Macrofaunal Taxa Research Articles

Spatial distribution of meiofaunal and macrofaunal assemblages in the tidal flats of the southern Korean coast in relation to natural and anthropogenic impacts

We investigated the spatial variability of macrofaunal and meiofaunal assemblages in intertidal flats on the southern coast of Korea. Abiotic and biotic samples were collected at five stations. The species richness, density, and composition of the assemblages differed significantly among stations. Nematoda and Annelida were the most dominant meiofaunal and macrofaunal taxa, respectively, although taxon dominance differed among stations. Distance-based linear models showed that sediment-related variables and heavy metals were the main environmental factors determining the spatial variability of the assemblages. Macrofauna had only sediment-related variables and heavy metals as major environmental factors, but meiofauna were also influenced by other environmental factors such as sea surface temperature, dissolved oxygen-related variables, and salinity. This study can provide basic ecological data for understanding the spatial distribution of macro-meiofaunal assemblages and aid in the development of marine environmental management strategies on the western south coast of Korea.

Effects of Local Acidification on Benthic Communities at Shallow Hydrothermal Vents of the Aeolian Islands (Southern Tyrrhenian, Mediterranean Sea).

Simple SummaryOcean acidification is causing major changes in marine ecosystems, with varying levels of impact depending on the region and habitat investigated. Here, we report noticeable changes in both meio- and macrobenthic assemblages at shallow hydrothermal vents located in the Mediterranean Sea. In general, the areas impacted by the vent fluids showed decrease in the abundance of several taxa and a shift in community composition, but with a clear biomass reduction evident only for macrofauna. CO2 emissions at shallow hydrothermal vents cause a progressive simplification of community structure and a general biodiversity decline due to the loss of the most sensitive meio- and macrofaunal taxa, which were replaced by the more tolerant groups, such as oligochaetes, or highly mobile species, able to escape from extreme conditions. Our results provide new insight on the tolerance of marine meio- and macrofaunal taxa to the extreme conditions generated by hydrothermal vent emissions in shallow-water ecosystems.The Aeolian Islands (Mediterranean Sea) host a unique hydrothermal system called the “Smoking Land” due to the presence of over 200 volcanic CO2-vents, resulting in water acidification phenomena and the creation of an acidified benthic environment. Here, we report the results of a study conducted at three sites located at ca. 16, 40, and 80 m of depth, and characterized by CO2 emissions to assess the effects of acidification on meio- and macrobenthic assemblages. Acidification caused significant changes in both meio- and macrofaunal assemblages, with a clear decrease in terms of abundance and a shift in community composition. A noticeable reduction in biomass was observed only for macrofauna. The most sensitive meiofaunal taxa were kinorhynchs and turbellarians that disappeared at the CO2 sites, while the abundance of halacarids and ostracods increased, possibly as a result of the larger food availability and the lower predatory pressures by the sensitive meiofaunal and macrofaunal taxa. Sediment acidification also causes the disappearance of more sensitive macrofaunal taxa, such as gastropods, and the increase in tolerant taxa such as oligochaetes. We conclude that the effects of shallow CO2-vents result in the progressive simplification of community structure and biodiversity loss due to the disappearance of the most sensitive meio- and macrofaunal taxa.

Soil invertebrates of coniferous forests along a gradient of air pollution (Komi Republic).

BackgroundThe role of soil invertebrates in the cycle of substances, soil-forming processes and the provision of ecosystem services is undeniable. Therefore, soil invertebrates are valuable in bioindication studies. Comprehensive research of soil invertebrates in the production area of Mondi Syktyvkar JSC as the largest pulp and paper enterprise in the European part of Russia was initiated in 2003. A huge amount of data about composition, abundance and structure of soil macro- and mesofauna along an impact gradient was accumulated during the period from 2003 to 2019 years. These data can be used to study local biodiversity, monitor the state of soil invertebrate communities and assess the impact of the pulp and paper industry on the environment.New informationDatasets here presented include information from a monitoring programme for soil invertebrates that inhabit coniferous forests in the production area of Mondi Syktyvkar JSC (Komi Republic). The assemblages' structure of macrofauna, collembolans and nematodes are described. Information on the number of individuals of springtail species, nematodes genera and macrofauna taxa is given. A total of 11146 sampling events of macrofauna, 6673 sampling events of Collembola, and 2592 sampling events of Nematoda are recorded along a gradient of air pollution from pulp and paper industry emissions.

