Dietary-morphological relationships of fishes in Liangzi Lake, China

Species in Liangzi Lake were clustered into four trophic groups: Hemiramphus kurumeus and Hemiculter bleekeri bleekeri fed predominantly on terrestrial insects; Carassius auratus auratus and Abbottina rivularis on non-animal food; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonis on cladocerans or copepods; Culterichthys erythropterus on decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. glurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over-dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary-morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non-animal feud, with an increase in gut length associated with an increase in non-animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary-morphological relationships supported the eco-morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co-existing fish species. (C) 2001 The Fisheries Society of the British Isles.

Surface sediment diatoms from the western Pacific marginal seas and their correlation to environmental variables

Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed. The results of canonical correspondence analysis show that summer sea-surface salinity (SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature (SST) with winter SST. The correlations between SSSs and SSTs are less positively correlated, which may be due to interactions of regional current pattern and monsoon climate. The correlations between diatom species, sample sites and environmental variables concur with known diatom ecology and regional oceanographic characters. The results of forward selection of the environmental variables and associated Monte Carlo permutation tests of the statistical significance of each variable suggest that summer SSS and winter SST are the main environmental factors affecting the diatom distribution in the area and therefore preserved diatom data from down core could be used for reconstructions of summer SSS and winter SST in the region.

The environment effect on fish assemblage structure in waters adjacent to the Changjiang (Yangtze) River estuary (1998-2001)

We collected fish abundance data in the Changjiang (Yangtze River) estuary and adjacent waters in November 1998, May 1999, November 2000, and May 2001. Using the data, we evaluated the characteristics of the fish assemblages at each site and investigated the effect of several environmental factors. We used a multivariate analysis, including community ordination methods such as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA), and two-way indicator species analysis (TWINSPAN). We analyzed the biological community structure and environmental factors to determine their spatial distributions, temporal dynamics, and seasonal variations. Among the fish species, five exceeded 5% of the total abundance: Harpodon nehereus (42.82%), Benthosema pterotum (13.85%), Setipinna taty (11.64%), Thryssa kammalensis (9.17%) and Apogonichthys lineatus (6.49%). These were separated into four ecological assemblages: hypsithermal-saline, hypsithermal-brackish, hypothermal-brackish, and hypothermal-saline. We evaluated the degree of influence of environmental factors on the fish community. Our analyses suggested that environmental factors including water depth, salinity, turbidity, transparency, nutrient, and suspended matter formed a synthetic spatial gradient between the coastal and pelagic areas. Ecological and environmental factors changed temporally from 1998 to 2001, and drove the fish community succession. The environmental factors driving the fish community structure included bottom temperature, water depth, bottom and surface pH, surface total phosphorous, and bottom dissolved oxygen. This investigation was completed before completion of the Three Gorges Dam; therefore the results of this study provide an important foundation for evaluating the influence of the human activities.

Mire ontogeny, environmental and climate change inferred from fossil beetle successions from Hatfield Moors, eastern England

Results of a fossil Coleoptera (beetle) fauna from a fen edge sequence from Hatfield Moors, Humberhead Levels, are presented. Mire ontogeny inferred from this location and others are discussed, particularly in the light of previous palynological and plant macrofossil investigations. Peat initiation across most of the site centres around 3000 cal BC, characterised by a Calluna-Eriophorum heath with areas of Pinus-Betula woodland. The onset of peat accumulation on the southern margins of the site was delayed until 1520-1390 cal BC and appears to overlap closely with a recurrence surface at a pollen site (HAT 2) studied by Brian Smith (1985, 2002) dated to 1610-1440 cal BC, suggesting that increased surface wetness may have caused mire expansion at this time. The faunas illustrate the transition from eutrophic and mesotrophic fen to ombrotrophic raised mire, although the significance of both Pinus- and Calluna-indicating species through the sequence suggests that heath habitats may have continued to be important. Elsewhere, this earlier phase of rich fen is lacking and mesotrophic mire developed immediately above nutrient poor sands, with ombrotrophic conditions indicated soon after. Correspondence analysis of the faunas provides valuable insights into the importance of sandy heath habitats on Hatfield Moors. The continuing influence of the underlying coversands suggests these may have been instrumental in mire ontogeny. The research highlights the usefulness of using Coleoptera to assess mire ontogeny, fluctuations in site hydrology and vegetation cover, particularly when used in conjunction with other peatland proxies. The significance of a suite of extinct beetle species is discussed with reference to forest history and climate change.

