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Abstract Quantifying the structural complexity provided by biogenic habitat structures is important in ecology, conservation and management, and yet remains a challenging task, particularly in deep sea and polar environments, that current photogrammetry tools can alleviate. In this study, we demonstrate how small remotely operated vehicles and compact underwater GoPro® action cameras can be easily integrated into coastal Antarctic surveys to quantify structural complexity of under‐ice benthos via underwater photogrammetry. Forty‐four pairs of 1 m2 quadrats at 1 cm resolution, each comprising an orthomosaic and three‐dimensional reconstructions, were analyzed to describe relationships between benthic cover and structural complexity metrics. The study case provided insights into a unique biogenic habitat, highlighting the role of integrating structural complexity metrics in Antarctic benthic surveys. Although no clear relationships between structural complexity and biodiversity were found, high cover of live reef‐building polychaetes was associated with higher levels of structural complexity, particularly fractal dimension (D). Further, broken biogenic structures, product of disturbance events retain habitat structural complexity known to be associated with larvae settlement and biogenic reef growth. This suggests that D can be used as a metric for detecting subtle changes in biogenic structural complexity. We build from available open‐source code, a reproducible scientific workflow that is expected to facilitate the acquisition and analysis of structural complexity metrics. The workflow presented aims to encourage and accelerate the use of photogrammetry tools for benthic studies aiming to quantify biogenic structural complexity across depths and latitudes.

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The mesophotic zone is a relatively poorly studied area of the Mediterranean Sea, drawing great interest by the scientific community in the last years. This zone represents a connection between the shallow water and the deep-sea communities, in which photophilic framework builders (e.g. coralline red algae) are gradually replaced by heterotrophic ones, such as ahermatypic corals and the bivalve Neopycnodonte cochlear. In this habitat the framework-forming organisms produce a hard substrate with a high topographic complexity, hosting a great biodiversity of secondary structuring taxa like bryozoans. During a survey on coralligenous banks in the mesophotic zone in c. 60 m depth off Gallipoli (southern Apulia), epibiotic aggregations of N. cochlear were found on the fans of the hexacoral Savalia savaglia. In the present paper the diversity of cheilostomatid bryozoans hosted by these bivalve aggregations is described and compared with published information on similar nearby habitats. A total of 48 taxa were found, six of which are newly described: Crassimarginatella matildae sp. nov., Micropora biopesiula sp. nov., Haplopoma celeste sp. nov., Schizomavella (Schizomavella) cerranoi sp. nov., Schizomavella (Calvetomavella) biancae sp. nov., and Schizoporella adelaide sp. nov. The species richness known from the southern Apulian shelf at this depth (47 species) is hereby raised to 83 cheilostomatid bryozoans. Moreover, only 12 species are shared with the other localities studied previously, while 36 are restricted to Gallipoli, supporting the hypothesis of a high rate of exclusivity among Apulian sites in terms of species composition. The differences in faunal composition, and particularly the presence of several new species discovered at Gallipoli, show once more that our knowledge of the bryozoan fauna in certain Mediterranean habitats is still incomplete and warrants further studies.https://doi.org/urn:lsid:zoobank.org:pub:DDC82039-EF44-4169-8198-C67F60B14BA0

The mesophotic zone is a relatively poorly studied area of the Mediterranean Sea, drawing great interest by the scientific community in the last years. This zone represents a connection between the shallow water and the deep-sea communities, in which photophilic framework builders (e.g. coralline red algae) are gradually replaced by heterotrophic ones, such as ahermatypic corals and the bivalve Neopycnodonte cochlear. In this habitat the framework-forming organisms produce a hard substrate with a high topographic complexity, hosting a great biodiversity of secondary structuring taxa like bryozoans. During a survey on coralligenous banks in the mesophotic zone in c. 60 m depth off Gallipoli (southern Apulia), epibiotic aggregations of N. cochlear were found on the fans of the hexacoral Savalia savaglia. In the present paper the diversity of cheilostomatid bryozoans hosted by these bivalve aggregations is described and compared with published information on similar nearby habitats. A total of 48 taxa were found, six of which are newly described: Crassimarginatella matildae sp. nov., Micropora biopesiula sp. nov., Haplopoma celeste sp. nov., Schizomavella (Schizomavella) cerranoi sp. nov., Schizomavella (Calvetomavella) biancae sp. nov., and Schizoporella adelaide sp. nov. The species richness known from the southern Apulian shelf at this depth (47 species) is hereby raised to 83 cheilostomatid bryozoans. Moreover, only 12 species are shared with the other localities studied previously, while 36 are restricted to Gallipoli, supporting the hypothesis of a high rate of exclusivity among Apulian sites in terms of species composition. The differences in faunal composition, and particularly the presence of several new species discovered at Gallipoli, show once more that our knowledge of the bryozoan fauna in certain Mediterranean habitats is still incomplete and warrants further studies. [ABSTRACT FROM AUTHOR]

The Cambrian Series 2–Miaolingian transition is a pivotal period during Earth history, which witnessed the decline of biodiversity and the reduction in biomass, i.e., the redlichiid–olenellid trilobite extinction. The notable δ13C excursion (RECE) near the Cambrian Series 2–Miaolingian boundary in east Gondwana and China apparently corresponds with the redlichiid trilobite extinction. To better understand the causal mechanism of this biotic crisis, we report the carbon isotope stratigraphy and facies changes from Cambrian Series 2–Miaolingian transition of the Mantou Formation on the southern North China Craton. The carbon isotope excursions at the Cambrian Series 2–Miaolingian transition in the study area are 0.7‰ in the Chishanhe section and −0.2‰ in the Luoquan section, respectively, showing a weak negative excursion or even no negative excursion. The sedimentary environments in the study area gradually changed through time from a clastic tidal flat to a carbonate platform across the transition, which indicated a gradual rise in sea level, with anoxic conditions occurring predominantly before the RECE δ13C excursion. Microbially induced sedimentary structures and oncoids occurred widely at the top of Cambrian Series 2. Abundant metazoan trace fossils were preserved in the Miaolingian Series of the study area. The evolution of biogenic structures across the Cambrian Series 2–Miaolingian transition indicates the emergence of harsh environments associated with the proliferation of MISS and oncoids at the RECE horizon and the recovery of benthic metazoan fauna after the RECE biotic crisis. [ABSTRACT FROM AUTHOR]

