bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deep‐water aquatic plant communities in an oligotrophic lake: physiological responses to variable light
Authors: HOWARD‐WILLIAMS CLIVE , SCHWARZ ANNE‐MAREE , VINCENT WARWICK F. 
Published: May 2006

SUMMARY1. Oligotrophic Lake Waikaremoana, New Zealand, is used for hydroelectric power generation and the lake levels are manipulated within an operating range of 3 m. There was concern that rapidly changing water levels adversely affected the littoral zone by decreasing light availability in two ways: local turbidity caused by shoreline erosion at low water levels; and decreased light penetration to the deep littoral zone caused by high water levels in summer.2. The littoral zone was dominated by native aquatic plants with vascular species to 6 m and a characean meadow below this to 16 m. The biomass and heights of the communities in the depth zone 0–6 m were reduced at a site exposed to wave action relative to those at a sheltered site. However, the community structure below 6 m was similar at exposed and sheltered sites. The lower boundary of the littoral zone was sharply delimited at 16 m and this bottom boundary remained constant throughout the year despite large seasonal changes in solar radiation and the 3 m variation in lake level.3. There was evidence that the deep‐water community consisting of Chara corallina had adapted physiologically to low‐light conditions. Net light saturated photosynthesis (CO2 exchange) per unit chlorophyll a (Chl a) was reduced to 1.7 μg C (μg Chl a)−1 h−1 at the lower boundary, half of that recorded at 5 m. The concentration of Chi a per gram of biomass (dry weight), was considerably greater at the lower boundary than higher in the profile [c. 7 mg Chl a (g dry wt)−1 at 16 m vs. 4 mg Chl a (g dry wt)−1 at 5 m]. Chl b also increased with depth and there was no change in the ratio of Chl a and Chl b with increasing depth. The saturation light intensity (Ik) of the community at the lower boundary was only 78 μmol photons m−2 s−1. Photosynthetic parameters (Ik and α) as well as the Chl a content remained relatively constant throughout the seasonal and short‐term changes in radiation.4. The photosynthetic characteristics of the littoral community were therefore not greatly affected by the lake level change caused by the present hydroelectric operations. However, the sharpness of the lower boundary and its extreme shade characteristics imply that the deep‐water community would be sensitive to any further changes in underwater light availability.
Nutrient enrichment effects on biofilm metabolism in a Mediterranean stream
Authors: GUASCH HELENA , MARTÍ EUGÈNIA , SABATER SERGI 
Published: May 2006

SUMMARY1. Biofilm biomass and metabolism were analysed in La Solana, a calcareous, undisturbed second‐order stream. Measurements were carried out in two Mediterranean climatic extremes, summer and winter. Two on‐site experimental channels were used to study changes following nutrient addition to one of them.2. Algal biomass (chlorophyll a), NDPP (net daily primary production), GDPP (gross daily primary production) and R (respiration) increased in the enriched channel, and these increases were greater in summer.3. Photosynthetic capacity (Pmaxchl) decreased during summer, possibly due to enhanced self‐shading accompanying the increase in biomass.4. In winter, Pmaxchl increased and reached values similar to those in the summer control channel. Because grazing was low, the higher values of Pmaxchl were attributed to partial substitution of the cyanobacterial assemblage by a green‐algae dominated assemblage with higher photosynthetic capacity as well as the low increase in biomass preventing any significant self‐shading.
The impact of pH on interactions among phytoplankton algae, zooplankton and perch (Perca fluviatilis) in a shallow, fertile lake
Authors: BEKLIOGLU MERYEM , MOSS BRIAN 
Published: May 2006

