Macrofaunal Composition Research Articles

Temporal changes in benthic macrofauna on the west coast of Norway resulting from human activities

Quantitative analyses of soft bottom invertebrate fauna from four Norwegian sill fjords show increased macrofaunal abundance, species richness, and a considerably changed benthic deep water macrofaunal composition in the inner parts of the fjord system. In retrospect, the analyses show significantly altered benthic macrofaunal community structure that was not reflected by the changes in the Shannon-Wiener diversity indices during regular monitoring. The observed changes are mainly due to an increased abundance of opportunistic species, especially of the polychaete Polydora sp. during the last 10–15 years which is correlated significantly to declining dissolved oxygen, rising temperature in the bottom water and increasing total organic matter in the sediment. Possible anthropogenic and climatic impact factors related to the observed macrofaunal changes and environmental consequences of the changes are discussed.

Rubber plantation ageing controls soil biodiversity after land conversion from cassava

The rapid expansion of perennial crops is a major threat to biodiversity in Southeast Asia. The biodiversity losses related to the conversion of forest lands to oil palm or rubber plantations (RP) are well documented by recent studies. However, the impact of the conversion from intensively managed annual crops to perennial crops on soil biodiversity has not yet been addressed. This study aims at assessing the impact on soil biodiversity of a) the short-term effect of land use conversion from cassava crop to RP, and b) the long-term effect of RP ageing. Soil biodiversity (bacterial, fungal and macrofaunal), microbial activities and pedoclimatic characteristics were measured over a chronosequence of 1–25 years old of RP compared to cassava fields, the former crop, in Thailand. The conversion from cassava to young RP (1–3 yr) had a significant effect on microbial biomass and activities and fungal composition, but did not impact the bacterial and macrofaunal diversity. This effect of land use conversion could be explained by the change in land management due to the cultivation of pineapple in the inter-row of the young RP. Canopy closure appeared to be the main driver of soil biota shifts, as most of the biotic parameters, composition, abundance and activities were significantly modified after 7 years of RP. The changes of composition in older rubber plantations originated from the dominance of Trichoderma (fungi), Firmicutes (bacteria), and earthworms. Old rubber plantations (23–25 yr) harboured the highest microbial and macrofaunal biomass; however, they were also characterised by a significant decrease in bacterial richness. The change in pedoclimatic conditions across the rubber chronosequence, i.e. increase in soil moisture, litter and organic carbon content, was a stronger driver of soil biota evolution than land use conversion. The macrofaunal composition was more resistant to land use conversion than the bacterial composition, whereas the microbial biomass was sensitive to land use conversion, but showed resilience after 20 years. However, bacterial, fungal and macrofaunal diversity, macrofaunal and microbial biomass and microbial activities were all sensitive to RP ageing.

Caracterización ecológica de la macrofauna edáfica en dos sitios de bosque siempreverde en El Salón, Sierra del Rosario, Cuba

The richness, abundance, diversity and functional composition of soil macrofauna were studied in two sites of the evergreen medium forest (Helechal and Vallecito), located at the Ecological Reserve El Salon from Sierra del Rosario; they were analyzed with respect to other land use systems evaluated in Cuba. The macrofauna was collected in situ from 25 × 25 × 20 cm monoliths extracted from the soil. In this type of ecosystem, 34 families of the edaphic macrofauna belonging to 18 orders were found. The Vallecito site showed higher families richness, density and diversity of the macrofauna (34 families, 1,298.5 individuals m-2 and H’ = 2.72) compared to Helechal (19 families, 749.2 individuals m-2 and H’ = 2.57). Although, only richness showed significant differences between the two locations. The seasonality in the sampling marked the variations between the sites, which was carried out during a rainy month in Helechal (October 2009) and during a dry month in Vallecito (March 2011). The functional composition of the edaphic community was similar in both sites, where the most outstanding guilds were litter detritivores, soil engineers and predators. However, the dominant families within each functional group changed between sites. The structure found of the macrofauna was very similar to those of other tropical forests, and hardly changed in relation to secondary forests studied in Cuba, although it did change in relation to more disturbed systems such as pastures and crops.

