Benthic faunas of streams of low pH but contrasting water chemistry in New Zealand

Water chemistry and benthic invertebrate communities were investigated at 37 sites on acid streams originating on the Stockton-Denniston Plateau, North Westland, New Zealand. The region is characterised by high rainfall and runoff, highly acidic soils and the presence of extensive coal measures that have been mined for over 120 years. Four groups of streams were identified: naturally acid plateau streams with clear water and very low conductivity; brown water (humic) streams with pH<4 and low conductivity; coastal plains streams with higher pH and conductivity; and streams contaminated by acid mine drainage. TWINSPAN and cluster analysis also grouped streams into four groups based on presence-absence of invertebrate taxa, the groups being similar to, but not identical to those based on physico-chemical factors. Diptera (mainly Chironomidae) were represented by most species in all site groups followed by Plecoptera in plateau streams, and Trichoptera on the coastal plain and where mine drainage occurred. Species of Orthocladiinae (Chironomidae), Plecoptera and Trichoptera were found at the most contaminated sites (pH <3, conductivity >900 µS cm^–1, total reactive aluminium >25 mg 1^–1). The leptophlebiid mayfly Deleatidium was found at 32 of the 37 sites, and some species of Plecoptera, Trichoptera and Chironomidae were also widely distributed. Our findings indicate that species tolerant of low pH (i.e., <4.5) are not confined to humic waters as has been postulated, but also occur in soft, non-humic waters where concentrations of labile, non-organically bound aluminium may be elevated.     

Impact of acidification and eutrophication on the distribution of fish species in shallow and lentic soft waters of The Netherlands: an historical perspective

The species richness and composition of fish assemblages were examined in lentic soft waters in The Netherlands. The selected bodies of water reflected a large variation in geomorphological and limnological factors. In total, 24 fish species were encountered in Dutch soft waters. During 1983–1984 Esox lucius, Perca fluviatilis, Rutilus rutilus, Scardinius erythrophthalmus, Tinca tinca and Umbra pygmaea were quite common. In slightly acid and alkaline waters (pH≥5) Rutilus rutilus, Scardinius erythrophthalmus, Perca fluviatilis, Ictalurus nebulosus and Cyprinus carpio accounted for about 90% of the total number of specimens in the catches. Strongly acid waters (pH < 5) generally were fishless. If fish were present in these waters, however, the catches mainly consisted of Umbra pygmaea. Only in a few strongly acid systems were other species collected. The lowest pH at which certain fish species occurred varied from 3.1 to 7.0. In particular, Umbra pygmaea was extremely acid-tolerant. The percentage of waters which harboured fish as well as the average number offish species per water decreased steeply between pH 6 and 4. The sampled waters showed remarkable differences in their fish assemblages. With hierarchical classification, six groups of waters could be distinquished with respect to their fish fauna. The site groups are defined and characterized physico-chemically and their fish assemblages described. Multivariate analysis showed that the structure of fish communities is strongly related to the pH, the alkalinity, trophic level and the ionic composition of the water. Comparison of historical and recent data on the occurrence of fish strongly indicated that in many sampling sites fish species or even entire fish assemblages had disappeared. Ordination of available data also illustrated recent changes in community structure. At least 67% of the nowadays extremely acid waters formerly harboured fish populations. The impoverishment of fish communities or the total loss of fish were primarily caused by cultural acidification. Limited nutrient enrichment of soft waters only resulted in minor alterations of fish assemblages.     