Studying exceptionally well-preserved biotas can bring significant answers to the rela)tionship between micro-organisms, biosignatures, and preservational processes. Among impressions of plants from Triassic and Jurassic beds of southernmost Brazil, there are branches and leaves coated by iron crusts, attributed to the precipitation of iron oxide-oxyhydroxides. Underneath the crusts, the leaves retained minute anatomical features of their epidermal cells and stomatal complexes, which are rare in other types of preservation. We evaluate the chemical nature and microstructure of these crusts to solve their genesis and the role of micro-organisms in the precipitation of iron minerals. For this purpose, we apply the following analytical geochemical techniques: Raman spectroscopy and Mössbauer spectrometry, X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The crusts are composed of α-goethite and traces of smectite. We identified potential biogenic microstructures such as ferrihydrite nodules, bacterial exudates morphologically compatible to extracellular polymeric substances (EPS), and structures like twisted stalks and sheaths that fit the biogenicity criteria established so far. These microstructures suggest that the iron crusts were produced by the activity of fresh-water microaerophilic and neutrophilic organisms. The studied material allows us to reconstruct key diagenetic processes that facilitated authigenic preservation along with exceptionally well-preserved biosignatures. [ABSTRACT FROM AUTHOR]

The northern Adriatic continental shelf hosts several coralligenous reefs rising from the sedimentary bottom and characterized by three main benthic assemblages, respectively, dominated by algal turfs, encrusting calcareous rhodophyte (ECRs) or erect sponges. Bioconstruction and bioerosion processes have been investigated using recruitment travertine limestone tiles deployed in a random site for each main benthic assemblages off Chioggia, 6.1–14.4 km offshore and 20.2–25.4 m depth. Tiles were retrieved after 3 and 12 years and analyzed by X-ray computed tomography (CT), allowing for non-destructively identifying and quantifying deposited and eroded limestone. The main builders were ECRs, serpulids, bryozoans, barnacles, and the bivalves Anomia ephippium, while the most effective borers were sponges from the genus Cliona and the bivalve Rocellaria dubia. The deposition of limestone after 12 years was greater at the site MR08 dominated by ECRs (12.52 ± 2.22 kg m–2), intermediate at the site P213 dominated by erect sponges (4.20 ± 1.24 kg m–2), and lower in the site P204 dominated by algal turfs (2.20 ± 0.72 kg m–2). At MR08, the deposition rate did not vary much over time (from 1.295 ± 0.270 to 1.080 ± 0.198 kg m–2 a–1), while in the other two sites, it significantly slowed down after the first survey period: from 0.952 ± 0.199 to 0.350 ± 0.103 kg m–2 a–1 at P213, and from 1.470 ± 0.462 to 0.203 ± 0.058 kg m–2 a–1 at P204. The amount of eroded limestone increased with the exposure time, with no significant differences among sites, from 1.13 ± 0.29 to 10.39 ± 1.14 kg m–2 on average at 3 and 12 years, respectively. The bioerosion rate also increased with the exposure time and was slightly higher at MR08 (from 0.682 ± 0.208 to 1.105 ± 0.088 kg m–2 a–1), mostly eroded by Cliona rhodensis in addition to C. viridis, compared to P204 (from 0.267 ± 0.078 to 0.676 ± 0.172 kg m–2 a–1) and P213 (from 0.179 ± 0.065 to 0.816 ± 0.171 kg m–2 a–1). Overall, bioconstruction has overcome the bioerosion processes in 3 years. In 12 years, the estimated net balance was essentially nil at all sites. Combining field experiment and CT analysis, this study provides the first quantification of the bioerosion and bioconstruction processes in the northern Adriatic coralligenous reefs, a fundamental step toward their conservation.

Earth mounds, locally known as murundus, are ~ 4000 year old natural formations resulting from termite excavation and occur as mound fields in the Caatinga, the largest dry forest region in South America. Termites are ecosystem engineers and the bioturbation caused by them can influence the colonization of other insect species, e.g., the giant ants Dinoponera quadriceps, which are conspicuous in mound fields. We hypothesized that (i) nests and individuals of giant ants are more prevalent in mound fields when compared to regions in Caatinga with no earth mounds, (ii) nests may be located close to trees with large trunks, and (iii) amidst soils rich in organic matter. We placed sampling plots in four sites: two mound fields and two sites with no earth mounds in the state of Bahia, Brazil. Ant nests were more abundant in mound fields when compared to areas with no earth mounds. Thus, mound fields are important sites for ant nests at the landscape scale. The nests were more often found between mounds where termite tunnels occur, suggesting that ants avoid nesting on the top of earth mounds which are bare resulting from anthropogenic removal of vegetation and litter over the past few decades. Thus, the continued conversion of Caatinga into pasture may endanger populations of D. quadriceps, similar to the fate of D. lucida in the Atlantic Forest. The local extinction of the giant ant that are important seed dispersers in this biome can result in the impoverishment of Caatinga floristic structure and diversity. [ABSTRACT FROM AUTHOR]

Bryozoan assemblages of three mesophotic habitats, recently found in the Adriatic and Ionian Seas, were investigated in terms of species composition and diversity, colonial growth forms, and species ecological affinity, with the purposes to analyze variations and similarities between the different bioconstructions and to compare the mesophotic assemblages with those of other benthic habitats. Bryozoans came from three sites off the Apulian coast: Monopoli, 30–55-m depth, where scleractinians are dominant; Otranto, 45–64-m depth; and Santa Maria di Leuca, 45–70-m depth, where the bivalve Neopycnodonte cochlear is the main bioconstructor. A total number of 50 species of bryozoans were recorded, accounting for about 10% of the total number of Mediterranean species. Only few species were shared between the three sites, whereas a considerable pool of species was characteristic of each site. The β-diversity and Sörensen similarity analyses highlighted the highest similarity between the two southern sites, Otranto and Santa Maria di Leuca, with respect to the northern site of Monopoli, in agreement with the hydrological pattern of the area. The encrusting zoarial type was the most abundant in each site, and few species with erect, celleporiform and petraliform colonies were found. The Sörensen similarity, based on data of zoarial forms composition, revealed values considerably higher than those based on species composition, thus highlighting the similar ecological role played by the bryozoans in all the sites. Moreover, significant differences between the mesophotic bryozoan assemblages and those of other benthic Mediterranean habitats were highlighted, showing higher affinity with the coralligenous and detritic sciaphilic habitats. The relevant ecological role of bryozoans as binders in the bioconstructions of the Mediterranean mesophotic zone has been exhibited.