Spatial and seasonal changes in benthic macrofauna from two dissipative sandy beaches in eastern Brazil)

Abstract Sandy beaches are dynamic ecosystems with strong interaction of sediments, waves and tidal energy, with marked effects on benthic assemblages. Although there are numerous efforts in understanding spatial-temporal variation of benthic macrofauna on sandy beaches along the southern and southeastern Marine Ecoregions in Brazil, there is poor sampling along beaches of the Eastern Marine Ecoregion (EME). Here we examined spatial and temporal scales of variability in benthic macrofauna (> 500 µm) through a hierarchical sampling of two dissipative sandy beaches within the EME between two seasons (winter 2011 and summer 2012). We tested the hypothesis that spatial changes (i.e., meters to hundreds of meters scales) in the structure of benthic assemblages will be more pronounced compared to the weak seasonal fluctuations at this tropical region. We found weak temporal and spatial changes in sediment grain size and beach slope, but differences in macrofaunal assemblages were evident. Contrary to our hypothesis, hierarchical sampling indicated significant changes in macrofaunal composition and density at multiple local scales (meters to hundreds of meters) and on seasonal scales. The macrofauna density and composition was directly related to changes on the sediment organic matter and grain size.

Short-term effects of non-grazing on plants, soil biota and aboveground-belowground links in Atlantic mountain grasslands

Mountain grasslands in the Iberian Peninsula are the result of extensive grazing. However, a progressive abandonment of grazing activity is currently observed in the study region. The objective of this work was to evaluate the short-term (2 years) effects of non-grazing on the diversity and composition of plants, soil microorganisms (prokaryotes, fungi, arbuscular mycorrhiza), mesofauna, macrofauna and aboveground-belowground links, through the study of 16 grazed vs. non-grazed areas in Atlantic grasslands located in the Basque Country (Spain). Sites were divided between 4 habitat types with different elevation, pasture productivity, vegetation type and parent material. Herbivores appeared to influence plant community composition, contributing to increase aboveground diversity, while having unequal effects on belowground communities depending on the organisms analysed. This may be explained by the different habitat and trophic level of each soil organism, which may be more or less affected by the predominating negative effects of grazing, such as soil compaction, and only partially compensated by other positive effects. Finally, habitat type appeared to be the strongest influence on both above- and belowground communities, also influencing the effect of the absence of grazing.

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.

Long-term (1998 vs. 2010) large-scale comparison of soft-bottom benthic macrofauna composition in the Gulf of Lions, NW Mediterranean Sea

We achieved a long term (i.e., 1998 vs. 2010) large scale (i.e., whole Gulf of Lions) study of benthic macrofauna composition in the Gulf of Lions based on the resampling of 91 stations located along 21 inshore-offshore transects. Results show that the 3 main benthic communities identified in 1998 were still present in 2010 although their composition changed. Using only year and station of sampling we found a significant space-time interaction explaining changes in macrofaunal community composition, and, in this study, stations differ primarily in terms of depth and distance to the Rhône river mouth. Temporal changes in benthic macrofauna composition were clearly most important at shallow stations (i.e., in the Littoral Fine Sand community) than at deep ones (i.e., Terrigenous Coastal Mud community). These results are in good agreement with the current paradigm according to which climatic oscillations such as NAO (North Atlantic Oscillation) and WeMO (Western Mediterranean Oscillation) are indirectly (i.e., through changes in the frequency of occurrence and the intensity of storms) controlling benthic macrofauna composition in the Gulf of Lions. This hypothesis is further supported by a meta-analysis of changes in the average and maximal yearly abundances of the polychaete Ditrupa arietina. At last, the spatial modelling of 1998 and 2010 benthic macrofauna compositions both suggested a significant effect of Rhône River inputs on the spatial distribution of benthic macrofauna in the Gulf of Lions.

