Marine sponges as a powerful tool for trace elements biomonitoring studies in coastal environment

Application of marine sponges for biomonitoring active pharmaceutical ingredients (APIs) in coral reefs. Optimization of an SPME and ESI-LC-MS/MS method

Chemical pollution is a threat to coral reefs. To preserve them, it is crucial to monitor novel contaminants and assess the related risks. The occurrence of active pharmaceutical ingredients (APIs) in coral reefs has been poorly investigated until now. Under this light, we tested the use of the marine sponge Cf. Hyrtios as bio-monitors and conducted a pilot study in the Faafu Atoll (Maldives). Analyses were carried out by in vivo solid-phase microextraction (SPME) and liquid chromatography (LC) electrospray ionization (ESI) tandem mass spectrometry (MS/MS). Twelve APIs were selected for method optimization. Limits of quantitation (LOQs) were in the 0.6 and 2.5 ng/g range, accuracy between 86.5 % and 104.7 %, and precision between 3.0 % and 14.9 %. All the sponges located in the inner reefs resulted contaminated with at least one API. Gabapentin and Carbamazepine displayed the highest detection rates, while Ketoprofen had the highest concentration (up to 15.7 ng/g).

Out of the blue: Hyperaccumulation of molybdenum in the Indo-Pacific sponge Theonella conica

Molybdenum is an essential micronutrient, but because of its toxicity at high concentrations, its accumulation in living organisms has not been widely demonstrated. In this study, we report that the marine sponge Theonella conica accumulates exceptionally high levels of molybdenum (46,793 micrograms per gram of dry weight) in a wide geographic distribution from the northern Red Sea to the reefs of Zanzibar, Indian Ocean. The element is found in various sponge body fractions and correlates to selenium. We further investigated the microbial composition of the sponge and compared it to its more studied congener, Theonella swinhoei. Our analysis illuminates the symbiotic bacterium Entotheonella sp. and its role in molybdenum accumulation. Through microscopic and analytical methods, we provide evidence of intracellular spheres within Entotheonella sp. that exhibit high molybdenum content, further unraveling the intricate mechanisms behind molybdenum accumulation in this sponge species and its significance in the broader context of molybdenum biogeochemical cycling.

Methylmercury exposure of the sponge O. lobularis induces strong tissue and cell defects

Mediterranean marine biota suffers from various anthropogenic threats. Among them, pollutants such as mercury (Hg) represent important environmental issues that are exacerbated by bioaccumulation and bioamplification along food webs via its organic form, monomethylmercury (MMHg). To date, very little is known regarding the impact of mercury on Porifera and the few available studies have been exclusively focused on Demospongiae. This work studies the effect of MMHgCl at different biological levels of Oscarella lobularis (Porifera, Homoscleromorpha). Bioaccumulation assays show that MMHgCl significantly accumulated in sponge tissues after a 96-h exposure to 0.1 μg L-1. Toxicity assays (LC5096h) show a sensibility that depends on life-stage (adult vs bud). Additionally, we show that the exposure to 1 μg L-1 MMHgCl negatively impacts the epithelial integrity and the regeneration process in buds, as shown by the loss of cell-cell contacts and the alteration of osculum morphogenesis. For the first time in a sponge, a whole set of genes classically involved in metal detoxification and in antioxidant response were identified. Significant changes in catalase, superoxide dismutase and nuclear factor (erythroid-derived 2)-like 2 expressions in exposed juveniles were measured. Such an integrative approach from the physiological to the molecular scales on a non-model organism expands our knowledge concerning sensitivity and toxicity mechanisms induced by MMHg in Porifera, raising new questions regarding the possible defences used by marine sponges.

Hyper-accumulation of vanadium in animals: Two sponges compete with urochordates

Vanadium (V) concentrations in organisms are usually very low. To date, among animals, only some urochordate and annelid species contain very high levels of V in their tissues. A new case of hyper-accumulation of V in a distinct animal phylum (Porifera), namely, the two homoscleromorph sponge species Oscarella lobularis and O. tuberculata is reported. The measured concentrations (up to 30 g/kg dry weight) exceed those reported previously and are not found in all sponge classes. In both Oscarella species, V is mainly accumulated in the surface tissues, and in mesohylar cells, as V(IV), before being partly reduced to V(III) in the deeper tissues. Candidate genes from Bacteria and sponges have been identified as possibly being involved in the metabolism of V. This finding provides clues for the development of bioremediation strategies in marine ecosystems and/or bioinspired processes to recycle this critical metal.