SUMMARY1. The combined effects of increasing pH (< 9–11) and increasing densities of perch (0, two, four per enclosure) have been investigated in polyethylene enclosures of volume about 1100 1 in a shallow, fertile lake in Cheshire.2. Increasing pH decreased carbon dioxide concentrations, chlorophyll a concentrations and diatom biomass. It led to increases in the proportions of Cryptophyta (to pH 10) and Chlorophyta (to pH 11). Although ample inocula were present, significant growths of cyanophytes were not recorded, contrary to expectation.3. Increasing pH led to increases in numbers of Daphnia hyalina particularly at pH 10 but collapse at pH 11. This persistence at pH 10, independent of perch number, is attributed to reduced feeding of the fish, which survived at this pH. Other zooplankters (Ceriodaphnia spp., Bosmina longirostris, Polyphemus pediculus, Cyclops spp.) all declined with increasing pH.4. Increasing fish density resulted in an increase in chlorophyll a concentration and in the biomass of Chlorophyta but had no effect on cyanophyte or cryptophyte biomass.5. Increasing fish density led to declines in Daphnia in the untreated lake‐water controls (pH < 9) and at pH 9, but had no effect at pH 10 where Daphnia hyalina was very abundant. Numbers of Ceriodaphnia spp. and Bosmina longirostris increased with increasing fish density, whilst numbers of Polyphemus pediculus and Cyclops spp. were independent of it.6. The results are discussed in the light of contemporary knowledge of the factors resulting in large cyanophyte growths and of the factors controlling the stability of macrophyte‐dominated and phytoplankton‐dominated states in shallow lakes. The interaction between pH and fish density and consequent non‐linear response of Daphnia hyalina is particularly notable because of the significance of zooplankton grazing in shallow lakes.
The application of habitat templets and traits to hyphomycete fungi in a mid‐European river system
Authors: PATTEE E. , CHERGUI H. 
Published: May 2006

SUMMARY1. The general knowledge about hyphomycetes is summarized and traits of some of these organisms in the Rhône floodplain are described to assess compliance with the river habitat templet (RHT) and patch dynamics concept (PDC) hypotheses. This investigation corresponds with those for other taxonomic groups reported in a recent Freshwater Biology Special Issue on the Ecology of the Upper Rhône River (Statzner, Resh & Dolédec, 1994).2. Three groups of fungi were considered: aquatic, terrestrial, and aero‐aquatic hyphomycetes.3. The main factors controlling distribution of these micro‐organisms are food (mostly organic matter), dissolved oxygen and biotic interactions.4. With contrasting strategies, hyphomycetes exploit both fallen leaves, a discrete ephemeral resource, and wood fragments, which are more durable.5. Fungal propagules (spores, hyphae) are distributed in the water, and even the air, largely throughout the year. This explains the resilience of these organisms to disturbance.6. A major problem is the spatial (boundary layer, dead zones) and temporal (leaf input) scale at which these micro‐organisms live and their interactions at the scale adopted for the other organisms referred to in the Special Issue on the Ecology of the Upper Rhône.7. Our scant knowledge of the microbial ecology in the Rhône floodplain, together with the scale problem and high microbial resilience to environmental stress, render the RHT and PDC hypotheses difficult to test. Only three traits could be tested on hyphomycetes, but all three confirmed the RHT hypotheses.8. Hyphomycete communities appear to be biologically controlled in more favourable and temporally stable environments, and physico‐chemically controlled in harsher and more perturbed environments.
Microfaunal response to fertilization of an arctic tundra stream
Authors: RUBLEE P. A. , PARTUSCH‐TALLEY A. 
Published: May 2006

SUMMARY1. As part of a whole‐system study, the response of the heterotrophic microfaunal community colonizing artificial substrata (polyfoam units) to fertilization of an arctic tundra stream was followed for 6 weeks during the summer.2. Dominant heterotrophic microfauna observed included amoebae (approximately 40% of colonizing biomass), rotifers (36% of biomass) and ciliates (25% of biomass).3. Biomass of heterotrophic microfauna on artificial substrata was not significantly different in a control reach and an experimental reach fertilized with phosphorus (loading rate ten times ambient), but in a reach fertilized with both phosphorus and nitrogen (loading rates ten times ambient) biomass was double that of the control and phosphorus‐fertilized reaches. The lack of response in the phosphorus reach was probably due to greater insect grazing as a result of previous phosphorus fertilization of this reach.4. Abundance of microfauna on epilithic surfaces in the river was higher on rocks from pools than on rocks from riffle areas, but abundance on the artificial substrata was higher than on the natural rocks.5. The results suggest that microfauna of arctic tundra streams are regulated by grazers and that their importance in transfers among trophic levels is greater in pools than in riffles.
Fossil record of cladoceran and algal responses to fishery management practices
Authors: MISKIMMIN BRENDA M. , LEAVITT PETER R. , SCHINDLER DAVID W. 
Published: May 2006