The relationships between infaunal diversity and ecosystem function of biogenic structures in the Eastern Canadian Arctic remain poorly documented. Our study investigated the influence of sponge gardens at the Frobisher Bay site (137 m) and bamboo corals at the Baffin Bay site (1007 m) on the infaunal community structure and benthic ecosystem functioning. The occurrence of both types of biogenic structure type enhanced particular taxa and/or feeding guilds. A large density of suspension filter feeders was observed in bamboo coral sediment, whereas bare sediment exhibited a large proportion of nematodes and deposit-detritus feeders. Sponge gardens’ sediment showed a high proportion of isopods, Paraonidae polychaetes and up/down conveyors whereas bare sediment exhibited a large density of filter feeders. Through incubation cores, we measured ex situ benthic nutrient and oxygen fluxes at the sediment-water interface in each habitat and site. Biogeochemical fluxes varied significantly between habitats in the Baffin Bay site with a significant impact of bamboo coral habitat on nutrient fluxes (nitrate, ammonium, and silicate). Surprisingly, the sediment hosting bamboo corals acted as a source of nitrate and ammonium reaching values similar or higher to the Frobisher site despite the difference in water depth, and thus food supply between the two sites. These significant releases could derive from (i) a high organic matter deposition in bamboo coral habitat, allowed by their erected structure, (ii) a high efficiency of bioturbators (surficial modifiers and burrowers) mixing the surface layer of the sediment, and (iii) the difference in sediment type. Our study highlighted that, compared to its adjacent habitat, the presence of bamboo corals appeared to enhance the infaunal density and nutrient release of its sediment. In contrast, the impact of sponge gardens was not as clear as for bamboo coral habitat, likely due to the relatively significant presence of megabiota in the sponge garden adjacent habitat. Thus, our results based on a relatively small sample size, indicate that the bamboo coral habitat seems to increase the efficiency of deep-benthic ecosystem functioning, while that of sponge garden on the shallow ecosystem functioning remains uncertain.

[Display omitted] • Liometopum apiculatum is an ecologically significant insect species that inhabits scrub vegetation. • Similar to other ant species, L. apiculatum nests in the soil, and its life cycle can alter the soil's physical and chemical properties. • The activities of L. apiculatum enrich the physical and chemical properties of the soil they inhabit compared to the surrounding areas. • This is the first investigation of soils in nests of L. apiculatum in Mexico. Ants are among the organisms that are considered habitat engineers due to their ability to induce changes in the soil. An economically significant ant species is Liometopum apiculatum MAYR, 1870, as its pupae are utilized for human consumption. This ant has been extensively studied using various biological and ecological approaches in diverse habitats across North America. However, there is limited research documenting the properties of the soil in which they nest. The objective of this research was to analyze the physical and chemical properties of soil from Liometopum apiculatum nests and random sites, and to explain how ants can modify the soil in a semi-arid area of north-central Mexico. A sample size of 45 nests distributed in scrub vegetation was determined. Soil samples (2.5 kg) were collected from nests and random sites (20 m in a random direction) at a depth of 20 cm, and aggregates of 3 to 4 cm in length were included during the excavations. The physical variables evaluated were moisture, texture, bulk density and mechanical penetration resistance (MPR); while the chemical ones were pH, electrical conductivity, organic matter, nitrogen, phosphorus and potassium. The variables moisture (p = 0.031), bulk density (p < 0.01), MPR (p = 0.0289); pH (p < 0.001), electrical conductivity (p < 0.01) and organic matter (p < 0.01) had statistical differences between soil from nests and random sites. This research adds to the existing body of knowledge on Liometopum apiculatum by presenting information on the physical and chemical properties of the soil in which they establish their nests. [ABSTRACT FROM AUTHOR]

The study of the Silurian stromatolites revealed the diversity of biogenic structures and similarity of their morphology to that of the bacterial forms found in the ancient Archean stromatolites and modern cyanobacterial mats. The diversity of biogenic structures indicates high activity of microorganisms that formed cyanobacterial mats and confirms the microbial nature of the Silurian stromatolite buildups of the Timan-Northern Ural region. [ABSTRACT FROM AUTHOR]

Biogenic structures edified by crustose coralline algae (CCA) are known to enhance biodiversity, but the mechanisms involved are only partially defined. This study aims at contributing to the knowledge of the interaction between habitat-builder CCA and epibiont assemblages through a manipulative approach. To achieve this objective, transplantations of the CCA Lithophyllum stictiforme were performed to test the following hypotheses: 1) the structure of L. stictiforme epibiont assemblage changes between depth and biogeographic area; 2) L. stictiforme epibiont assemblage is different and more diversified than the assemblage recruited on bare rock; 3) the early L. stictiforme epibiont assemblage differ from the mature L. stictiforme epibiont assemblage. A total of 63 epibiontic taxa were found on the transplanted L. stictiforme thalli, such as 7 Chlorophyta, 10 Ochrophyta, 40 Rhodophyta, 1 Sarcomastigophora, 1 Porifera, 4 Bryozoa. The sessile assemblage recruited on transplanted L. stictiforme thalli depended on sites and depths, and it had a higher taxa richness compared to that colonizing the bare rock. The early recruited assemblage on L. stictiforme transplanted thalli compared to the mature assemblage on untouched thalli was different mostly in the relative abundance of taxa, rather than in species composition. These manipulative experiments highlighted for the first time the role of a common CCA on the development and biodiversity of coralligenous assemblages, contributing to emphasize the importance of CCA conservation efforts. • Lithophyllum stictiforme thalli were transplanted at different depths and sites. • The interaction between crustose coralline algae and epibionts was investigated. • The assemblages had a higher diversity on transplanted thalli than on bare rock. [ABSTRACT FROM AUTHOR]

These last twenty years have seen the development of an abundant literature on the influence of soil macrofauna on soil structure. Amongst these organisms, earthworms, termites and ants are considered to play a key role in regulating the physical, chemical and microbiological properties of soils. Due to these influential impacts, soil ecologists consider these soil macro-invertebrates as ‘soil engineers’ and their diversity and abundance are nowadays considered as relevant bioindicators of soil quality by many scientists and policy makers. Despite this abundant literature, the soil engineering concept remains a ‘preach to the choir’ and bioturbation only perceived as important for soil ecologists. We discussed in this article the main mechanisms by which soil engineers impact soil structure and proposed to classify soil engineers with respect to their capacity to produce biostructures and modify them. We underlined the lack of studies considering biostructure dynamics and presented recent techniques in this purpose. We discussed why soil engineering concept is mainly considered by soil ecologists and call for a better collaboration between soil ecologists and soil physicists. Finally, we summarized main challenges and questions that need to be answered to integrate soil engineers activities in soil structure studies. [ABSTRACT FROM AUTHOR]

