Functional diversity does not explain the co-occurrence of non-native species within a flow-modified African river system.

Globally, there is growing concern on the occurrence of multiple non-native species within invaded habitats. Proliferation of multiple non-native species together with anthropogenic-driven habitat modifications raise questions on the mechanisms facilitating the co-occurrence of these species and their potential impact within the recipient systems. Using the Great Fish River system (South Africa) which is anthropogenically-modified by inter-basin water transfer (IBWT), as a case study, this research employed trait-based approaches to explore patterns associated with the co-occurrence of multiple non-native fish species. This was achieved by investigating the role of functional diversity of non-native and native fishes in relation to their composition, distribution and environmental relationships. Nineteen functional traits that defined two broad ecological attributes (habitat use and feeding) were determined for 13 fish species that comprised eight native and five non-native fishes. We used these data to, firstly, evaluate functional diversity patterns and to compare functional traits of native and non-native fishes in the Great Fish River system. Secondly, we employed multivariate ordination analyses (factor analysis, RLQ and fourth-corner analyses) to investigate interspecific trait variations and potential species-trait-environmental relationships. From a functional diversity perspective, there were no significant differences in most functional diversity indices between native and non-native species. Despite interspecific variation in body morphology-related traits, we also found no clear separation between native and non-native species based on the ordination analysis of the functional traits. Furthermore, while RLQ ordination showed broad spatial patterns, the fourth-corner analyses revealed no significant relationships among species distribution, functional traits and environmental variables. The weak species-trait-environment relationship observed in this study suggests that environmental filtering was likely a poor determinant of functional trait structure within the Great Fish River. Modification of the natural flow regime may have weakened the relationship between species traits and the environment as has been shown in other systems.

Life-history traits predict responses of wild bees to climate variation.

Life-history traits, which are physical traits or behaviours that affect growth, survivorship and reproduction, could play an important role in how well organisms respond to environmental change. By looking for trait-based responses within groups, we can gain a mechanistic understanding of why environmental change might favour or penalize certain species over others. We monitored the abundance of at least 154 bee species for 8 consecutive years in a subalpine region of the Rocky Mountains to ask whether bees respond differently to changes in abiotic conditions based on their life-history traits. We found that comb-building cavity nesters and larger bodied bees declined in relative abundance with increasing temperatures, while smaller, soil-nesting bees increased. Further, bees with narrower diet breadths increased in relative abundance with decreased rainfall. Finally, reduced snowpack was associated with reduced relative abundance of bees that overwintered as prepupae whereas bees that overwintered as adults increased in relative abundance, suggesting that overwintering conditions might affect body size, lipid content and overwintering survival. Taken together, our results show how climate change may reshape bee pollinator communities, with bees with certain traits increasing in abundance and others declining, potentially leading to novel plant-pollinator interactions and changes in plant reproduction.

Landscape heterogeneity filters functional traits of rice arthropods in tropical agroecosystems.

Biological control services of agroecosystems depend on the functional diversity of species traits. However, the relationship between arthropod traits and landscape heterogeneity is still poorly understood, especially in tropical rice agroecosystems, which harbor a high diversity of often specialized species. We investigated how landscape heterogeneity, measured by three metrics of landscape composition and configuration, influenced body size, functional group composition, dispersal ability, and vertical distribution of rice arthropods in the Philippines. We found that landscape composition and configuration acted to filter arthropod traits in tropical rice agroecosystems. Landscape diversity and rice habitat fragmentation were the two main gradients influencing rice-arthropod traits, indicating that different rice arthropods have distinct habitat requirements. Whereas small parasitoids and species mostly present in the rice canopy were favored in landscapes with high compositional heterogeneity, predators and medium-sized species occupying the base of the rice plant, including planthoppers, mostly occurred in highly fragmented rice habitats. We demonstrate the importance of landscape heterogeneity as an ecological filter for rice arthropods, identifying how the different components of landscape heterogeneity selected for or against specific functional traits. However, the contrasting effects of landscape parameters on different groups of natural enemies indicate that not all beneficial rice arthropods can be promoted at the same time when using a single land management strategy. Increasing compositional heterogeneity in rice landscapes can promote parasitoids but may also negatively affect predators. Future research should focus on identifying trade-offs between fragmented rice habitats and structurally diverse landscapes to maximize the presence of multiple groups of beneficial arthropods.

