Biological Traits Analysis Research Articles

Incorporating functional traits with habitat maps: patterns of diversity in coastal benthic assemblages

Benthic species assemblages are groups of species that co-occur on the seafloor. Linking assemblages to physical environmental features allows for understanding and predicting their spatial distribution. Species identity and abundance are commonly quantified using a taxonomic approach to assess benthic diversity, yet functional traits that describe the behavior, life history, and morphology of a species may be equally or more important. Here, we investigate the biodiversity of five benthic species assemblages in relation to their habitat and environmental conditions in an Ecologically and Biologically Significant Area (EBSA) along Canada’s east coast, using both a taxonomic approach and biological traits analysis. Random Forest regression was applied to map spatial patterns of functional and taxonomic diversity metrics, including richness, Shannon index, and Rao’s quadratic entropy. We evaluate discrepancies between related taxonomic and trait measures, and the community-weighted mean of trait data was calculated to characterize each assemblage. Taxonomic and functional richness – representing the number of species and the species community volume in the trait space, respectively – showed similar spatial patterns. However, when considering diversity, which also accounts for the relative abundance and differences among species or traits, these patterns diverged. Taxonomically different assemblages exhibited similar trait compositions for two assemblages, indicating potential trait equivalencies, while one assemblage exhibited traits potentially indicating sensitivity to human activity. The taxonomic and functional metrics of richness and diversity were low close to the coast, which could be indicative of disturbance. Consideration of functional metrics can support spatial planning and prioritization for management and conservation efforts by assessing the sensitivity of traits to different stressors.

Benthic taxonomic and functional diversity change across a depth gradient in the Southern Benguela Shelf ecoregion

Functional trait-based approaches improve biodiversity assessment and have consequently been gaining traction in ecology, including marine benthic studies. However, taxonomic diversity is still the default biodiversity metric applied to monitor benthic community responses to environmental variation despite not always representing functional diversity change. Therefore, we used Biological Traits Analysis (BTA) to quantify functional diversity for infauna and epifauna communities collected from the same locations across a depth gradient in the Southern Benguela Shelf ecoregion. Infauna experienced an increase in functional uniqueness with depth, whereas epifauna experienced an increase in functional redundancy with depth. As a result, the epifauna species assemblage predicted 43 % of the epifauna trait assemblage, whereas the infauna species assemblage predicted only 8 % of the infauna trait assemblage. These findings suggest that taxonomic diversity and functional diversity changes are not congruent within and between marine benthic faunal groups. We emphasize the need to utilise both biodiversity metrics when quantifying marine biodiversity for conservation and management objectives.

A Reinforcement Learning approach to study climbing plant behaviour

A plant’s structure is the result of constant adaptation and evolution to the surrounding environment. From this perspective, our goal is to investigate the mass and radius distribution of a particular plant organ, namely the searcher shoot, by providing a Reinforcement Learning (RL) environment, that we call Searcher-Shoot, which considers the mechanics due to the mass of the shoot and leaves. We uphold the hypothesis that plants maximize their length, avoiding a maximal stress threshold. To do this, we explore whether the mass distribution along the stem is efficient, formulating a Markov Decision Process. By exploiting this strategy, we are able to mimic and thus study the plant’s behavior, finding that shoots decrease their diameters smoothly, resulting in an efficient distribution of the mass. The strong accordance between our results and the experimental data allows us to remark on the strength of our approach in the analysis of biological systems traits.

Multidecadal changes in coastal benthic species composition and ecosystem functioning occur independently of temperature-driven community shifts.