Metallic trace elements in marine sponges living in a semi-enclosed tropical lagoon

The ability of marine filter feeders to accumulate metals could help monitor the health of the marine environment. This study examined the concentration of metallic trace elements (MTE) in two marine sponges, Rhabdastrella globostellata and Hyrtios erectus, from three sampling zones of the semi-enclosed Bouraké Lagoon (New Caledonia, South West Pacific). MTE in sponge tissues, seawater, and surrounding sediments was measured using inductively coupled plasma with optical emission spectroscopy. The variability in sponge MTE concentrations between species and sampling zones was visually discriminated using a principal component analysis (PCA). Sponges showed Fe, Mn, Cr, Ni, and Zn concentrations 2 to 10 times higher than in the surrounding sediments and seawater. Hyrtios erectus accumulated 3 to 20 times more MTE than R. globostellata, except for Zn. Average bioconcentration factors in sponge tissues were (in decreasing order) Zn > Ni > Mn > Fe > Cr relate to sediments and Fe > Ni > Mn > Cr > Zn relate to seawater. The PCA confirmed higher MTE concentrations in H. erectus compared to R. globostellata. Our results confirm that marine sponges can accumulate MTE to some extent and could be used as a tool for assessing metals contamination in lagoon ecosystems, particularly in New Caledonia, where 40% of the lagoon is classified as a UNESCO World Heritage Site.

The use of marine sponge species as a bioindicator to monitor metal pollution in Red Sea, Saudi Arabia

The existing data on trace elements of benthic sea organisms is scarce. Yet, the pressing issue of environmental contamination has spurred a surge in the use of organisms as biomonitors. In this study, sediment cores were sampled with the sponges, and metal concentrations were determined in both samples using ICP-MS. The mean concentrations of metals in benthic sediments and sponge species analyzed in this study differed significantly (Sediment > Phorbas species > Negombata magnifica > Callyspongia species > Amphimedon chloros). This could be due to the varying capacity of each sponge species to accumulate a particular metal by different means. Negombata magnifica and Phorbas species appear to be indicators, accumulators, or hyper-accumulators of Cu and Mn, while Callyspongia species is an indicator, accumulator, or hyper-accumulator of Cu only due to bioconcentration factor > 1 for the aforementioned metals. Concentrations of Cu and As in sediment were below the Effects Range Median but above the Effects Range Low threshold, hence the need to give more attention to these metals. This research provides a baseline dataset for designing monitoring strategies on this ecosystem and using sponge species for biomonitoring.

Microplastics in coastal and oceanic surface waters and their role as carriers of pollutants of emerging concern in marine organisms

Microplastics (Mps) pose a significant environmental challenge with global implications. To examine the effect of Mps on coastal and oceanic surface waters, as well as in marine organisms, 167 original research papers published between January 2013 and September 2022 were analyzed. The study revealed an unequal distribution of research efforts across the world. Fragments and fibers were the most frequently detected particles in ocean surface waters and marine biota, which mainly consisted of colored and transparent microparticles. Sampling of Mps was primarily done using collecting nets with a mesh size of 330 μm. Most articles used a stereomicroscope and Fourier-Transform Infrared spectroscopy for identification and composition determination, respectively. Polyethylene and polypropylene were the most frequent polymers found, both in coastal waters and in marine organisms. The major impact observed on marine organisms was a reduction in growth rate, an increase in mortality, and reduced food consumption. The hydrophobic nature of plastics encourages the formation of biofilms called the "plastisphere," which can carry pollutants that are often toxic and can enter the food chain. To better define management measures, it is necessary to standardize investigations that assess Mp pollution, considering not only the geomorphological and oceanographic features of each region but also the urban and industrial occupation of the studied marine environments.