Contrasting altitudinal variation of alpine plant communities along the Swedish mountains

Changes in abiotic factors along altitudinal and latitudinal gradients cause powerful environmental gradients. The topography of alpine areas generates environmental gradients over short distances, and alpine areas are expected to experience greater temperature increase compared to the global average. In this study, we investigate alpha, beta, and gamma diversity, as well as community structure, of vascular plant communities along altitudinal gradients at three latitudes in the Swedish mountains. Species richness and evenness decreased with altitude, but the patterns within the altitudinal gradient varied between sites, including a sudden decrease at high altitude, a monotonic decrease, and a unimodal pattern. However, we did not observe a decline in beta diversity with altitude at all sites, and plant communities at all sites were spatially nested according to some other factors than altitude, such as the availability of water or microtopographic position. Moreover, the observed diversity patterns did not follow the latitudinal gradient. We observed a spatial modularity according to altitude, which was consistent across sites. Our results suggest strong influences of site‐specific factors on plant community composition and that such factors partly may override effects from altitudinal and latitudinal environmental variation. Spatial variation of the observed vascular plant communities appears to have been caused by a combination of processes at multiple spatial scales.     

Tracking environmental stress gradients using three biotic integrity indices: Advantages of a locally-developed traits-based approach

Estuarine and coastal ecosystems are productive and functionally diverse areas that provide a wide range of societal benefits. Along with human exploitative uses comes an array of anthropogenic disturbances that can affect ecological integrity, including changes to the composition and resilience of benthic macroinvertebrate communities. To understand the responses of ecological communities to anthropogenic disturbance and to manage and mitigate effects, indices for assessing the ecological integrity of estuarine and coastal waters have proliferated worldwide. Using data from 84 intertidal sites in Auckland, New Zealand, we evaluated the suitability of two widely used measures of ecological integrity that were developed in USA and Europe, respectively: the Benthic Index of Biotic Integrity (B-IBI) and the AZTI's Marine Biotic Index (AMBI). We then developed a local index based on macrofaunal traits and verified its utility using independent data from >100 additional sites. The local traits based index (TBI), constructed from the richness of macrofaunal taxa in seven functional groups, responded to changes in sediment mud percentage and heavy metal contaminant concentration gradients below international guidelines. The TBI performed better than the indices developed overseas, probably because they were designed to track organic enrichment and hypoxia, which are not the predominant stressors in New Zealand at present. The TBI successfully tracked the stressors that were the most relevant locally and indicated the relative levels of within-group taxonomic richness at various sites. As within-group richness is a component of functional redundancy and ecological resilience, the TBI offers a trifecta of simplicity, robustness and meaningfulness that will facilitate management.     

Role of altitude and water temperature as regulating factors for the geographical distribution of Tetracapsuloides bryosalmonae infected fishes in Switzerland

The role of water temperature and altitude of the river sites on distribution, prevalence and infection intensity of Tetracapsuloides bryosalmonae infected salmonids was investigated. The study is based on a 6 year survey of salmonids, mainly brown trout, Salmo trutta from 2000 to 2006 at 287 sampling sites across Switzerland. Almost 7000 fishes were tested for the presence of T. bryosalmonae by histological and immunohistochemical techniques. A good correlation between altitude and water temperature in Swiss rivers could be demonstrated. Therefore, the relation between altitude and sites tested for T. bryosalmonae infected fishes was investigated since water temperature values from these sites were not available. Percentage of sites with positive (infected) fishes was identical for altitudes between 200 and 800 m above sea level (m a.s.l.), while above 800 m a.s.l. only three sites with infected fishes were recorded. Site‐specific prevalence values ranging from 0 to 100% and infection intensities from 0 to 6 were found over the whole altitude range from 200 to 800 m a.s.l., and no correlation with altitude was found. Conditions at altitudes >800 m may not be favourable for the establishment of the infection in fishes. With rising temperatures due to climatic changes, however, the prevalence of T. bryosalmonae infected fishes in altitudes >800 m a.s.l. could increase.     

