Biogenic Structures Research Articles

Habitat forming species explain taxonomic and functional diversities in a Mediterranean seamount

Complexity provided by habitat-forming species in marine ecosystems has been linked to higher species richness and biodiversity as well as enhancing ecosystem functioning. This study assesses how the presence of biogenic component of benthic habitats affects the taxonomic richness and functional diversities of a seamount benthos. We used a variety of complementary metrics on abundance data and quantitative community analyses to detail the composition, structure, diversity and functionality of eight biogenic and five non-biogenic benthic habitats across the Seco de los Olivos Seamount, located to the south of the Iberian Peninsula, in the western Mediterranean. This study shows that the presence of habitat-forming species in benthic habitats increases richness and enhances α and functional diversities. Their influence is more evident in soft and mixed bottoms, where the multiplying effect on structural complexity is proportionally greater than in rocky habitats. Biogenic habitats hosted a higher number of single species in comparison with non-biogenic habitats. The presence of habitat-forming species also determines β diversity among habitats at similar depth and type of substrate, with variation in species richness responsible for the most β diversity; turnover, however, dominated β diversity among habitats of different environments. Species richness hotspots were also associated to biogenic structures and were found restricted to the summit of the central guyot and other areas located on the surrounding ridges. Different functional composition of these benthic habitats also suggested differences in ecosystem functioning: biogenic habitats resembled more stable or at advanced stages of successional maturity than non-biogenic habitats and are characterized by biological traits that allow them to better promote benthic-pelagic coupling. From aconservation perspective an increased functional redundancy was found related to the occurrence of habitat-forming species in high abundance, which favours functional replacement and makes communities less vulnerable to environmental changes. The results of this study can help managers to develop specific management tools to ensure the future evaluation and monitoring of benthic communities.

Macrobenthic community establishment on artificial reefs with Macrocystis pyrifera over barren-ground and soft-bottom habitats

Kelps provide important habitat for a range of species, however they are suffering increasing levels of degradation. This has prompted efforts to restore these ecosystems, however, the trajectory of community establishment on artificial reefs has not being widely described. We examined the composition of the species and functional groups of invertebrates and fish in relation to the artificial reefs over soft-bottom and barren-ground habitats over a 10-month period. We evaluated the community structure based on species richness, biomass, species diversity, and dominance of species and functional groups. We assessed the trajectories of the ecological succession of artificial reefs planted with kelp on each bottom type and determined the changes in the dissimilarity of species and functional groups over time. We also analysed the relationship between the biogeny (of macroalgae) over time (months) and the changes in macrobenthic community structure. Successional development of reefs communities was similar across the two habitat types, macroalgae contributed most to the early stage, while invertebrates and fish were the groups that contributed the most during the middle and late successional stages. A positive relationship was found between the presence of artificial reefs with kelp seedlings and the biomass of specific species and functional groups. This study showed that new kelp habitats promote the construction of biogenic structures that increase the habitat complexity, promote biodiversity, and increase populations of commercially harvested species. In this sense, artificial reefs should be considered an important tool for restoring the function of degraded benthic ecosystems.

Compound biogenic structures resulting from ontogenetic variation: An example from a modern dipteran

Several families of Diptera are known to be active burrowers. Fly larvae of the genus Symplecta (family Limoniidae) were observed in a sandy substrate of an orange grove in Lepe, SW Spain. Traces produced by Symplecta display: (1), a proximal segment characterized by a winding furrow trail; (2), an intermediate part consisting of burrow segments arranged in zigzag; and (3), a distal part formed by a complex U-shaped burrow. The most complex morphology is present in the intermediate zigzag burrow system, which varies from irregularly sinuous and curved in its most proximal part to spiraled. In the fossil record, the trace would be ascribed to different ichnotaxa depending on the part preserved. In fact, this is a compound trace recording multiple behavioural patterns. The winding furrow shows affinities with Helminthopsis, the zigzag burrows with Treptichnus, and the U-shaped burrow with Arenicolites. Furthermore, the spiral portion shows some similarities with Spirophycus and Spirodesmos. Interestingly, formation of these compound traces is connected with different ontogenetic stages of the producer. The winding and zigzag segments are produced, respectively, by Symplecta larvae and pupae for feeding purposes, whereas the U-shaped burrow is excavated during the end of pupal stage for protection until adulthood. In the fossil record, this incipient compound trace potentially may occur in lake-margin, fluvio-estuarine and overbank deposits, including levee, crevasse splay and pond deposits, forming part of the Scoyenia or the Mermia ichnofacies. Structures similar to those produced by modern diptera are known from freshwater ichnofaunas since the Devonian