Biofilms, or microbial mats, are common associations of microorganisms in tidal flats; they generally consist of a large diversity of organisms embedded in a matrix of Extracellular Polymeric Substances (EPS). These molecules are mainly composed of carbohydrates and proteins, but their detailed monomer compositions and seasonal variations are currently unknown. Yet this composition determines the numerous roles of biofilms in these systems. This study investigated the changes in composition of carbohydrates in intertidal microbial mats over a year to decipher seasonal variations in biofilms and in varying hydrodynamic conditions. This work also aimed to assess how these compositions are related to microbial assemblages. In this context, natural biofilms whose development was influenced or not by artificial structures mimicking polychaete tubes were sampled monthly for over a year in intertidal flats of the Chausey archipelago. Biofilms were compared through the analysis of their fatty acid and pigment contents, and the monosaccharide composition of their EPS carbohydrates. Carbohydrates from both colloidal and bound EPS contained mainly glucose and, to a lower extent, galactose and mannose but they showed significant differences in their detailed monosaccharide compositions. These two fractions displayed different seasonal evolution, even if glucose accumulated in both fractions in summer; bound EPS only were affected by artificial biogenic structures. Sediment composition in fatty acids and pigments showed that microbial communities were dominated by diatoms and heterotrophic bacteria. Their relative proportions, as well as those of other groups like cryptophytes, changed between times and treatments. The changes in EPS composition were not fully explained by modifications of microbial assemblages but also depended on the processes taking place in sediments and on environmental conditions. These variations of EPS compositions are likely to alter different ecosystem processes such as biostabilisation or pollutants trapping. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nutrient pools from ant mounds comprised from 5.3% to 7.6% of the total marsh soils. [•] The contributions of ant mounds on soil nutrient pools varied by ant species. [•] First time to address contribution of ant mound on soil pools for Chinese wetland. [•] Ant also influenced on soil properties under mound and among soil layers. [Copyright &y& Elsevier]

Abstract: Biogenic structures produced by soil ecosystem engineers mediate soil functions and ecosystem services. Ant mounds are important biogenic structures in marsh wetlands, where they can occur at high densities. However, little information is available on their roles in the C and N cycling in these ecosystems. We measured CO2, CH4 and N2O emissions from ant mounds of three different ant species (Lasius flavus, Lasius niger and Formica candida) and estimated their contribution to the total gas emissions of soils from May to September 2010 in a Calamagrostis angustifolia-Carex schmidtii marsh wetland of the Sanjiang Plain, in northeastern China. Average CO2 emissions from ant mounds ranged from 0.84 to 1.95 g CO2 m−2 h−1 and were 1.08–3.09 times higher than from the surrounding marsh soils. Soil CO2 emissions from ant mounds were significantly influenced by mound type and sampling season. On the whole, average soil CO2 emissions from L. niger mounds were lower in comparison to those from F. candida mounds and L. flavus mounds. Ant mound soils were CH4 sinks (−0.39～−0.19 mg m−2 h−1) while the control marsh soils were CH4 emission sources (0.13–0.76 mg m−2 h−1). Soil CH4 and N2O emissions did not significantly differ among the three different types of ant mounds. Compared with control marsh soils (0.034–0.045 mg m−2 h−1), N2O emissions from ant mounds (0.007–0.13 mg m−2 h−1) were influenced more by sampling season. Overall, ant mounds contributed measurable amounts to soil gas emissions from the wetland, averaging 7.02%, −4.28% and 3.35% of total soil CO2, CH4 and N2O emission, respectively. Ant mounds also increased the spatial and temporal heterogeneity of soil gas emissions in the marsh. Thus ant mounds may be important to a complete understanding of wetland ecosystem C and N cycles and balances. Research on more ant species from more ecosystems is needed to establish ant mound impacts on soil gas emissions at a global scale. [Copyright &y& Elsevier]

Abstract: Studies of modern, Holocene, and Pleistocene sediments around saline to hypersaline, alkaline Lake Bogoria and Lake Magadi show that evidence of flamingo activity in marginal areas of these lakes is nearly ubiquitous. Flamingos produce discrete structures such as webbed footprints (~9cm long, ~11cm wide) and nest mounds (~30cm wide, ~20cm high), and they also extensively rework sediments in delta front, delta plain, and shoreline areas. Large (~0.5–2cm in diameter), pinched, ‘bubble pores’ and ped-like mud clumps are formed by the trampling and churning of wet clay-rich sediments in these settings. Flamingo nest mounds, although superficially similar to some thrombolite mounds, are typically internally structureless, unless formed on pre-existing sediments that preserve internal structures. The flamingo mounds consist of a dense, packed oval-shaped core, a surrounding ‘body’ of packed sediment, and an external layer with a ped-like texture of clumped mud. The nests may contain open holes from roots or feather shafts incorporated into the nest, and (or) burrows produced once the nests are abandoned. In areas with high densities of flamingos, lake margin sediments may be preferentially compacted, particularly at breeding sites, and become resistant to subaerial erosion and the effects of transgressive ravinement on time scales ranging from seasons to tens of thousands of years. The relatively well-compacted nest mounds and associated sediments also contribute to the stability of delta distributary channels during regressive-transgressive cycles, and can lead to the minor channelization of unconfined flows where currents are diverted around nest mounds. Pleistocene exhumed surfaces of relatively well-indurated lake margin sediments at Lake Bogoria and Lake Magadi that are interpreted as combined regressive and transgressive surfaces (flooding surface/sequence boundary) preserve evidence of flamingo activities, and are overlain by younger, porous lacustrine silts that preserve large bubble pores produced by flamingos. [Copyright &y& Elsevier]

Temporal and spatial variations in benthic metabolism and anaerobic carbon oxidation pathways were assessed in an anthropogenically impacted (Mtoni) and a pristine (Ras Dege) mangrove forest in Tanzania. The objectives were (1) to evaluate how benthic metabolism is affected by organic carbon availability; (2) to determine the validity of diffusive release of CO as a measure benthic carbon oxidation; and (3) to assess the partitioning of anaerobic carbon pathways and factors controlling the availability of electron acceptors (e.g. oxidized iron). Microbial carbon oxidation measured as diffusive exchange of O and CO (32-67 and 28-115 mmol m day, respectively) showed no specific temporal patterns. Low intertidal sediments at Mtoni fed by labile algal carbon of anthropogenic origin had higher diffusive CO release than high intertidal sediments that primarily received less reactive mangrove detritus. Diffusive release of CO apparently underestimated total sediment carbon oxidation due to CO loss from deep sediments via emission through biogenic structures (i.e. crab burrows and pneumatophores) and porewater seepage into creeks. We propose that diffusive fluxes in the present mangrove sediments are roughly equivalent to depth-integrated reactions occurring in the upper 12 cm. Anaerobic carbon oxidation was dominated by FeR irrespective of anthropogenic influence in sediments where the oxidizing effects of biogenic structures increased the Fe(III) level. More than 80% of the anaerobic carbon oxidation in Mtoni and Ras Dege sediments was due to FeR when reactive Fe(III) exceeded 30 μmol cm. The anthropogenic influence at Mtoni was primarily noted as up to one order of magnitude higher denitrification than at Ras Dege, but this process always accounted for less than 1% of total carbon oxidation. It is noteworthy that organic and nutrient enrichment of anthropogenic origin in Mtoni has no measurable effect on microbial processes, other than carbon oxidation in the low intertidal area and denitrification throughout the forest, and indicates a strong resilience of mangrove environments towards disturbances. [ABSTRACT FROM AUTHOR]