黄土高原丘陵沟壑区柠条与沙棘冠层的持水能力

2011年5-10月, 以黄土高原人工造林主要灌木树种柠条(Caragana korshinskii)和沙棘(Hippophae rhamnoides)为研究对象, 通过测定冠层截留数据与冠层各组分持水能力, 采用Pereira回归分析法和直接测量法, 对柠条与沙棘的冠层持水能力进行了研究。结果表明: 受不同因素的影响, 两种方法测定的冠层持水能力有一定差异。回归分析法主要受植株叶面积指数(LAI)季节性变化与穿透雨观测方法的影响, 得到的柠条与沙棘冠层最大持水能力分别为0.68 mm和0.72 mm; 而直接测量法主要受冠层结构特征影响, 得到的柠条与沙棘冠层最大持水能力分别为0.73 mm和0.76 mm。直接测量法得到的柠条各组分最大持水量依次为枝(0.31 mm) >叶(0.27 mm) >树干(0.15 mm), 沙棘为树干(0.33 mm) >枝(0.29 mm) >叶(0.14 mm)。     

Macroinvertebrates of inlets and outlets of the Tatra Mountain lakes (Slovakia)

The composition of invertebrates of inlets and outlets of selected West Tatra and High Tatra lakes (Slovakia, 49°10′ N, 20°00′ E) was analyzed. Twenty-seven sampling sites representing 11 inlets and 16 outlets of 19 mountain lakes were investigated. In total, 10,692 aquatic invertebrates from 27 samples were sorted, 7,314 from inlets and 3,378 from outlets. Altogether, 110 zoobenthic taxa (81 in inlets and 85 in outlets) belonging to 12 higher taxonomic groups were identified. The most constant benthic groups found both in lets and outlets, at more than half of all sites, were Oligochaeta (93% of all sites), Chironomidae (78%), Trichoptera (63%), Plecoptera (59%) and Turbellaria (56%). The most abundant groups were Chironomidae (4,697 ind.), Oligochaeta (2,473 ind.) and Turbellaria (2,236 ind.). No statistically significant differences were found between the benthic communities of inlets and outlets. On the contrary, significant differences (P < 0.05) were found in some parameters of benthic communities of inlets situated in different altitudes (< 1800 m a.s.l., 1800–2000 m a.s.l., > 2000 m a.s.l), outlets of different altitudes, and finally, outlets of lakes with different areas (< 5 ha and ≥ 5 ha). Cluster analysis relatively clearly separated outlets of subalpine lakes from the alpine lakes. Also, outlets of lakes with the lowest pH were separated from the other sites. In the case of inlets, West Tatra sites were separated from the High Tatra sites.     

Impacts of forestry planting on primary production in upland lakes from north‐west Ireland

Planted forests are increasing in many upland regions worldwide, but knowledge about their potential effects on algal communities of catchment lakes is relatively unknown. Here, the effects of afforestation were investigated using palaeolimnology at six upland lake sites in the north‐west of Ireland subject to different extents of forest plantation cover (4–64% of catchment area). ²¹⁰Pb‐dated sediment cores were analysed for carotenoid pigments from algae, stable isotopes of bulk carbon (δ¹³C) and nitrogen (δ¹⁵N), and C/N ratios. In lakes with >50% of their catchment area covered by plantations, there were two‐ to sixfold increases in pigments from cryptophytes (alloxanthin) and significant but lower increases (39–116%) in those from colonial cyanobacteria (canthaxanthin), but no response from biomarkers of total algal abundance (β‐carotene). In contrast, lakes in catchments with <20% afforestation exhibited no consistent response to forestry practices, although all lakes exhibited fluctuations in pigments and geochemical variables due to peat cutting and upland grazing prior to forest plantation. Taken together, patterns suggest that increases in cyanobacteria and cryptophyte abundance reflect a combination of mineral and nutrient enrichment associated with forest fertilization and organic matter influx which may have facilitated growth of mixotrophic taxa. This study demonstrates that planted forests can alter the abundance and community structure of algae in upland humic lakes of Ireland and Northern Ireland, despite long histories of prior catchment disturbance.     

