bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pattern, process and prediction in aquatic ecology. A limnological view of some general ecological problems
Authors: HARRIS GRAHAM P. 
Published: May 2006

SUMMARY1. New scientific concepts such as models of chaos, complex dynamics and non‐linear interactions have the potential to contribute to an improved understanding of ecological patterns and processes. This paper discusses some of the known dynamics of phytoplankton, pelagic food chains and nutrient cycles in the light of some of these new concepts. The paper brings these new conceptual models together with data from a wide range of sources in an attempt to produce a synthesis of system behaviour which allows us to understand why some things are inherently more predictable than others. In particular it looks at the limnological management tools of empirical biomass models and biomanipulation and at the need for prediction of species composition.2. The structures observed in ecosystems (nutrient pools, sizes, species, temporal/spatial patterns) show properties at a spectrum of scales, as do the processes (fluxes, grazing, competition). Both respond to a spectrum of external perturbations that may be climatologically or anthropogenically induced. Empirical biomass models work because of the annual averaging of pattern and process and because of some inherent properties of the functioning of pelagic ecosystems. Many aspects of ecosystem pattern and process vary in a regular way with trophic state. Examination of empirical data sets can lead to an improved understanding of system behaviour if questions are asked about why things happen the way they do.3. Feedbacks between pattern, process and periodicity are seen to be an inherent property of the system. Understanding the fundamental dynamics of non‐linear interactions in ecosystems may make it possible to exploit the external spectrum of environmental perturbations and to control system function. For example, by imposing external physical perturbations on pelagic systems it may be possible to manipulate the species composition of the phytoplankton community. Because of the complexity of possible interactions both ‘horizontally’ between species and ‘vertically’ within the food chain, any prediction of species composition will necessarily be probabilistic.
Stress responses and metal exchange kinetics following transplant of the aquatic moss Fontinalis antipyretica
Authors: LOPEZ JESUS , VAZQUEZ M. DOLORES , CARBALLEIRA ALEJO 
Published: May 2006

SUMMARY1. We studied stress responses and metal exchange (uptake and loss) kinetics in the aquatic moss Fontinalis antipyretica Hedw. following transplant (in plastic mesh bags) to clean and metal‐contaminated river sites and under laboratory conditions.2. The stress response (estimated on the basis of chlorophyll:phaeophytin ratio) was more pronounced, and the moss took longer to recover, following transplant to heavily contaminated sites.3. Metal uptake over the 28 day exposure period was predicted well by a two‐compartment kinetic model: uptake velocity was initially high and gradually declined, with metal concentration in the moss showing a tendency to reach an equilibrium with metal concentration in the water. Mean uptake rate, time to reach equilibrium and metal concentration in moss at equilibrium all increased with increasing metal concentration in the water.4. Bioconcentration constants calculated on the basis of our data rank the metals studied in the order Zn < Ni < Co < Cu < Pb < Cd.5. Following retransplant of mosses to a clean site, metal loss was not predicted well by a passive exchange mode of the above type; instead, two phases (rapid and slow) were apparent. Loss rates during both phases, and proportion of metal load lost during the rapid phase, were proportional to the concentration of metal in the moss at the start of the recuperation trial.6. We present nomograms to allow estimation of severity of contamination on the basis of metal concentration in moss and duration of transplant.
Latitudinal patterns in leaf litter breakdown: is temperature really important?
Authors: IRONS JOHN G. , OSWOOD MARK W. , STOUT R. JEAN , PRINGLE CATHY M. 
Published: May 2006