Controls on the contemporary distribution of lake thecamoebians (testate amoebae) in the Greater Toronto Area and their potential as water quality indicators.

Thecamoebians were examined from 71 surface sediment samples collected from 21 lakes and ponds in the Greater Toronto Area to (1) elucidate the controls on faunal distribution in modern lake environments; and (2) to consider the utility of thecamoebians in quantitative studies of water quality change. This area was chosen because it includes a high density of kettle and other lakes which are threatened by urban development and where water quality has deteriorated locally as a result of contaminant inputs, particularly nutrients. Fifty-eight samples yielded statistically significant thecamoebian populations. The most diverse faunas (highest Shannon Diversity Index values) were recorded in lakes beyond the limits of urban development, although the faunas of all lakes showed signs of sub-optimal conditions. The assemblages were divided into five clusters using Q-mode cluster analysis, supported by Detrended Correspondence Analysis. Canonical Correspondence Analysis (CCA) was used to examine species-environment relationships and to explain the observed clusterings. Twenty-four measured environmental variables were considered, including water property attributes (e.g., pH, conductivity, dissolved oxygen), substrate characteristics, sediment-based phosphorus (Olsen P) and 11 environmentally available metals. The thecamoebian assemblages showed a strong association with phosphorus, reflecting the eutrophic status of many of the lakes, and locally to elevated conductivity measurements, which appear to reflect road salt inputs associated with winter de-icing operations. Substrate characteristics, total organic carbon and metal contaminants (particularly Cu and Mg) also influenced the faunas of some samples. A series of partial CCAs show that of the measured variables, sedimentary phosphorus has the largest influence on assemblage distribution, explaining 6.98% (P < 0.002) of the total variance. A transfer function was developed for sedimentary phosphorus (Olsen P) using 58 samples from 15 of the studied lakes. The best performing model was based on weighted averaging with inverse deshrinking (WA Inv, r jack 2= 0.33, RMSEP = 102.65 ppm). This model was applied to a small modern thecamoebian dataset from a eutrophic lake in northern Ontario to predict phosphorus and performed satisfactorily. This preliminary study confirms that thecamoebians have considerable potential as quantitative water quality indicators in urbanising regions, particularly in areas influenced by nutrient inputs and road salts.

Peat multi-proxy data from Mannikjarve bog as indicators of late Holocene climate changes in Estonia

As part of a wider project on European climate change over the past 4500 years, a 4.5-m peat core was taken from a lawn microform on Mannikjarve bog, Estonia. Several methods were used to yield proxy-climate data: (i) a quadrat and leaf-count method for plant macrofossil data, (ii) testate amoebae analysis, and (iii) colorimetric determination of peat humification. These data are provided with an exceptionally high resolution and precise chronology. Changes in bog surface wetness were inferred using Detrended Correspondence Analysis (DCA) and zonation of macrofossil data, particularly concerning the occurrence of Sphagnum balticum, and a transfer function for water-table depth for testate amoebae data. Based on the results, periods of high bog surface wetness appear to have occurred at c. 3100, 3010-2990, 2300, 1750-1610, 1510, 14 10, 1110, 540 and 3 10 cal. yr BP, during four longer periods between c. 3170 and 2850 cal. yr BP, 2450 and 2000 cal. yr BP, 1770 and 1530 cal. yr BP and in the period from 880 cal. yr BP until the present. In the period between 1770 and 1530 cal. yr BP. the extension or initiation of a hollow microtope occurred, which corresponds with other research results from Mannikjarve bog. This and other changes towards increasing bog surface wetness may be the responses to colder temperatures and the predominance of a more continental climate in the region, which favoured the development of bog microdepressions and a complex bog microtopography. Located in the border zone of oceanic and continental climatic sectors, in an area almost without land uplift, this study site may provide valuable information about changes in palaeohydrological and palaeoclimatological conditions in the northern parts of the eastern Baltic Sea region.

