Subtle population structure and male-biased dispersal in two <Emphasis Type="Italic">Copadichromis</Emphasis> species (Teleostei,Cichlidae) from Lake Malawi,East Africa

Marine protected areas are generally designed and managed on the basis of the presence and extent of specific habitat types or the habitats of important species. However, it has become clear that in addition to including these ‘structural’ elements of marine systems, management strategies should incorporate a consideration of the functional aspects of the ecosystems. Biological traits analysis (BTA) has been successfully used to describe ecological functioning in marine benthic systems. BTA uses a number of biological characteristics expressed by the taxa present as indicators of key ecosystem functions. Two expert workshops were used to examine the potential for the application of BTA in the designation and management of MPAs. They concluded that BTA represented the best tool currently available for quantifying ecological functioning and agreed on 10-key ecological functions delivered by marine benthic communities. Twenty-four biological traits were also identified by the workshops as indices of these ten functions. In order to demonstrate the practical utility of the approach, BTA using these traits, was applied to a dataset covering benthos from within and around the proposed Eddystone Special Area of Conservation (SW England). The case study demonstrated that with the type of data normally available from conservation assessment type surveys, and a knowledge of the relevant biological traits, it is possible to use a consideration of ecological functioning to set boundaries for the MPA and to inform the site management objectives. The use of structure and function information to inform the designation process and subsequent management of marine protected areas is discussed. Guest editors: J. Davenport, G. Burnell, T. Cross, M. Emmerson, R. McAllen, R. Ramsay & E. Rogan Challenges to Marine Ecosystems     

Biological traits approaches in benthic marine ecology: Dead ends and new paths

Biological traits analysis (BTA) links community structure to both ecological functions and response to environmental drivers through species’ attributes. In consequence, it has become a popular approach in marine benthic studies. However, BTA will reach a dead end if the scientific community does not acknowledge its current shortcomings and limitations: (a) uncertainties related to data origins and a lack of standardized reporting of trait information; (b) knowledge gaps on the role of multiple interacting traits on driving the organisms’ responses to environmental variability; (c) knowledge gaps regarding the mechanistic links between traits and functions; (d) a weak focus on the spatial and temporal variability that is inherent to the trait expression of species; and, last but not least, (e) the large reliance on expert knowledge due to an enormous knowledge gap on the basic ecology of many benthic species. BTA will only reach its full potential if the scientific community is able to standardize and unify the reporting and storage of traits data and reconsider the importance of baseline observational and experimental studies to fill knowledge gaps on the mechanistic links between biological traits, functions, and environmental variability. This challenge could be assisted by embracing new technological advances in marine monitoring, such as underwater camera technology and artificial intelligence, and making use of advanced statistical approaches that consider the interactive nature and spatio‐temporal variability of biological systems. The scientific community has to abandon some dead ends and explore new paths that will improve our understanding of individual species, traits, and the functioning of benthic ecosystems.     

Assessment of the subtidal macrobenthic community functioning of a temperate estuary following environmental restoration

Biological Traits Analysis (BTA) is a recently proposed method for addressing ecological functioning based on traits exhibited by members of biological assemblages. This multi-trait approach was applied to the soft-bottom subtidal macrobenthic communities of the Mondego estuary (Portugal), aiming to assess its functioning following a management measure implemented in this system. In particular, the response of benthic assemblages to restoration efforts was investigated over a 5-year period, testing for temporal differences before and after management, in order to assess the effectiveness of this recovery action.BTA revealed to be a useful approach providing valuable information on the functioning of the subtidal benthic communities. Overall, results suggested that there have been some changes in the ecosystem over the study period, although the success of the management measure at the benthic functional level revealed unclear. The climatic variability experienced in the estuary over the monitoring period seemed to have played a significant role in masking the potential effects of restoration. Furthermore, evidence suggested a possible persistence in the benthic functioning despite the occurrence of shifts in taxonomic composition, assured by the potential ability of different species with an alike set of traits to perform similar roles in the ecosystem.To best of our knowledge, this study constituted one of the first attempts to investigate the effects of a management measure in an estuary by means of Biological Traits Analysis. As such, it can thus be useful as a guideline for further management actions in the Mondego estuary extendable to other poikilohaline estuaries as well, and to provide insights on the BTA application to this type of ecosystems.     