Biogenic structures of Architectonica laevigata (Gastropod: Architectonicidae) were studied along the lagoon of the Modwa spit area, Mandvi, Gulf of Kachchh. The traces are bilobed in cross-section, forming complex meandering trails, while their burrows are closely packed small holes about 1-2 mm in diameter. The traces are produced during low tides and are concentrated in specific areas within the intertidal zone, and also show substrate preference. These traces and burrows are intimately associated with each other, which reflect their behaviour modification to avoid steep thermal gradients and desiccation stress during low tide conditions in the lagoon and intertidal area. Similar traces are comparable with the ichnogenera Gyrochorte and Scolicia, which are abundant from Precambrian times to recent. Such traces, if preserved, serve as a good indicator for paleo-environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract: Benthic metabolism (measured as CO2 production) and carbon oxidation pathways were evaluated in 4 mangrove mesocosms subjected daily to seawater or 60% sewage in the absence or presence of mangrove trees and biogenic structures (pneumatophores and crab burrows). Total CO2 emission from darkened sediments devoid of biogenic structures at pristine conditions was comparable during inundation (immersion) and air exposure (emersion), although increased 2–7 times in sewage contaminated mesocosms. Biogenic structures increased low tide carbon gas emissions at contaminated (30%) and particularly pristine conditions (60%). When sewage was loaded into the mesocosms under unvegetated and planted conditions, iron reduction was substituted by sulfate reduction and contribution of aerobic respiration to total metabolism remained above 50%. Our results clearly show impacts of sewage on the partitioning of electron acceptors in mangrove sediment and confirm the importance of biogenic structures for biogeochemical functioning but also on greenhouse gases emission. [Copyright &y& Elsevier]

Zoophycos is a complex three dimensional trace fossil that is abundant in deep ocean sediments worldwide, but has not been described previously from Cenozoic continental margin deposits of Antarctica. In the ANDRILL 1B core drilled through the north-west McMurdo ice shelf, Zoophycos occurs in a 17m thick unit of interglacial sediments bounded above and below by glacial surfaces of erosion. This unit was deposited during the transition from the relatively warm Early Pliocene characterized by productive open waters to the cooler Late Pliocene with fluctuating subpolar ice sheets. Globally, Late Cenozoic Zoophycos are most abundant at great depths (.1000 m), and where sedimentation rates and TOC levels are low; the Zoophycos producer, probably a worm-like animal, was (is) a slow colonizer. Application of these preferences to the ANDRILL 1B core indicates that the Zoophycos-bearing unit was deposited episodically, with sufficient time between events to allow for the slow processes of colonization and construction. The foray of Zoophycos producer into the relatively shallow ANDRILL 1B depths (200-1000 m) during the Pliocene documents ''emergence'' of benthic animals, supporting suggestions that the unique modern Antarctic and Southern Ocean faunas result from both ''emergence'' and ''submergence'' during the Cenozoic. [ABSTRACT FROM AUTHOR]

Abstract: The influence of three different species of tubicolous worms (Pygospio elegans, Polydora ciliata and Lagis koreni) on the hydrodynamic bottom roughness length (z 0) was analysed in this study. Flume experiments and geospatial methods were combined to determine the potential interactions between worm tubes and the near-bed flow regime and the resulting effects on sediment transport in the south-western Baltic Sea. The three selected species are common in the area of interest (3539 km2). Their species-specific population densities were taken from existing macrozoobenthos datasets and transferred into a Geographic Information System (GIS). In analogy to the sediment roughness length, the hydrodynamic roughness lengths generated by the tubicolous worms were calculated and corresponding sediment transport values, derived from flume experiments with artificial tube lawns, were geospatially analysed using GIS. In order to show the direct influence of worm tubes on the surrounding sediment surface flume experiments were conducted at two given current velocities of 20 cm s−1 for sediment displacement effects and 5 cm s−1 for deposition effects. The roughness length was shown to increase by a factor of 2 to 30 in the presence of biogenic structures such as the worm tubes. The near-bed hydrodynamic conditions are significantly influenced at low roughness densities through independent or isolated flow conditions at 0.7 to 1.9% and at high roughness densities between 4.2 and 7.5%, resulting in unaffected sediment surfaces through “skimming flow”, as well. The GIS analysis revealed that this effect occurs over 4% (137 km2) of the area of investigation, whereas sediment displacement at roughness densities between 0.7 and 1.9% due to increased turbulence is the predominant effect over 33% (present on 1172 km2) of the area of investigation. These findings reveal the important influence of species-generated microtopography on sediment transport processes. [Copyright &y& Elsevier]

Abstract: We investigated the influence of bioturbation by macrofauna on the vertical distribution of living (stained) benthic foraminifera in marine intertidal sediments. We investigated the links between macrofaunal bioturbation and foraminiferal distribution, by sampling from stations situated on a gradient of perturbation by oyster-farming, which has a major effect on benthic faunal assemblages. Sediment cores were collected on the French Atlantic coast, from three intertidal stations: an oyster farm, an area without oysters but affected by oyster biodeposits, and a control station. Axial tomodensitometry (CT-scan) was used for three-dimensional visualization and two-dimensional analysis of the cores. Biogenic structure volumes were quantified and compared between cores. We collected the macrofauna, living foraminifera, shells and gravel from the cores after scanning, to validate image analysis. We did not investigate differences in the biogenic structure volume between cores. However, biogenic structure volume is not necessarily proportional to the extent of bioturbation in a core, given that many biodiffusive activities cannot be detected on CT-scans. Biodiffusors and larger gallery-diffusors were abundant in macrofaunal assemblage at the control station. By contrast, macrofaunal assemblages consisted principally of downward-conveyors at the two stations affected by oyster farming. At the control station, the vertical distribution of biogenic structures mainly built by the biodiffusor Scorbicularia plana and the large gallery-diffusor Hediste diversicolor was significantly correlated with the vertical profiles of living foraminifera in the sediment, whereas vertical distributions of foraminifera and downward-conveyors were not correlated at the station affected by oyster farming. This relationship was probably responsible for the collection of foraminifera in deep sediment layers (>6 cm below the sediment surface) at the control station. As previously suggested for other species, oxygen diffusion may occur via the burrows built by S. plana and H. diversicolor, potentially increasing oxygen penetration and providing a favorable microhabitat for foraminifera in terms of oxygen levels. By contrast, the absence of living foraminifera below 6 cm at the stations affected by oyster farming was probably associated with a lack of biodiffusor and large gallery-diffusor bioturbation. Our findings suggest that the effect of macrofaunal bioturbation on the vertical distribution of foraminiferal assemblages in sediments depends on the effects of the macrofauna on bioirrigation and sediment oxidation, as deduced by Eh values, rather than on the biogenic structure volume produced by macrofauna. The loss of bioturbator functional diversity due to oyster farming may thus indirectly affect infaunal communities by suppressing favorable microhabitats produced by bioturbation. [Copyright &y& Elsevier]