Dinoflagellate cyst-based reconstructions of mid to late Holocene winter sea-surface temperature and productivity from an anoxic fjord in the NE Pacific Ocean

Published contemporary dinoflagellate distributional data from the NE Pacific margin and estuarine environments (n = 136) were re-analyzed using Canonical Correspondence Analysis (CCA) and partial Canonical Correspondence Analysis (pCCA). These analyses illustrated the dominant controls of winter temperature and productivity on the distribution of dinoflagellate cysts in this region. Dinoflagellate cyst-based predictive models for winter temperature and productivity were developed from the contemporary distributional data using the modern analogue technique and applied to subfossil data from two mid to late Holocene (~5500 calendar years before present–present) cores; TUL99B03 and TUL99B11, collected from Effingham Inlet, a 15 km long anoxic fjord located on the southwest coast of Vancouver Island that directly opens to the Pacific Ocean through Barkley Sound. Sedimentation within these basins largely comprises annually deposited laminated couplets, each made up of a winter deposited terrigenous layer and spring to fall deposited diatomaceous layer. The Effingham Inlet dinoflagellate cyst record provides evidence of a mid-Holocene gradual decline in winter SST, ending with the initiation of neoglacial advances in the region by ~3500 cal BP. A reconstructed Late Holocene increase in winter SST was initiated by a weakening of the California Current, which would have resulted in a warmer central gyre and more El Niño-like conditions.

Testate amoebae as indicators of hydroseral change: an 8,500 year record from Mer Bleue Bog, eastern Ontario, Canada.

Testate amoebae have been used widely as a proxy of hydrological change in ombrotrophic peatlands, although their response to abiotic controls in other types of mire and fenland palaeo-environments is less well understood. This paper examines the response of testate amoebae to hydroseral and other environmental changes at Mer Bleue Bog, Ontario, Canada, a large ombrotrophic peatland, which evolved from a brackish-water embayment in the early Holocene. Sediments, plant macrofossils and diatoms examined from a 5.99 m core collected from the dome of the bog record six stages of development: i) a quiet, brackish-water riverine phase (prior to ca. 8500 cal BP); ii) a shallow lake (ca. 8500–8200 cal BP); iii) fen (8200–7600 cal BP); iv) transitional mire (7600–6900 cal BP); v) pioneer raised mire (6900–4450 cal BP); and vi) ombrotrophic bog (4450 cal BP-present).

Testate amoebae, notably small (<25 µm diameter) specimens of Centropyxis aculeata type, first appear in low abundances in sediments ascribed to the lacustrine phase. Diatoms from the same horizons record a shallowing in water depth, a decline in salinity and the development of emergent macrophytic vegetation, which may have provided favourable conditions for testate amoeba colonization. The testate amoeba communities of the inferred fen phase are more diverse and include centropyxids, cyclopyxids, Arcellidae and Hyalospheniidae, although the assemblages show some differences to those recently reported in modern European fen environments. The Fen–Bog Transition (FBT) is also dominated by C. aculeata type. The change in testate amoeba communities around this key transition is apparent in the results of Detrended Correspondence Analysis (DCA), and appears to reflect a latent nutrient gradient and a secondary moisture gradient. DCA analyses of plant macrofossil remains around the FBT show a similar trend, although the sensitivity of the two proxies to the inferred environmental changes differs. Comparisons with other regional mid-Holocene peatland records confirm the important influence of reduced effective precipitation on the testate amoeba communities during the initiation and development of Sphagnum-dominated, raised bog communities.

Testate amoebae (thecamoebians) as water quality indicators in lakes: development of a modern distributional dataset from the Greater Toronto Area

Thecamoebians were examined from 123 surface sediment samples collected from 45 lakes in the Greater Toronto Area (GTA) and the surrounding region to i) elucidate the controls on faunal distribution in modern lake environments; and ii) to consider the utility of thecamoebians in quantitative studies of water quality change. This area was chosen because it includes a high density of lakes that are threatened by urban development and where water quality has deteriorated locally as a result of contaminant inputs, particularly nutrients. Canonical Correspondence analysis (CCA) and a series of partial CCAs were used to examine species-environment relationships. Twenty-four environmental variables were considered, including water properties (e.g. pH, DO, conductivity), substrate characteristics, nutrient loading, and environmentally available metals. The thecamoebian assemblages showed a strong association with Olsen's Phosphorus, reflecting the eutrophic status of many of the lakes, and locally to elevated conductivity measurements, which appear to reflect road salt inputs associated with winter de-icing operations. A transfer function was developed for Olsen P using this training set based on weighted averaging with inverse deshrinking (WA Inv). The model was applied to infer past changes in Phosphorus enrichment in core samples from several lakes, including eutrophic Haynes Lake within the GTA. Thecamoebian-inferred changes in sedimentary Phosphorus from a 210Pb dated core from Haynes Lake are related to i) widespread introduction of chemical fertilizers to agricultural land in the post WWII era; ii) a steep decline in Phosphorous with a change in agricultural practices in the late 1970s; and iii) the construction of a golf course in close proximity to the lake in the early 1990s. This preliminary study confirms that thecamoebians have considerable potential as indicators of eutrophication in lakes and can provide an estimate of baseline conditions.