Oxygen limitations on marine animal distributions and the collapse of epibenthic community structure during shoaling hypoxia

Deoxygenation in the global ocean is predicted to induce ecosystem‐wide changes. Analysis of multidecadal oxygen time‐series projects the northeast Pacific to be a current and future hot spot of oxygen loss. However, the response of marine communities to deoxygenation is unresolved due to the lack of applicable data on component species. We repeated the same benthic transect (n = 10, between 45 and 190 m depths) over 8 years in a seasonally hypoxic fjord using remotely operated vehicles equipped with oxygen sensors to establish the lower oxygen levels at which 26 common epibenthic species can occur in the wild. By timing our surveys to shoaling hypoxia events, we show that fish and crustacean populations persist even in severe hypoxia (<0.5 mL L^?1) with no mortality effects but that migration of mobile species occurs. Consequently, the immediate response to hypoxia expansion is the collapse of community structure; normally partitioned distributions of resident species coalesced and localized densities increased. After oxygen renewal and formation of steep oxygen gradients, former ranges re‐established. High frequency data from the nearby VENUS subsea observatory show the average oxygen level at our site declined by ~0.05 mL L^?1 year^?1 over the period of our study. The increased annual duration of the hypoxic (<1.4 mL L^?1) and severely hypoxic periods appears to reflect the oxygen dynamics demonstrated in offshore source waters and the adjacent Strait of Georgia. Should the current trajectory of oxygen loss continue, community homogenization and reduced suitable habitat may become the dominant state of epibenthic systems in the northeast Pacific. In situ oxygen occurrences were not congruent with lethal and sublethal hypoxia thresholds calculated across the literature for major taxonomic groups indicating that research biases toward laboratory studies on Atlantic species are not globally applicable. Region‐specific hypoxia thresholds are necessary to predict future impacts of deoxygenation on marine biodiversity.     

Consequences of Increasing Hypoxic Disturbance on Benthic Communities and Ecosystem Functioning

Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota) effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface) by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days) in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential), gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH₄ ⁺ and dissolved Si. Although effluxes of PO₄ ³⁻ were not altered significantly, changes were observed in sediment PO₄ ³⁻ sorption capability. The duration of hypoxia (i.e. number of days of stress) explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the benthic habitat matters, and that the link between biodiversity and ecosystem function is likely to be affected by a range of factors in complex, natural environments.     

Quantifying Hypoxia Impacts on an Estuarine Demersal Community Using a Hierarchical Ensemble Approach

In coastal marine ecosystems, hypoxia and anoxia are emerging as growing threats whose ecological impacts are difficult to ascertain because of the frequent lack of adequate references for comparison. We applied conventional and hierarchical ensemble analyses to evaluate the weight of evidence in support of hypoxia impacts on local densities of individual and groups of demersal fish and invertebrate species in Hood Canal, WA, which is subject to seasonal hypoxia in its southern reaches. Central to our approach was a sample design and analysis scheme that was designed specifically to consider multiple alternative hypotheses regarding factors that dictate local species’ densities. We anticipated persistent effects of hypoxia (felt even when seasonal hypoxia was absent) on species densities would be most pronounced for sessile species, but that immediate effects (felt only when seasonal hypoxia was present) would dominate for mobile species. Conventional analysis provided strong evidence that densities of sessile species were persistently reduced in the hypoxic-impacted site, but did not indicate widespread immediate density responses during hypoxic events among mobile species. The absence of strong weights of evidence for hypoxia effects was partly a consequence of alternative hypotheses that better explained spatial-temporal variation in species’ densities. The hierarchical ensemble analysis improved the precision of species-specific effect sizes, and also allowed us to make inferences about the response of aggregated groups of species. The estimated mean density reductions during hypoxic events (dissolved oxygen ~2 mg/l) ranged from 73 to 98% among mobile invertebrates, benthic, and benthopelagic fishes. The large reduction in benthic and benthopelagic species suggests substantial effects of hypoxia in Hood Canal even at oxygen levels that were marginally hypoxic. Understanding the full ecological consequence of hypoxia will require a greater knowledge on the spatial extent of distributional shifts and their effects on competitive and predator–prey interactions.     

Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment

Biodiversity has diminished over the past decades with climate change being among the main responsible factors. One consequence of climate change is the increase in sea surface temperature, which, together with long exposure periods in intertidal areas, may exceed the tolerance level of benthic organisms. Benthic communities may suffer structural changes due to the loss of species or functional groups, putting ecological services at risk. In sandy beaches, free-living marine nematodes usually are the most abundant and diverse group of intertidal meiofauna, playing an important role in the benthic food web. While apparently many functionally similar nematode species co-exist temporally and spatially, experimental results on selected bacterivore species suggest no functional overlap, but rather an idiosyncratic contribution to ecosystem functioning. However, we hypothesize that functional redundancy is more likely to observe when taking into account the entire diversity of natural assemblages. We conducted a microcosm experiment with two natural communities to assess their stress response to elevated temperature. The two communities differed in diversity (high [HD] vs. low [LD]) and environmental origin (harsh vs. moderate conditions). We assessed their stress resistance to the experimental treatment in terms of species and diversity changes, and their function in terms of abundance, biomass, and trophic diversity. According to the Insurance Hypothesis, we hypothesized that the HD community would cope better with the stressful treatment due to species functional overlap, whereas the LD community functioning would benefit from species better adapted to harsh conditions. Our results indicate no evidence of functional redundancy in the studied nematofaunal communities. The species loss was more prominent and size specific in the HD; large predators and omnivores were lost, which may have important consequences for the benthic food web. Yet, we found evidence for alternative diversity–ecosystem functioning relationships, such as the Rivets and the Idiosyncrasy Model.     

Bioturbation in a declining oxygen environment, in situ observations from Wormcam

Bioturbation, the displacement and mixing of sediment particles by fauna or flora, facilitates life supporting processes by increasing the quality of marine sediments. In the marine environment bioturbation is primarily mediated by infaunal organisms, which are susceptible to perturbations in their surrounding environment due to their sedentary life history traits. Of particular concern is hypoxia, dissolved oxygen (DO) concentrations ≤2.8 mg l(-1), a prevalent and persistent problem that affects both pelagic and benthic fauna. A benthic observing system (Wormcam) consisting of a buoy, telemetering electronics, sediment profile camera, and water quality datasonde was developed and deployed in the Rappahannock River, VA, USA, in an area known to experience seasonal hypoxia from early spring to late fall. Wormcam transmitted a time series of in situ images and water quality data, to a website via wireless internet modem, for 5 months spanning normoxic and hypoxic periods. Hypoxia was found to significantly reduce bioturbation through reductions in burrow lengths, burrow production, and burrowing depth. Although infaunal activity was greatly reduced during hypoxic and near anoxic conditions, some individuals remained active. Low concentrations of DO in the water column limited bioturbation by infaunal burrowers and likely reduced redox cycling between aerobic and anaerobic states. This study emphasizes the importance of in situ observations for understanding how components of an ecosystem respond to hypoxia.     