Rising global temperatures are often identified as the key driver impacting ecosystems and the services they provide by affecting biodiversity structure and function. A disproportionate amount of our understanding of biodiversity and function is from short-term experimental studies and static values of biodiversity indices, lacking the ability to monitor long-term trends and capture community dynamics. Here, we analyse a biennial dataset spanning 32 years of macroinvertebrate benthic communities and their functional response to increasing temperatures. We monitored changes in species' thermal affinities to examine warming-related shifts by selecting their mid-point global temperature distribution range and linking them to species' traits. We employed a novel weighted metric using Biological Trait Analysis (BTA) to gain better insights into the ecological potential of each species by incorporating species abundance and body size and selecting a subset of traits that represent five ecosystem functions: bioturbation activity, sediment stability, nutrient recycling and higher and lower trophic production. Using biodiversity indices (richness, Simpson's diversity and vulnerability) and functional indices (richness, Rao's Q and redundancy), the community structure showed no significant change over time with a narrow range of variation. However, we show shifts in species composition with warming and increases in the abundance of individuals, which altered ecosystem functioning positively and/or non-linearly. Yet, when higher taxonomic groupings than species were excluded from the analysis, there was only a weak increase in the measured change in community-weighted average thermal affinities, suggesting changes in ecosystem functions over time occur independently of temperature increase-related shifts in community composition. Other environmental factors driving species composition and abundance may be more important in these subtidal macrobenthic communities. This challenges the prevailing emphasis on temperature as the primary driver of ecological response to climate change and emphasises the necessity for a comprehensive understanding of the temporal dynamics of complex systems.

Functional diversity of macrozoobenthos under adverse oxygen conditions in the southern Baltic Sea

Oxygen deficiency is a major problem in the Baltic Sea. To study the impact of hypoxia on the functional diversity of benthic fauna and the possibility of macrozoobenthos recovery, data were analyzed in a gradient of oxygen conditions in the Gdańsk Basin. The research conducted on the basis of biological traits analysis enabled us to analyze the number, type and spatial distribution of biological traits—a proxy for functions performed by macrozoobenthos. A significant depletion of macrofauna was already observed under conditions of reduced oxygen above the bottom, both in terms of functional diversity and biomass. Although taxa observed in hypoxia (DO < 2 mL L−1) perform a number of functions, the remaining species do not form complex structures in the sediments or cause deep bioturbation and bioirrigation. Moreover, their extremely low biomass plays an irrelevant role in benthic–pelagic coupling. Thus, benthic fauna under hypoxia is not an element that ensures the functioning of the ecosystem. We assess that traits important for species dispersal and the presence of taxa resistant to short-term hypoxia in the oxic zone above the halocline provide a “backup” for ecosystem functioning under altered diverse oxygen conditions below the halocline after cessation of hypoxia in the southern Baltic Sea.

Environmental heterogeneity of cold seep by biological trait analysis of marine nematodes at Site F cold seep in South China Sea

Cold seeps provide high environmental heterogeneity for marine benthos. Site F is one of the active cold seeps in the South China Sea. In this study, free-living marine nematode communities were investigated at Site F and the adjacent deep-sea area. A total of 67 genera and 32 families were identified. The mean density at cold seep sites ranged from 13.6 to 181.8 ind./10 cm2, and that at the adjacent deep-sea sites ranged from 36.9 to 301.4 ind./10 cm2. At cold seep sites, the most dominant nematode genera were Desmoscolex, Pierrickia, Sabatieria, Halalaimus, and Dorylaimopsis while at deep-sea sites, the most dominant genera were Retrotheristus, Thalassomonhystera, Desmoscolex, Cobbia, and Halalaimus. Deposit feeders of nematodes were dominant at all sites. Results of biological trait analysis showed that there was high environmental heterogeneity for nematodes at Site F. Water depth, sediment organic matter content, and sand proportion had important influences on nematode communities.

Structural and functional diversity patterns of macrofaunal communities from a semi-enclosed inlet of Northeast Atlantic: The influence of environmental conditions