SUMMARY1. Forest stream food webs depend largely on input of dead riparian zone leaves for their energy, which is converted into living biomass by microbes, macroinvertebrates and fish.2. Temperature has been invoked as important in controlling breakdown rates, and aquatic biologists have suggested that by normalizing processing rates to degree days rather than days, one can ‘factor out’ the effect of temperature and compare processing rates in streams with different thermal regimes (e.g. different seasons or study sites in different biomes).3. We examined processing rates (k) along a latitudinal (i.e. thermal) gradient by using reciprocal transplants of leafpacks. We placed leafpacks of ten tree species (representing a large range of leaf litter quality) in streams in Costa Rica, Michigan and Alaska using coarse‐mesh (20mm) litter bags. We then examined both the ‘per day’(kday) and ‘per degree day’ (kdegree day) models of leaf litter processing. While processing rates (per day) were fastest at the Costa Rica site (as expected), rates at the Alaska and Michigan sites were similar to each other, which we would not predict if temperature were the principal factor controlling breakdown rate. If using degree days eliminates any effect of differing thermal regimes, rates should be similar across latitudes; however, rates at the Alaska site were much faster (per degree day) than rates at the sites in Costa Rica and Michigan.4. We compared our data with studies in the North American literature. Regression analysis of kday and kdegree day against latitude of the study site revealed that processing rates (kday) of leaves (from a wide range of tree species in a wide range of stream types) showed no significant change with increasing latitude. However, when normalized for temperature (kDegree day), a positive correlation was found between processing rates and latitude, causing us to reject the hypothesis that normalizing processing rates to cumulative degree days removes the effect of temperature.5. We suggest three hypotheses: (i) shredding insect populations have adapted to the local thermal regime, and invertebrate‐mediated processing rates are either similar between regions (showing no latitudinal pattern), or increase with latitude; (ii) microbial populations are less active at colder temperatures, and the rate of microbially mediated processing of leaf litter will show a decrease with latitude, and consequently (iii) the relative importance of invertebrate v microbial processing changes on a latitudinal gradient, with invertebrates being more important at high latitudes.
Behavioural and genetic differences in populations of Daphnia subjected to different levels of predation
Authors: YOUNG STEPHEN , WATT PENELOPE J. 
Published: May 2006

SUMMARY1. Predictions based on a genetic control mechanism for vertical migration were tested by monitoring the vertical migration behaviour of electro‐phoretically distinct clones of Daphnia longispina and Daphnia magna collected from ponds with different levels of predation.2. The number of predator species in a pond (a measure of predation) had a significant effect on the vertical migration behaviour of the clones found within that pond, and a phenogram constructed on the basis of the percentage dissimilarity between the genotypes of the clones indicated that clones from the same site were more closely related genetically than clones from different sites.3. There were significantly different vertical migration behaviour patterns between clones from different sites and between‐site variation in behaviour was significantly greater than that found within a site.4. Clones differed in the average depth they maintained in the waterbody regardless of the pond from which they were collected, but clones from the same site did have similar behavioural profiles suggesting a tendency to show the same behavioural patterns.5. These findings, which support predictions based on a genetic control mechanism, are discussed in relation to phenotypically plastic mechanisms of vertical migration control widely reported in the literature.
The critical thermal limits for the stone loach, Noemacheilus barbatulus, from three populations in north‐west England
Authors: ELLIOTT J.M. , ELLIOTT J.A. , ALLONBY J.D. 
Published: May 2006

SUMMARY1. The chief objective was to determine the upper and lower thermal limits for feeding and survival in the stone loach, Noemacheilus barbatulus, using juveniles (total length 30–45 mm, live weight 0.25–0.80 g) from one population and adults (total length 77–100 mm, live weight 3.6–7.9 g) from three populations.2. Fish were acclimatized to constant temperatures of 3, 7, 10, 15, 20, 25 and 27°C; then the temperature was changed at a rate of 1°C/30min to determine the critical limits for feeding, survival over 7 days (incipient lethal temperature), or survival for 10 min or less (ultimate lethal temperature). The rate of 1°C/30min was the optimum value from preliminary experiments, using nine rates from 0.5°C/48h to 18°Ch−1. As values for adults were not significantly different between populations, they were pooled to provide arithmetic means (with 95% CL) for the thermal limits at each acclimation temperature.3. Feeding limits increased with acclimation temperature to upper and lower mean values of 28.0 ± 0.15°C and 5.1 ± 0.55°C for adults, 25.0 ± 0.54°C and 6.1 ± 0.92°C for juveniles. Incipient lethal levels defined a tolerance zone within which stone loach survive for a considerable time; upper limits increased with acclimation temperature to reach a maximum plateau of 29.1 ± 0.18°C for adults and 29.0 ± 0.40°C for juveniles; lower limits also increased from near 0°C to 3.0 ± 0.40°C for adults and juveniles. Upper limits for the ultimate lethal level increased with acclimation temperature to a maximum plateau of 33.5°C for adults (95% CL ± 0.19) and juveniles (95% CL ± 0.40), whilst the lower limits increased from near 0°C to 2.5 ± 0.30°C. At acclimation temperatures below 20°C, upper incipient and ultimate lethal values were significantly lower for juveniles than those for adults.4. The thermal tolerance of stone loach was higher than that of juvenile Atlantic salmon or brown trout, one or both of these species often being dominant in streams with stone loach.
Species traits in relation to a habitat templet for river systems
Authors: TOWNSEND COLIN R. , HILDREW ALAN G. 
Published: May 2006