SUMMARY1. We hypothesized that the fishery management practices of toxaphene application and trout stocking would affect non‐target organisms in lakes. Because these practices were rarely monitored in the past, cladoceran and algal assemblages were quantified in sediment cores from two lakes treated 30+ years ago to determine the long‐term response of organisms near the base of the food chain.2. Chydorids were remarkably resistant over the short term (a few years) in both the oligotrophic and eutrophic lakes despite toxaphene treatments that extirpated native fish and other invertebrates. In the oligotrophic lake (Annette Lake), six chydorid taxa were less abundant in the years following treatment, although no loss of species richness was detected. In the eutrophic lake (Chatwin Lake), the dominant Chydorus cf. sphaericus declined coincident with toxaphene treatment, but longer‐term declines of all taxa were probably related to food web or other changes rather than to toxaphene toxicity. Cause and effect coupling was complicated by the fact that many chydorids were present at low concentrations in some pretreatment samples.3. The algal communities (as fossil pigments) responded to treatment differently in the two lakes. In the oligotrophic lake, planktonic diatoms, dinoflagellates and chlorophytes were replaced as dominants by deep‐water or benthic blooming cryptophytes, chrysophytes and cyanobacteria. This shift occurred along with increases in large daphnids and the ‘grazing indicator’, pheophorbide a. While both lakes appear to have had enhanced pigment preservation following treatment, the eutrophic lake encountered few long‐term changes in its fossil pigment assemblage. Redundancy analysis estimated that the presence or absence of stocked trout explained much of the variation in the algal assemblages, particularly in the oligotrophic lake.4. Toxaphene remained elevated in profundal sediments from these lakes 30 and 35 years after treatment.
The effects of iron and manganese on diatom colonization in a Vermont stream
Authors: WELLNITZ T.A. , SHELDON S.P. 
Published: May 2006

SUMMARY1. Neutral streams with elevated concentrations of iron and manganese can develop blooms of ferromanganese‐depositing bacteria within oxide deposition zones. Algal abundance declines within these blooms. An in situ experiment was conducted in a Vermont stream to assess the importance of increased concentrations of iron and manganese, without the confounding effects of ferromanganese‐depositing bacteria, on limiting diatom colonization.2. Diatom abundance in treatments receiving iron increased over time, but densities were lower by a factor of ten or more compared with either control or manganese treatments. These results indicate that the presence of ferromanganese‐depositing bacteria is not necessary for lowering algal abundance.3. We speculate that ferromanganese‐depositing bacteria may thrive in iron oxide deposition zones, in part because iron oxides help displace periphytic algae which may be superior competitors for space and/or limiting nutrients.
The horizontal distribution of plankton in a deep, oligotrophic lake—Loch Ness, Scotland
Authors: JONES R.I. , FULCHER A.S. , JAYAKODY J.K.U. , LAYBOURN‐PARRY J. , SHINE A.J. , WALTON M.C. , YOUNG J.M. 
Published: May 2006