Composition of abyssal macrofauna along the Vema Fracture Zone and the hadal Puerto Rico Trench, northern tropical Atlantic

We analyzed composition and variations in benthic macrofaunal communities along a transect of the entire length of the Vema-Fracture Zone on board of RV Sonne (SO-237) between December 2014 and January 2015 in order to test whether the Mid-Atlantic Ridge serves as a barrier limiting benthic taxon distribution in the abyssal basins on both sides of the ridge or whether the fracture zone permits the migration of species between the western and eastern abyssal Atlantic basins. The Puerto Rico Trench, much deeper than the surrounding abyssal West Atlantic, was sampled to determine whether the biodiversity of its hadal macrofauna differs from that of the abyssal Atlantic.The composition of the macrofauna from the epibenthic sledge catches yielded a total of 21,332 invertebrates. Crustacea occurred most frequently (59%) with 12,538 individuals followed by Annelida (mostly Polychaeta) (26%) with 5491 individuals, Mollusca (7%) with 1458 individuals, Echinodermata (4%) with 778 individuals, Nematoda (2%) with 502 individuals and Chaetognatha (1%) with 152 and Porifera (1%) with 131 individuals. All other taxa occurred with overall less than ten individuals (Hemichordata, Phoronida, Priapulida, Brachiopoda, invertebrate Chordata, Echiurida, Foraminifera (here refereed to macrofaunal Komokiacea only), Chelicerata, Platyhelminthes). Within the Crustacea, Peracarida (62.6%) with 7848 individuals and Copepoda (36.1%) with 44,526 individuals were the most abundant taxa. Along the abyssal Vema-Fracture Zone macrofaunal abundances (ind./1000m2) were generally higher on the eastern side, while the highest normalized abundance value was reported in the Puerto Rico Trench at abyssal station 14-1 2313 individuals/1000m2. The lowest abundance was reported at station 11-4 with 120 ind./1000m2 located at the western side of the Vema-Fracture Zone. The number of major macrofaunal taxa (phylum, class) ranged between five (stations 12-5, 13-4 and 13-5 at hadal depths in the Puerto Rico Trench) and 14 (station 9-8) in the western abyssal basin of the Vema-Fracture Zone. Differences are seen in the distribution of Porifera at macrofaunal level between eastern and western sides of the Vema-Fracture Zone. Macrofaunal composition of the study area is compared with data from other expeditions in the Atlantic and the northwest Pacific Ocean.

Macrofaunal community structure in Bahía Concepción (Chile) before and after the 8.8 Mw Maule mega-earthquake and tsunami

Faunal assemblages of subtidal sedimentary environments are key components of coastal ecosystems. Benthic communities inhabiting the coastal zone near urban centers in Concepción Bay (Chile) have been described as highly disturbed (i.e. impoverished in diversity and species richness). This is due to the frequent presence of hypoxic conditions at the bottom due to the intrusion of low oxygen Equatorial Subsurface Water, high natural productivity and the high load of organic matter generated by several anthropogenic activities. A mega-earthquake (8.8 Mw) and subsequent tsunami occurred on the coast of south-central Chile on February 27, 2010 (27F), heavily impacting Concepción Bay, which is located 30 km south of the epicenter. The objectives of the present study are: (i) to evaluate the effect produced by the mega-earthquake and tsunami on the benthic community, and (ii) to assess dissimilarity in macrofauna composition and abundance in Concepción Bay at an inter-decadal time scale based on a comparison between our sampling conducted between 2010 and 2013 and information published since 1969. Our results show that the benthic macrofauna of Concepción Bay was disturbed by the 27F (i.e. high community dissimilarity in 2010). Changes in community structure were observed at an inter-annual scale (i.e. diminished community dissimilarity in 2013), suggesting a recovery post-27F. At an inter-decadal scale, community structure post-27F was dissimilar to the structure described for the 1980's and 1990's but more similar to that reported for 1969. The reducing conditions of the sediments due to the high input of organic matter that took place in the 1980's and 1990's may explain this dissimilarity.