Macroinvertebrate communities in streams in the Himalaya, Nepal

• 1 Macroinvertebrates were sampled in the riffles of fifty-eight streams from three regions of the Himalaya (Anapurna, Langtang and Everest) in Nepal. A semi-quantitative method with identification to family level was used to describe communities on-site.
• 2 Stream physicochemistry was assessed and the community structure of macroinvertebrates was related to chemistry, physiography (substratum composition, altitude and size), geographical location and the dominant land use in each catchment (terraced agriculture, forest or scrub). Community data were analysed by ordination (DECORANA) and classification (TWINSPAN).
• 3 The concentration of cations in stream water decreased significantly with altitude. Chemistry also differed between regions; sites from Anapurna had a higher pH and conductivity than those in the other two areas.
• 4 Communities were dominated by aquatic insect larvae, with Ephemeroptera, in particular the Baetidae, most numerous across sites.
• 5 There were, nevertheless, differences in community structure between sites, which were related closely to stream physicochemistry. Ordination scores were strongly correlated with altitude, magnesium concentration and substratum composition. Classification was also linked to altitude and chemistry, differentiating high-altitude sites with low silica concentrations from others. Sites from the Anapurna and Everest regions, with their contrasting chemistry, were also separated.
• 6 Community structure was also related to land use: streams draining catchments dominated by terraced agriculture had different communities from those in scrub or forest. This result was confounded, however, by the strong relationship between land use, altitude and chemistry; sites in terracing were at lower altitude, had higher concentrations of silica and a higher proportion of fine sediments than those in the other land-use types.
• 7 Overall, our data indicate that natural features of the relief and geology in the Himalaya create strong gradients in their invertebrate faunas, but that activities of man may have an effect on stream structure and ecology through catchment management.

     

The impact of conifer plantation forestry on the Chydoridae (Cladocera) communities of peatland lakes

Conifer plantation forestry is recognised as a potential source of diffuse pollution to surface waters and represents a risk to their ecological status. In this study, the water chemistry and Chydoridae (Cladocera) communities of 26 small blanket bog lakes were investigated to assess the impact of plantation forestry. The study was conducted over a 12-month period in 2009?C2010 by comparing lakes with three distinct catchment land uses: (i) unplanted blanket bog only present in the catchment, (ii) mature conifer plantation forests only present in the catchment and (iii) catchments containing mature conifer plantation forests with recently clearfelled areas. All three catchment land uses were replicated across two geologies: sandstone and granite. Lakes with afforested catchments had very high concentrations of plant nutrients (P and N), total dissolved organic carbon (TDOC) and heavy metals (Al and Fe), the highest concentrations being recorded from the clearfelled lakes. Similarly, the chydorid communities differed between lakes of contrasting catchment land use. The dominance of Alonopsis elongata in the unplanted blanket bog lakes shifted to dominance by the smaller bodied Chydorus sphaericus, along with Alonella nana, Alonella excisa and Alonella exigua, in the plantation forestry-effected lakes, consistent with a shift in lake trophy. Our findings have shown that plantation forestry can have a profound impact on the water quality of small peatland lakes, especially at the clearfell stage. The response of the chydorid communities is consistent with plantation forestry exerting a trophic, rather than an acidic or toxic, effect on lake ecosystems.     

Distribution of greenhouse gases in hyper-arid and arid areas of northern Chile and the contribution of the high altitude wetland microbiome (Salar de Huasco,Chile)