Abstract: This paper describes the novel application of high resolution micro computer tomography (microCT) to the quantification of the properties of marine biogenic structures. CT scanning has been used to examine sediments in the past but the resolution of most previous techniques has been dependent upon commercial medical CT scanners which only have a slice thickness of ≥0.625 mm. In addition adequate software has not previously been available to rapidly quantify all the properties of biogenic structures. The microCT technique developed here used a standard core sample of estuarine sediment and new software was developed to calculate the axial variation of the following burrow parameters: number, diameter, volume, surface area and density. The increased resolution has resulted in the first quantification of meiofaunal burrow structures. A test core has shown, as an example, that the total volume of burrows created by macrofaunal organisms decreased from 827 mm3, within the top 15 mm of the core, to 204.2 mm3 at a depth 60 –75 mm within the core. Total burrow surface area decreased from 1883 mm2 to 512 mm2, for these depth ranges, respectively and burrow diameter ranged from 2.37–2.58 mm, remaining fairly constant between depths. Meiofaunal burrow structures decreased from 1.3–0.1 mm3 within the top 6 mm of the core with burrow surface area decreasing from 33.52–3.4 mm2. Again, burrow diameter remained relatively constant, ranging from 0.23–0.25 mm. Quantification to this resolution is required to identify the impact of infaunal organisms on factors such as oxygen penetration, vertical and horizontal (across burrow walls) gradients in redox conditions and chemical/nutrient speciation and flux. The quantification of these burrow properties will improve the ability to examine the interrelationships between chemical, physical and biological processes and their role in ecological functioning. The present study indicates that there is potential for further development of this software to allow more detailed analysis of burrow structures and surface features including parameters such as burrow length, shape and sediment surface roughness. [Copyright &y& Elsevier]

Burrowing and feeding benthic invertebrates generate various biogenic sediment structures. Such bioengineering is associated with a re-location of nutrients and, in most cases, with a disruption of the benthic community. We investigated the effects of different morphotypes of small-scale biogenic structures on the distribution and activity of bacteria in Arctic deep-sea sediments. Bacteria showed highly variable abundances, cellular biomasses and activities (estimated by thymidine and leucine incorporation) as a result of interacting driving forces: (i) Laterally transported organic particles accumulate at small-scale sediment elevations and depressions. (ii) Organic material is left behind crawling organisms as mucus or faeces. (iii) A significant proportion of bacteria is removed by predation or sediment relocation. In this context, the uppermost sediment layer beneath burrows and plough traces contained less bacteria of higher cellular biomass. Any nonconformity with biomass synthesis from organic compounds probably indicates a community shift because of sediment disturbance. Macrofaunal crawling and feeding tracks were shown to favour bacteria, both in abundance and cellular biomass. A high spatial patchiness along the track courses is suggested to depend on the availability of macrobenthic, metabolic products, as confirmed by faecal castings stimulating bacterial activity. This variable and highly complex scenario of microspatial bacterial community dynamics points to the potential of benthic fauna to cause habitat heterogeneity and to create micro-scale ‘hot spots’ at the deep seafloor. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate the impact of subterranean fungus-growing termites on the structure of soil microorganism communities. We tested whether termites significantly modify the abundance and structure of microbial communities within their below-ground nests (fungus-comb chambers) and whether these effects are species-specific. The investigations were carried out in a humid savanna reserve with material collected from the fungus-comb chamber walls of two widespread species differing in the mode of nest construction. Ancistrotermes builds diffuse and ephemeral nests while chambers of Odontotermes are mostly concentrated and occupy the same area for a comparatively much longer period of time then creating lenticular mounds. The soil properties (pH, texture and C, N content) and the microbial biomass were analysed and automated rRNA intergenic spacer analysis (ARISA) was used to characterise bacterial (B-ARISA) and fungal (F-ARISA) communities. Our results illustrate that the nest structures created by termites offer a diverse range of physical and chemical environments that differ strongly from those present in the general soil mass. Odontotermes had strong effects on microbial properties at the scale of the fungus-comb chamber and at the scale of the lenticular mound. In the fungus-comb chambers, the microbial biomass is not affected by termites but the structure of microbial community is different from that in the control open savanna soil. In the lenticular mound, the microbial biomass is higher and the structure of bacterial community is distinct than that in the fungus-comb chambers. Ancistrotermes also strongly influenced the structure of soil bacterial and fungal communities in the open savanna. However, we did not find any significant modification of bacterial and fungal community structures in the lenticular mound. The impact of fungus-growing termites is, therefore, species-specific and varies depending on the study site (open savanna vs. lenticular mound). [Copyright &y& Elsevier]

Fungus-growing termites (Isoptera, Macrotermitinae) play an important role in tropical ecosystems in modifying soil physical properties. Most of the literature regarding the impact of termites on soil properties refers to termite epigeous mounds. In spite of their abundance and activity in African savannas, few studies deal with the properties of underground nest structures (fungus-comb chambers) built by subterranean Macrotermitinae termites. We tested whether these termites significantly modify the soil physico-chemical properties within their nests in a humid tropical savanna and whether these effects are different for two termite species with differing building behaviour. Termite-worked soil material was collected from fungus-comb chamber walls of two widespread species: Ancistrotermes cavithorax, which builds diffuse and ephemeral nests and Odontotermes nr pauperans, which most often builds concentrated and permanent nests for a comparatively much longer period of time. Neither species influenced soil pH but both significantly modified soil texture and C-N content in their nest structures. A strong impact on clay-particle size was also detected but no significant differences in clay mineralogy. Thus Odontotermes has a greater effect on soil properties, that could be explained by its building behaviour and the concentration in space of its nest units. Therefore, spatial pattern and life-span of fungus-comb chambers should be an important parameter to be considered in the functional role of subterranean Macrotermitinae termites in the savanna. [ABSTRACT FROM AUTHOR]