Small proportions of silt linked to distinct and predictable differences in marine macrofaunal assemblages on the continental shelf of the Pacific Northwest

Increasing interest in offshore development has motivated intensified efforts to map the seafloor for marine spatial planning. However, surficial geologic maps do not accurately represent habitats for various species groups of concern. This study used a bottom-up approach to integrate macrofaunal densities and benthic conditions on the Pacific Northwest shelf to identify macrofaunal assemblages and associated habitat features. Benthic cores and water-column profiles were collected from 137 stations from 50 to 110m depth. Analyses grouping stations based on both similar species abundances and benthic conditions resulted in six broad habitats. Within the sampled depth and latitudinal range, sediment characteristics were the primary structuring variable. A major break in assemblages was detected between sediment that had less than 1% silt/clay and those containing more than 1% silt/clay. Assemblages differed primarily in the bivalve species present and secondarily in polychaete species. Within the greater than and less than 1% silt/clay habitats, further discretization of assemblages was based mostly on differing abundances of characteristic bivalves and polychaetes associated with differing median grain sizes, which did not correspond to traditional definitions of fine or medium sand. These data show that a bottom-up methodology is necessary to discern habitats for macrofauna and that site-specific physical sampling is necessary to predict macrofaunal assemblage composition. However, if detailed sediment characteristics are known, macrofaunal assemblages may be predicted without time-intensive biological sampling and processing. These results also indicate that seemingly small sedimentary changes due to offshore installations may have measureable effects on the relative abundances and even the species composition of macrofauna.

KEANEKARAGAMAN MAKROFAUNA TANAH PADA BERBAGAI TIPE TEGAKAN DI AREAL BEKAS TAMBANG SILIKA DI HOLCIM EDUCATIONAL FOREST, SUKABUMI, JAWA BARAT Soil Macrofauna Diversity on Various Types of Stands in Silicas’ Post-Mining Land in Holcim Educational Forest...

Soil Macrofauna has a very important role in maintaining soil fertility through the decomposition of organic matter, nutrient distribution, increasing soil aeration and so on. The existence of soil macrofauna are very important in helping the process of rehabilitation of post-mining land because they contribute to the improvement of the physical, chemical, and biological properties of soil. The purposes of this study are to identify and quantify the diversity of soil macrofauna in various types of stands and land without stand in Holcim Educational Forest. The highest abundance of soil macrofauna was found in mixed stand with 240 individuals in nine plots of observation, each plot was 40 cm x 40 cm. Layers of soil (0-10 cm) has an abundance of soil macrofauna higher than in the litter layer, because soil layer can provide protection from direct sunlight and enough food for soil macrofauna. Mixed stand has the highest soil macrofauna diversity (H '= 2.52, DMG = 6.93, J' = 0.63), as it has a more diverse vegetation and highest canopy density. Environmental conditions such as soil temperature, canopy density, and soil organic matter can influence the composition and abundance of soil macrofauna, so that the soil macrofauna can be used as an indicator in monitoring environmental quality. Soil macrofauna that dominates in all the stands and land without stand, were red ants (Formicidae 7), termites (Rhinotermitidae 1), earthworms (Megascolecidae 1), and larvae of Coleoptera (Scarabaeidae 1).Key words: abundance, diversity, environment, soil macrofauna

Cold-seep-like macrofaunal communities in organic- and sulfide-rich sediments of the Congo deep-sea fan

Methane-rich fluids arising from organic matter diagenesis in deep sediment layers sustain chemosynthesis-based ecosystems along continental margins. This type of cold seep develops on pockmarks along the Congo margin, where fluids migrate from deep-buried paleo-channels of the Congo River, acting as reservoirs. Similar ecosystems based on shallow methane production occur in the terminal lobes of the present-day Congo deep-sea fan, which is supplied by huge quantities of primarily terrestrial material carried by turbiditic currents along the 800km channel, and deposited at depths of up to nearly 5000m. In this paper, we explore the effect of this carbon enrichment of deep-sea sediments on benthic macrofauna, along the prograding lobes fed by the current active channel, and on older lobes receiving less turbiditic inputs. Macrofaunal communities were sampled using either USNEL cores on the channel levees, or ROV blade cores in the chemosynthesis-based habitats patchily distributed in the active lobe complex.The exceptionally high organic content of the surface sediment in the active lobe complex was correlated with unusual densities of macrofauna for this depth, enhanced by a factor 7–8, compared with those of the older, abandoned lobe, whose sediment carbon content is still higher than in Angola Basin at same depth. Macrofaunal communities, dominated by cossurid polychaetes and tanaids were also more closely related to those colonizing low-flow cold seeps than those of typical deep-sea sediment. In reduced sediments, microbial mats and vesicomyid bivalve beds displayed macrofaunal community patterns that were similar to their cold-seep counterparts, with high densities, low diversity and dominance of sulfide-tolerant polychaetes and gastropods in the most sulfidic habitats. In addition, diversity was higher in vesicomyid bivalve beds, which appeared to bio-irrigate the upper sediment layers. High beta-diversity is underscored by the variability of geochemical gradients in vesicomyid assemblages, and by the vesicomyid population characteristics that vary in density, size and composition. By modifying the sediment geochemistry differently according to their morphology and physiology, the different vesicomyid species play an important role structuring macrofauna composition and vertical distribution. Dynamics of turbiditic deposits at a longer temporal scale (thousands of years) and their spatial distribution in the lobe area also resulted in high heterogeneity of the “cold-seep-like communities”. Dynamics of chemosynthetic habitats and associated macrofauna in the active lobe area resembled those previously observed at the Regab pockmark along the Congo margin and rapid succession is expected to cope with high physical disturbance by frequent turbiditic events and huge sedimentation rates. Finally, we propose a model of the temporal evolution of these peculiar habitats and communities on longer timescales in response to changes in distributary channels within the lobe complex.