SUMMARY1. The horizontal distribution of plankton in Loch Ness, a deep, oligotrophic lake with a simple trench morphometry, was studied on three occasions in 1993. Samples were collected from ten stations spaced along the length of the loch and the abundance of algae, bacteria, protozoa, rotifers and crustacean zooplankton was determined.2. Horizontal variability was found to be greatest for the metazoan zooplankton and for the algae, especially two cryptomonad flagellates. Bacteria and heterotrophic protozoa showed relatively little horizontal variability. The degree of horizontal variability was not sufficient seriously to affect studies of the seasonality of plankton abundance conducted from a single sampling station.3. Gradients of plankton distribution along the length of the loch were dependent on the recent wind history. The direction of the gradient could readily reverse with a shift in wind direction. These results indicate that the horizontal distribution of plankton in Loch Ness is more dependent on wind‐induced water circulation patterns than on differential growth of plankton in water masses of differing chemistry.
Use of an encounter model to predict size‐selective predation by a stream‐dwelling cyprinid
Authors: RINCÓN PEDRO A. , LOBÓN‐CERVIÁ JAVIER 
Published: May 2006

SUMMARY1. The increased probability of detection of larger prey in the drift appeared to be the major determinant of prey consumption by red roach (Rutilus arcasi) in an Iberian stream. We developed a model of prey encounter incorporating this factor that explained 68% of the overall variation in the consumption of prey of different size. When the same model was applied to benthic size distributions the variance explained was 16%.2. Gape‐limited ingestion also was a significant factor influencing prey consumption and, when added to the model, the variance explained increased to 85% (32% for the benthos), but its importance was strongly dependent on both: (i) the maximum prey size available and (ii) fish size.3. The exact shape of red roach reactive fields and, as a consequence, their degree of size‐selectivity appeared to vary seasonally and ontogenetically. In summer, younger fish exhibited apparently reduced reactive fields. We hypothesize that this can be the result of factors such as microhabitat shifts or a reduced range of prey sizes.
Estimating morphologically determined connectance and structure for food webs of freshwater invertebrates
Authors: WARREN PHILIP H. 
Published: May 2006

SUMMARY1. Connectance is a parameter of central importance in determining food‐web structure, but the processes determining its value remain unclear. In evaluating possible explanations it is useful to know what patterns, and values, of connectance occur in food webs assembled at random from a set of species in a regional species pool; i.e. where the number of links is determined by the morphological features of the species present, not by the immediate effects of energetics or stability on the particular web.2. This study examines, by means of laboratory experiments, the occurrence of potential feeding interactions among a set of freshwater invertebrate species randomly selected from different freshwater sites in a geographical region. The results from pairwise feeding trials are used to construct two ‘theoretical’ food webs, in which the patterns and values of connectance are examined.3. Analyses of these webs indicate that their structure is consistent with the observed values in previously documented ‘real’ webs. Directed connectance values of 0.12–0.16 (or less) suggest that the assembled webs are no more connected than many freshwater webs from natural systems. The number of links per species increases curvilinearly with the number of species, during web assembly, consistent with recent hypotheses.4. These results also indicate that quantifying, and understanding the determinants of, trophic generalism or specialism does have implications for understanding how connectance is constrained in real webs. Freshwater invertebrates seem to be relatively generalist, and freshwater food webs perhaps correspondingly highly connected. Such arguments have implications for interpreting other aspects of food‐web structure in these systems, and for parameterizing models that are based on connectance.
APPLIED ISSUES The effect of ammonium nitrate on the feeding and development of larvae of the smooth newt, Triturus vulgaris (L.), and on the behaviour of its food source, Daphnia
Authors: WATT PENELOPE J. , OLDHAM ROBERT S. 
Published: May 2006