Comprehending the mechanisms and circumstances responsible for the dynamics of biological communities is a fundamental step for predicting responses to environmental changes as well as efficient conservation and management efforts. Macrofaunal assemblages support a wide range of ecosystem services, serving as integral components of the biogeochemical cycle. Here, we examine the structure of the subtidal macrofaunal community in a semi-enclosed bay system located in the Northeast Atlantic. Employing a functional approach, our aim is to understand the interplay between water depth, geographical position, colonisation development and the communities. Our findings did not reveal the influence of water depth (range of 4 m–12 m) on the functional structures of the communities. Instead, only significant differences were demonstrated for ‘time of colonisation’ and ‘site’. The community with 1 month of colonisation presented limited functional diversity lacking overall ecological resilience. It was mainly characterised by ‘small-sized’, ‘short-lived’, ‘mobile’, and ‘deposit-feed’ organisms indicating an incipient state of development. Communities Site 2 and Site 3 revealed significant differences in the functional structure of the communities. They exhibited similar levels of functional diversity, yet significant differences emerged in the Biological Trait Analysis. Community Site 2 was characterised by ‘sessile’, ‘long-lived’, ‘large-sized’ ‘suspension feed’ while community Site 3 was characterised by ‘herbivore/grazer’, ‘tubicolous’, and ‘medium-lived’ organisms. Site 2 focuses on the transport of elements from pelagos to the benthos and from benthos to pelagos while Site 3 focus on the transport of elements within the benthos and from benthos to pelagos, and effectively contributes to decomposition and resuspension processes. Moreover, they differ in their sensitivity to disturbance, which suggests that their location in the Ría influences the functional composition of the communities. Understanding these patterns within this environment of significant ecological and economic importance holds profound implications for the effective preservation of ecosystem services.

The seafloor from a trait perspective. A comprehensive life history dataset of soft sediment macrozoobenthos

Biological trait analysis (BTA) is a valuable tool for evaluating changes in community diversity and its link to ecosystem processes as well as environmental and anthropogenic perturbations. Trait-based analytical techniques like BTA rely on standardised datasets of species traits. However, there are currently only a limited number of datasets available for marine macrobenthos that contain trait data across multiple taxonomic groups. Here, we present an open-access dataset of 16 traits for 235 macrozoobenthic species recorded throughout multiple sampling campaigns of the Dutch Wadden Sea; a dynamic soft bottom system where humans have long played a substantial role in shaping the coastal environment. The trait categories included in this dataset cover a variety of life history strategies that are tightly linked to ecosystem functioning and the resilience of communities to (anthropogenic) perturbations and can advance our understanding of environmental changes and human impacts on the functioning of soft bottom systems.

Understanding the impact of sand extraction on benthic ecosystem functioning: a combination of functional indices and biological trait analysis

Marine aggregates have been intensively extracted in the North-East Atlantic over the past decades. This study aimed to assess the effect of sand extraction on benthic ecosystem functioning using a combination of biological traits and functional indices (the bioturbation (BPc) and irrigation potential (IPc) and secondary production (SPc) of the macrobenthic community). Data on macrobenthos, sediment properties and extraction intensity were collected over a time period of ten years (2010 – 2019) for three coarse sediment extraction areas in the Belgian Part of the North Sea, each with a different extraction regime. Sediment parameters such as the medium sand fraction (250 – 500 µm) and median grain size showed a significant effect on all functional indices. Whilst sand extraction variables only significantly affected secondary production estimates. The secondary production of the macrobenthic community decreased following a high yearly extraction intensity, whereas a high cumulative (10-year period) extraction intensity resulted in a slightly increased secondary production. Species-specific responses revealed that these high cumulative extraction volumes increased the abundance of opportunistic species, which could have contributed to the higher SPc values observed in cumulative disturbed areas. Response traits such as tube-living and sessile individuals with a pelagic egg development were positively influenced by a long-term disturbance, an indication of a more disturbance-tolerant community. A short-term disturbance rather seemed to favor a macrobenthic community characterized by a higher burrowing capability. In terms of effect traits, both short- and long-term extraction clearly favored deposit feeders, which can structure organic matter distribution and thus indirectly influence nutrient and oxygen fluxes as well. Future in situ measurements in sand extraction areas could help to unravel and strengthen our understanding of the ecosystem processes linked to these trait-based observations.