Macroinvertebrate communities from the shallow soft-bottoms of Deception Island (Southern Ocean): A paradise for opportunists

Deception Island (South Shetland Islands) is an atypical spot in its Antarctic context, being a still active volcano with a submerged caldera. Although the sea-floor of its enclosed bay, Port Foster, has been extensively studied from 40 m down, little is known about the macrozoobenthic composition of its shallower areas. The aim of this study was to characterize the so far unexplored soft-bottom marine macroinvertebrate communities living within the first few meters depth in Port Foster. Eight sampling stations were selected, and three replicates per station and depth (5 and 15 m) were collected by SCUBA diving using 0.008 m-2 corers. Six clusters of samples were distinguished, showing a high variability in the composition of the shallow-water macrofauna. This heterogeneity did not appear to be related to the proximity of the sites to the open sea (entrance of the caldera) or depth, nor to the sediment type or the organic matter content. Overall, the assemblages within each cluster were generally dominated by highly abundant opportunistic species, including the annelids Capitella perarmata, Mesospio moorei, Leitoscoloplos kerguelensis, Apistobranchus glacierae, and Tharyx cincinnata, the amphipod Cheirimedon femoratus, and the bivalve Aequiyoldia eightsii. The remarkably high densities reported in several stations, suggest that the shallow-water environment of Port Foster is highly productive. In light of these results, we propose a general trophic web for the shallow waters of Port Foster linking the unusually high densities of macroinvertebrates with the also high occurrence of megafaunal echinoderms present in this area.

The vesicomyid bivalve habitat at cold seeps supports heterogeneous and dynamic macrofaunal assemblages

The high biodiversity found at cold seeps, despite elevated concentrations of methane and hydrogen sulfide, is attributed to multiple sources of habitat heterogeneity. In addition to geological and geochemical processes, biogenic habitats formed by large symbiont-bearing taxa, such as bivalves and siboglinid tubeworms, or by microbial mats drive the biodiversity of small-sized fauna. However, because these habitat-forming species also depend on geochemical gradients, the respective influence of abiotic and biotic factors in structuring associated macrofaunal communities is often unresolved. The giant pockmark Regab located at 3200m depth on the Congo margin is characterized by different fluid-flow regimes, providing a mosaic of the most common biogenic habitats encountered at seeps: microbial mats, mussel beds, and vesicomyid clam beds; the latter being distributed along a gradient of environmental conditions from the center to the periphery of the pockmark. Here, we examined the structure of macrofaunal communities in biogenic habitats formed in soft sediment to (1) determine the influence of the habitats on the associated macrofaunal communities (inter-habitat comparison), (2) describe how macrofaunal communities vary among vesicomyid clam beds (intra-habitat comparison) and (3) assess the inter-annual variation in vesicomyid beds based on repeated sampling at a three-year interval. The highest densities were found in the microbial mat communities in intermediate fluid-flow areas, but they had low diversity — also observed in the sediment close to mussel beds. In contrast, vesicomyid beds harbored the highest diversity. The vesicomyid beds did not show a homogeneous macrofaunal community across sampled areas; instead, density and composition of macrofauna varied according to the location of the beds inside the pockmark. The clam bed sampled in the most active, central part of the pockmark resembled bacterial mat communities by the presence of highly sulfide-tolerant species living at the sediment surface, along with vesicomyid juveniles. This similarity suggests a gradual change in community composition from mats to clam beds. Inter-annual comparisons of the different clam beds highlighted that the most active central site had a more variable community than its peripheral counterparts. Finally, a rapid shift in community structure, particularly in polychaete families, in experimentally reduced oxygen concentrations in the central part of Regab, suggests that high beta-diversity communities can withstand intense variation in geochemical conditions. These community dynamics are likely related to the diversity and to the plasticity of the vesicomyids themselves, because they can cope with high spatial and temporal environmental variability at a very local scale.