Soil macrofauna: Study problems and perspectives

The soil macrofauna, including animals between 1–2 mm and 20–30 mm in size, uses soil differently from the mesofauna, which lives in cavities, or microfauna that inhabits water films. In some ecosystems, the macrofauna accounts for most of the total soil animal biomass and substantially contributes to soil food-web functioning. Additionally, the macrofauna can be among the most diverse groups in the soil environment. A few macrofaunal taxa (e.g. earthworms and termites) are considered to be ecosystem engineers attracting research focus, while studies on most other soil macrofauna remain scattered and uneven. An analysis of 80 publications conducted for this study showed inconsistent definitions of soil macrofauna by specialists. Further, a comparison of taxa listed among the soil macrofauna and mesofauna deduced that researchers allocate soil animals to either group by higher-level taxonomic categories and not by size. The main challenge in soil macrofaunal surveys is the extremely high diversity of species from widely different taxa, which require highly specialised taxonomists to identify them to species level. The abovementioned publication analysis showed that small taxa, mainly insects, are often not surveyed. In addition, animals of the same species at different ontogenetic stages that coinhabit the soil are not analysed separately. This tendency leads to an underestimation of the abundance and biomass of early larval stages. Hence, the soil macrofauna is seldom included in analyses of soil ecosystem functioning and modelling. Synchronised and unified studies across biomes could draw more attention to this size group and increase research focus and output from soil ecologists and other scientists.

Benthic metabolism on Chatham Rise, New Zealand continental margin: Temporal and spatial variability, and relationships with macrofauna and environmental factors

Predicting the impacts of anthropogenic disturbance on deep-sea ecosystems requires a thorough understanding of both environmental and faunal drivers of ecosystem function. Studies of deep-sea ecosystems, however, typically consider environmental drivers only and seldom investigate the effects of seabed communities on ecosystem processes. Here, we describe spatial and temporal variation in sediment community oxygen consumption (SCOC), a measure of benthic metabolism and carbon mineralisation, across several sites on Chatham Rise, off the east coast off New Zealand's South Island, and investigate relationships between environmental factors, macrofauna community parameters, and SCOC in order to quantify their relative contributions to benthic metabolism. SCOC differed significantly among sites but not between the two sampling events in August and December 2015. SCOC was significantly and most strongly correlated with estimated particulate organic carbon flux in both August and December in marginal regressions (R2 = 0.53–0.61), followed by macrofaunal abundance (0.28–0.52), macrofaunal taxon richness (0.09–0.50) and water depth (0.30–0.35). Variation partitioning analysis showed that in late winter (August), most of the variability in SCOC was accounted for by environmental variables independently of macrofauna, whereas in summer (December), most of the variability in SCOC was accounted for by the combined effects of environment and macrofauna. We also observed a greater effect of macrofauna independent of environment in summer than in late winter (R2 = 0.13 and 0.05, respectively). Our findings indicate that the contribution of macrofauna to benthic metabolism can be substantial and vary temporally. In addition, our findings suggest that the shifts in ecosystem function resulting from anthropogenic stressors will be difficult to predict due to the interactive effects of environment and macrofauna on benthic metabolism. Nevertheless, if particulate organic carbon flux decreases on Chatham Rise as predicted in climate change scenarios, we anticipate that impacts on benthic metabolism will be most strongly felt in the less productive areas of the rise due to the stronger link between macrofauna and SCOC at low macrofaunal densities.