Effects of Habitat Fragmentation of a Mediterranean Marine Reef on the Associated Fish Community: Insights from Biological Traits Analysis

Habitat fragmentation (HF) is an ecological process, which is potentially also one of the main causes of diversity loss. Many studies have debated the best tools to adopt for assessing the effects of HF. The traditional application of biodiversity metrics might not fully describe the biotic community associated to a particular habitat or the ongoing ecological processes. The community-weighted mean (CWM) seems to be a valid investigation index, since biological traits (BTs) of the associated community are selected by local environmental factors. Furthermore, by combining species with common BTs into Functional Groups (FGs), it is possible to account for ecological functions that are supported by the inclusion of the response of key species within the same context. In our case study, we investigated the possible effect of HF of different Sicilian vermetid reefs on the associated infralittoral fish community based on the (i) vermetid fragmentation level, (ii) nature of the infralittoral substratum and (iii) conservational level of protection. We expected HF to be the main factor in shaping the local fish community; however, the nature of the infralittoral substratum proved to be the principal driver of the ichthyofaunal community. By analysing separately the two infralittoral substrata considered in the study, we observed how HF might affect the associated fish community differently. A pristine vermetid reef seems to sustain a higher number of FGs when established on a rocky substratum. On the other hand, in the presence of a sandy substratum, a fragmented vermetid reef seems to attract a more functionally rich fish community than those accounted for a pristine status. Our results provide some evidence in support of the need to include a broad spectrum of community function descriptors for a more comprehensive characterisation of a habitat and for the assessment of the functioning of its ecosystem.

Detecting sediment recovery below an offshore longline mussel farm: A macrobenthic Biological Trait Analysis (BTA)

Expansion of bivalve aquaculture offshore reports lower environmental impacts compared to inshore farms. Taking a Before-After Control-Impact approach, this study presents the first functional diversity analysis and long-term Biological Trait Analysis (BTA) of infauna functional traits following the development of the United Kingdom's first large-scale, offshore longline mussel farm. Located in an area historically impacted by mobile fishing gear, farm sites had the greatest number of taxa and abundance compared to control sites. Functional diversity varied significantly across treatments (farm, near control, far control); while Functional Diversity, Richness, Divergence and Dispersion increased over time within the farm, Functional Evenness and Redundancy decreased. Bioturbation, body size, diet, feeding mode, life span, motility, sediment position, sensitivity and substrate type were chosen for Community-level Weighted Mean analysis, depicting the most frequently affected biological traits by shellfish farming. Farm sites developed a wider range of traits enhancing ecosystem function and habitat recovery after years of seabed damage. Outcomes support the use of functional diversity and BTA analysis to perform ecosystem assessment, supporting decision-makers implement policy and management.

Deciphering benthic ecosystem functioning and resilience in a major port and marine protected area via the multi-trait approach

The preservation of ecosystem functioning of coastal zones, in face of increasing environmental stressors and species extinctions, relies on the functional redundancy and inherent resilience of its inhabitants. To compare the benthic functioning and resilience of a disturbed area with a relatively less impacted area, a study was conducted in Mumbai Port and Malvan Marine Protected Area (MPA), which exhibited contrasting characteristics. The hypothesis posited that the anthropogenically influenced Mumbai port would exhibit lower functional parameters and resilience compared to Malvan. Overall, the MPA presented higher species richness and functional diversity with a greater presence of sensitive species, while Mumbai was dominated by the presence of opportunistic species, as anticipated. However, our findings demonstrated that despite varied trends in species diversity metrics, in both the coastal areas, the resemblance in benthic functioning was high due to similarity in dominant trait profiles. Surprisingly, Functional Richness was higher at Mumbai, while Functional Evenness, Divergence and Dispersion were comparable at both sites. The resilience, as quantified by Functional Redundancy, was also comparable at both areas attributable to the presence of clusters of species with similar traits and a low occurrence of rare traits. The combination of traits observed in both areas was influenced by the extant environmental conditions, as revealed by RLQ analyses. This study underscores the valuable insights provided by the application of Biological Trait Analysis (BTA) tool in deciphering the relationship between species diversity and ecosystem functioning, as well as the resilience capabilities of ecosystems subjected to varying levels of perturbation. Moreover, the incorporation of functional diversity indices yielded valuable inferences regarding ecosystems resilience, which can aid future ecosystem management strategies.