Ant communities in disturbed subtropical landscapes: is climate more important than stochastic processes?

Functional trait-based approaches have provided advances in the understanding of community assembly rules. Broad generalisations remain, however, limited due to the idiosyncratic nature of taxa and ecosystems, especially in tropical regions. We use fine scale resolution (30 m grid) environmental variables and community surveys from nearly 100 secondary tropical forest sites to study niche-based or neutral assembly mechanisms in ground dwelling ants. This provides a unique opportunity for understanding fine scale drivers of taxonomic, functional and phylogenetic diversity in a region characterized by large topographic and climatic differences on a relatively small geographic scale. Precipitation emerged as the most consistent environmental correlate, in shaping taxonomic, phylogenetic and functional aspects of the communities. Functional diversity was weakly associated with topography and temperature related variables. The fourth corner model revealed that femur, scape and mandible length were key traits in response to precipitation, and that communities showed a functional homogenization towards shorter appendages at wetter sites. Our results suggest that neutral and deterministic assembly processes act in concert to shape the taxonomic, phylogenetic and functional aspects of leaf litter ant assemblages. The use of multiple complementary metrics and approaches along environmental gradients are powerful to reveal the subtilities of assembly processes and provide insight into the ways future communities might change.

Successional syndromes of saplings in tropical secondary forests emerge from environment-dependent trait-demography relationships.

Identifying generalisable processes that underpin population dynamics is crucial for understanding successional patterns. While longitudinal or chronosequence data are powerful tools for doing so, the traditional focus on community-level shifts in taxonomic and functional composition rather than species-level trait-demography relationships has made generalisation difficult. Using joint species distribution models, we demonstrate how three traits-photosynthetic rate, adult stature, and seed mass-moderate recruitment and sapling mortality rates of 46 woody species during secondary succession. We show that the pioneer syndrome emerges from higher photosynthetic rates, shorter adult statures and lighter seeds that facilitate exploitation of light in younger secondary forests, while 'long-lived pioneer' and 'late successional' syndromes are associated with trait values that enable species to persist in the understory or reach the upper canopy in older secondary forests. Our study highlights the context dependency of trait-demography relationships, which drive successional shifts in sapling's species composition in secondary forests.

Soil chemistry drives below ground traits in an alternate successional pathway from forest to heath.

To understand impacts of post-disturbance assembly mechanisms on the functional diversity (FD) of plant communities, it is necessary to determine how the environment drives their functional trait composition. In the boreal forest, post-fire abiotic filters may control community assembly by selecting plants with specific traits. Ericaceous heaths are characterized by low FD and are thought to be subject to such filters. We hypothesized that soil parameters select for a specific suite of traits and act as a secondary abiotic filter in post-fire ericaceous heath and contribute to the observed reduction of FD. We measured six soil parameters, five functional traits, and plant species abundances in eight post-fire heath and four regenerating forest sites in Eastern Canada. We conducted a combined analysis of RLQ (R-table Linked to Q-table) and fourth-corner methods to examine the links between plant traits and plot-level soil parameters, mediated by species abundances. Only below ground traits were significantly linked to soil variables. Specific root length and ericoid mycorrhizal associations were negatively linked to total soil nitrogen, available ammonium, and pH. Post-fire heath soils favour a specific suite of species traits. Only a portion of the regional species pool possesses the above-mentioned traits, and when they are favoured by habitat conditions, they assemble into a community with low FD. The novelty of our study is here we show how the relationship between traits and soil chemistry can act as a secondary filter and exert community-level trait changes responsible for the low functional diversity observed in heaths.

Larval and phenological traits predict insect community response to mowing regime manipulations.