A new benthic macrofauna and sediments sampler for attaching to otter trawl nets: comparison with the Van Veen grab

Most bottom trawling around the world occurs in shelf areas covered by unconsolidated sediments, which can negatively affect bottom communities in several ways. We present a new bottom sampler device that can be attached to trawl nets or other bottom fishing gears. This device consists of a steel tube with a piston positioned in the interior to slide the material collected after the trawling and two lateral supports for fixing the device to the footrope of the trawl. Sampling design consisted in comparison two distinct sites, in each of them were conducted three tows with the sediment sampler device and at the begin and final of each tow it were collected sediment samples with Van Veen grab. PERMANOVA test on macrofauna composition indicated no significant difference in relation to both sampler devices. During the experiment, was not detected any problems in relation to positioning and using the new sampler. The addition of extra weight to the ballast cord did not unestablished the net and the device returned to the surface full of sediment in all the trawls, thus enabling the analysis of macrofauna and sediment particle size. Since this device does not interfere with the operation of the vessel or fishing performance, suggest a promising use of this equipment to collect samples in soft bottoms, as well as analysis of macrofauna and determining the size and composition of sediment.

Small-scale removal of seagrass (Zostera marina L.): effects on the infaunal community

ABSTRACTEelgrass meadows are a common feature in shallow waters along the Norwegian coast, where they provide a habitat for a diverse infaunal community. Recreational boat anchoring and moorings physically scour seagrass and may affect the ecosystem functioning and resilience of the system to natural and anthropogenic disturbances. A small-scale eelgrass (Zostera marina) removal experiment was conducted to study the effects on macro- and meiofauna. Entire plants, including the rhizomes, were removed from 4 m2 patches in three eelgrass meadows in the inner Oslofjord in October 2010. Core samples were taken after a recovery period of 10 months, from the removed patches as well as from the surrounding meadow. Macrofauna (>500 μm) and meiofauna (63–500 μm) in the sediment were investigated for possible effects of the eelgrass removal. Macrofauna and meiofauna composition were site specific and therefore location was identified as the main determinant for the infaunal community. The eelgrass did not regrow within the recovery period and bare sediment patches with only single eelgrass shoots were present during the sampling. Our analyses support an influence of the removal on individual species, but not the complete community. In particular one species, the gastropod Peringia ulvae, was encountered in higher numbers in samples from the removed patches than in control samples. From a management perspective, such minor removal of eelgrass, on the scale of square metres, appears to have no long-lasting detrimental effect to the infaunal community in sheltered meadows with muddy sediments.

Macrofauna composition of two beaches with distinct morphodynamism degrees in the beach arc Barra de São João – Ponta Pai Vitorio promontory – RJ.

This study was performed in the intertidal zone of Rasa and Unamar beach, located in the beach arc Barra de São João – Ponta do Pai Vitório Promontory, northern coastline of Rio de Janeiro, a poorly studied area. In order to assess the macrofauna composition samplings were carried out at both beaches on winter of 2003 and summer of 2004. The differences between the beaches are significant regarding both morphodynamic and macrofaunal composition. The Unamar beach is narrow and has a steeper slope, where waves reach directly the foreshore, being classified as reflective with a typical fauna of this morphodynamic stage, where crustaceans were the dominant taxon represented by Emerita brasiliensis , Excirolana braziliensis, Atlantorchestoidea brasiliensis and Lepidopa richmondi. Rasa beach, on the other hand, has a larger width with a gentle slope and an extense surf zone, classified as dissipative, with Dean’s Morphodynamic index (Ω) equal to 5,1 and 8,5 respectively on winter and summer. The fauna is richer and extremely distinct from other beaches in Rio de Janeiro state, presenting unique species, as Talorchestia tucurauna, Platorchestia monodi, Aspidosiphon (Aspidosiphon) muelleri and Austinixa patagoniensis. The coleopteran Bledius hermani also found at this beach represents the first occurrence to Rio de Janeiro.