Functional redundancy as an indicator for evaluating functional diversity of macrobenthos under the mussel raft farm near Gouqi Island

Biological traits analysis (BTA) helps to evaluate the effects of different environmental variables on the traits-based functional composition of macrobenthos. However, research on functional traits of macrobenthos under mussel farming is limited. We investigated the spatial and temporal response of the benthic system in terms of taxonomic and functional diversity to environmental variables of farming and natural stressors resulting from suspended mussel farming near Gouqi Island of eastern China Sea. The functional traits of macrobenthic assemblages under mussel farming were characterized by “medium adult body size”, “vermiform body form”, “high flexibility”, “infauna”, “semi-motile”, “gonochoristic”, “surface deposit-feeders”, “carnivores”, “semi-motile burrowers”, and “tube-dwellers”. Functional redundancy was stable in response to mussel farming stresses among seasons, whereas species diversity showed efficient to evaluate natural variables. Functional diversity was significantly affected by farming stressors rather than natural variables, Further analysis using multivariate methods together with continuous monitoring were highlighted to evaluate the impacts of mussel farming. Our results reinforce the importance of macrobenthic species and functional traits analysis to evaluate human stresses driven impacts in offshore ecosystems. By analysing the environmental variables with different sources, independently, we concluded the main effects of human pressures on macrobenthic community. Such distinction could be particularly effective to isolate variable environmental descriptors and evaluate their effects on functional diversity, making the current approach promising for the evaluation of ecological effects of anthropogenic stressors in aquaculture areas.

Unveiling the meiobenthic community structure of Prydz Bay, Antarctica during austral summer

Meiobenthos are bottom-dwelling aquatic invertebrates having a size range of 63–500 μm. They play a pivotal role in ecosystem functioning, biogeochemical and trophic nutrient cycling. Due to the presence of Antarctic Circumpolar Current and steep gradient in nutrients and temperature, many taxa of the Southern Ocean (SO) show diverse biodiversity patterns in comparison to other deep sea areas of the world. Over the years, several Indian SO Expeditions have been carried out in the Indian sector of SO (ISSO), but this is a pioneer attempt to unveil the meiobenthic community structure and their functional diversity pattern from Prydz Bay (Indian sector of Southern Ocean), Antarctica. Meiobenthic community structures were investigated in eight different sampling sites along with their vertical profiling from the Prydz Bay during the austral summer 2020. Total meiofaunal abundance ranged from 24 to 521 indv. 10 cm-2, with the highest abundance recorded at station 23 and the lowest at station 9. A total of 9 meiobenthic taxa were found from this eco-region, with the highest percentage being the free-living marine nematodes as metazoan taxa. A total of 86 free-living nematode species were identified, where Sabatieria was the most common genus and represented by eleven species. Several univariate and multivariate analyses deciphered a distinct spatial variation in the meiobenthic community structure. Sediment texture and depth were the most significant environmental variables in shaping nematode assemblages. Biological Trait Analysis was performed using a total of 24 traits in 5 categories to unravel the functional diversity of free-living marine nematodes. The most dominant morphotypes were slender body shape, conical tail shape, dotted cuticle pattern, and non-selective deposit feeders with colonizing abilities of 2 (c–p score 2, in a scale from 1 to 5). Maturity Index (MI) and Index of Trophic Diversity (ITD) were highest in stations 15 and 32, respectively. RLQ approach with fourth-corner analysis was used to decipher the relationship between traits and environmental parameters. The RLQ analysis revealed the positive association of non-selective deposit feeder and slender body-shaped nematodes with higher water depth. The characterization of meiobenthic (especially nematode) communities in the context of taxonomic and functional attributes could help to evaluate the ecological status of ISSO. Further long term monitoring is also needed to get a comprehensive idea about their role in benthic ecosystem functioning in the milieu of global climate change.

AlgaeTraits: a trait database for (European) seaweeds

Abstract. The analysis of biological and ecological traits has a long history in evolutionary and ecological research. However, trait data are often scattered and standardised terminology that transcends taxonomic and biogeographical context are generally missing. As part of the development of a global trait database of marine species, we collated trait information for European seaweeds and structured the data within the standardised framework of the World Register of Marine Species (WoRMS). We collected 45 175 trait records for 21 biologically and ecologically relevant traits of seaweeds. This resulted in a trait database for 1745 European seaweed species of which more than half (56 %) of the records were documented at the species level, while the remaining 44 % were documented at a higher taxonomic level and subsequently inherited at lower levels. The trait database for European seaweeds will serve as a foundation for future research on diversity and evolution of seaweeds and their responses to global changes. The data will contribute to developing detailed trait-based ecosystem models and will be an important tool to inform marine conservation policies. The data are publicly accessible through the AlgaeTraits portal, https://doi.org/10.14284/574 (AlgaeTraits, 2022).

Responses of biological traits of macrobenthic fauna to a eutrophication gradient in a semi-enclosed bay, China

The impacts of eutrophication on benthic ecological functions are of increasing concern in recent years. In order to assess the response of macrobenthic fauna to increasing eutrophication, two field sampling surveys were conducted during the summer (July–August 2020) and autumn (October–November 2020) from offshore, nearshore to estuarine sediments in Bohai Bay, northern China. Biological trait analysis was employed for the assessment of macrofaunal samples. The results indicated that there was an increase in the proportion of benthic burrowering or tube-dwelling sediment feeders and taxa with higher larval dispersal ability, but a decrease in the proportion of taxa showing high motility in areas with higher nutrient levels. Seasonal differences were also noted in the shift in biological traits, with a significantly lower similarity among the sampling areas in summer and a higher proportion of carnivorous taxa in autumn. The findings suggested that long-term disturbance can lead to the dominance of smaller body-sized benthic species and reduced sediment quality, impeding ecological recovery of benthic organisms under such harsh environment.

Unraveling the functional diversity of macrobenthic community from Prydz Bay, Indian sector of the Southern Ocean

Antarctic marine ecosystems show rich macrobenthic diversity with a high level of endemism and biomass which is under the threat of global climate change. Till date, information regarding the structure of macrobenthic communities from Prydz Bay is extremely meagre. The present study investigates the spatial pattern of macrobenthic communities, and their response to environmental factors from Prydz Bay complemented with trait-based functional diversity patterns. Samples were collected from 8 stations during the 11th Indian scientific expedition to the Southern Ocean. A total of 57 species of macrobenthos belonging to 8 phyla and 33 families were identified. The macrobenthic communities were dominated by families, Lumbrineridae, Glyceridae, Ophiuridae, and Epimeriidae. Macrobenthos abundance in the study area ranged from 0 to 1592 indv.m-2, whereas biomass ranged from 0 to 1210.2 g m-2. CLUSTER analysis divided the entire macrobenthic community into four groups based on 13.5% similarity. SIMPER analysis delineated species Nacella kerguenlensis and Rossella antarctica as the main contributors for establishing similarity in macrobenthic community composition across the groups. Canonical correspondence analysis (CCA) showed environmental variables like clay %, depth, and sediment total organic carbon as the governing factors in structuring the composition of macrobenthic species. Biological trait analysis (BTA) was performed to visualize the functional diversity of the total macrobenthic population based on morphological and ecological characteristics. A total of 23 traits in 6 categories were used to assess the functional diversity of the study area. The most widespread trait categories were epifaunal environmental position, motile locomotion strategy, sexual brooder and spawner, burrowing living habitat, predatory and detritivore feeding strategies. Investigating the functional diversity of macrobenthic assemblages using BTA represents a novel step towards evaluating the ecological status of the benthic realm of Prydz Bay. RLQ approach in combination with fourth-corner analysis was used to evaluate the relationships among biological traits, macrobenthic species and environmental parameters.The RLQ analysis revealed the positive association of tube dwelling and burrowing polychaetes with silty substratum, and the sessile organisms were found to be negatively correlated with the presence of carnivores/predators. The present study gives a comprehensive understanding about the macrobenthic community structure along with biological trait categories from Prydz Bay.