Preliminary inter-port study of the quality of environments using physiological responses of invertebrates exposed to chronic trace element and organic contamination in Corsica (Mediterranean Sea)

Port areas are socio-ecosystems impacted by chronic mixture pollution. Some marine species benefit from living there and may be studied to define the ecological state of such environments. In this study, the risks of chronic chemical contamination and its consequences on three marine molluscs were evaluated in North Corsica (France) port areas. Mediterranean mussel Mytilus galloprovincialis, tubular sea cucumber Holothuria tubulosa and Mediterranean limpet Patella sp. were sampled in three port areas and a reference location. A set of biomarkers was analysed to evaluate oxidative stress, detoxification, energetic metabolism, neurotoxicity, immunity and bioaccumulation (metallic trace elements and organic pollutants). The objectives were to assess pollution-induced effects in organisms, to determine the best bioindicator species for the selected locations and to validate a "pool" sampling technique (when the analysis is done on a single pool of samples and not on individual samples). The results validate the sampling techniques as "pool" for management purposes. St-Florent was demonstrated as the most contaminated location. All the other locations present a low contamination, below the recommended threshold values (for metallic trace elements and organic pollutants). Finally, the limpet appears to be the best bioindicator for the selected locations. Mussel and sea cucumber are inappropriate due to their absence in this oligotrophic region and the lack of responses observed, respectively.

The sponge Oscarella lobularis (Porifera, Homoscleromorpha) as a suitable biomonitor of metallic contamination in Mediterranean coastal ecosystems

The biomonitoring of metallic contamination in marine ecosystems is often focused on animal species of commercial interest and in lesser extent on non-model marine invertebrates. The aim of this study was to compare the metal concentrations (Li, Al, Ti, Cr, Fe, Ni, Cu, Zn, As, Ag, Cd, Hg, Pb) in seven marine sponges with a particular interest in the homoscleromorph sponge Oscarella lobularis at different sites of the Bay of Marseille, France. Inter-species variabilities suggest that the seven sponge species studied accumulate metals differently. In O. lobularis, a multi-site analysis shows different bioaccumulation between the eight sampled populations. These inter-site differences may reflect differences in the hydrodynamic features and in past and present industrial activities. Because Oscarella lobularis shows a homogeneous metal accumulation pattern in comparison with the other tested species, it appears to be suitable for metal contamination biomonitoring in Mediterranean coastal waters, in particular of the coralligenous communities.

Are physiological responses in foraminifera reliable environmental stress bioindicators? A systematic review

Foraminifera are considered good bioindicators of environmental stress based on morphological abnormalities, but physiological responses occur far earlier and have not been evaluated as pollution markers. The aim of this review was to collate all published articles reporting physiological changes in foraminifera after environmental and anthropogenic stressors, to evaluate their reliability as early markers of environmental stress. We reviewed 70 studies, meeting the inclusion criteria, reporting 13 physiological effects classes after exposure to 17 different stressors. Immune functions, bleaching and lifecycle disruptions, were the most reported. Amphistegina and Ammonia showed high proportion of effects with lead and mercury, with a significant relationship between these heavy metals and the number of physiological effects classes in Ammonia, and between bleaching in Amphistegina gibbosa and Amphistegina lobifera with solar light and temperature. This suggests physiological responses are potentially reliable early indicators of environmental stress. It is necessary to increase quantitative physiological measures and standard exposure protocols in order to properly evaluate these organisms as pollution bioindicators.

Adding functions to marine infrastructure: Pollutant accumulation, physiological and microbiome changes in sponges attached to floating pontoons inside marinas

The rate of introduction of man-made habitats in coastal environments is growing at an unprecedented pace, as a consequence of the expansion of urban areas. Floating installations, due to their unique hydrodynamic features, are able to provide great opportunities for enhancing water detoxification through the use of sessile, filtering organisms. We assessed whether the application of sponges to floating pontoons could function as a tool for biomonitoring organic and inorganic pollutants and for improving water quality inside a moderately contaminated marina in the NW Mediterranean. Fragments of two common Mediterranean sponges (Petrosia (Petrosia) ficiformis and Ircinia oros) were fixed to either suspended natural fibre nets beneath a floating pontoon or to metal frames deployed on the sea bottom. We assessed the accumulation of organic and inorganic contaminants in sponge fragments and, in order to provide an insight into their health status, we examined changes in their metabolic and oxidative stress responses and associated microbiomes. Fragments of both sponge species filtered out pollutants from seawater on both support types, but generally showed a better physiological and metabolic status when fixed to nets underneath the pontoon than to bottom frames. P. (P) ficiformis maintained a more efficient metabolism and exhibited a lower physiological stress levels and higher stability of the associated microbiome in comparison with I. oros. Our study suggests that the application of sponges to floating pontoon represents a promising nature-based solution to improve the ecological value of urban environments.