Detection of mineralogically accentuated biogenic structures with high-resolution geophysics: implications for ichnology and geoecology

Identification and mapping of small-scale physical and biogenic structures in sand has been a challenge to sedimentologists and ichnologists. Under natural conditions, biogenic activity (trampling tracks, burrows) alter primary sedimentary structures, but also serve as important paleoenvironmental indicators of geotechnical properties of sediments, omission surfaces, and ecosystem dynamics. Therefore, the ability to recognize such structures as anomalies in shallow subsurface, especially when using indirect non-invasive methods, such as geophysical imaging, is an important aspect of assessing their relative contribution to the overall erosional-depositional record. This study presents experimental evidence of the viability of two highresolution geophysical methods in detecting sediment deformation that mimics shallow animal traces. High-frequency (800 MHz) ground-penetrating radar (GPR) imaging aided in visualizing a buried depression produced by a deer hoofprint cast indenter, with high-amplitude reflection return enhanced by a heavy-mineral concentration (HMC). Bulk in situ low-frequency (930 Hz), low-field magnetic susceptibility (MS) experiment supported the theoretical pattern of a decrease in MS over the thickest cover sand (maximum indentation depth) to ~0 mSI and the highest values over raised HMC horizon (marginal ridge; >8 mSI). Because both methods are affected by the presence and relative abundance of heavy minerals, the present approach can be applied in most siliciclastic settings. This study demonstrates the promise of extending the 2D visualization of subsurface targets to 3D datasets, with potential implications for sedimentological, ichnological, archaeological, and geoecological research that involves animal-sediment interaction at different scales.

Influence of Deep-Water Corals and Sponge Gardens on Infaunal Community Composition and Ecosystem Functioning in the Eastern Canadian Arctic

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 (138 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.

GEOLOGY AND MINERAL RESOURCES OF EBONYI STATE, SOUTHEASTERN NIGERIA

Ebonyi State is underlain at depth by the Precambrian Basement Complex and by Cretaceous sedimentary units which include the Abakaliki Formation, Nkalagu Limestone, Amasiri Sandstone and Afikpo Sandstone and spans through Southern Benue Trough and Anambra Basin. Shales, sandstones, siltstones and limestones which range from shallow to deep marine depositional environments have intermediate to basic intrusive dolerites, extrusives and pyroclastics rocks emplaced in them. The sediments are dominated by physical structures such as faults, folds, fractures, joints, cross beds, mud cracks and an unconformity; chemical structures such as concretions and solution cavity; and biogenic structures such as burrows and bioturbation. The presence of benthic foraminifera such as Bolivina anambra and Haplopragmoides sp. suggest an upper bethyal deep to shallow marine environment for the sediments. Natural resources and mineral deposits such as lead, zinc, granite, limestone, dolerite, pyroclastics, salt-lake/brine, sand, laterites, clay, kaolin, iron ores, chalcopyrite, illmenite, fluorite, marble stone, quartz and copper ore which spread across the area, contribute largely to the gross domestic products of the state. Data gathered shows that 26% of the mineral deposits are partially exploited, 30 % are locally exploited, 4 % are highly exploited, while 39 % are dormant. Unfortunately, the reserve estimate of these mineral deposits are yet to be documented. Keywords: Anambra Basin, Ebonyi State, Mineral deposits, Southern Benue Trough, Structure; Uncomformity

Revealing hydrogen peroxide as an external stressor in macrophyte-dominated coastal ecosystems.