SUMMARY

This paper focuses on the premise that the habitat provides the templet upon which evolution forges characteristic species traits. Alternative hypotheses are that there are historic and phylogenetic constraints on the match between organism and environment.
In our analysis of river systems, as one dimension of the templet we choose temporal heterogeneity and assume some relationship between this and the frequency of disturbance. The second dimension is spatial heterogeneity in the physicochemical environment and we pay particular attention to the way such variation can ameliorate the influence of disturbances through the provision of refugia.
We derive predictions about the traits of species, including size, generation time, reproductive tactics, body form, mobility and potential for regeneration, that are likely to occur in particular regions of the two‐dimensional templet. We also present predictions about community‐level characteristics such as number of species per resource category and total species richness. The general predictions are intended to apply to a wide range of plants, micro‐organisms and animals, provided the measurements have been made at a scale appropriate to them.
Hypotheses can be tested by comparing traits predicted for particular habitats, whose spatial and temporal heterogeneity have been quantified, with those actually observed. If the fit turns out to be good, we will be able to conclude that the habitat templet approach offers a sound framework within which to pose questions in river ecology.
Theoretical habitat templets, species traits, and species richness: Plecoptera and Ephemeroptera in the Upper Rhône River and its floodplain
Authors: USSEGLIO‐POLATERA PHILIPPE , TACHET HENRI 
Published: May 2006

SUMMARY

Ephemeroptera and Plecoptera in two sites of the Upper Rhône River (France) were examined using multivariate analyses to determine: (i) relationships among seventeen species traits; (ii) habitat utilization of the fifty‐five species present; (iii) the relationship between species traits and habitat utilization; (iv) trends of species traits and species richness in a framework of spatial and temporal habitat variability.
The species traits having the highest correlation ratios correspond to reproduction or life cycle, behavioural, and morphological characteristics. According to their traits, species of Baetidae, Caenidae, and Leptophlebiidae (Ephemeroptera) are opposite species of Perlidae and Perlodidae (Plecoptera).
The distribution of species in thirteen habitat types of the Upper Rhône River floodplain demonstrates a transverse gradient from the main channel to the oxbow lakes. Plecoptera are restricted to the different main channel habitats; in contrast, Ephemeroptera families have a broader distribution with Baetidae and Leptophlebiidae occurring in most floodplain habitats.
Plecoptera exhibit a significant relationship between species traits and habitat utilization but no relationship is evident for Ephemeroptera. Baetidae use many habitat types and have diverse species traits; in contrast, Leptophlebiidae, Heptageniidae, and Caenidae use many habitat types but each family has a rather uniform set of traits.
Trends in species traits were significantly related to both the spatial and temporal variability of habitats. Considering only temporal variability, the distribution of species trait modalities (= categories) corresponded well to predictions on trends in the river habitat templet for ‘minimum age at reproduction’ and ‘potential longevity’, and in general for ‘descendants per reproductive cycle’, ‘reproductive cycles per year’, ‘potential size’, and ‘body flexibility’ trends in six other traits did not match predictions.
No trends in species richness were evident in spatial–temporal framework of habitat variability.
Theoretical habitat templets, species traits, and species richness: aquatic insects in the Upper Rhône River and its floodplain
Authors: USSEGLIO‐POLATERA PHILIPPE 
Published: May 2006