Soil structures built by litter-feeding termites are one of the main soil translocation processes in dry tropical savanna. Runways (soil sheeting) made of soil particles cemented with salivary secretions covering the dead plant pieces collected on the ground surface represent the main soil structures. The aim of this study was to determine the impact of this soil engineering activity on the microbially-mediated N transformations (nitrification and denitrification) associated with termite sheeting. We investigated the hypothesis that the physicochemical and microbial properties of termite soil sheeting depend on (i) the termite species and (ii) the type of organic substrate consumed. Soil sheeting built by two of the main savanna species,Macrotermes subhyalinusandOdontotermes nilensis, were sampled on field plots treated with three different types of litter (Acacia leaves, millet straw, both whole and ground (<500µm), and cattle manure). The soil’s organic C, total N, inorganic N, microbial biomass, potential CO2 respiration, nitrification and denitrification were measured. For both termite species and all types of litter, the soil sheeting was enriched in organic C and inorganic N, resulting in an increase in soil respiration, whereas the microbial biomass was unchanged with respect to the reference soil. With the exception of the soil nitrification potential, the type of organic substrate did not significantly affect the properties of the soil sheeting measured. However, the nitrogen cycle was affected differently by the two termite species. InO. nilensissheeting, the denitrification potential was reduced with respect to the reference soil, whereas the nitrification potential was inhibited inM. subhyalinussheeting. The changes in the nitrogen cycle processes resulted in an increase in NH4+ and NO3- in the termite soil sheeting, increasing the availability of nitrogen to plants. This study reinforces the importance of termites as a keystone savanna group whose building activities have an effect on tropical soil mineralization. [ABSTRACT FROM AUTHOR]

The method for the sequential extraction of P proposed by Jensen et al. [Mcglathery, K.J., Marino, R., Howarth, R.W. (1998) Limnol. Oceanogr. 43, 799–810] was used to study the spatial distribution of sedimentary P in superficial sediments of a mesohaline coastal lagoon located in a watershed formed by carboniferous sandstone in the Western Mediterranean (Minorca Island, Spain). Dissolved inorganic phosphate (IP), dissolved organic phosphate (OP), Fe, Ca, Al, and F were analyzed in the extractions to assess adequacy of this method to clay sediments. The elemental composition of the solid phase (Al, Fe, K, Ti, Si, Mg and Ca) was also analyzed to relate concentrations of P pools to the mineral composition. Samples from marine carbonated sediments, rock and some materials of biological origin (tubes of polychaete Ficopomatus enigmaticus, bivalve shell debris) were analyzed for comparative purposes. The sequential procedure allowed to extract almost all sedimentary P from carbonate sediments and biogenic debris, but only 70% of total phosphorus (TP) from clay sediments and rock. Main IP pools in the lagoon were Fe-bound P (16.6% of TP), CaCO3-bound P mainly from Ficopomatus tubes (12.0% of TP), and detrital carbonate fluorapatite (7.8% of TP). The most abundant P pool was refractory P (20.3% of TP), which appeared associated to the (Fe,K)Al-silicate fraction and to humic P. This indicated that clay–humic–organic P complexes were the main P reservoir in the lagoon. Spatial distribution of P pools reflected differential sedimentation of allochthonous materials, authigenic precipitation of Fe-oxides, and Fe-bound P as well as the differential distribution of organisms such as Ficopomatus. [Copyright &y& Elsevier]

Humus forms are the seat of most biological transformations taking place in terrestrial ecosystems, being at the interface between plants, animals and microbes. The diversity of terrestrial humus forms (mor, moder and mull) can be attributed to the existence of different patterns (strategies) for the capture and use of resources by ecosystems, in ascending order of biodiversity and bioavailability. Arguments are found in the parallel development of humus forms and terrestrial ecosystems, in exclusion mechanisms between organisms living in different humus forms, and in palaeontological studies. The diversification of terrestrial life forms in the course of Earth history, concomitant with an improvement in resource availability due to the development of sedimentary layers at the surface of continents, may explain the successive appearance of more active humus forms enabling the co-existence of an increasing number of organisms. Contradictory reports about the relationships between biodiversity and stability of ecosystems can be explained by the existence of different belowground pathways making ecosystems more stable. [Copyright &y& Elsevier]

Organism-built structures have long been useful artifacts for students of evolution and systematics, because they represent a permanent record of a set of behaviors. These structures also represent an investment of energy by an organism, and to persist in the fossil record, the energetic investment in the structure must pay off for the organisms that build it, in either improved survivorship, increased physiological efficiency or enhanced fecundity. A useful way to think about this aspect of organism-built structures is to treat them as external organs of physiology, channeling or tapping into energy sources for doing physiological work. This paper reviews briefly how burrows and nests can act as external organs of physiology at various levels of organization, and introduces the notion of organism-built structures as adaptive structures, in which feedback controls confer adaptability to organisms’ external constructions, and which promote homeostasis of the organism and its local environment. Miller’s concept of trace fossils as behavioral tokens reflects this aspect of animal-built structures, and may illuminate many unanswered questions concerning their origins and persistence in the fossil record. [Copyright &y& Elsevier]

At the water–sediment interface of aquatic ecosystems, the presence of biogenic structures produced by benthic invertebrates strongly affects biogeochemical processes. The quantification of these structures and the assessment of the vertical distribution of fauna are essential for determining the impact of communities in sediments. In the present study, computer axial tomodensitometry (CAT-scan) was used to measure the space occupied by an intertidal community of the St. Lawrence estuary. Three cores were sampled at a site that was considered homogeneous according to surface sediments. The vertical distribution of biogenic structures and gravel were measured in the three cores using CAT-scan; the vertical distribution of fauna was also analysed for each core. The biogenic structures were highest at the water–sediment interface and decreased with depth in the three cores. The number of invertebrates also decreased with depth. We observed similar distributions of biogenic structures in cores 1 and 2. However, fewer biogenic structures were observed below 90 mm in core 3. This result was correlated with a high quantity of gravel from 90 to 140 mm in core 3 whereas the other cores had lower quantities of coarse material. We found relationships among the distributions of biogenic structures, fauna, and sediment characteristics (gravel quantity) that can affect species distribution. The vertical distributions of Macoma balthica, Mya arenaria, Nereis virens, and small-sized gallery-producing species (nematodes and oligochaetes) could also be recorded with the CAT-scan method. Thus, CAT-scan is an excellent tool to determine the fine-scale heterogeneity in the space occupied by benthic invertebrates in sediments. [Copyright &y& Elsevier]