Long-term warming affects ecosystem functioning through species turnover and intraspecific trait variation

Effects of climate change on natural ecosystems can be mediated by ecological processes, but also by rapid evolutionary adaptations and/or non-heritable trait changes in organisms. So far, most studies testing the importance of inter- versus intraspecific changes for how communities and their functioning responds to climate change are either short-term laboratory experiments in highly controlled (artificial) environments, or long-term field surveys suffering from lack of experimental manipulation. Here, we quantified how community composition and functioning has changed in response to long-term warming, including the potential direct and indirect effects via immediate and delayed physiological, non-heritable plastic, ecological, evolutionary and eco-evolutionary responses. We used a site-for-time approach, sampling sites in an artificially heated basin and a nearby area to quantify how >30 years of experimental warming in situ affects benthic grazer communities and traits of grazer taxa, as well as their contribution to a key ecosystem function: grazing on filamentous algae. The community composition shifted with warming, because a non-native species was highly common, and taxa with higher mobility, became more common in the heated areas compared to the control sites. Warming altered community functioning but the underlying mechanisms varied between traits: increased metabolism was caused by intraspecific trait change, while increased grazing rate was mainly driven by species turnover. Our results suggest that both population- and community-level processes mediate the responses of natural communities to long-term environmental change, and that the ongoing warming of coastal waters is likely to alter the functioning of key marine ecosystems.     

Using species traits to assess human impacts on near shore benthic ecosystems in the Canadian Arctic

Human activities have the potential to alter the diversity and composition of biological communities in natural environments, which can cause changes in ecosystem functioning. This has led to the development of environmental assessment techniques that take into account species identity, as species can contribute differently to various ecosystem processes. Biological Traits Analysis (BTA) is used to compare the abundances of specific biological traits in samples to produce information about how ecosystem functioning may change across a specific terrestrial or aquatic system. In the present study, BTA was used to assess the influence of municipal wastewater effluent on benthic marine communities in near shore soft sediments in four locations across the Canadian Arctic Territory of Nunavut, Canada. Shifts in trait composition were assessed relative to indicators of sediment enrichment (sediment chlorophyll, organic content, degree of anoxia), and natural variation in habitat characteristics (water depth, porosity, average grain size) at a site receiving wastewater and a reference site in each sampling location. The results indicated a mild enrichment effect of wastewater, as evidenced by changes in trait composition at three of the four sites that received wastewater inputs. However, the amount of variance in trait composition explained by metrics of wastewater enrichment in these locations were generally equal to or lower than the amount of variance explained by sediment characteristics related to natural processes. These results provide greater insight into the underlying causes and consequences of human activities than more traditional methods for environmental impact assessment, and can be directly applied in a management context.     

烟台牟平海洋牧场季节性低氧对大型底栖动物群落的生态效应

由于气候变化和人类活动的影响, 世界许多海区尤其是近岸海区发生了不同程度的低氧现象, 导致海洋动物大量死亡, 对海洋生态系统产生了不同程度的影响。为明确烟台牟平海洋牧场低氧对大型底栖动物的生态效应, 我们于2016年夏季(6月、8月、9月共3个航次)在该海域进行现场调查, 分析低氧对大型底栖动物群落时空变化的影响。结果表明: 牟平海洋牧场8月低氧事件发生时, 大型底栖动物群落的优势种为短叶索沙蚕(Lumbrinereis latreilli)、不倒翁虫(Sternaspis scutata)和内肋蛤(Endopleura lubrica)。低氧在一定程度上改变了大型底栖动物的群落结构, 表现为物种组成和优势种变化上。例如, 耐受低氧的机会种数量增加, 如短叶索沙蚕; 敏感种数量减少, 如微小海螂(Leptomya minuta)、长吻沙蚕(Glycera chirori)、大蝼蛄虾(Upogebia major)、极地蚤钩虾(Pontocrates altamarimus)、塞切尔泥钩虾(Eriopisella sechellensis)等。同时, 低氧也导致了物种多样性的降低, 但丰度和生物量受其影响不明显, 这主要是由于机会种短叶索沙蚕丰度和生物量的剧增所致。大型底栖动物不同物种耐受低氧的阈值不同。例如, 短叶索沙蚕在溶解氧(DO) < 1.0 mg/L受影响最大, 在DO = 2.0 mg/L时受到的影响不明显, 而其他敏感种如微小海螂、大蝼蛄虾、极地蚤钩虾、塞切尔泥钩虾等在DO < 2.5 mg/L时, 已表现出明显的不适。低氧事件之后, 大型底栖动物群落得到一定程度的恢复, 其恢复程度和需要的时间长短与低氧发生的程度有关。     