Northern Chile harbors different bioclimatic zones including hyper-arid and arid ecosystems and hotspots of microbial life, such as high altitude wetlands, which may contribute differentially to greenhouse gases (GHG) such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). In this study, we explored ground level GHG distribution and the potential role of a wetland situated at 3800 m.a.s.l, and characterized by high solar radiation <?1600 W m^?2, extreme temperature ranges (?12 to 24 °C) and wind stress (<?17 m s^?1). The water source of the wetland is mainly groundwater springs, which generates streams and ponds surrounded by peatlands. These sites support a rich microbial aquatic life including diverse bacteria and archaea communities, which transiently form more complex structures, such as microbial mats. In this study, GHG were measured in the water and above ground level air at the wetland site and along an elevation gradient in different bioclimatic areas from arid to hyper-arid zones. The microbiome from the water and sediments was described by high-throughput sequencing 16S rRNA and rDNA genes. The results indicate that GHG at ground level were variable along the elevation gradient potentially associated with different bioclimatic zones, reaching high values at the high Andean steppe and variable but lower values in the Atacama Desert and at the wetland. The water areas of the wetland presented high concentrations of CH₄ and CO₂, particularly at the spring areas and in air bubbles below microbial mats. The microbial community was rich (>?40 phyla), including archaea and bacteria potentially active in the different matrices studied (water, sediments and mats). Functional microbial groups associated with GHG recycling were detected at low frequency, i.e., <?2.5% of total sequences. Our results indicate that hyper-arid and arid areas of northern Chile are sites of GHG exchange associated with various bioclimatic zones and particularly in aquatic areas of the wetland where this ecosystem could represent a net sink of N₂O and a source for CH₄ and CO₂.     

Development of a Fish Based Lake Typology for Natural Austrian Lakes >50 ha Based on the Reconstructed Historical Fish Communities

Based on the reconstructed native fish communities all natural Austrian lakes >50 ha (n = 43) were classified into four groups using cluster analysis methods. Sentinel species (i.e. species with highest discriminating value for lake types and characteristic for a specific lake group) and type specific fish species (accompanying species with additional value for characterising lake groups) were defined by a newly developed index and by similarity analysis. The first group included 16 lakes of high altitude, small surface area and low fish species number with arctic char as a sentinel species. The second group (n = 10) was characterized by intermediate altitude, large surface area and high maximum water depth with the minnow as sentinel species. The third group contained 14 lakes with low maximum water depths and a long retention time. For this group the bleak was found as a sentinel species. The lakes of the eastern part of Austria represented the last group (n = 3) and were characterized by low altitude and very shallow water depth with pike‐perch as a sentinel species. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

蒋家沟流域不同海拔灌草层群落特征与土壤关系的研究

为了解干热河谷区不同海拔梯度植物群落灌草层物种多样性与土壤养分、水分之间的关系,该文选择干热河谷典型流域——蒋家沟流域作为研究区域,在流域内海拔1 400～3 000 m范围设置样带,对样带内8个海拔梯度的植物群落进行样方调查,统计不同海拔梯度灌草层的物种组成,测定土壤养分、土壤含水量和持水量,并将土壤指标与植被多样性指数进行主成分分析和皮尔逊相关性分析。结果表明:流域内样地共发现灌草层植物32科77属80种,且灌草层植物群落组成、土壤有机碳(SOC)含量、全磷(TP)含量、土壤含水量和持水量均受海拔梯度的影响显著(P<0.05)。其中,土壤含水量、持水量、植物群落的丰富度指数和多样性指数均随着海拔升高不断增加,且高海拔区域SOC含量显著高于中低海拔区域(P<0.05)。土壤TP含量与Pielou指数、土壤含水量与Margalef指数、Shannon-Wiener指数和物种数均呈显著正相关(P<0.05),说明除海拔梯度外,土壤养分、水分含量是影响植物群落灌草层组成和多样性的关键因子。     

Persistent surface water acidification in an organic soil-dominated upland region subject to high atmospheric deposition: The North York Moors,UK