For the restoration of biodiversity in agricultural grasslands, it is essential to understand how management acts as an ecological filter on the resident species. Mowing constitutes such a filter: only species that possess functional traits enabling them to withstand its consequences can persist in the community. We investigated how the timing of mowing modulates this filtering effect for insects. We predicted that two traits drive species responses. Species with larval development within the meadow vegetation will suffer more from mowing than species whose larvae develop in or on the ground, or outside the meadows, while species with a later phenology should benefit from later mowing. We conducted a five-year experiment, replicated at 12 sites across the Swiss lowlands, applying three different mowing regimes to low-intensity hay meadows: (1) first cut of the year not earlier than 15 June (control regime); (2) the first cut delayed until 15 July; and (3) leaving an uncut grass refuge on 10-20% of the meadow area (after earliest first cut on 15 June). Before the first cut in years 4 or 5, we sampled larvae of Lepidoptera and sawflies, and adults of moths, parasitoid wasps, wild bees, hoverflies, ground beetles, and rove beetles. Overall, before the first cut of the year, abundances of species with vegetation-dwelling larvae were higher in meadows with delayed mowing or an uncut grass refuge, with some taxon-specific variation. In contrast, species whose larval development is independent of the meadow vegetation showed no differences in abundance between mowing regimes. Species richness did not differ among regimes. For species with vegetation-dwelling larvae, a fourth-corner analysis showed an association between early phenology and the control regime. No associations were found for the other functional groups. Our results show that slight modifications of mowing regimes, easily implementable in agri-environmental policy schemes, can boost invertebrate abundance, potentially benefitting insectivorous vertebrates.

Trait-based functional dietary analysis provides a better insight into the foraging ecology of bats.

The degree of trophic specialization determines the ability of predators to cope with changing foraging conditions, but in predators that prey on hundreds of species it is challenging to assess, especially when prey identity varies among predator individuals and across space and time. Here, we test the hypothesis that a bat species foraging on flying insects like moths will show ample flexibility in trophic niche, and this irrespective of phylogenetic relationships among moths, so as to cope with a high diversity of prey types that vary across seasons. We predict that individual bats will show functional dietary differences consistent with energetic requirements and hunting skills. We used DNA metabarcoding to determine the diet of 126 Mediterranean horseshoe bats (Rhinolophus euryale) from two different sites during three seasons. Simultaneously, we measured moth availability and characterized the traits of 290 moth taxa. Next, we explored the relationship between phylogeny and traits of all consumed and available moth taxa. Finally, we assessed the relationship between individual traits of bats and traits related to prey profitability, for which we used the RLQ and fourth-corner statistical techniques. Seasonality was the main factor explaining the functional dietary variation in adult bats, with moths consumed irrespective of their phylogenetic relationships. While adults consumed moths with a broad range in wing loading, body mass and echolocation detection ability, juveniles consumed slower, smaller and lighter moths, which suggests that young individuals may undergo some fitness gain and/or psychomotor learning process during which they would acquire more effective foraging skills. Our approach revealed a degree of functional flexibility in the trophic niche previously unknown for an insectivorous bat. Rhinolophus euryale consumed a wide variety of moth taxa differing in profitability throughout seasons and between ontogenetic stages. We showed the validity of trait-based approaches to gain new insights in the trophic specialization of predators consuming hundreds of species of prey.

Integrating spatial and phylogenetic information in the fourth-corner analysis to test trait-environment relationships.

The fourth-corner analysis aims to quantify and test for relationships between species traits and site-specific environmental variables, mediated by site-specific species abundances. Since there is no common unit of observation, the significance of the relationships is tested using a double permutation procedure (site based and species based). This method implies that all species and sites are independent of each other. However, this fundamental hypothesis might be flawed because of phylogenetic relatedness between species and spatial autocorrelation in the environmental data. Here, using a simulation-based experiment, we demonstrate how the presence of spatial and phylogenetic autocorrelations can, in some circumstances, lead to inflated type I error rates, suggesting that significant associations can be misidentified. As an alternative, we propose a new randomization approach designed to avoid this issue, based on Moran's spectral randomization. In this approach, standard permutations are replaced by constrained randomizations so that the distribution of the statistic under the null hypothesis is built with additional constraints to preserve the phylogenetic and spatial structures of the observed data. The inclusion of this new randomization approach provides total control over type I error rates and should be used in real studies where spatial and phylogenetic autocorrelations often occur.

