"Species Trait" Approaches for Theoretical and Applied Issues in Freshwater Communities I
Presiding: L Bache, University of California, Berkeley; N Bonada, University of Barcelona
NB13F-01 INVITED 13:30h
Modelling and Prediction of Trait Response and Functional Diversity of Stream Invertebrates: how to Deal With Fuzzy Coded Species Traits?
Since the special session `Synthesizing long-term riverine research: new multivariate approaches to test ecological theory' at the 41th NABS Calgary meeting in 1993, several authors have continued the quantification of stream invertebrate biological traits using a flexible fuzzy coding technique. Fuzzy correspondence analysis was designed for the description of such information. However, the growing need for predictive models has urged scientists towards designing appropriate statistical tools. Here, we present a statistical approach based on Vector Generalized Linear Models suitable for multidimensional responses and preserving the conditional relationships among trait modalities. To investigate the potential of VGLM, we have used stream invertebrate sampling and associated habitat characteristics at 67 quasi-reference condition sites in 8 European rivers. Altitude and stream gradient were the most frequently selected variables in models associated to traits such as trophy or size. Temperature range participated in modelling traits associated to life cycles. Local hydraulics were essential to modelling body form. Finally, our model enabled the detection of human impacts on patterns in life cycle confirming a priori predictions. These results suggest the potential specific responses of traits to environmental conditions and the potential applicability of VGLM for elaborating a trait-based monitoring tool.
NB13F-02 INVITED 13:45h
Are Biological Traits of Benthic Macroinvertebrate Assemblages Able to Indicate Different Stressors in Rivers at a pan-European Scale?
Combinations of species traits, selected or modified for depending on environmental characteristics of systems, have the potential to indicate the mechanisms - including human-induced disturbances - structuring communities. To examine the response of benthic macroinvertebrate assemblages to anthropogenic disturbances, we analysed modifications of 21 bio-ecological trait profiles in benthic macroinvertebrate communities of 25 river types throughout Europe, using a large set of impacted and reference sites. Impacted sites, covering the whole range from 'reference' to 'heavily degraded', reflected acidification, toxic contamination, organic pollution and morphological degradation (European STAR programme). A simultaneous ordination of trait profiles and abundance distributions of taxa was used to check for a potential relationship between species traits and habitat characteristics, taking into account the stressor category and magnitude. Statistical comparisons of trait profiles for impacted and reference sites within a given stressor type permitted to determine significant differences between more or less 'impacted' sites and corresponding 'reference' sites. Results allow describing a functional typology of community bio-ecological responses to stressors that (1) could be used at a large spatial scale, and (2) should be considered as the first step to a biologically based river assessment system using potential traits of benthic macroinvertebrates.
NB13F-03 INVITED 14:00h
Comparative life-history strategies of native and non-native fishes in the Colorado River Basin: Using species traits to understand rates of invasions and extirpations over the past century
In this presentation we use a comprehensive database of morphological, behavioural, physiological and life-history traits for the native and non-native fish species pools of the Colorado River Basin to explore a number of hypotheses regarding linkages between human-induced environmental change, the creation of ecological niches opportunities, and invasion and extirpation of fish species over the past 150 years. Using the life-history model of Winemiller and Rose (1992), we quantitatively evaluate how rates of non-native species spread and range contraction of native species reflects the combined effects of similarities in life history strategies and a changing adaptive landscape caused by human environmental alteration. Our results revealed a number of intriguing findings. First, non-native species were located throughout the adaptive surface defined by the life-history attributes and surround the ecological niche volume represented by the native fish species pool. Second, native species exhibiting the highest similarity to the novel life-histories represented by non-native species have shown the greatest distributional declines. Third, non-native fishes exhibiting among the fastest rates of spread, in general, occupied "vacant" niche positions in life-history space that reflect "novel" anthropogenically-created environmental conditions (evidence for abiotic resistance) or showed the least similarity with native life-history strategies (evidence for biotic resistance).
NB13F-04 INVITED 14:15h
Selecting Species Traits for Biomonitoring Applications in light of Phylogenetic Relationships among Lotic Insects
The use of species traits as indicators of environmental disturbance is being considered for biomonitoring programs globally. As such, methods to select relevant and informative traits for inclusion in biometrics need to be developed. In this research, we identified 20 traits of aquatic insects within six trait groups: morphology, mobility, life-history strategy, thermal tolerance, feeding guild and ecology (e.g., habitat preference). We constructed phylogenetic trees for 1) all lotic insect species of North America and 2) all Ephemeroptera, Plecoptera and Trichoptera species based on morphology- and molecular-based analyses and classifications. We then measured variability (i.e., plasticity) of the 20 traits and six trait groups across the two phylogenetic trees. Traits with higher degrees of plasticity indicated traits that were less phylogenetically constrained, and were considered informative for biomonitoring purposes. Thermal tolerance, rheophily, body size at maturity and feeding guild showed the highest plasticity across both phylogenetic trees. Two mobility traits, occurrence in drift and adult dispersal distance, showed moderate plasticity. By contrast, adult exiting ability, degree of attachment, adult lifespan and body shape showed low variability and were thus less informative. Plastic species traits that are less phylogenetically constrained may be most useful in detecting community change along environmental gradients.
NB13F-05 INVITED 14:30h
Biological and ecological traits of Trichoptera: the influence of phylogeny on life history and behavioral traits
Biological and ecological traits of fauna have the potential to indicate changes in community structure that relate to function as an alternative to using traditional taxonomic descriptors. However, traits may be inherited, and consequently, not all species traits are independent of phylogeny. When used in analyses of community structure, results based on traits may be difficult to interpret; suites of traits may respond together even if only one trait is responding to changes in the habitat. To determine the relationship between traits and phylogeny, we examined life history and behavioral traits for the extant 45 families of Trichoptera. Traits such as larval size, respiratory strategies, case or net materials, locomotion, food and functional feeding group, voltanism, diapause, habitat, and reproduction were collected from published life histories. Traits were then coded and mapped onto the phylogeny of Trichoptera to determine the correlations between traits, as well as correlations directly influenced by the phylogeny. Traits such as functional feeding group, reproductive strategies, and building materials were correlated with phylogeny, while traits such as locomotion and habitat type were less influenced by phylogeny. Consideration of macroinvertebrate phylogenies when selecting biological and ecological traits may be essential for accurate interpretation of community function.
NB13F-06 INVITED 14:45h
Heavy Metal Impacts on Stream Macroinvertebrate Communities: a Species Trait Approach
Heavy metal pollution can have significant impacts on stream macroinvertebrate communities. These impacts are often quantified using either laboratory-based toxicity tests, which measure physiological response of individuals, or field-based ecological surveys, which measure change in community composition. Surprisingly, work that provides the linkage between physiological response of individuals and community response is scarce. Examination of biological or species traits can provide that important link and potentially offers a greater understanding of, not only the community response, but also the mechanisms operating to produce an observed ecological effect. We present results of an investigation into the effects of heavy metals associated with mining activities on the Coromandel Peninsula, New Zealand. We have found that species traits allow us to identify specific life history, resistance and physiological characteristics of organisms, which respond differentially to metal contamination. Such information provides insight into the links between the mechanisms of toxicity to individuals and the translation of that toxicity to community level impacts. We have also found that species traits methods are at least as effective as "traditional" methods (e.g. community composition) in differentiating metal contaminated sites and provide additional evidence to address the ecological significance of stressor effects.