Temporal variation in the water chemistry of northern Victoria Land lakes (Antarctica)

Concentrations of major ions, silicate and nutrients (total N and P) were measured in samples of surface water from 28 lakes in ice-free areas of northern Victoria Land (East Antarctica). Sixteen lakes were sampled during austral summers 2001/02, 2003/04, 2004/05 and 2005/06 to assess temporal variation in water chemistry. Although samples showed a wide range in ion concentrations, their composition mainly reflected that of seawater. In general, as the distance from the sea increased, the input of elements from the marine environment (through aerosols and seabirds) decreased and there was an increase in nitrate and sulfate concentrations. Antarctic lakes lack outflows and during the austral summer the melting and/or ablation of ice cover, water evaporation and leaching processes in dry soils determine a progressive increase in water ion concentrations. During the five-year monitoring survey, no statistically significant variation in the water chemistry were detected, except for a slight (hardly significant) increase in TN concentrations. However, Canonical Correspondence Analysis (CCA) indicated that other factors besides distance from the sea, the presence of nesting seabirds, the sampling time and percentage of ice cover affect the composition of water in Antarctic cold desert environments.

Taxonomic and functional diversity of farmland bird communities across Europe:Effects of biogeography and agricultural intensification

In eight European study sites (in Spain, Ireland, Netherlands, Germany, Poland, Estonia and Sweden), abundance of breeding farmland bird territories was obtained from 500 × 500 m survey plots (30 per area, N = 240) using the mapping method. Two analyses were performed: (I) a Canonical Correspondence Analysis of species abundance in relation to geographical location and variables measuring agricultural intensification at field and farm level to identify significant intensification variables and to estimate the fractions of total variance in bird abundance explained by geography and agricultural intensification; (II) several taxonomic and functional community indices were built and analysed using GLM in relation to the intensification variables found significant in the CCA. The geographical location of study sites alone explains nearly one fifth (19. 5%) of total variation in species abundance. The fraction of variance explained by agricultural intensification alone is much smaller (4. 3%), although significant. The intersection explains nearly two fifths (37. 8%) of variance in species abundance. Community indices are negatively affected by correlates of intensification like farm size and yield, whereas correlates of habitat availability and quality have positive effects on taxonomic and functional diversity of assemblages. Most of the purely geographical variation in farmland bird assemblage composition is associated to Mediterranean steppe species, reflecting the bio-geographical singularity of that assemblage and reinforcing the need to preserve this community. Taxonomic and functional diversity of farmland bird communities are negatively affected by agricultural intensification and positively affected by increasing farmland habitat availability and quality. © 2011 Springer Science+Business Media B.V.

Arcellacea (Testate Amoebae) as Bio-indicators of Road Salt Contamination in Lakes

Winter deicing operations occur extensively in mid- to high-latitude metropolitan regions around the world and result in a significant reduction in road accidents. Deicing salts can, however, pose a major threat to water quality and aquatic organisms. In this paper we examine the utility of Arcellacea (testate amoebae) for monitoring lakes that have become contaminated by winter deicing salts, particularly sodium chloride. We analysed 50 sediment samples and salt-related water-property variables (chloride concentrations; conductivity) from 15 lakes in the Greater Toronto Area and adjacent areas of southern Ontario, Canada. The sampled lakes included lakes in proximity to major highways and suburban roads, and control lakes in forested settings away from road influences. Samples from the most contaminated lakes, with chloride concentrations in excess of 400 mg/l and conductivities of >800 μS/cm, were dominated by species typically found in brackish and/or inhospitable lake environments and by lower faunal diversities (lowest Shannon Diversity Index values) than samples with lower readings. Q-R-mode cluster analysis and Detrended Correspondence Analysis (DCA) resulted in the recognition of four assemblage groupings. These reflect varying levels of salt contamination in the study lakes, along with other local influences, including nutrient loading. The response to nutrients can, however, be isolated if the planktic eutrophic indicator species Cucurbitella tricuspis is removed from the counts. The findings show that the group have considerable potential for biomonitoring in salt-contaminated lakes, and through application to lake sediment cores, may provide significant insights into long-term benthic community health, which is integral for remedial efforts.