The North York Moors National Park, in Northeast England, is one of the few upland areas of the United Kingdom located immediately downwind of major sulphur and nitrogen emission sources. Despite this, few studies of air pollution impacts have been undertaken, and there is no formal long-term upland water quality monitoring site. We examined the condition of surface waters in the National Park based on (1) a unique 20 year stream pH record from three locations; and (2) a snapshot survey of 51 surface waters draining moorland and conifer plantations. Interpretation was supported by sulphur isotope analysis of a subset of water samples, and a diatom survey of one of the monitoring streams. Long-term pH data for a stream draining the peat plateau demonstrate extreme, year-round acidification, with recovery only evident in the last few years. Lower-elevation sites are less acidic, but show similar temporal trends, and are characterised by frequent and severe acid episodes. The snapshot survey confirmed that acidification of the moorland area is widespread, to a degree observed in few other areas globally; out of 37 moorland streams sampled, 32 had an acid neutralising capacity (ANC) below −50 μequiv. l⁻¹. Sulphate was found to be (by far) the dominant cause of acidification, and sulphur isotope analysis confirmed that this derives primarily from atmospheric deposition. Nitrate concentrations remain low, indicating that the organic moorland soils continue to retain most incoming nitrogen. It appears that conifer planting has exacerbated acidification, leading to fivefold higher nitrate and threefold higher aluminium concentrations compared to the moorland sites. Available biological data suggest that waters in the region have been impoverished by acidification. We speculate that the slow recovery of surface waters in the North York Moors is due to the release of a legacy of stored sulphur from the peats, released during droughts. We conclude that: (1) acidification is far from being a solved problem in this sensitive near-source upland region, despite reductions in sulphur deposition; (2) plantation forestry has exacerbated the effects of atmospheric pollution, and triggered nitrogen saturation; (3) the lack of any formal long-term monitoring in the North York Moors represents a major gap in the current evidence base for the effects of long-range air pollutants on UK upland ecosystems.     

A numerical analysis of Tasmanian higher plant endemism

KIRKPATRICK, J. B. & BROWN, M. J., 1984. A numerical analysis of Tasmanian higher plant endemism. Tasmanian endemic plant taxa at the species level or below were placed in geographic elements according to the distribution of their genera. These elements are associated with different environments, the endemic and Antarctic elements being most prominent in rainforest and alpine communities; the cosmopolitan element in alpine communities, and the Australian element in the fire-prone lowland communities. A monothetic divisive classification and minimum spanning tree analysis of a matrix of the occurrence of 242 Tasmanian endemic species from 366 areas resulted in groups of species and lists whose distributions were closely related to precipitation, altitude and vegetation type. The proportions of endemic species in local Tasmanian floras were almost totally explained by altitude and precipitation in a stepwise multiple regression analysis. However, it is possible that many of the endemic species have not been able to occupy their potential range in Tasmania as a result of insufficient time having elapsed for them to fully expand from Glacial refugia.     

Variations in Soil Microbial Communities and Residues Along an Altitude Gradient on the Northern Slope of Changbai Mountain,China

Altitudinally-defined climate conditions provide specific vegetation types and soil environments that could influence soil microbial communities, which in turn may affect microbial residues. However, the knowledge is limited in terms of the degree to which microbial communities and residues present and differ along altitude. In this study, we examined the soil microbial communities and residues along the northern slope of Changbai Mountain, China using phospholipid fatty acid (PLFA) and amino sugar analysis, respectively. Soil samples were taken from five different vegetation belts defined by climates. Principal component analysis (PCA) revealed substantial differences in soil microbial community composition among study sites, appeared to be driven primarily by soil pH and C/N ratio on the first principal component (PC1) which accounted for 50.7% of the total sample variance. The alpine tundra was separated from forest sites on the second principal component (PC2) by a signifiscantly higher amount of fungal PLFA (18:2ω6,9). Soil pH and C/N ratio were also correlated with the ratios of Gram-positive to Gram-negative bacteria (Gm⁺/Gm⁻), glucosamine to galactosamine (GluN/GalN), and glucosamine to muramic acid (GluN/MurA). Both total PLFAs and amino sugars were positively correlated with soil organic carbon, inorganic nitrogen, available phosphorus and potassium. We concluded that soil pH and C/N ratio were the most important drivers for microbial community structure and amino sugar pattern, while substrate availability was of great importance in determining the concentrations of microbial communities and residues. These findings could be used to facilitate interpretation of soil microbial community and amino sugar data derived from measurements in latitude or managed forests.     