Use of limpets as alternative to mussels in metal pollution monitoring; application in the Canary Islands

Metal pollution monitoring programs make use of organisms, such as mussels, as biomonitors to evaluate and compare the metal pollution status of coastal areas worldwide. Despite the widespread distribution of mussels of the genus Mytilus, there are places where these organisms are absent or where their abundance is insufficient for biomonitoring purposes, such as in the Canary Islands (Spain). This study considers the use of limpets of the genus Patella as alternative/complementary species in metal pollution monitoring, and compares the bioaccumulation capacity of mussels and limpets collected simultaneously during several sampling campaigns at 11 sampling sites along the continental Spanish Atlantic coastline. Results show that there are some differences in bioaccumulation capacity between limpets and mussels, with limpets showing in average higher concentrations of Cd, Cr, Ni, As and Cu, and lower concentrations of Zn, while concentrations of Hg and Pb were similar for both types of organisms. Significant correlations between metal concentration in mussels and limpets were found for most metals, with the notable exception of Cd, that showed a very different bioaccumulation pattern in both types of organisms. Limpet to mussel metal concentration ratios were derived that can be used to compare the results of metal biomonitoring using either limpets or mussels, and limpets were successfully used in a monitoring survey in the Canary Islands.

Endemic sponge Lubomirskia baikalensis as a bioindicator of chemical elements pollution in Lake Baikal

To evaluate the prospects of using Baikal endemic sponges as bioindicators of chemical elements pollution, the elemental composition of sponges, water and substrate samples, collected in two areas with different levels of anthropogenic loading of the Baikal Lake, was determined using two analytical techniques. The content of Cl, Ca, V, Zn, As, Se, Ba, Cd, and Cu in the sponges collected in Listvennichny Bay was significantly higher than in Bolshye Koty Bay. The values of the pollution indices point at the slight to moderate pollution of the substrates. According to the bioaccumulation factor values, sponges accumulate mainly Cd, Cu and Br from the substrate, and the main part of the elements from water. The distribution of elements longwise the sponges and their intraspecific variation were evaluated. It was shown that Lubomirskia baikalensis sponges were suitable bioindicators to assess the pollution of Lake Baikal.

Phototrophic sponge productivity may not be enhanced in a high CO2 world

Sponges are major components of benthic communities across the world and have been identified as potential "winners" on coral reefs in the face of global climate change as result of their tolerance to ocean warming and acidification (OA). Previous studies have also hypothesised that photosymbiont-containing sponges might have higher productivity under future OA conditions as a result of photosymbionts having increased access to CO₂ and subsequently greater carbon production. Here we test this hypothesis for a widespread and abundant photosymbiont-containing sponge species Lamellodysidea herbacea at a CO₂ seep in Papua New Guinea simulating OA conditions. We found seep sponges had relatively higher cyanobacterial abundance, chlorophyll concentrations and symbiont photosynthetic efficiency than non-seep sponges, and a three-fold higher sponge abundance at the seep site. However, while gross oxygen production was the same for seep and non-seep sponges, seep sponge dark respiration rates were higher and instantaneous photosynthesis: respiration (P:R) ratios were lower. We show that while photosymbiont containing sponges may not have increased productivity under OA, they are able to show flexibility in their relationships with microbes and offset increased metabolic costs associated with climate change associated stress.

Marine sponges as coastal bioindicators of rare earth elements bioaccumulation in the French Mediterranean Sea

In recent years, the widespread use of rare earth elements (REEs) has raised the issue of their harmful effects on the aquatic environment. REEs are now considered as contaminants of emerging concern. Despite the increasing interest of REEs in modern industry, there is still a lack of knowledge on their potential impact on the environment and especially in the marine environment. In this context, the need for monitoring tools to assess REEs pollution status in marine ecosystems is considered as the first step towards their risk assessment. Similar to mussels, filter-feeder sponges have emerged as a key bio-monitor species for marine chemical pollution. Their key position at a low level of the trophic chain makes them suitable model organisms for the study of REEs potential transfer through the aquatic food web. We therefore undertook a comparative study on seven marine sponge species, assessing their capability to bioaccumulate REEs and to potentially transfer these contaminants to higher positions in the trophic chain. A spike experiment under controlled conditions was carried out and the intra- and inter-species variability of REEs was monitored in the sponge bodies by ICP-MS. Concentrations were found to be up to 170 times higher than the corresponding control specimens. The tubular species Aplysina cavernicola showed the highest concentrations among the studied species. This study shows, for the first time, the potential of marine sponges as bio-monitor of REEs as well as their possible application in the bioremediation of polluted sites.