Forest bees are replaced in agricultural and urban landscapes by native species with different phenologies and life-history traits.

Anthropogenic landscapes are associated with biodiversity loss and large shifts in species composition and traits. These changes predict the identities of winners and losers of future global change, and also reveal which environmental variables drive a taxon's response to land use change. We explored how the biodiversity of native bee species changes across forested, agricultural, and urban landscapes. We collected bee community data from 36 sites across a 75,000 km2 region, and analyzed bee abundance, species richness, composition, and life-history traits. Season-long bee abundance and richness were not detectably different between natural and anthropogenic landscapes, but community phenologies differed strongly, with an early spring peak followed by decline in forests, and a more extended summer season in agricultural and urban habitats. Bee community composition differed significantly between all three land use types, as did phylogenetic composition. Anthropogenic land use had negative effects on the persistence of several life-history strategies, including early spring flight season and brood parasitism, which may indicate adaptation to conditions in forest habitat. Overall, anthropogenic communities are not diminished subsets of contemporary natural communities. Rather, forest species do not persist in anthropogenic habitats, but are replaced by different native species and phylogenetic lineages preadapted to open habitats. Characterizing compositional and functional differences is crucial for understanding land use as a global change driver across large regional scales.

Disentangling the effects of farmland use, habitat edges, and vegetation structure on ground beetle morphological traits.

Land-use change due to agriculture has a major influence on arthropod biodiversity, and may influence species differently depending on their traits. It is unclear how species traits vary across different land uses and their edges, with most studies focussing on single habitat types and overlooking edge effects. We examined variation in morphological traits of carabid beetles (Coleoptera:Carabidae) on both sides of edges between woodlands and four adjoining, but contrasting farmland uses in an agricultural landscape. We asked: (1) how do traits differ between woodlands and different adjoining farmland uses (crop, fallow, restoration planting, and woody debris applied over crop), and do effects depend on increasing distances from the farmland-woodland edge? (2) Does vegetation structure explain observed effects of adjoining farmland use and edge effects on these traits? We found that carabid communities varied in body size and shape, including traits associated with diet, robustness, and visual ability. Smaller sized species were associated with woodlands and larger sized species with farmlands. Farmland use further influenced these associations, where woodlands adjoining plantings supported smaller species, while fallows and crops supported larger species. Vegetation structure significantly influenced body size, flying ability, and body shape, and helped explain the effects of farmland use and distance from edges on body size. We highlight the important role of vegetation structure, farmland use, and edge effects in filtering the morphological traits of carabid assemblages across a highly modified agricultural landscape. Our findings suggest that farmland management can influence body size and dispersal-related traits in farmland and adjacent native vegetation.

Foraging traits modulate stingless bee community disassembly under forest loss.