Implications of afforestation for bird communities: the importance of preceding land-use type

Afforestation of open habitats is one of the principal land-use changes underway in Europe and elsewhere in the world at present, and it can have a considerable impact on local biodiversity. The sustainable expansion of global forest plantations requires an understanding of the factors that determine the ecological impacts of afforestation. This study set out to determine the importance of preceding land-use type in determining the outcomes of afforestation for bird communities. Paired comparisons of 5-year-old exotic conifer plantations and matching non-forested sites were studied in areas of low (peatland), intermediate (wet grassland) and high (improved grassland) management intensity. Afforestation resulted in an overall increase in total bird density in all three habitat types. The effects of forest planting on bird conservation were found to be positively related to prior management intensity at the site. The density of bird species of conservation concern increased in response to the planting of intensively managed grassland sites, but decreased in response to afforestation of peatlands and of grasslands under intermediate management intensity. This study shows that plantation forests can, in some contexts, offer opportunities for bird conservation, and the findings highlight the trade-offs that are an integral part of land-use change. Therefore, where afforestation planning includes consideration of its impact on bird communities, planting should take place predominantly on sites of low biodiversity value, such as agriculturally improved grasslands. Furthermore, the preservation of sites of high conservation value within areas of afforestation would confer advantages on bird communities.     

Links between Geographic Location, Environmental Factors, and Microbial Community Composition in Sediments of the Eastern Mediterranean Sea

The bacterial community composition of marine surface sediments originating from various regions of the Eastern Mediterranean Sea (12 sampling sites) was compared by parallel use of three fingerprinting methods: analysis of 16S rRNA gene fragment heterogeneity by denaturing gradient electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP), and analysis of phospholipid-linked fatty acid composition (PLFA). Sampling sites were located at variable depths (30–2860 m; water column depth above the sediments) and the sediments differed greatly also in their degree of petroleum contamination (0.4–18 μg g⁻¹), organic carbon (0.38–1.5%), and chlorophyll a content (0.01–7.7 μg g⁻¹). Despite a high degree of correlation between the three different community fingerprint methods, some major differences were observed. DGGE banding patterns showed a significant separation of sediment communities from the northern, more productive waters of the Thermaikos Gulf and the oligotrophic waters of the Cretan, S. Ionian, and Levantine Sea. T-RFLP analysis clearly separated the communities of deep sediments (>1494 m depth) from their shallow (<617 m) counterparts. PLFA analysis grouped a shallow station from the productive waters of the north with the deep oligotrophic sediments from the Ionian and Levantine Sea, with low concentrations of PLFAs, and hence low microbial biomass, as the common denominator. The degree of petroleum contamination was not significantly correlated to the apparent composition of the microbial communities for any of the three methods, whereas organic carbon content and sediment chlorophyll a were important in this regard.     

Temporary forest pools: can we see the water for the trees?

Temporary waters, in general, are fascinating habitats in which to study the properties of species adapted to living in highly variable environments. Species display a remarkable array of strategies for dealing with the periodic loss of their primary medium that sets them apart from the inhabitants of permanent water bodies. Survival of individuals typically depends on exceptional physiological tolerance or effective migrational abilities, and communities have their own, distinctive hallmarks. This paper will broadly overview the biology of temporary ponds, but will emphasize those in temperate forests. In particular, links will be sought between aquatic community properties, the nature of the riparian vegetation, and forestry practices. Quite apart from their inherent biological interest, temporary waters are now in the limelight both from a conservation perspective, as these habitats come more into conflict with human activities, and a health-control perspective, as breeding habitats for vectors of arboviruses. Traditionally, many temporary waters, be they pools, streams or wetlands, have been considered to be ȁ8wastedȁ9 areas of land, potentially convertible to agriculture/silviculture once drained. In reality, they are natural features of the global landscape representing distinct and unique habitats for many species – some that are found nowhere else, others that reach their maximum abundance there. To be effective, conservation measures must preserve the full, hydroseral range of wetland types.