First evaluation of foraminiferal metabarcoding for monitoring environmental impact from an offshore oil drilling site

At present, environmental impacts from offshore oil and gas activities are partly determined by measuring changes in macrofauna diversity. Morphological identification of macrofauna is time-consuming, expensive and dependent on taxonomic expertise. In this study, we evaluated the applicability of using foraminiferal-specific metabarcoding for routine monitoring. Sediment samples were collected along distance gradients from two oil platforms off Taranaki (New Zealand) and their physico-chemical properties, foraminiferal environmental DNA/RNA, and macrofaunal composition analyzed. Macrofaunal and foraminiferal assemblages showed similar shifts along impact gradients, but responded differently to environmental perturbations. Macrofauna were affected by hypoxia, whereas sediment grain size appeared to drive shifts in foraminifera. We identified eight foraminiferal molecular operational taxonomic units that have potential to be used as bioindicator taxa. Our results show that metabarcoding represents an effective tool for assessing foraminiferal communities near offshore oil and gas platforms, and that it can be used to complement current monitoring techniques.

Mussels of a marginal population affect the patterns of ambient macrofauna: A case study from the Baltic Sea

In contemporary ecosystems, organisms are increasingly confronted with suboptimal living conditions. We aimed to understand the role of ecosystem engineering species in suboptimal habitats from a population inhabiting the species range margin in naturally stressful conditions. We determined the impact of 2–4 cm sized patches of dwarfed mussels Mytilus trossulus close to its lower salinity limit in the North-Eastern Baltic Sea, on epibenthic community patterns. Mussels affected total macrofaunal abundance and biomass and the taxonomic and functional community structure based on abundances, as well as the species composition of macrofauna. Mussels did not affect ephemeral algae or sediment chlorophyll content, but increased the abundance, biomass, richness, and diversity of grazers, within a radius approximately twelve times the size of mussel patches. We can expect marginal populations of ecosystem engineers in suboptimal habitats to contribute to spatial heterogeneity in biotic patterns and eventual ecosystem stability.

Bathymetric and regional changes in benthic macrofaunal assemblages on the deep Eastern Brazilian margin, SW Atlantic

Deep-sea continental slopes have valuable mineral and biological resources in close proximity to diverse, undersampled and fragile marine benthic ecosystems. The eastern Brazilian Continental Margin (19.01°S to 21.06°S, 37.88°W to 40.22°W) is an important economic region for both fishing and oil industries, but is poorly understood with respect to the structure of the soft-sediment benthic fauna, their regional distribution and their bathymetric patterns. To identify spatial and temporal patterns of benthic macrofaunal assemblages on the slope (400 to 3000m), the Espirito Santo Basin Assessment Project (AMBES, coordinated by Cenpes-Petrobras) sampled 42 stations across the Brazilian Eastern Slope during both Summer 2012 and Winter 2013. We found a significant decrease in macrofaunal abundance at the 400m isobath along the slope near the northern region of the Espirito Santo Basin, suggesting benthic responses to upwelling events towards the south in Campos Basin and southern Espirito Santo Basin. The taxonomic diversity and assemblage composition also changed significantly across depth zones with mid-slope peaks of diversity at 1000–1300m. In general, macrofaunal assemblages were strongly related to slope depth, suggesting a strong influence of productivity gradients and water mass distribution on this oligotrophic margin. Sediment grain size was marginally important to macrofaunal composition on the upper slope. In general, macrofaunal assemblages on the slope of Espirito Santo Basin are similar to other areas of the SE Brazilian margin, but regional changes in response to productivity and depth need to be considered for management strategies in the face of increasing economic activities off-shore.