Multiple stressors,nonlinear effects and the implications of climate change impacts on marine coastal ecosystems

Global climate change will undoubtedly be a pressure on coastal marine ecosystems, affecting not only species distributions and physiology but also ecosystem functioning. In the coastal zone, the environmental variables that may drive ecological responses to climate change include temperature, wave energy, upwelling events and freshwater inputs, and all act and interact at a variety of spatial and temporal scales. To date, we have a poor understanding of how climate‐related environmental changes may affect coastal marine ecosystems or which environmental variables are likely to produce priority effects. Here we use time series data (17 years) of coastal benthic macrofauna to investigate responses to a range of climate‐influenced variables including sea‐surface temperature, southern oscillation indices (SOI, Z4), wind‐wave exposure, freshwater inputs and rainfall. We investigate responses from the abundances of individual species to abundances of functional traits and test whether species that are near the edge of their tolerance to another stressor (in this case sedimentation) may exhibit stronger responses. The responses we observed were all nonlinear and some exhibited thresholds. While temperature was most frequently an important predictor, wave exposure and ENSO‐related variables were also frequently important and most ecological variables responded to interactions between environmental variables. There were also indications that species sensitive to another stressor responded more strongly to weaker climate‐related environmental change at the stressed site than the unstressed site. The observed interactions between climate variables, effects on key species or functional traits, and synergistic effects of additional anthropogenic stressors have important implications for understanding and predicting the ecological consequences of climate change to coastal ecosystems.     

On the origin of Antarctic marine benthic community structure

Environmental conditions fostering marine communities around Antarctica differ fundamentally from those in the rest of the world's oceans, particularly in terms of pronounced climatic fluctuations and extreme cold. Here, we argue that the rarity of pelagic larval stages in Antarctic marine benthic invertebrate species is a consequence of evolutionary temperature adaptation and that this has greatly contributed to the current structure of the Antarctic benthic community. In arguing this position, we challenge the likelihood of previously suggested survival strategies of benthic communities on the Antarctic continental shelf and slope during Cenozoic glacial periods. By integrating evidence from marine geology and geophysics, we suggest that the Antarctic continental shelf and slope were both unfavourable environments for benthic communities during glacial periods and that community survival was only possible in the deep sea or in shelters on the continental shelf as a result of the diachronism in maximum ice extent.     

A biological trait approach to assess the functional composition of subtidal benthic communities in an estuarine ecosystem

Within transitional/estuarine environments ‘ecosystem functioning’ has been mostly investigated with “traditional” taxonomic analysis, based on the taxonomic composition of benthic invertebrate communities. However, ‘ecosystem functioning’ depends also greatly on the functional characteristics (biological traits) of organisms.It was a priori suggested that the biological traits of the subtidal benthic invertebrate communities within an estuarine environment would respond to the high variability of environmental pressures (natural and human induced) within this type of ecosystem.For this study, traditional taxonomic analysis (species richness, species density and Shannon–Wiener diversity) as well as biological trait analysis were used together for the first time to investigate the response of the subtidal benthic invertebrate communities to the environmental pressures within the Mondego estuary (Portugal).Biological trait analysis, in addition to traditional taxonomic analysis provided a more comprehensive understanding of the functioning within this type of ecosystem. Some of the most important outcomes are: (i) the trait “salinity preference” was the most important trait that distributed the species along the estuary, (ii) the central part of the estuary appeared to be under higher environmental stress levels than the other areas, as suggested by a dominance of some “opportunistic” traits (e.g. small short-lived species), (iii) the ratio between functional diversity (FD) and Shannon–Wiener diversity (H′) indicated lower functional redundancy at the upper reaches of the estuary. Our results, suggest that the ratio (FD/H′) might be a helpful tool to visualize this functional attribute and could potentially be applied to different communities from distinct environments. Using the traditional taxonomic analysis alone, this last functional aspect would not be detectable. Therefore, the inclusion of biological traits analysis is recommendable for estuarine ecological studies.     

The influence of fire on phylogenetic and functional structure of woody savannas: Moving from species to individuals

Fire is a key determinant of tropical savanna structure and functioning. High fire frequencies are expected to assemble closely related species with a restricted range of functional trait values. Here we determined the effect of fire on phylogenetic and functional diversity of woody species and individuals in savanna communities under different fire frequencies. We found phylogenetic signals for one third of the functional traits studied. High numbers of fires simultaneously led to phylogenetic overdispersion and functional clustering when communities were represented by mean trait values with all traits that putatively should be affected or respond to fire. This finding is important, because it shows that the relationship between ecological processes and the phylogenetic structure of communities is not straightforward. Thus, we cannot always assume that close relatives are more similar in their ecological features. However, when considering a different set of traits representing different plant strategies (fire resistance/avoidance, physiological traits and regeneration traits), the results were not always congruent. When asking how communities are assembled in terms of individuals (not species) the outcome was different from the species-based approach, suggesting that the realised trait values – rather than mean species trait values – have an important role in driving community assembly. Thus, intraspecific trait variability should be taken into account if we want fully to improve our mechanistic understanding of assembly rules in plant communities.     

Tracking environmental stress gradients using three biotic integrity indices: Advantages of a locally-developed traits-based approach

Estuarine and coastal ecosystems are productive and functionally diverse areas that provide a wide range of societal benefits. Along with human exploitative uses comes an array of anthropogenic disturbances that can affect ecological integrity, including changes to the composition and resilience of benthic macroinvertebrate communities. To understand the responses of ecological communities to anthropogenic disturbance and to manage and mitigate effects, indices for assessing the ecological integrity of estuarine and coastal waters have proliferated worldwide. Using data from 84 intertidal sites in Auckland, New Zealand, we evaluated the suitability of two widely used measures of ecological integrity that were developed in USA and Europe, respectively: the Benthic Index of Biotic Integrity (B-IBI) and the AZTI's Marine Biotic Index (AMBI). We then developed a local index based on macrofaunal traits and verified its utility using independent data from >100 additional sites. The local traits based index (TBI), constructed from the richness of macrofaunal taxa in seven functional groups, responded to changes in sediment mud percentage and heavy metal contaminant concentration gradients below international guidelines. The TBI performed better than the indices developed overseas, probably because they were designed to track organic enrichment and hypoxia, which are not the predominant stressors in New Zealand at present. The TBI successfully tracked the stressors that were the most relevant locally and indicated the relative levels of within-group taxonomic richness at various sites. As within-group richness is a component of functional redundancy and ecological resilience, the TBI offers a trifecta of simplicity, robustness and meaningfulness that will facilitate management.     

Seasonal structuring of a benthic community exposed to regular hypoxic events

The Western Trough of the Lough Hyne Marine Reserve in southern Ireland features annual episodes of profound hypoxia beneath an oxy-thermocline that develops each summer. Previous work had indicated that the hypoxia caused mass mortality of the sessile benthic fauna, but information about the winter fauna, or about mobile species was lacking. Here we report on a combined remote-operated vehicle, SCUBA and baited trap study, backed by regular oxygen-temperature-depth monitoring of the Trough. Our results show that there is community of resident benthic and mobile species during the oxic winter months that disappears in the summer. Mobile fish and crustaceans avoid the hypoxic areas of the Trough, though the prawn Palaemon serratus will venture into the hypoxic zone to scavenge on baits. At the oxy-thermocline itself, burrows of benthic fauna remain evident in summer, but their inhabitants show much reduced activity or death. Regular hypoxic episodes clearly structure the benthic community of the Trough, but this is not a simple matter of alternating mass mortality and recolonization; mobile species are clearly capable of avoiding the hypoxic zone in summer, but benefit from its productivity in winter and spring.     

Changes in the fish fauna of the Ria de Aveiro estuarine lagoon (Portugal) during the twentieth century

The fish biodiversity of the Ria de Aveiro has been analysed during the 20th century, as an indicator of the biological integrity of the ecosystem. Ninety-two distinct species and 38 families of Agnatha, Chondrichthyes and Osteichthyes occurred during the period. The family and species richness showed two levels of magnitude, from the 1910s, with high values (26–28 families and 51–52 species), and during the last two decades with more variable values (20–27 families and 38–55 species). A total of 13 species (four non-sporadic species) have disappeared recently. The lagoon system has been affected by large-scale anthropogenic influences mainly the substantial development of industries and the increasing population in the watershed, in addition to overfishing, climatic changes and dredging. In general, as shown by an analysis of the ecotrophic guilds present, the area maintained a similar structure during the whole period. No significant differences in time were recorded for any of the designated guilds. The twenty-two frequent species, which occurred in six or seven surveys, were mainly estuarine resident species or marine adventitious species, living in the substratum (benthic fish), on soft substratum and vegetated bottoms. They were feeding either on invertebrates alone or on invertebrates and fish, and producing pelagic or benthic eggs. The 19 sporadically-recorded species, recorded only once, were mostly marine adventitious, demersal fishes, living above rough bottom and vegetation, feeding strictly on invertebrates, and producing eggs benthically or deposited into vegetation. It is concluded that the Ria de Aveiro estuarine coastal lagoon has supported similar fish communities during the past century and that these comprise representatives of various ecological types.     

Functional diversity of marine macrobenthic communities from sublittoral soft-sediment habitats off northern Chile

Benthic communities show changes in composition and structure across different environmental characteristics and habitats. However, incorporating species biological traits into the analysis can provide a better understanding of system functioning within habitats. We compare the functional diversity of macrobenthic communities from a contrasting shallow (15 m) and deep (50 m) sublittoral soft-sediment habitats in northern Chile, using biological traits analysis. Our aim was to highlight the biological characteristics responsible for differences between habitats and the implications for ecosystem functioning. Trait analysis showed that the deep habitat was restricted in providing functionally important biogenic structure and bioturbation and supports less diverse feeding-related energy pathways. The shallow habitat is characterized by more diverse energy pathways and a higher potential for matter exchange through bioturbation. We provide support to the predictions of transfer of energy from the benthos to upper trophic levels in the shallow, which is characterized mainly by normoxia and little organic matter content in the sediment. In the deep habitat, characterized by hypoxia and more organic matter, energy appears to be transferred to microbial components. We suggest that trait analysis should be added to the traditional approaches based on species diversity, because it provides indicators of ecosystem stress.     

The multidimensionality of the niche reveals functional diversity changes in benthic marine biotas across geological time

Despite growing attention on the influence of functional diversity changes on ecosystem functioning, a palaeoecological perspective on the long-term dynamic of functional diversity, including mass extinction crises, is still lacking. Here, using a novel multidimensional functional framework and comprehensive null-models, we compare the functional structure of Cambrian, Silurian and modern benthic marine biotas. We demonstrate that, after controlling for increases in taxonomic diversity, functional richness increased incrementally between each time interval with benthic taxa filling progressively more functional space, combined with a significant functional dissimilarity between periods. The modern benthic biota functionally overlaps with fossil biotas but some modern taxa, especially large predators, have new trait combinations that may allow more functions to be performed. From a methodological perspective, these results illustrate the benefits of using multidimensional instead of lower dimensional functional frameworks when studying changes in functional diversity over space and time.