Anthropogenic land use change is an important driver of impacts to biological communities and the ecosystem services they provide. Pollination is one ecosystem service that may be threatened by community disassembly. Relatively little is known about changes in bee community composition in the tropics, where pollination limitation is most severe and land use change is rapid. Understanding how anthropogenic changes alter community composition and functioning has been hampered by high variability in responses of individual species. Trait-based approaches, however, are emerging as a potential method for understanding responses of ecologically similar species to global change. We studied how communities of tropical, eusocial stingless bees (Apidae: Meliponini) disassemble when forest is lost. These bees are vital tropical pollinators that exhibit high trait diversity, but are under considerable threat from human activities. We compared functional traits of stingless bee species found in pastures surrounded by differing amounts of forest in an extensively deforested landscape in southern Costa Rica. Our results suggest that foraging traits modulate competitive interactions that underlie community disassembly patterns. In contrast to both theoretical predictions and temperate bee communities, we found that stingless bee species with the widest diet breadths were less likely to persist in sites with less forest. These wide-diet-breadth species also tend to be solitary foragers, and are competitively subordinate to group-foraging stingless bee species. Thus, displacement by dominant, group-foraging species may make subordinate species more dependent on the larger or more diversified resource pool that natural habitats offer. We also found that traits that may reduce reliance on trees-nesting in the ground or inside nests of other species-correlated with persistence in highly deforested landscapes. The functional trait perspective we employed enabled capturing community processes in analyses and suggests that land use change may disassemble bee communities via different mechanisms in temperate and tropical areas. Our results further suggest that community processes, such as competition, can be important regulators of community disassembly under land use change. A better understanding of community disassembly processes is critical for conserving and restoring pollinator communities and the ecosystem services and functions they provide.

Community trait structure in phytoplankton: seasonal dynamics from a method for sparse trait data.

The distribution of functional traits in communities, and how trait distributions shift over time and space, is critical information for understanding community structure, the maintenance of diversity, and community effects on ecosystem function. It is often the case that traits tightly linked to ecological performance, such as physiological capacities, are laborious to measure and largely unknown for speciose communities; however, these traits are particularly important for unraveling the mechanistic basis of community structure. Here I develop a method combining sparse trait data with a statistical niche model to infer trait distributions for phytoplankton communities and how they vary over 10 yr in the western English Channel. I find that community-average nitrate affinity, light-limited growth rate, and maximum growth rate all show major seasonal patterns, reflecting alternate limitation by light vs. nitrogen. Trait diversity exhibits a variety of patterns distinct from community trait means, which suggests complex regulation of functional diversity. Patterns such as these are important for predicting how ocean ecosystems will respond to global change, and for developing trait-based models of emergent community structure. The statistical approach used here could be applied to any kind of organism, if it exhibits strong relationships between traits and statistical niche estimates.

Let's go beyond taxonomy in diet description: testing a trait-based approach to prey-predator relationships.

Understanding 'Why a prey is a prey for a given predator?' can be facilitated through trait-based approaches that identify linkages between prey and predator morphological and ecological characteristics and highlight key functions involved in prey selection. Enhanced understanding of the functional relationships between predators and their prey is now essential to go beyond the traditional taxonomic framework of dietary studies and to improve our knowledge of ecosystem functioning for wildlife conservation and management. We test the relevance of a three-matrix approach in foraging ecology among a marine mammal community in the northeast Atlantic to identify the key functional traits shaping prey selection processes regardless of the taxonomy of both the predators and prey. Our study reveals that prey found in the diet of marine mammals possess functional traits which are directly and significantly linked to predator characteristics, allowing the establishment of a functional typology of marine mammal-prey relationships. We found prey selection of marine mammals was primarily shaped by physiological and morphological traits of both predators and prey, confirming that energetic costs of foraging strategies and muscular performance are major drivers of prey selection in marine mammals. We demonstrate that trait-based approaches can provide a new definition of the resource needs of predators. This framework can be used to anticipate bottom-up effects on marine predator population dynamics and to identify predators which are sensitive to the loss of key prey functional traits when prey availability is reduced.

Ellenberg Indicator Values Disclose Complex Environmental Filtering Processes in Plant Communities along an Elevational Gradient.

Ellenberg indicator values (EIVs) express plant preferences for temperature, light, continentality, soil moisture, pH, and soil nutrients, and have been largely used to deduce environmental characteristics from plant communities. However, EIVs might also be used to investigate the importance of filtering mechanisms in shaping plant communities according to species ecological preferences, a so far overlooked use of EIVs. In this paper, we investigated how community-weighted means (CWM), calculated with EIVs, varied along an elevational gradient in a small mountain in Central Italy. We also tested if species abundances varied according to their ecological preferences. We found that the prevalence of thermophilous species declines with elevation, being progressively replaced by cold-adapted species. Heliophilous species prevail at low and high elevations (characterized by the presence of open habitats), whereas in the middle of the gradient (occupied by the beech forest), sciophilous species predominate. Variations for moisture and soil nutrient preferences followed a similar pattern, probably because of the high moisture and nutrient levels of forest soils with a lot of humus. No distinct pattern was detected for EIVs for pH and continentality since these factors are subject to more local variations. These results highlight the possible role of EIVs to investigate how environmental gradients shape plant communities.