Contribution of soft-bodied meiofaunal taxa to Italian marine biodiversity

Meiofauna includes an astonishing diversity of organisms, whose census is far from being complete. Most classic ecological studies have focused on hard-bodied Ecdysozoan taxa (notably Copepoda and Nematoda), whose cuticle allows determination at species-level after fixation, rather than soft-bodied, Spiralian taxa, which most often lose any diagnostic feature in fixed samples. Yet, metabarcoding studies have recently revealed a species-richness of soft-bodied taxa comparable, and in cases superior, to that of Copepoda and Nematoda together. However, given objective difficulties inherent to their study, which necessarily has to be performed on living individuals, and their limited utilisation for ecological and applicative research, taxonomic expertise on soft-bodied organisms has declined over the years, and diversity of these phyla in most areas of the world is presently completely unknown. Here we present an expert-based survey of current knowledge on the composition and distribution of soft-bodied meiofaunal taxa in Italy, with special references to the predominantly or exclusively meiobenthic phyla Gastrotricha, Gnathostomulida, Platyhelminthes, Rotifera, Xenacoelomorpha, and macrofaunal taxa with conspicuous meiofaunal representatives (Annelida, Mollusca and Nemertea). A total of 638 described species have been reported from Italian coasts; furthermore, the existence of a large number of undescribed species is mentioned. Knowledge of Annelida, Gastrotricha, and Rotifera appears particularly detailed, placing Italy among the best-known country worldwide. In contrast, knowledge of Platyhelminthes and Xenacoelomorpha appears patchy, and limited to few areas. Sampling effort has been uneven, with most species recorded from the Tyrrhenian Sea, while large sections of the Adriatic and Ionian seas have been poorly explored. Results highlight the role that Marine Biological Stations, notably the Zoological Station “Anton Dohrn” in Naples, have had in promoting the study of soft-bodied taxa in Italy.

Biodiversity, trait composition and ecological functioning: impacts of coastal urbanisation on subtropical mudflats

The world’s coastlines have become heavily modified over the last century, with the adjacent natural habitats declining in biodiversity and health under increasing pressure from urbanisation. In this study we assessed the structure and biological traits of macrofaunal assemblages from 24 south-east Queensland mudflats in order to determine whether ecological functioning (e.g. primary production, nutrient cycling) and the delivery of ecosystem services was affected by urbanisation. This work represents the most comprehensive assessment of mudflat assemblages in the region to date. The mudflats contained 50 macrofaunal taxa and so were comparable to other local intertidal systems. Summer assemblages contained more species, more individuals and had differing taxonomic composition. When indexed as a proportion of subcatchment area, urbanisation did not correspond to a clear impact on macrofaunal composition; rather, the nature of the industry or activity was critical. Mudflats from subcatchments with industries producing organic wastes significantly differed from subcatchments with <1.3% cover of these industries. Functioning was conserved in mudflats experiencing current levels of enrichment, but this may decline with growing pressure from human populations. The results of this study illustrate that large-scale spatial data, such as from satellites, can be used to detect the cumulative effects of urbanisation when the pressures are highly resolved.

Reduced macrofauna diversity and abundance in response to red macroalgal detritus

Macrophyte detritus from exogenous sources can play an important role in structuring benthic communities. Macrofaunal responses to seagrass wrack, mangrove leaf litter, and detritus from brown and green macroalgae have previously been examined through enrichment experiments. Yet effects from red macroalgal detritus, which is a major component of algal drift in many regions, are not well understood. In this study, enrichment experiments were performed on a shallow subtidal sandflat in Puget Sound, Washington, USA with detritus from three species of red macroalgae to assess: (1) whether macrofaunal assemblages were affected by two different “dosages” of red macroalgal enrichment (100 ml vs 500 ml per 0.079 m3 of sediment); (2) whether macrofaunal response differed between one-time and repeated (weekly) additions of red macroalgae; and (3) whether responses to red macroalgal enrichment changed over time. There appeared to be little or no effect on macrofauna from one-time enrichment regardless of the amount/dosage of algae added. However, weekly additions of red macroalgae led to negative responses across macrofaunal taxa. These responses occurred rapidly, within the first 3 weeks, and were largely unchanged after 7 weeks, intensifying for only 2 of the 10 most common taxa. No opportunistic responses to weekly additions were observed. Frequent influx of some types of red macroalgae may degrade the quality of sedimentary habitats by leaching chemically defensive compounds or through other mechanisms, which should be investigated in future studies. Although weekly enrichment treatments were informed by previous estimates of detrital delivery rates near hard-bottom habitats in the same locality, further research is needed to assess detrital influx frequency and community response in other regions where red macroalgal detritus is common, and to understand the broader implications of exogenous detritus from red macroalgae on benthic ecosystems.