Benthic primary producers in coastal ecosystems provide important habitat for marine organisms through the provision of complex 3D habitat. Primary producers produce organic matter, while simultaneously producing reactive oxygen species, including hydrogen peroxide (H2O2), a driver of oxidative stress. Through their high biomass, productivity and effect on local hydrodynamics, benthic primary producers can potentially increase H2O2 concentrations surrounding the biogenic structures they form. The aim of this study was to identify the potential role of H2O2 produced by benthic primary producers as an external stressor in coastal ecosystems. This was achieved by measuring H2O2 concentrations within sea lettuce blooms (Ulva sp.), giant kelp forests (Macrocystis pyrifera), and seagrass meadows (Zostera muelleri); quantifying H2O2 production rates of these species; and testing heterotrophic bacterial response to relevant H2O2 concentrations. Ulva sp. produced five times more H2O2 than other species. At in situ concentrations, H2O2 inhibited bacterial production and carbon flow through the microbial loop by 75%. This study reveals H2O2 as an additional stressor in bloom-forming Ulva sp. with higher H2O2 production compared to the ecosystem engineers M. pyrifera and Z. muelleri. H2O2 production by benthic primary producers can affect carbon flow through the microbial loop, with the potential to propagate a stress signal up the food web.

The ecosystem services provided by social insects: traits, management tools and knowledge gaps.

Social insects, i.e. ants, bees, wasps and termites, are key components of ecological communities, and are important ecosystem services (ESs) providers. Here, we review the literature in order to (i) analyse the particular traits of social insects that make them good suppliers of ESs; (ii) compile and assess management strategies that improve the services provided by social insects; and (iii) detect gaps in our knowledge about the services that social insects provide. Social insects provide at least 10 ESs; however, many of them are poorly understood or valued. Relevant traits of social insects include high biomass and numerical abundance, a diversity of mutualistic associations, the ability to build important biogenic structures, versatile production of chemical defences, the simultaneous delivery of several ESs, the presence of castes and division of labour, efficient communication and cooperation, the capacity to store food, and a long lifespan. All these characteristics enhance social insects as ES providers, highlighting their potential, constancy and efficiency as suppliers of these services. In turn, many of these traits make social insects stress tolerant and easy to manage, so increasing the ESs they provide. We emphasise the need for a conservation approach to the management of the services, as well as the potential use of social insects to help restore habitats degraded by human activities. In addition, we stress the need to evaluate both services and disservices in an integrated way, because some species of social insects are among the most problematic invasive species and native pests. Finally, we propose two areas of research that will lead to a greater and more efficient use of social insects as ES providers, and to a greater appreciation of them by producers and decision-makers.

English

Termitarian, the epigeal biogenic structure constructed by termites are widespread in the forest and derived savannah regions of Nigeria. Soil modification, with particular focus on the mineralogy, variation in geochemical composition and geotechnical properties of termite mound soil samples collected from nine location in the Ika area, Delta State of Nigeria are the objectives of this report. The major elements geochemical composition of the termite mound soil samples determined by XRF was found to be mainly SiO2 (40.25%), Fe2O3 (29.27%), Al2O3 (24.25%) and T1O2 (4.27%). The other major elements; CaO, MnO, MgO, Na2O and P2O5 were present at less than 1%. Trace element compositions of the termite mound soil samples were found to be Cr (8.20- 23.10 mg.kg-1), Pb (3.95- 13.85 mg.kg-1); Cu (2.75-12.00 mg.kg-1), Zn (3.60-9.60 mg.kg-1) and Cd (1.90-3.15 mg.kg-1). Minerological composition of the termite mound soil samples determined by XRD revealed significant hematatic composition with a range of 60.17-83.78%, antigorite (5.24 -24.17%) and quartz (7.14-14.67%). Anthophylite (19.92%) was found in only one termite mound soil samples. The geotechnical tests carried out on the termite mound soil samples included: Grain size, atterberg limit, compaction and triaxial tests. The range of values of the determined properties: Uniformity coefficient (3.75-7.50), coefficient of curvature (0.20-2.70), plasticity index (10.83-28.45%), plasticity limit (13.47- 19.57%), optimium moisture content (7.20- 15.40%), maximum dry density (1.72-2.10g.cm-3), angles of friction (2.83- 24.77°) and cohesion of up to about 50.11 KN.m2, suggest that the termite mound soil may have limited application in soil stabilization and concrete works. Key words: Ika, geotechnical, geochemical, termite, mound.

Effectiveness of acoustic cameras as tools for assessing biogenic structures formed by Sabellaria in highly turbid environments

Abstract Accurately mapping the extent and status of biogenic reefs formed by polychaete worms of the genus Sabellaria is of conservation importance given their protected status across Europe. Traditionally, side‐scan sonar (SSS) combined with ground‐truthing in the form of seabed photography and videography has been widely accepted as the most suitable approach for mapping these reefs in the subtidal zone. In highly turbid environments visibility at the seabed can be near zero, however, rendering optical‐based ground‐truthing redundant. Consequently, the true distribution and status of Sabellaria reefs in some shallow subtidal areas around the UK remains unclear despite their designation as Annex‐I features of several Special Areas of Conservation (SACs) under the Habitats Directive. Acoustic camera imagery (ACI) collected using acoustic cameras in two deployment configurations matched well with the backscatter signatures of seabed features in corresponding SSS data. The ACI was of suitable resolution for visualizing Sabellaria colony structures, allowing for their Annex‐I ‘reef’ defining attributes (extent, patchiness, and elevation) to be assessed. Colony formation ‘type’ was also distinguishable in the ACI, although confidence in differentiating between low‐lying Sabellaria formations and surrounding substrates was low, particularly when using a pole‐mounted configuration. This study provides a proof of concept for using acoustic cameras as tools for ground‐truthing SSS interpretation and assessing the status of Sabellaria bioconstructions in low‐visibility environments. Further development of this approach and incorporating it into statutory monitoring programmes could improve the management of the reef habitats in subtidal areas of the Severn Estuary and other highly turbid environments.

The overlooked role of taphonomy in ecology: post‐mortem processes can outweigh recruitment effects on community functions

Biogenic structures that persist post‐mortem are ubiquitous, but rarely considered as key ecological features. Post‐mortem structures in many ecological systems exert community‐level effects and thus the dynamics of their degradation (i.e. taphonomy) become important in affecting community functions and ecosystem services, and these often‐overlooked effects may rival the influence of recruitment and typical post‐recruitment processes. Moreover, in some highly researched habitat types, post‐mortem structures may be mistaken for living organisms, thus introducing significant error into our understanding of population processes. We examined widespread patterns and processes in marine assemblages with calcareous tubeworms and brackish‐water assemblages with bryozoans, in order to test the importance of taphonomy for populations and communities. In tubeworm assemblages, taphonomic variability caused differential accumulation of post‐mortem structures, exerting community‐level influence, and importantly it negated effects from recruitment on the community functions. For tubeworms and bryozoans, proportions of post‐mortem structures varied between sheltered and exposed habitats with overall distributional variability being caused by the share of post‐mortem structures, not living animals. Population‐level inferences in such systems would be extremely problematic without careful differentiation of dead/living structures. Dynamics emerging from the interaction of taphonomic processes and recruitment ecology are relevant for many other important biogenic habitats, especially coral reefs with death assemblages of bleached corals; a failure to consider variability in processes acting on the death assemblages, alongside the living, may severely distort understanding of patterns and processes in populations and communities.

Precision conservation: from visual analysis of soil aggregates to the use of neural networks

The concept of precision conservation can be defined as a set of space technologies and other procedures linked to mappable environmental variables. These technologies and procedures can be used to program conservation management practices for natural resources that take into account the variability of such variables in space and time within natural or agricultural systems. In this context, the structural loss of soil due to human activities is considered as a process with spatial and temporal variations. The management of soil aggregation conditions can contribute to more regenerative and sustainable agricultural processes. It admits spatial analysis technologies through georeferenced visual indicators or even the use of systems with automatic learning, known as deep learning. In this sense, a fair visual method was developed with analysis of fuzzy logic to classify aggregates in terms of shape, surface roughness, and biogenic structures. Thus, in a second stage, a model of artificial neural network was developed. This model is capable of detecting and classifying different forms of soil aggregates, thus enabling a brief discussion of the topic and its potential application in conservation management through the analysis of aggregates via automatic sorting systems. Elements of research motivation and development on adaptive technologies are presented to support decision-making that can help integrate dynamic and spatial information for understanding of the structural condition of soil and hence its more precise preservation.

Meiobenthos from biogenic structures of the abyssal time-series station in the NE Pacific (Station M)

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.

Biogenic Structures in the Silurian Stromatolites (Timan-Northern Ural Region)

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.

Impact of pesticide monocrotophos on microbial populations and histology of intestine in the Indian earthworm Lampito mauritii (Kinberg)

Soil contamination has enlarged over the decades due to intensive use of pesticides and chemical fertilizers in agronomy. Earthworms are significant organisms in the soil community. Earthworms are the major role in soil fertility in most ecological system and the production of biogenic structures. Moreover, earthworm gut mucus enhances the beneficial soil microorganism potential biological activities. They are used as model organisms for assessing the ecological risks of chemicals. Enrichment of essential nutrients in soil through earthworm is a cost-effective and eco-friendly approach. In India, the organophosphorus pesticide monocrotophos is commonly used to control agricultural pests. Hence, it is important to study the effect of monocrotophos on the gut microbiota in Lampito mauritii. A 15-day exposure to a low (1/10th of the LC50 after 96 h i.e., 0.093 ppm kg−1) and high sublethal concentration (1/3rd of the LC50 after 96 h i.e., 0.311 ppm kg−1) of monocrotophos led to reduced proliferation of the gut microbiota in L. mauritii. However, exposure for 30 days led to a recuperation of the microbial populations to near control values. Among the eight bacterial and five fungal species that inhabit the gut of L. mauritii, only six bacterial and three fungal species were able to survive after exposure to monocrotophos. In addition to the study, histopathological changes were observed in the intestine of L.mauritii after application of lower sublethal concentration of monocrotophos. Severe pathological changes such as vacuolization, degenerated nuclei, damaged villi and congestion of the blood sinuses were noticed in the intestine on 1st and, 5th day of the experiment. But in 30th day the damages were slowly recovered due to degradation of monocrotophos by the presence of some pesticides degrading bacterial and fungal species and regenerative capability of chloragogen cells in the intestine. The results suggested that reduced microbial populations and pathological damages in intestine were observed during the application of monocrotophos. So, the monocrotophos have several harmful impacts on earthworms.

KARAKTERISTIK STRUKTUR DAN SIFAT KIMIA PRODUK BIOGENIK RAYAP SCHEDORHINOTERMES SPP DARI CAMPURAN LIMBAH KERTAS KORAN DENGAN LIMBAH PENGOLAHAN TAHU

Biological activity of termites consistently generates various biogenic products depend of the type of food sources. Furthermore, the biogenic product is believed to have an important role in the improvement of soil physical and chemical properties. The purpose of this study is to determine the structure and chemical properties of biogenic products resulted from the activity of termites Schedorhinotermes spp. using newsprint paper and tofu processing wastes as food sources. Newsprint paper waste was mixed with tofu processing wastes water at a different levels, i.e. 10 %, 20 %, and 30 % (w/v) for the objective of study. Each of the mixture with weight of 18,8 g equivalent to oven dry weight was then placed in the sample container unit size 6 x 6 cm, placed at about 3 cm underground with the indicated of termite Schedorhinotermes spp activity, and covered by PVC stopper. The testing unit were left in place for about 6 weeks to allow the termite attacks. The attacked sample unit were then analyzed for their structure and chemical properties including bulk density, aggregate fraction distribution, pH, C-organic content. The soil around the sample unit were took using a 7 cm diameter ground ring to be used as a reference or comparison with biogenic structures formed by termites. The result showed that the biogenic products have better structure and chemical compared to the its surrounding soil.

BURROWS AND ICHNOFABRIC PRODUCED BY CENTIPEDES: MODERN AND ANCIENT EXAMPLES

ABSTRACT Centipedes extend to the Silurian yet have a relatively poor fossil record. Many species of extant centipedes are semi-fossorial to fossorial and contribute to soil processes, suggesting that their trace fossils should be common in paleosols. The goal of this project was to document the types of biogenic structures produced by two species of large, semi-fossorial centipedes, Hemiscolopendra marginata andScolopendra polymorpha, to aid in the recognition of fossil centipede burrows. Ten specimens of each species were placed in large, sediment-filled terrariums and observed over periods of 14 days. The centipedes burrowed via intrusion, compression, and excavation, moving throughout the enclosure both near the surface and deep within the sediment. Open burrows produced by the centipedes were cast with plaster and the ichnofabric produced was observed through the enclosure walls. The centipedes primarily produced J-, U-, and Y-shaped burrows as well as complexes of linked burrows. The burrows were elliptical in cross section and possessed thin, intermittent, compressional linings. The centipede burrows were compared to burrows of other extant soil arthropods including millipedes, spiders, and scorpions as well as Pennsylvanian to Permian ichnofossils. The centipede burrows were distinct from those of other soil arthropods and many aspects of the ichnofossils were similar to those produced by the centipedes. Description of burrows produced by centipedes can aid in the interpretation of continental ichnofossils and improve our understanding of the composition of ancient soil ecosystems. This knowledge is especially important given the poor preservation potential of centipedes in the environments they inhabit.

Role of Reef-Building, Ecosystem Engineering Polychaetes in Shallow Water Ecosystems

Although the effect of ecosystem engineers in structuring communities is common in several systems, it is seldom as evident as in shallow marine soft-bottoms. These systems lack abiotic three-dimensional structures but host biogenic structures that play critical roles in controlling abiotic conditions and resources. Here I review how reef-building polychaetes (RBP) engineer their environment and affect habitat quality, thus regulating community structure, ecosystem functioning, and the provision of ecosystem services in shallow waters. The analysis focuses on different engineering mechanisms, such as hard substrate production, effects on hydrodynamics, and sediment transport, and impacts mediated by filter feeding and biodeposition. Finally, I deal with landscape-level topographic alteration by RBP. In conclusion, RBP have positive impacts on diversity and abundance of many species mediated by the structure of the reef. Additionally, by feeding on phytoplankton and decreasing water turbidity, RBP can control primary production, increase light penetration, and might alleviate the effects of eutrophication affecting supporting ecosystem services, such as nutrient cycling. They can also modulate cultural ecosystem services by affecting recreational activities (e.g., negative impacts on boating and angling, increased value of sites as birdwatching sites). Acknowledging the multiplicity of synergistic and antagonistic effects of RBP on ecosystems and linking changes in habitat structure, filter-feeding activities, and biodeposition to ecosystem services are essential for effective decision-making regarding their management and restoration.

A comparative study of naturally and synthetically derived bioceramics for biomedical applications

Hydroxyapatite (HAp) is a bioactive material, similar to the mineral constituent of natural bone and teeth. Naturally derived HAp is currently used in various types of orthopedic and maxillofacial applications because of their osteoconductive properties and tissue responses. In recent years, the use of natural biogenic structures and materials for medical purpose has been motivated by limitations in producing synthetic materials. Our study mainly focused to synthesis of hydroxyapatite from biogenic waste (squid pens) material. Naturally derived HAp can develop a tight bond with bone tissue, which is stable towards bio resorption and has no adverse effects on the human body. For these reasons the scope of the present work is focused on the synthesis of HAp derived from biogenic waste for biomedical applications. Our results showed that biogenic HAp is non-toxic and improve the cell adhesion. All the as-synthesized sample were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray analysis (EDAX).

Is tourism affecting polychaete assemblages associated with rhodolith beds in Northeastern Brazil?

ABSTRACT. Introduction: Rhodoliths are biogenic structures distributed worldwide, formed by several types of calcareous algae. They may host a great diversity of marine invertebrates, among which polychaetes are conspicuous and diversified representatives. Rhodolith beds are notwithstanding vulnerable to several human activities (e.g. exploitation of commercial species associated with rhodoliths, petroleum exploration, fishing activities, effluent discharges, and tourism), which may compromise that diversity. Tourism is presently increasing its impact on rhodolith beds. Global warming and ocean acidification are also determinant factors in faunal change. Objective: to analyse the polychaete assemblages associated with rhodolith beds subject to different intensities of touristic pressure at Seixas Beach (NE Brazil), where tourism is gradually increasing over time. Methods: Effects were evaluated at two depths, 1.5 m and 4.0 m. Sampling was done every two months during 2015, encompassing the two marked seasons of the year in the region (rainy and dry). Quadrats of 15 x 15 cm were placed in each depth during sampling. All rhodoliths present within the quadrat were collected (usually four to five rhodoliths). Our hypothesis was that the deeper depth and the samples from the dry season months would be increasingly subject to the impact of tourism. Results: Overall, 49 species were found (from 21 different families), and a total of 733 individuals were collected. The most abundant species was Eunice wasinensis (280 individuals, 38.2% of total abundance). The species Eurythoe complanata, Eunice biannulata, E. wasinensis, Lysidice ninetta, Oxydromus pugettensis and Ceratonereis (Ceratonereis) singularis appeared in all months. The study detected a tendency for higher diversity to occur at the depth of 1.5 m for all indices, but only the Shannon-Wiener values were significantly higher there (p < 0.05). No clear differences were found regarding months or season. Conclusions: These results suggest that a higher potential pressure due to tourism may occur at 4.0 m due to more intense craft shipping activities (traffic of catamaran boats transporting tourists to and from the reefs) in that area.