SUMMARY1. Larvae of the smooth newt, Triturus vulgaris, were exposed to four concentrations of ammonium nitrate in artificial pond water (50, 100, 200 and 500 mg 1‐−1) under controlled laboratory conditions.2. Larvae exposed to a 50 mg 1‐−1 solution of ammonium nitrate showed no significant difference to control larvae in feeding rate, mass at metamorphosis or time to metamorphosis. However, larvae exposed to 200 or 500 mg 1‐−1 ammonium nitrate, for a single period of 24, 48 or 72 h, were significantly smaller than controls at metamorphosis. Larvae exposed to 100 mg 1‐−1 had a significantly higher feeding rate than those reared under control conditions or those exposed to 200 or 500 mg 1‐−1 ammonium nitrate, but this was not reflected in their size at metamorphosis, which was not significantly different from the controls. Larval survival remained high in all trials.3. In separate trials, Daphnia, used as a food source for the newt larvae, were exposed to the same series of ammonium nitrate concentrations. Daphnia behaviour was affected by exposure to 200 and 500 mg 1‐−1 ammonium nitrate, and in both cases animals were significantly more likely to be found at the top of the water column than those exposed to 50 or 100 mg 1‐−1 ammonium nitrate or the control medium.
Simultaneous immunohistochemical expression of HBME‐1 and galectin‐3 differentiates papillary carcinomas from hyperfunctioning lesions of the thyroid
Authors: Rossi E D , Raffaelli M , Mule' A , Miraglia A , Lombardi C P , Vecchio F M , Fadda G 
Published: May 2006

Aims : The histological diagnosis is critical for the postsurgical management and follow‐up of thyroid malignancies. The differential diagnosis between papillary carcinoma and hyperfunctioning lesions, either with papillary hyperplasia or with a follicular architecture, can create real diagnostic difficulty. The aim of this study was to evaluate the expression of several antibodies considered to be markers of malignancy in malignant and hyperfunctioning thyroid neoplasms and to include the most effective of them in a diagnostic panel.Methods and results : One hundred resected thyroid nodules—58 hyperfunctioning benign lesions and 42 papillary carcinomas (14 follicular variant, 14 macrofollicular variant and 14 classic type)—were immunohistochemically studied for HBME‐1, galectin‐3, cytokeratin (CK) 19 and RET‐proto‐oncogene. HBME‐1 and galectin‐3 showed 92.8% and 89% sensitivity, respectively, and their coexpression was present in 36 out of 42 papillary carcinomas (85.7%) and absent in non‐malignant lesions. Their association increased sensitivity to 94.7% and the diagnostic accuracy to 97.9% and involved the highest number of cases (95%) in comparison with two other panels including, respectively, three (HBME‐1, galectin‐3, CK19) and all four antibodies.Conclusion : An immunohistochemical panel consisting of HBME‐1 and galectin‐3 can make a correct distinction between malignant and hyperfunctioning thyroid neoplasms with high diagnostic accuracy.
Immunohistochemical detection of ubiquitin‐positive intracytoplasmic eosinophilic inclusion bodies in diffuse alveolar damage
Authors: Yamada T , Uehara K , Kawanishi R , Mizutani T , Sunagawa K , Araya J , Kawabata Y 
Published: May 2006

Aims : To clarify the relationship between ubiquitin‐positive pneumocytes and intracytoplasmic eosinophilic inclusion bodies (IB) in patients who died of diffuse alveolar damage (DAD).Methods and results : Eighteen patients with DAD were studied, in whom hyaline membranes were present in one or more out of five sections from each lobe of the lungs and 15 patients with no DAD. Light microscopy revealed hyaline membrane in over 25% of lobes from 18 patients with DAD. The cytoplasm of pneumocytes from six of 18 cases of DAD contained IB. Immunohistochemically, all IBs were characteristically positive for both ubiquitin (Ub) and cytokeratin KL‐1. Cytoplasmic granules were also Ub+ in four cases of DAD without IB. IB+ or Ub+ pneumocytes were undetectable in non‐DAD patients. We evaluated DAD severity based on hyaline membrane formation; the mean score in DAD with IB (3.60; n = 6) was significantly higher than that in Ub– (2.92; n = 8). Ub+ pneumocytes were found with or without IB among those cases with high DAD scores.Conclusions : These findings suggest that disordered proteolysis in the Ub‐mediated proteasome system leads to the accumulation of abnormal ubiquitinated protein, which includes cytokeratin, in pneumocytes. This is the first report to suggest that Ub+ pneumocytes are associated with disease severity in patients with DAD.