Changes of Benthic Macrofaunal Composition on a Tidal Flat of Río Gallegos Estuary, Argentina

This work analyzed the variation in composition and abundance of benthic assemblages in an intertidal environment of the Rio Gallegos estuary, Argentina (51°35′ S - 69° 01′ W). The macrofauna was sampled in a tidal flat adjacent to the city in late summer of 2006 and 2013 (March). In total 27 macrofauna taxa were identified; the most abundant species were Darina solenoides (44%) in 2006 and Fabricinuda sp. (89%) in 2013. Biogenic structures composed of aggregates of polychaete (Fabricinuda sp.) tubes and sediment were observed for the first time in December 2006; they are spherical or of irregular shape, 1 to 3 m2 in area, and up to 50 cm in height. In 2013 benthic composition was compared between biogenic aggregates (“patch”) and the area outside them (“non-patch”). Species richness and total abundance of individuals were higher in the patch. The associated benthos was different; Fabricinuda sp. was dominant in the patch (107,780.7 indiv.m-2, SD = 44,772.6), and Kinbergonuphis dorsalis (2139 indiv.m-2, SD = 840) and Notocirrus lorum (1830 indiv.m-2, SD = 516.4) in the non-patch. In 2013, four taxa that were not found in 2006 were recorded only in the patch samples, two bivalves (Sphenia hatcheri and Malletia cumingii) and two polychaetes (Fabricinuda sp. and Ophioglycera eximia). Polychaete aggregations have produced changes in number and abundance of benthic species at the lowest level of the tidal flat.

Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

Submarine canyons are major conduits of terrestrial and shelf organic matter, potentially benefiting the seafloor communities in the food-deprived deep sea; however, strong bottom currents driven by internal tides and the potentially frequent turbidity currents triggered by storm surges, river flooding, and earthquakes may negatively impact the benthos. In this study, we investigated the upper Gaoping Submarine Canyon (GPSC), a high-sediment-yield canyon connected to a small mountain river (SMR) off southwest (SW) Taiwan. By contrasting the benthic meiofaunal and macrofaunal communities within and outside the GPSC, we examined how food supplies and disturbance influenced the benthic community assemblages.The benthic communities in the upper GPSC were mainly a nested subset of the adjacent slope assemblages. Several meiofaunal (e.g. ostracods) and macrofaunal taxa (e.g. peracarid crustaceans and mollusks) that typically occurred on the slope were lost from the canyon. The polychaete families switched from diverse feeding guilds on the slope to motile subsurface deposit feeders dominant in the canyon. The diminishing of epibenthic peracarids and proliferation of deep burrowing polychaetes in the GPSC resulted in macrofauna occurring largely within deeper sediment horizons in the canyon than on the slope. The densities and numbers of taxa were depressed with distinct and more variable composition in the canyon than on the adjacent slope. Both the densities and numbers of taxa were negatively influenced by internal tide flushing and positively influenced by food availability; however, the internal tides also negatively influenced the food supplies. While the meiofauna and macrofauna densities were both depressed by the extreme physical conditions in the GPSC, only the macrofaunal densities increased with depth in the canyon, presumably related to increased frequency and intensity of disturbance toward the canyon head. The population densities of meiofauna, on the other hand, rebounded more rapidly due to their fast growth rate and short generation time and thus did not display bathymetric pattern in the canyon.To our knowledge, this is the first benthic ecological study in a submarine canyon connected to a high-sediment-yield SMR. The biological responses to extreme physical conditions in the GPSC could have broad implications on understanding the anthropogenic and climate change impacts in the deep-sea ecosystems.

The Community Structure of Deep-Sea Macrofauna Associated with Polymetallic Nodules in the Eastern Part of the Clarion-Clipperton Fracture Zone