Ecology of testate amoebae in an Amazonian peatland and development of a transfer function for palaeohydrological reconstruction

Tropical peatlands represent globally important carbon sinks with a unique biodiversity and are currently threatened by climate change and human activities. It is now imperative that proxy methods are developed to understand the ecohydrological dynamics of these systems and for testing peatland development models. Testate amoebae have been used as environmental indicators in ecological and palaeoecological studies of peatlands, primarily in ombrotrophic Sphagnum-dominated peatlands in the mid- and high-latitudes. We present the first ecological analysis of testate amoebae in a tropical peatland, a nutrient-poor domed bog in western (Peruvian) Amazonia. Litter samples were collected from different hydrological microforms (hummock to pool) along a transect from the edge to the interior of the peatland. We recorded 47 taxa from 21 genera. The most common taxa are Cryptodifflugia oviformis, Euglypha rotunda type, Phryganella acropodia, Pseudodifflugia fulva type and Trinema lineare. One species found only in the southern hemisphere, Argynnia spicata, is present. Arcella spp., Centropyxis aculeata and Lesqueresia spiralis are indicators of pools containing standing water. Canonical correspondence analysis and non-metric multidimensional scaling illustrate that water table depth is a significant control on the distribution of testate amoebae, similar to the results from mid- and high-latitude peatlands. A transfer function model for water table based on weighted averaging partial least-squares (WAPLS) regression is presented and performs well under cross-validation (r 2apparent=0.76,RMSE=4.29;r2jack=0.68,RMSEP=5.18. The transfer function was applied to a 1-m peat core, and sample-specific reconstruction errors were generated using bootstrapping. The reconstruction generally suggests near-surface water tables over the last 3,000 years, with a shift to drier conditions at c. cal. 1218-1273 AD

Spatio-temporal feeding selection of red deer in a mountainous landscape

Understanding the dietary consumption and selection of wild populations of generalist herbivores is hampered by the complex array of factors. Here, we determine the influence of habitat, season, and animal density, sex, and age on the diet consumption and selection of 426 red deer (Cervus elaphus scoticus) culled in Fiordland National Park, New Zealand. Our site differs from studies elsewhere both in habitat (evergreen angiosperm-dominated forests) and the intensity of hunting pressures. We predicted that deer would not consume forage in proportion to its relative availability, and that dietary consumption would change among and within years in response to hunting pressures that would also limit opportunities for age and sex segregation. Using canonical correspondence analysis, we evaluated the relative importance of different drivers of variation in diet consumption assessed from gut content and related these to available forage in the environment. We found that altitude explained the largest proportion of variation in diet consumption, reflecting the ability of deer to alter their consumption and selection in relation to their foraging grounds. Grasses formed a high proportion of the diet consumption, even for deer culled several kilometres from the alpine grasslands. In the winter months, when the alpine grasslands were largely inaccessible, less grass was eaten and deer resorted to woody plants that were avoided in the summer months. Surprisingly, there were no significant dietary differences between adults and juveniles and only subtle differences between the sexes. Sex-based differences in diet consumption are commonly observed in ungulate species and we suggest that they may have been reduced in our study area owing to decreased heterogeneity in available forage as the diversity of palatable species decreased under high deer browsing pressures, or by intense hunting pressure. © 2009 The Authors. Journal compilation © 2009 Ecological Society of Australia.

Changes in epilithic biomasses and invertebrate community structure over a deposit metal concentration gradient in upland headwater streams

Stream bed metal deposits affect the taxon richness, density and taxonomic diversity of primary and secondary producers by a variety of direct or indirect abiotic and biotic processes but little is known about the relative importance of these processes over a deposit metal concentration gradient. Inorganic matter (IM), algal and non-photosynthetic detrital (NPD) dry biomasses were estimated for 10 monthly samples, between 2007 and 2008, from eight sites differing in deposit density. Invertebrate abundance, taxon richness and composition were also determined. Relations between these variables were investigated by canonical correspondence analysis (CCA), generalized estimating equation models and path analysis. The first CCA axis correlates with deposit density and invertebrate abundance, with lumbriculids and chironomids increasing in abundance with deposit density and all other taxa declining. Community structure changes significantly above a deposit density of approximately 8 mg cm, when algal biomass, invertebrate richness and diversity decline. Invertebrate richness and diversity were determined by direct effects of NPD biomass and indirect effects of IM. Algal biomass only had an effect on invertebrate abundance. Possible pH, oxygen, food and ecotoxicological effects of NPD biomass on the biota are discussed.