A functional perspective of nematode assemblages as proxy of quality in tropical estuarine tidal flats

Functional aspects of biological communities influence ecosystem processes and it is urgent to understand how human disturbances affect functional diversity and ecosystem functions and services. Our purpose was to address the use of different functional metrics of nematode assemblages to evaluate the ecological status of tropical estuaries subjected to different human activities, aiming to advance and improve the knowledge about the usefulness of functional attributes as indicators of environmental quality. Three approaches were compared: functional diversity indexes, single trait, and multi traits using the Biological Traits Analysis. The RLQ + fourth-corner combined method was used to identify relationships among functional traits, inorganic nutrients, and metals concentrations. Lower values of FDiv, FSpe, and FOri indicate a convergence of functions, characterizing impacted conditions. A dominant set of traits was related to disturbance, mainly inorganic nutrient enrichment. All the approaches allowed for the detection of disturbed conditions, however, multi traits was the most sensitive one.

Crustaceans functional diversity in mangroves and adjacent mudflats of the Persian Gulf and Gulf of Oman

The effects of mangrove vegetation on functional features of crustacean assemblages were investigated using the Biological Traits Analysis (BTA). The study was carried out at four major sites in the arid mangrove ecosystem of the Persian Gulf and Gulf of Oman. Samples of Crustacea and associated environmental variables were taken seasonally (February 2018 and June 2019) from two habitats: a vegetated area with both mangrove trees and pneumatophores, and an adjacent mudflat. In each site, functional traits for the species were assigned using seven categories based on bioturbation, adult mobility, feeding habits and life-strategy traits. The results showed that the crabs (i.e., Opusia indica, Nasima dotilliformis and Ilyoplax frater) were widely distributed across all sites and habitats. The vegetated habitats supported higher taxonomic diversity than the mudflats, which highlights the importance of mangrove structural complexity for crustacean assemblages. Species inhabiting vegetated habitats were characterized by stronger presence of conveyor building species, detritivore, predator, grazer, lecithotrophic larval development, body size of 50–100 mm, and swimmer trait modalities. While, mudflat habitat enhanced the occurrences of surface deposit feeder, planktotrophic larval development, body size of <5 mm, and life span of 2–5 years. The results of our study showed that taxonomic diversity increased from the mudflats to the mangrove vegetated habitats. However, functional diversity did not differ between habitats. The significant differences in species and functional trait composition were observed between vegetated habitats and adjacent mudflats, stressing that different habitats may harbor different species and trait sets, likely as a result of habitat complexity. The use of taxonomic and functional attributes generate complementary information that can helps us to reach more efficient conclusions in terms of biodiversity conservation and ecosystem functionality in mangrove ecosystems.

Joint use of biological traits, diversity and biotic indices to assess the ecological quality status of a Mediterranean transitional system

In the present study, we tested the effectiveness of biological trait analysis (BTA) as an ecological indicator in support of the assessment of the Ecological Quality Status (EQS) of a Mediterranean transitional system by commonly used macrobenthic assemblage diversity (e.g. H’ and Margalef) and biotic (BENTIX, M−AMBI and M−bAMBI) indices. Ten biological traits describing morphological, behavioral and life history characteristics were considered for the analysis of the functional structure of macrobenthos. As a test study, a historical dataset obtained from the Cabras lagoon (Sardinia, Italy) comprising a riverine site, the lagoonal main body, a confined pond, a seaward creek and a marine channel connected to the Gulf of Oristano was analyzed. Our results showed clear spatial changes in macrobenthic density, number of species and diversity indices along the riverine-lagoon-sea gradient, which were well reflected in the EQS values based on M−AMBI and to a lesser extent on M−bAMBI. The abundance-based functional diversity was significantly related to the structure and taxonomic diversity of the benthic community. Similarly, the Community-level Weighted Mean test computed with abundance data, rather than with biomass data, supported major evidence for differences in the ecological conditions of the different study sites. In particular, all riverine, lagoonal and confined stations had poor or bad EQS, indicating unstable and warning conditions in this Mediterranean transitional water body. Overall, the BTA approach appeared to be a very promising method in reporting the expected environmental and biotic variability in the Cabras lagoon system and in supporting the EQS assessment by M−AMBI. We conclude that an in-depth knowledge of the benthic communities in terms of both taxonomic and functional aspects is an indispensable basic tool for understanding the variability of the brackish-water systems and for properly assessing their environmental quality.