SUMMARY

For five orders of Insecta (Plecoptera, Ephemeroptera, Odonata, Trichoptera, and Coleoptera) in two sites of the Upper Rhône River (France), the following are examined: (i) relationships among nineteen species traits; (ii) habitat utilization of species; (iii) the relationship between species traits and habitat utilization; and (iv) trends of species traits and species richness in a templet of spatial‐temporal habitat variability.
The species traits having the highest correlations correspond to reproduction, life cycle, nutritional, and morphological features. Species trait characteristics of Coleoptera are distinctly contrasted with those of Plecoptera and Ephemeroptera; Odonata and Trichoptera are intermediate to these orders.
The distribution of species in fourteen habitat types of the Upper Rhône River floodplain demonstrates a transverse gradient from the main channel to the oxbow lakes and the temporary water habitats, and a vertical gradient from interstitial to superficial habitats.
Despite a significant relationship between species traits and habitat utilization, superposition between species traits and habitat utilization is limited. At the order level, species form usually one (Ephemeroptera, Trichoptera, Odonata) or several (Coleoptera) groups of relatively homogeneous species traits; however, the species of each of these groups utilize rather different habitat types.
Only for some life history traits, e.g. the minimum age of reproduction or the number of reproductive cycles per year, do the trends observed in the framework of spatial—temporal variability of habitat types agree with the predictions from the river habitat templet. This mismatch mainly results from the unique phylogenetic history of the Coleoptera compared with that of the other four orders.
Species richness peaks at an intermediate level of temporal variability; however, it does not gradually increase with increasing spatial variability, nor increase from low to intermediate temporal variability.
Theoretical habitat templets, species traits, and species richness: aquatic macrophytes in the Upper Rhône River and its floodplain
Authors: BORNETTE GUDRUN , HENRY CHRISTOPHE , BARRAT MARIE‐HÉLÈNE , AMOROS CLAUDE 
Published: May 2006

SUMMARY

The objective of this study, which is based on forty‐two species of hydrophytes and helophytes, is to investigate: (i) relationships among species traits; (ii) habitat utilization by species; (iii) the relationship between species traits and habitat utilization; (iv) trends in species traits in the framework of spatial–temporal habitat variability, and if trends match predictions from the river habitat templet; and (v) trends in species richness in the framework of spatial–temporal habitat variability, and if trends match predictions of the patch dynamics concept.
Two data sets were used for this analysis: species traits (mainly reproductive and morphological characteristics) were documented from the literature; and species distribution across eight habitat types was from field surveys conducted in the floodplain of the Upper Rhone River, France. This information was structured by a fuzzy coding technique and analysed by ordination methods.
Several species traits, which are related to disturbances and reflect resistance (e.g. attachment to soil or substrate) or resilience (e.g. potential for regeneration of an individual), are closely related for aquatic macrophytes.
Habitat utilization by aquatic macrophytes separates the habitat types along a gradient of connectivity with the main channel, which corresponds to a gradient in flood disturbance frequency and the permanence of the different water‐bodies.
The relationship between species traits and habitat utilization is highly significant, indicating that a particular set of habitat types is used by taxa with a particular set of species trait modalities.
Observations in one habitat templet (in which scaling of the templet is primarily based on water level fluctuations for the temporal variability axis and on substrate characteristics for the spatial variability axis) generally do not support predictions on trends in species traits but do support predictions on trends in species richness.
Observations in an alternative habitat templet (in which scaling of the templet is based on frequency of flood scouring for the temporal variability axis and on heterogeneity of the substrate for the spatial variability axis) support theoretical predictions on trends for about half of the species traits for which predictions were available. However, trends in species richness in this alternative habitat templet are only partly in agreement with predictions.
Spatial and temporal variability in filament length of a toxic cyanobacterium (Anabaena affinis)
Authors: SMITH ALISON D. , GILBERT JOHN J. 
Published: May 2006