Deep-sea areas characterized by the presence of polymetallic nodules are getting increased attention due to their potential commercial and strategic interest for metals such as nickel, copper and cobalt. The polymetallic nodules occur in areas beyond national jurisdiction, regulated by the International Seabed Authority (ISA). Under exploration contracts, contractors have the obligation to determine the environmental baseline in the exploration areas. Despite a large number of scientific cruises to the central east Pacific Ocean, few published data on the macrofaunal biodiversity and community structure are available for the abyssal fields of the Clarion-Clipperton Fracture Zone (CCFZ). This study focused on the macrofaunal abundance, diversity and community structure in three physically comparable, mineable sites located in the license area of Global Sea Mineral Resources N.V., at ~ 4500 m depth. A homogeneous but diverse macrofaunal community associated with the sediment from polymetallic nodule areas was observed at a scale of 10s to 100s of km. However, slight differences in the abundance and diversity of Polychaeta between sites can be explained by a decline in the estimated flux of particulate organic carbon (POC) along a southeast-northwest gradient, as well as by small differences in sediment characteristics and nodule abundance. The observed homogeneity in the macrofaunal community is an important prerequisite for assigning areas for impact and preservation reference zones. However, a precautionary approach regarding mining activities is recommended, awaiting further research during the exploration phase on environmental factors structuring macrofaunal communities in the CCFZ. For instance, future studies should consider habitat heterogeneity, which was previously shown to structure macrofauna communities at larger spatial scales. Acknowledging the limited sampling in the current study, a large fraction (59-85%; depending on the richness estimator used and the macrofaunal taxon of interest) of the macrofaunal genus/species diversity from the habitat under study was characterized.

Temporal and spatial variations in the polychaete (Annelida) populations on the upper continental slope of the northern Gulf of Mexico

Polychaete worms (Annelida), the dominant macrofaunal taxon in most fine-grained marine sediments, were sampled in 1983–85 and then again in 2000–02 at nine locations at depths of 324–1454m. on the upper continental slope of the northern Gulf of Mexico (GoM). The assemblages exhibited relative stability in abundance and diversity, but fell into six separate groups of species (>35% similarity) that were related to time-of-sampling, location, depth. This depth gradient experiences an increase in oxygen from 2.5 to 4.5ml/L, a six degree decrease in temperature (10–12° down to 4°C) and a decline of 30–37mgCm−2day−1 down to 7mgCm−2day−1 in estimates of the particulate organic carbon (POC) input to the sea floor, but these steep gradients had secondary effects on species turnover or depth-related zonation (Beta diversity). The species composition of four of the six groups was separated on the basis of sampling between 1983–85 and 2000–02 as opposed to depth or location. The species composition of the two groups on the eastern transect was different from the western sites and the two eastern groups differed in species composition from each other between 1983–85 and 2000–02. The two groups of species at the three deeper sites to the west (864–1410m) were also separated on the basis of time-of-sampling but the group of species located at the three shallow locations (324–625m) was not; it was a mixture of the two sampling periods. Significantly higher densities (p<0.05) in April 1984, on the eastern transect, suggest that seasonal recruitment may have occurred but the higher densities were attributed to only two species.

Artificial hard substrate as a habitat for hard bottom benthic assemblages in the southern part of the Baltic Sea – a preliminary study

Abstract Benthic species associated with hard substrate are known to form communities characterized by high abundance and biomass. Although the bottom of the Southern Baltic Sea is dominated by soft sediments, such communities find favorable conditions to thrive on artificial substrates of offshore constructions. The aim of this research was to characterize both short-term and long-term benthic communities associated with artificial hard bottom provided by man-made structures in the Southern Baltic Sea. Species composition as well as the abundance and biomass were examined at various sites. An inactive World War II torpedo testing facility in the Gulf of Gdansk served as a site for sampling long-term communities while short-term communities were sampled using settlement panels and PVC cylinders. Panels were deployed at the torpedo testing facility for 127 days. PVC cylinders were deployed for 141-190 days in the Polish Exclusive Economic Zone. Twenty six macrofaunal taxa, including 12 crustaceans, were identified during the research. Mytilus edulis and Amphibalanus improvisus were the most abundant invertebrates at sampled surfaces. Six non-indigenous species were found. For the first time adult individuals of Mytilopsis leucophaeata were found in the Polish Marine Areas indicating that it is possible for this non-indigenous species to reproduce in this region.

Reef flattening effects on total richness and species responses in the Caribbean.

