation under field conditions. Development of any sensitivity index of plant responses to oiling should not be based on greenhouse experiments only. Field evaluations should be included which best depict plant responses to oiling. Thus, restoration measures of US Gulf of Mexico coastal marshes following oiling should rely primarily on field studies. The field research suggests that the US Gulf of Mexico coastal marsh vegetation are likely to recover from oil spills naturally without the need for remediation procedures.