SUMMARY1. This study examines the distribution of Anabaena affinis filament lengths under natural conditions as a function of depth and season, and in the laboratory as a function of growth phase. Because Anabaena affinis is only toxic when consumed, both its filament length and position in the water column are important determinants of its potential impact on zooplankton populations.2. Star Lake (Norwich, Vermont, U.S.A.), a natural, eutrophic pond, remained thermally stratified throughout the Anabaena bloom. Filament number and length differed significantly with both sampling date and water depth. Most filaments occurred at 0.5 m, particularly at the height of the bloom. Throughout the entire water column average filament length decreased from approximately 0.53 mm in May to 0.14 mm in July. The shortest filaments occurred at the 2.5 m depth. Filament length distributions (combined for all depths) for 29 May, 12 June and 3 July, corresponding to the beginning, middle and end of the bloom, respectively, differed significantly among the three dates. These patterns most likely reflect variable growth conditions, both during the season and in the water column.3. In the laboratory, Anabaena filament length was affected by medium composition and growth phase. Filaments were significantly longer when grown in MBL than in ASM medium. Also, the average length of Anabaena filaments grown in MBL changed significantly as cultures aged; by day 13 filament length (2.01 ± 0.38 mm, mean ± SD) was twice that on day 0 (0.97 ± 0.71 mm). As cell concentration continued to increase, mean filament length gradually decreased.
Alpine newts (Triturus alpestris) as top predators in a high‐altitude karst lake: daily food consumption and impact on the copepod Arctodiaptomus alpinus
Authors: SCHABETSBERGER ROBERT , JERSABEK CHRISTIAN D. 
Published: May 2006

SUMMARY1. Population dynamics and feeding ecology of adult and larval alpine newts (Triturus alpestris, Laurenti) were investigated in a high‐altitude karts lake to estimate their feeding pressure on the copepod Arctodiaptomus alpinuf (Imhof). Estimates of population size for reproducing adults ranged from 666 to 864 individuals in the lake during July and August. Total abundance of larvae before the onset of ice cover varied considerably between 4400 and 25400 individuals in different years.2. Arctodiaptomus alpinus was an important prey item for adult and larval alpine newts. During the second half of their aquatic period, adult newts moved to deeper water where the copepod reached its highest densities near the sediment. Adults and larvae exhibited no periodic feeding pattern. The feeding rhythm was more synchronized among the larvae than among the adults.3. Daily food consumption, estimated using the Elliott & Persson (1978) model, reached 4–21 mg dry biomass in adults. The daily ration of larvae was about 7% of body dry weight in the temperature range 6‐11°C. Compared to published estimates of daily food consumption in salmonid fishes, the feeding pressure of newts appears low.
Effect of zinc on four populations and two generations of Gammarus pulex (L.)
Authors: CRANE MARK 
Published: May 2006

SUMMARY1. The amphipod Gammarus pulex (L.) is increasingly used in toxicity assessments and is usually obtained from wild populations. Interpopulation variability in response to toxicants may be due to genetic or phenotypic differences and could be large in wild‐caught organisms exposed to different environmental conditions. This paper describes an investigation designed to assess the extent of lethal and sublethal variability between four different G. pulex populations when exposed to zinc, and to determine whether differences observed in the parental generation were also apparent in offspring bred in the laboratory.2. The mortality of G. pulex from one of the four field‐caught populations (Crags Stream) was significantly lower than for animals from the other three populations for the first 2 days of exposure. After 6 days’ exposure the LC50 values for all four populations did not differ significantly, and were approximately 1.0 mg Zn 1‐−1. Sublethal effects on feeding rate after 6 days’ exposure were also similar for all four populations (feeding rate EC50 approximately 0.5 mg Zn 1‐−1).3. Lethal effects on the F1 generation were similar among the four populations, in contrast to the short‐term differences observed in the parental generation. These results suggest that interpopulation differences in zinc tolerance in G. pulex are short‐lived, and phenotypically rather than genetically based.