Local and landscape environmental heterogeneity drive ant community structure in temperate seminatural upland grasslands.

Environmental heterogeneity is an important driver of ecological communities. Here, we assessed the effects of local and landscape spatial environmental heterogeneity on ant community structure in temperate seminatural upland grasslands of Central Germany. We surveyed 33 grassland sites representing a gradient in elevation and landscape composition. Local environmental heterogeneity was measured in terms of variability of temperature and moisture within and between grasslands sites. Grassland management type (pasture vs. meadows) was additionally included as a local environmental heterogeneity measure. The complexity of habitat types in the surroundings of grassland sites was used as a measure of landscape environmental heterogeneity. As descriptors of ant community structure, we considered species composition in terms of nest density, community evenness, and functional response traits. We found that extensively grazed pastures and within-site heterogeneity in soil moisture at local scale, and a high diversity of land cover types at the landscape scale affected ant species composition by promoting higher nest densities of some species. Ant community evenness was high in wetter grasslands with low within-site variability in soil moisture and surrounded by a less diverse landscape. Fourth-corner models revealed that ant community structure response to environmental heterogeneity was mediated mainly by worker size, colony size, and life history traits related with colony reproduction and foundation. We discuss how within-site local variability in soil moisture and low-intensity grazing promote ant species densities and highlight the role of habitat temperature and humidity affecting community evenness. We hypothesize that a higher diversity of land cover types in a forest-dominated landscape buffers less favorable environmental conditions for ant species establishment and dispersal between grasslands. We conclude that spatial environmental heterogeneity at local and landscape scale plays an important role as deterministic force in filtering ant species and, along with neutral processes (e.g., stochastic colonization), in shaping ant community structure in temperate seminatural upland grasslands.

Little time left. Microrefuges may fail in mitigating the effects of climate change on epiphytic lichens.

Climate change is already causing considerable reductions in biodiversity in all terrestrial ecosystems. These consequences are expected to be exacerbated in biomes that are particularly exposed to change, such as those in the Mediterranean, and in certain groups of more sensitive organisms, such as epiphytic lichens. These poikylohydric organisms find suitable light and water conditions on trunks under the tree canopy. Despite their small size, epiphytic communities contribute significantly to the functionality of forest ecosystems. In this work, we surveyed epiphytic lichen communities in a Mediterranean area (Sardinia, Italy) and hypothesized that 1) the effect of microclimate on lichens at tree scale is mediated by the functional traits of these organisms and that 2) micro-refuge trees with certain morphological characteristics can mitigate the negative effects of future climate change. Results confirm the first hypothesis, while the second is only partially supported, suggesting that the capability of specific trees to host specific conditions may not be sufficient to maintain the diversity and ecosystem functionality of lichen communities in the Mediterranean.

Effects of Meteorological Factors on Waterbird Functional Diversity and Community Composition in Liaohe Estuary, China.