In the upper layer of the sediment column, organic matter recycling is greatly influenced by bioturbation. However, there are many physical changes in the nature of the sediment that may disturb benthic communities and create a biogeochemical imbalance. Following a very heavy rainfall between 26 and 29 July 1996, an intense flash flood in the Saguenay Fjord caused discharges of 6 million cubic metres of sediments into Baie des Ha! Ha!. Unstable sediment deposits located at the top of the delta of the Rivie&grave;re des Ha! Ha! were sporadically exported to the deep basin. After this physical disturbance, meiobenthic and macrobenthic organisms progressively re-colonised the sediment column. To determine the impacts of such sedimentary depositions on benthic fauna, two stations, one at the head and one at the mouth of the Baie des Ha! Ha!, have been monitored since 1996. During this survey, we developed a new method for the quantification of biogenic structures using computer axial tomography (CAT-Scan). Benthic fauna analysis showed that the two stations were characterised by different temporal changes in the benthic dynamics according to their geographic location. Using CAT-Scan analysis of sediment cores, we were able to characterise the stability of the sediment column for the two stations in 1999 and 2000. Scan results suggest that colonisation processes were closely linked with the stability of the sediment column. Erosion and re-deposition of surficial sediments caused a succession in the formation of biogenic structures. These variations were characterised for the first time using CAT-Scan, which is a nondestructive, rapid, and precise method. Tomographic analysis showed the importance of the production and destruction rates of biogenic structures and the sedimentation rate for the preservation of burrows and potentially reactive components. This study finally demonstrated that each erosional event could be followed by a rapid formation of biogenic structures, allowing the re-oxidation of old deposits. [Copyright &y& Elsevier]

• Higher termite, earthworm and ant activities in woody residue amended soils. • Higher SOC, soil C/N ratio, NH 4 -N content in woody residue amended soils. • Soil N enrichments decreased the soil C/N ratio in woody residue amended soils. • Soil N enrichments inadequate to alleviate microbial catabolic limitations. • Woody residue amendments with and without N sources improved crop performance. Agroecological practices are emerging as efficient alternatives to address the challenge of sustainable agriculture. The objective of this study was to examine whether plant residue amendments from stems and leaves (SL) of an agroforestry shrub (Piliostigma reticulatum) enriched with nitrogen (N) sources improve nutrient cycling in Soudano-Sahelian cropping systems. The experimental design was organized into four replicates with six treatments consisting of two treatments of SL residue amendments (amended and non-amended) in combination with three treatments including additional N sources (natural soils, urea, and cowpea as intercrop). The results showed that the activity of termites (Nasutitermes torquatus) and ants (Messor galla and Pachycondyla rufipes) was 12–13 and 2–3 times higher in the SL amended soils than in non-amended soils, respectively. The activity of earthworms (Millsonia inermis) was highest in the SL amended soils associated with the cowpea intercrop, and was significantly lower in the urea enriched soils. SL amendments and N enrichments had no effect on soil basal respiration. The substrate-induced respiration with N substrates (L-alanine and L-arginine l) was 25 and 52 % higher in the SL amended soils than in the natural soils without any N inputs, indicating N limitation of microbial activity. This corroborates the higher C/N ratio (14.3) observed in the SL amended soils compared to the natural soils without any inputs (10.3). The N enrichment decreased the C/N ratio of the SL amended soils but was not efficient to alleviate microbial catabolic limitations, likely by switching from N to C limitation. Overall, the SL amendments with or without N enrichments triggered temporarily the soil macrofaunal activity, increased the NH 4 -N availability compared to that of NO 3 -N, and improved crop performance. [ABSTRACT FROM AUTHOR]

Feeding, burrowing, locomotion and death of larger organisms can significantly modify the appearance, texture and habitat conditions of the sediment surface. Such modifications create visible biogenic structures and associated microhabitats, which may have negative and/or positive effects on small-sized benthic communities. A series of dives with the submersible ALVIN was undertaken at the long-term monitoring Station M (4000 m, NE Pacific) in August 2006 to investigate, among other things, the influence of different biogenic structures on meiofauna and nematode assemblages. Five different biogenic structures were sampled; the tracks of two different species of sea urchins (Cystocrepis and Echinocrepis), one bioturbation mound, one decomposing kelp aggregate and one sponge. These were compared to a number of control samples taken away from the influence of the biogenic structures. Meiofauna ranged between 241 and 1277 ind per 10 cm2 and was dominated by nematodes, with their contribution ranging from 74% to 89%. The comparison of the meiofauna communities from the biogenic structures and the control samples indicated differences between microhabitats for meiofaunal composition and nematode functional groups, which were due to differences between the microhabitats at the mound. The bioturbation mound and the control area hosted the highest number of nematode genera, though statistical analysis did not indicate significant differences. Beta diversity analysis revealed higher variability of meiofauna between than within different biogenic structures, suggesting habitat heterogeneity that may contribute substantially to the overall deep-sea richness. It may be concluded that among the studied biogenic structures, the bioturbation mound appears to be critical in shaping deep-sea meiobenthic communities. [ABSTRACT FROM AUTHOR]

Termites inhabit complex underground mounds of intricate stigmergic labyrinthine designs with multiple functions as nursery, food storage and refuge, while maintaining a homeostatic microclimate. Past research studied termite building activities rather than the actual material structure. Yet, prior to understanding how multi-functionality shaped termite building, a thorough grasp of submillimetre mechanistic architecture of mounds is required. Here, we identify for Nasutitermes exitiosus via granulometry and Fourier transform infrared spectroscopy analysis, preferential particle sizes related to coarse silts and unknown mixtures of organic/inorganic components. High-resolution micro-computed X-ray tomography and microindentation tests reveal wall patterns of filigree laminated layers and sub-millimetre porosity wrapped around a coarse-grained inner scaffold. The scaffold geometry, which is designed of a lignin-based composite and densely biocementitious stercoral mortar, resembles that of trabecula cancellous bones. Fractal dimension estimates indicate multi-scaled porosity, important for enhanced evaporative cooling and structural stability. The indentation moduli increase from the outer to the inner wall parts to values higher than those found in loose clays and which exceed locally the properties of anthropogenic cementitious materials. Termites engineer intricately layered biocementitious composites of high elasticity. The multiple-scales and porosity of the structure indicate a potential to pioneer bio-architected lightweight and high-strength materials.