There has been ongoing flattening of Caribbean coral reefs with the loss of habitat having severe implications for these systems. Complexity and its structural components are important to fish species richness and community composition, but little is known about its role for other taxa or species-specific responses. This study reveals the importance of reef habitat complexity and structural components to different taxa of macrofauna, total species richness, and individual coral and fish species in the Caribbean. Species presence and richness of different taxa were visually quantified in one hundred 25-m(2) plots in three marine reserves in the Caribbean. Sampling was evenly distributed across five levels of visually estimated reef complexity, with five structural components also recorded: the number of corals, number of large corals, slope angle, maximum sponge and maximum octocoral height. Taking advantage of natural heterogeneity in structural complexity within a particular coral reef habitat (Orbicella reefs) and discrete environmental envelope, thus minimizing other sources of variability, the relative importance of reef complexity and structural components was quantified for different taxa and individual fish and coral species on Caribbean coral reefs using boosted regression trees (BRTs). Boosted regression tree models performed very well when explaining variability in total (82·3%), coral (80·6%) and fish species richness (77·3%), for which the greatest declines in richness occurred below intermediate reef complexity levels. Complexity accounted for very little of the variability in octocorals, sponges, arthropods, annelids or anemones. BRTs revealed species-specific variability and importance for reef complexity and structural components. Coral and fish species occupancy generally declined at low complexity levels, with the exception of two coral species (Pseudodiploria strigosa and Porites divaricata) and four fish species (Halichoeres bivittatus, H. maculipinna, Malacoctenus triangulatus and Stegastes partitus) more common at lower reef complexity levels. A significant interaction between country and reef complexity revealed a non-additive decline in species richness in areas of low complexity and the reserve in Puerto Rico. Flattening of Caribbean coral reefs will result in substantial species losses, with few winners. Individual structural components have considerable value to different species, and their loss may have profound impacts on population responses of coral and fish due to identity effects of key species, which underpin population richness and resilience and may affect essential ecosystem processes and services.

Composition and abundance of epibenthic-sledge catches in the South Polar Front of the Atlantic

An epibenthic sledge (EBS) was deployed at seven different deep-sea stations along the South Polar Front of the Atlantic in order to explore the composition and abundance of macrofaunal organisms and to identify the most abundant taxa in this transition zone to the Southern Ocean. In total 3,130 specimens were sampled by means of the EBS on board of RV Polarstern during the expedition ANT-XXVIII/3 in the austral summer of 2012. Benthic and suprabenthic Crustacea occurred to be most frequent in the samples. Among those, copepods were by far most numerous, with 1,585 specimens followed by the peracarid taxa Isopoda (236ind.), Amphipoda (103ind.), Tanaidacea (78ind.) and Cumacea (50ind.). Annelida were represented by a high number of specimens belonging to different polychaete taxa (404ind.). The molluscan fauna was clearly dominated by Bivalvia (255ind.), followed in numbers of specimens by Gastropoda (47ind.). The deep-sea benthos sampled along the Southern Polar Front occurred in surprisingly low abundances, contrasting the largely high surface productivity of the area. Numbers of specimens across different macrofaunal taxa and especially of peracarid crustaceans underscored by far those from South Ocean sites at higher latitudes in the Weddell Sea.

Diversity and composition of macro- and meiofaunal carapace epibionts of the hawksbill sea turtle (Eretmochelys imbricata Linnaeus, 1822) in Atlantic waters

The presence of macro-epibionts on turtle carapaces is a well-known phenomenon, whereby carapaces are occupied by dynamic and fully functional epibiont communities. However, meiofaunal organisms have been largely ignored in turtle shell studies despite their omnipresence and higher abundances and diversity than the macrofauna. Epifauna from the hawksbill sea turtle Eretmochelys imbricata was investigated during summer 2010 with the aim to advance our knowledge on meiofaunal epibiont communities on turtle carapaces and gain insights into their interaction with settled macrofauna. Eighteen epibiont higher taxa were found (17 meiofauna, 5 macrofauna), 5 of which are common for macro- and meiofauna. Meiofauna was present on all turtle carapaces, but macrofauna occurred on only 8 out of 19 investigated carapaces, suggesting that carapace colonization by meiofauna precedes macrofauna recruitment. In addition, the macrofauna embedded on the carapaces increased the microhabitat complexity, favoring richer and more abundant meiofauna communities. The significant positive correlations between meiofauna and macrofauna taxa (up to 90 %) suggests the presence of mutual facilitating processes and indicates the positive effects between meio- and macrofaunal epibionts important for their recruitment and establishment. The hawksbill sea turtle carapaces were occupied by fully functional and active epifaunal communities, with adult and reproductive stages for most meiofaunal and macrofaunal taxa. Turtle carapaces can therefore be seen as a biological substrate that can serve as a platform for faunal dispersal, as has been observed for barnacles, enhancing the geographical distribution of several species through sea turtle migration. In addition to the main focus of this paper on meio- and macrofaunal epibiont communities, we provide an updated list of taxa found on carapaces of the hawksbill sea turtle and discuss the geographical scope and dispersion potential of some of these taxa.