Functional trait diversity represents ecological differences among species, and the structure of waterbird communities is an important aspect of biodiversity. To understand the effect of meteorological changes on the waterbird functional diversity and provide suggestions for management and conservation, we selected a study area (726 km2) in Liaohe Estuary, located in northeast China. We explored the trends of the waterbird functional diversity changes in response to meteorological factors using fourth corner analysis. Our study demonstrated that temperature was a key factor that impacted waterbird functional diversity in spring, while precipitation had a greater impact in autumn. The population size of goose and duck was positively associated with temperature and negatively with precipitation, while that of the waders (Charadriiformes) showed opposite association trends. Herbivores and species nesting on the bare ground exhibited responses to meteorological factors similar to those of geese and ducks, while benthivores and waterbirds nesting under grass/shrubs exhibited trends similar to those of waterbirds. Waterbirds with smaller bodies, shorter feathers, and lower reproductive rates preferred higher temperatures and less precipitation than other waterbirds. In addition, we observed seasonal variations in waterbird functional diversity. In spring, we should pay attention to waders, herbivores, and waterbirds nesting on the bare ground when the temperature is low. In autumn, waders, benthivores, and omnivores need more attention under extreme precipitation. As the global climate warms in this study area, waterbird functional diversity is expected to decline, and community composition would become simpler, with overlapping niches. Biodiversity management should involve protecting intertidal habitats, supporting benthic macrofaunal communities, preparing bare breeding fields for waterbirds favoring high temperatures to meet their requirements for population increase, and preventing the population decline of geese and ducks, herbivores, and species nesting under grass/shrubs. The findings of our study can aid in developing accurate guidelines for waterbird biodiversity management and conservation.

Effect of multiple stressors on the functional traits of sub-tidal macrobenthic fauna: A case study of the southeast coast of India.

The use of functional information of taxa is a promising approach to uncover the underlying mechanism of ecosystem functioning. We used biological trait analysis (BTA) to assess the functional response of subtidal macrobenthos with multiple stressors. Seventeen environmental variables from 42 stations of five coastal districts were assessed along the southeast coast of India. Dominant fauna was assigned into 20 categories belonging to six functional traits. Additionally, we used five ecological groups (EG) of AMBI as a covariable trait to validate functional traits and EG relationship. The trait composition in the communities showed significant variation between undisturbed and disturbed areas. RLQ/Fourth corner combined approach illustrated the effects of stressors and isolated the corresponding species associated with different stressors. Smaller, short-lived, deposit-feeding, and discretely motile fauna occurred at the disturbed areas, whereas, larger, long-lived, and highly motile at the undisturbed area. Dissolved oxygen, organic enrichment, and metals concentration were the main environmental descriptors influencing the trait composition. The results highlight the importance of the BTA approach to uncover the response of the macrobenthic community to anthropogenic disturbances-driven impacts in multi-stressed near-shore coastal ecosystems.

Identifying and classifying macroinvertebrate indicator signature traits and ecological preferences along urban pollution gradient in the Niger Delta.

Urbanisation of riverine landscape is an increasing threat to the functionality of river ecosystems. In this study, we identify and classify macroinvertebrates indicator signature traits and ecological preferences.We hypothesised that urban pollution would differentially influence the distribution of macroinvertebrate traits and ecological preferences along a gradient of water quality deterioration. Hence, we identified and classified potential biological indicators traits and ecological preferences that were deemed tolerant of or sensitive to urban pollution gradient in the Niger Delta region of Nigeria. Physico-chemical variables (water temperature, depth, flow velocity, dissolved oxygen, biochemical oxygen demand, electrical conductivity (EC), nitrate, phosphate), and macroinvertebrates were collected from 2008 to 2012 seasonally during the wet and dry seasons once in a month in 11 stations in eight river systems. The results based on RLQ, fourth-corner and Kruskal-Wallis analyses indicate that traits/ecological preferences such as tegumental/cutaneous respiration, cased/tubed body armouring, a preference for silty water, bivoltinism, burrowing and a high tolerance for oxygen depletion, were statistically significantly associated with the heavily impacted stations. These traits were positively correlated with physico-chemical variables such as EC, nitrate and phosphate indicative of urban pollution. On the other hand, traits/ecological preferences such as permanent attachment, crawling, swimming, univoltinism and a moderate sensitivity to oxygen depletion were associated with the least impacted stations and were negatively correlated with physico-chemical variables indicative of urban pollution. Overall, the observed differential responses of traits and ecological preferences to urban pollution along a gradient of water quality impairment suggest that traits and ecological preferences can serve as useful biological indicators and thus supports the growing evidence of the utility of the trait-based approach.