Insights into bioaccumulation and bioconcentration of potentially toxic elements in marine sponges from the Northwestern Mediterranean coast of Morocco

The present research aimed to investigate the concentrations and patterns of six potentially toxic elements (PTEs) in three common sponge species collected along the Moroccan Mediterranean coast, as well as their levels in ambient seawater and sediments. Distinct inter-species variability in PTEs bioaccumulation was observed among the three species, suggesting that sponges have distinct selectivity for assimilating PTEs from the surrounding environment. C. crambe had a higher enrichment capacity for Cu, As, Cr and Ni, while P. ficiformis and C. reniformis exhibited the highest concentration of Cd and Pb, respectively. Interestingly, a similar spatial distribution patterns of PTEs was observed in the three media, with high values occurring in Tangier and Al-Hoceima locations. Overall, our results confirm that sponges reliably reflect the bioavailability of PTEs in their immediate environment, especially C. crambe, whose PTE tissue contents were highly and positively correlated with the contents of all PTEs in the sediments.

Investigation of Global Trends of Pollutants in Marine Ecosystems around Barrang Caddi Island, Spermonde Archipelago Cluster: An Ecological Approach

High-quality marine ecosystems are free from global trending pollutants' (GTP) contaminants. Accuracy and caution are needed during the exploitation of marine resources during marine tourism to prevent future ecological hazards that cause chain effects on aquatic ecosystems and humans. This article identifies exposure to GTP: microplastic (MP); polycyclic aromatic hydrocarbons (PAH); pesticide residue (PR); heavy metal (HM); and medical waste (MW), in marine ecosystems in the marine tourism area (MTA) area and Barrang Caddi Island (BCI) waters. A combination of qualitative and quantitative analysis methods were used with analytical instruments and mathematical formulas. The search results show the average total abundance of MPs in seawater (5.47 units/m3) and fish samples (7.03 units/m3), as well as in the sediment and sponge samples (8.18 units/m3) and (8.32 units/m3). Based on an analysis of the polymer structure, it was identified that the dominant light group was MPs: polyethylene (PE); polypropylene (PP); polystyrene (PS); followed by polyamide-nylon (PA); and polycarbonate (PC). Several PAH pollutants were identified in the samples. In particular, naphthalene (NL) types were the most common pollutants in all of the samples, followed by pyrene (PN), and azulene (AZ). Pb+2 and Cu+2 pollutants around BCI were successfully calculated, showing average concentrations in seawater of 0.164 ± 0.0002 mg/L and 0.293 ± 0.0007 mg/L, respectively, while in fish, the concentrations were 1.811 ± 0.0002 µg/g and 4.372 ± 0.0003 µg/g, respectively. Based on these findings, the BCI area is not recommended as a marine tourism destination.

Accumulation of heavy metals (Cd, Cr, Cu, Mn, Pb, Ni, Zn) in sediments, macroalgae (Cryptonemia crenulata) and sponge (Cinachyrella kuekenthali) of a coral reef in Moín, Limón, Costa Rica: An ecotoxicological approach

Moín, on the Caribbean coast of Costa Rica, is a multi-use coastal zone with a variety of human activities that can cause metal pollution. With the purpose of assessing the current environmental burden due to heavy metal presence in the marine environment of Moín, and their bioaccumulation in organisms of the nearby coral reef, we determined seven metals in samples of bottom sediments, macroalgae (Cryptonemia crenulata) and sponge (Cinachyrella kuekenthali). The results were compared with samples from the southern Caribbean, an area with little human activity. Using ICP-MS, results showed a concentration range for sediments Mn > Cu > Zn > Cr > Ni > Pb > Cd, algae Mn > Cu > Zn > Ni > Cr > Pb > Cd and sponge Mn > Cu > Zn > Ni > Cr > Cd > Pb, relatively low concentrations overall and no differences observed between sites. Bioconcentration factor > 1 was determined for Cd, Cu, Ni and Zn, while concentrations in sediments were below the SQG thresholds. Our study provides the first data on metal concentrations in a macroalgae and a sponge from the Costa Rican Caribbean.

The utility of jellyfish as marine biomonitors

Jellyfish are abundant in coastal waters across broad latitudinal ranges and are often considered pests and a group that can cause phase shifts in marine ecosystems. Recent studies have highlighted their potential as biomonitors of contaminants including metals, herbicides and nutrients. Traditionally, sedentary organisms like molluscs and annelid worms have been used, but some jellyfish have similar characteristics of localised distributions and in some cases sedentary behaviour. Broad gradients in contaminant accumulation have been shown for a number of planktonic jellyfish species. An alternative biomonitoring candidate is the tropical/sub-tropical upside-down jellyfish (Cassiopea spp.). In laboratory and field deployments, Cassiopea accumulate measurable contaminants over days to weeks, making them ideal for detecting short-term pulses. Furthermore, the decay curve of contaminants varies temporally post-exposure and contaminant type. This can provide an estimate of the timing of exposure. Cassiopea, along with other jellyfish, have the potential to be an interesting and valuable group of organisms for monitoring coastal impacts.

Anthracene and Pyrene Biodegradation Performance of Marine Sponge Symbiont Bacteria Consortium

Every petroleum-processing plant produces sewage sludge containing several types of polycyclic aromatic hydrocarbons (PAHs). The degradation of PAHs via physical, biological, and chemical methods is not yet efficient. Among biological methods, the use of marine sponge symbiont bacteria is considered an alternative and promising approach in the degradation of and reduction in PAHs. This study aimed to explore the potential performance of a consortium of sponge symbiont bacteria in degrading anthracene and pyrene. Three bacterial species (Bacillus pumilus strain GLB197, Pseudomonas stutzeri strain SLG510A3-8, and Acinetobacter calcoaceticus strain SLCDA 976) were mixed to form the consortium. The interaction between the bacterial consortium suspension and PAH components was measured at 5 day intervals for 25 days. The biodegradation performance of bacteria on PAH samples was determined on the basis of five biodegradation parameters. The analysis results showed a decrease in the concentration of anthracene (21.89%) and pyrene (7.71%), equivalent to a ratio of 3:1, followed by a decrease in the abundance of anthracene (60.30%) and pyrene (27.52%), equivalent to a ratio of 2:1. The level of pyrene degradation was lower than that of the anthracene due to fact that pyrene is more toxic and has a more stable molecular structure, which hinders its metabolism by bacterial cells. The products from the biodegradation of the two PAHs are alcohols, aldehydes, carboxylic acids, and a small proportion of aromatic hydrocarbon components.

Human impacts on deep-sea sponge grounds: Applying environmental omics to monitoring

Sponges (Phylum Porifera) are the oldest extant Metazoans. In the deep sea, sponges can occur at high densities forming habitats known as sponge grounds. Sponge grounds can extend over large areas of up to hundreds of km² and are biodiversity hotspots. However, as human activities, including deep-water hydrocarbon extraction, continue to expand into areas harbouring sponge grounds, understanding how anthropogenic impacts affect sponges and the ecosystem services they provide at multiple biological scales (community, individual and (sub)cellular levels) is key for achieving sustainable management. This chapter (1) provides an update to the chapter of Advances in Marine Biology Volume 79 entitled "Potential Impacts of Offshore Oil and Gas Activities on Deep-Sea Sponges and the Habitats They Form" and (2) discusses the use of omics as a future tool for deep-sea ecosystem monitoring. While metagenomics and (meta)transcriptomics studies have contributed to improve our understanding of sponge biology in recent years, metabolomics analysis has mostly been used to identify natural products. The sponge metabolome, therefore, remains vastly unknown despite the fact that the metabolome is a key link between the genotype and phenotype, giving us a unique new insight to how key components of an ecosystem are functioning. As the fraction of the metabolome released into the seawater, the sponge exometabolome has only just started to be characterised in comparative environmental metabolomic studies. Yet, the sponge exometabolome constitute a unique opportunity for the identification of biomarkers of sponge health as compounds can be measured in seawater, bypassing the need for physical samples which can still be difficult to collect in the deep sea. Within sponge grounds, the characterisation of a shared sponge exometabolome could lead to the identification of biomarkers of ecosystem functioning and overall health. Challenges remain in establishing omics approaches in environmental monitoring but constant technological advances and reduction in costs means these techniques will become widely available in the future.

Microplastic distribution in urban vs pristine mangroves: Using marine sponges as bioindicators of environmental pollution

Sessile benthic organisms are considered good bioindicators for monitoring environmental quality of coastal ecosystems. However, these environments are impacted by new pollutants such as microplastics (MPs), where there is limited information about organisms that can be used as reliable bioindicators of these emerging contaminants. We evaluated MP concentrations in three compartments: surface sediment, water and in three marine sponge species (Haliclona implexiformis, Halichondria melanadocia and Amorphinopsis atlantica), to determine whether these organisms accumulate MPs and reflect their possible sources. Results showed MPs in all three compartments. Average concentrations ranged from 1861 to 3456 items kg^-1 of dry weight in marine sponges, 130 to 287 items L^-1 in water and 6 to 11 items kg^-1 in sediment. The maximum MP concentration was in the sponge A. atlantica, which registered 5000 items kg^-1 of dry weight, in water was 670 items L^-1 and in sediment was 28 items kg^-1, these values were found in the disturbed study area. The three sponge species exhibited MP bioaccumulation and showed significant differences between disturbed and pristine sites (F = 11.2, p < 0.05), suggesting their use as bioindicators of MP.

High affinity of 3D spongin scaffold towards Hg(II) in real waters

This study focuses on the ability of commercial natural bath sponges, which are made from the skeletons of marine sponges, to sorb Hg from natural waters. The main component of these bath sponges is spongin, which is a protein-based material, closely related to collagen, offering a plenitude of reactive sites from the great variety of amino acids in the protein chains, where the Hg ions can sorb. For a dose of 40 mg L^-1 and initial concentration of 50 μg L^-1 of Hg(II), marine spongin (MS) removed ~90% of Hg from 3 water matrixes (ultrapure, bottled, and seawater), corresponding to a residual concentration of ~5 μg L^-1, which tends to the recommend value for drinking water of 1 μg L^-1. This value was maintained even by increasing the MS dosage, suggesting the existence of a gradient concentration threshold below which the Hg sorption mechanism halts. Kinetic modelling showed that the Pseudo Second-Order equation was the best fit for all the water matrixes, which indicates that the sorption mechanism relies most probably on chemical interactions between the functional groups of spongin and the Hg ions. This material can also be regenerated in HNO₃ and reused for Hg sorption, with marginal losses in efficiency, at least for 3 consecutive cycles.

Comparative study on Hg bioaccumulation and biotransformation in Mediterranean and Atlantic sponge species

In this work we present an assessment of mercury (Hg) and methyl mercury (MeHg) bioaccumulation in different species of marine sponges collected off the Northwestern Mediterranean and Northeastern Atlantic coasts. Overall the results showed significant accumulation of Hg in sponges, with the Mediterranean sponge Chondrilla nucula exhibiting the highest total Hg content (up to 0.5 mg kg^-1) and bio-concentration factor (BCF) up to 23. A significant inter-species variability of Hg bioaccumulation was observed among species collected at the same site. The sponges, collected in marine environment contaminated with Hg show consistently higher Hg accumulation, meaning that the bioaccumulation is proportional to the Hg availability in the surrounding environment. Different extraction protocols were tested for MeHg analysis and, generally, a low MeHg ratio in Hg species (4% and 17% average for Mediterranean and Irish sponges respectively) was detected suggesting a possible demethylation process and therefore a promising role of sponges for Hg bioremediation Additionally, the Hg isotopic composition in these organisms was determined and it showed that MDF (mass dependent fractionation) is the main process in sponges, with the absence of significant MIF. This result suggests a dominant role of associated microbial population in the methylation and/or demethylation processes.

Effects of freshwater sponge Ephydatia fluviatilis on conjugative transfer of antimicrobial resistance in Enterococcus faecalis strains in aquatic environments

Filter feeding is a biotic process that brings waterborne bacteria in close contact with each other and may thus support the horizontal transfer of their antimicrobial resistance genes. This laboratory study investigated whether the freshwater sponge Ephydatia fluviatilis supported the transfer of vancomycin resistance between two Enterococcus faecalis strains that we previously demonstrated to exhibit pheromone responsive plasmid conjugation. Microcosm experiments exposed live and dead colonies of laboratory-grown sponges to a vancomycin-resistant donor strain and a rifampicin-resistant recipient strain of Ent. faecalis. Enterococci with both resistance phenotypes were detected on double selection plates. In comparison to controls, abundance of these presumed transconjugants increased significantly in water from sponge microcosms. Homogenized suspensions of sponge cells also yielded presumed transconjugants; however, there was no significant difference between samples from live or dead sponges. Fluorescent in situ hybridization analysis of the sponge cell matrix using species-specific probes revealed the presence of enterococci clusters with cells adjacent to each other. The results demonstrated that sponge colonies can support the horizontal transfer of antimicrobial resistance although the mechanism underlying this process, such as binding of the bacteria to the sponge collagen matrix, has yet to be fully elucidated.

Tracing source and mobility of arsenic and trace elements in a hydrosystem impacted by past mining activities (Morelos state, Mexico)

The Sierra Huautla (Morelos State, Mexico) is a biological reserve with historical mines of Ag and Pb. In this area, waters used by inhabitants are contaminated by arsenic (As). An integrated environmental survey was realized both in waters and sediments to better constrain the source and the mobility of As and other trace elements. Two areas of interest were selected: (1) the Nexpa River ecosystem to determine the local geochemical background, and (2) the Huautla area, affected by past mining activities. This study allowed the definition of the local geochemical baseline in sediments or in waters, demonstrated uncontaminated by TE in the Nexpa area, except for As in the dissolved phase or for Cd in Suspended Particulate Matters (SPM). In the Huautla area, TE contents in water were higher than the World Health Organization (WHO) limits for Al, As and Mn in unfiltered waters, and only for As in the dissolved phase. Speciation analyses revealed arsenic to be present only as the toxic-inorganic arsenate species, As(+V). In SPM, Ag, As, Cd and Zn concentrations were higher than Sediment Quality Guidelines (SQG). The different geochemical indice (EF: 5, PLI: 3, EF: Igeo: 5-3) demonstrated that SPM were significantly contaminated and consistute an health risk for Huautla inhabitants exposed to As-contaminated waters and TE-rich SPM. The combination of mineralogy, chemistry, C and S stable isotopes with thermodynamic modeling indicate dissolutions of minerals from local geological formations, sorption-desorption phenomena from clays and oxy-hydroxides, and the weathering responsible for the transport of the TE-rich SPM (1.8 wt% for 17% of the total TE concentration). Moreover, the past mining activity would be a source of the contamination only for As in waters from flooded mines.

Role of Natural Flocculation in Eliminating Toxic Metals

Metals as the most common environmental pollutants derive from different sources and have far-reaching harmful impacts on flora, fauna and human health. Moreover, metals cause irreversible damages to marine ecosystems. Estuaries are most productive ecosystems for living creatures and act as a transporting corridor for exchanging materials from river to water bodies including oceans, seas and lakes. One of the most important processes in this region is flocculation. Not only does flocculation process convert a huge percentage of metals from dissolved phase to particulate phase in providing micronutrients to aquatic organisms, more importantly, but it also eliminates metals from aquatic ecosystems and gives aid to the pollution of water bodies to be on the decrease. Moreover, the chemical mass balance between river and sea is substantially influenced by flocculation process. Salinity, pH, dissolved oxygen, dissolved organic carbon and sodium hypochlorite as important factors affect the flocculation of metals during estuarine mixing of river water with seawater. It is vital to make use of natural processes in eliminating pollutants. Thus, natural processes need to be recognized and promoted by various means.

Perspectives on using marine species as bioindicators of plastic pollution

The ever-increasing level of marine pollution due to plastic debris is a globally recognized threat that needs effective actions of control and mitigation. Using marine organisms as bioindicators of plastic pollution can provide crucial information that would better integrate the spatial and temporal presence of plastic debris in the sea. Given their long and frequent migrations, numerous marine species that ingest plastics can provide information on the presence of plastic debris but only on large spatial and temporal scales, thus making it difficult to identify quantitative correlations of ingested plastics within well-defined spatio-temporal patterns. Given the complex dynamics of plastics in the sea, the biomonitoring of marine plastic debris should rely on the combination of several bioindicator species with different characteristics that complement each other. Other critical aspects include the standardization of sampling protocols, analytical detection methods and metrics to evaluate the effects of ingested plastics in marine species.