Macrofauna Activity Density in Contrasting Tillage Systems in Buenos Aires Province, Argentina

In Argentina, two tillage systems are used, conventional tillage (CT) and no‐till (NT). The aim was to determine the ground‐dwelling macrofauna taxa and compare the impacts of both NT and CT on their activity density. Samples were taken within wheat (Triticum aestivum L.) (August–December) and maize (Zea mays L.) (November–April) crop fields under CT and NT during three cropping seasons (Cycles 1, 2, and 3). Ten pitfall traps 10 m apart were placed in each field. Traps were collected every 15 d throughout the crop cycles to determine activity density (individuals plot–1) of soil macrofauna. Invertebrates were counted and identified to the class level; Insecta were further identified to order, family, or species levels. Higher mean total macrofauna activity density was found under NT than CT for Cycle 1 in wheat and Cycles 1 and 3 in maize. Arachnida activity density was higher under NT than CT in only a few crop cycles. Carabidae showed no preference for any tillage system. Orthoptera showed more activity density under NT than CT. The activity density of the Lepidoptera and Hymenoptera specimens were higher under CT than NT in some wheat and maize seasons. Diplopoda and Crustacea had higher activity density under NT than CT. In conclusion, the total activity density was consistently greater under NT, but there were differences within taxonomic groups.

Metals in benthic macrofauna and biogeochemical factors affecting their trophic transfer to wild fish around fish farm cages

Benthic macroinvertebrates and wild fish aggregating in the vicinity of four Mediterranean fish farms were sampled. Concentrations of metals and other elements were measured in macrofaunal taxa and in fish tissues (muscle, liver, gills, bone, gonad, stomach, intestine, and stomach content). Biological and geochemical characteristics play an important role in metal accumulation in benthic invertebrates, and consequently in metal transfer to higher trophic levels. Macroinvertebrates accumulated lower concentrations of most metals and elements than their respective sediment, except As, P, Na, Zn and Cd. Elemental concentrations of benthic organisms increased with increasing sediment metal content, except Cd, and with % silt, refractory organic matter and chlorophyll-a of sediment due to the influence of sediment geochemistry on metal bioavailability. Tolerant species were found to accumulate higher concentrations of most metals and elements, except for Cd, than equilibrium species. The ecological and morphological characteristics of the benthic invertebrates can affect the bioaccumulation of metals and elements in macrobenthos. Hg and P were found to increase their concentrations from zoobenthos to wild fish aggregating around fish cages feeding on macrofauna.

Paleobathymetry of foraminiferal assemblages from the Pliocene of the Western Sahel (North-Algeria)

The assessment of paleobathymetry is essential in paleogeographic reconstructions, and generally relies on the extrapolation of the depth distribution of modern taxa to fossil forms. Methods to estimate paleobathymetry take into account the depth range in which individual taxa have been encountered or parameters related to the depth variations found on present day bathymetric transects, as the planktic/benthic (P/B) ratio. This study presents a quantitative analysis of paleobathymetry of foraminiferal assemblages from the Pliocene of Western Sahel, complementing previous paleobathymetric reconstructions based on semi-quantitative data from macrofaunal taxa. The foraminiferal assemblages are assessed through correspondence analysis and resulting sample scores are plotted according to the main variability factor which is interpreted to reflect paleobathymetry. The calibration of the scores in terms of water depth allows a detailed bathymetric interpretation of the obtained curve. The validity of reconstructed paleodepths is tested against the bathymetries calculated from the P/B ratio.

Comparative Composition, Diversity and Trophic Ecology of Sediment Macrofauna at Vents, Seeps and Organic Falls

Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct macrofaunal assemblages at broad-scales contributing to ß diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities.