A laboratory bioassay was conducted to investigate the ecotoxicity of a chromium-enriched superfood, Spirulina platensis, on the meiofauna collected from the Ghar El Melh lagoon, Tunisia. After 1 month of exposure, the abundances of meiobenthic taxa and the taxonomic and morpho-functional diversity of nematodes showed significant differences between the Spirulina and Spirulina + chromium groups. The nematodes were more tolerant of all types of stressors compared to harpacticoids, polychaetes, and oligochaetes, and the lowest taxonomic and morpho-functional diversity of nematodes was observed in the highest sedimentary concentration of S. platensis (50% DW). The mixed treatments may have been richer in micro-habitats and subject to low selective pressure, thereby hosting nematodes with a wide range of adaptations. The responses of the nematode species differed depending on their functional traits. Spirulina enriched with chromium induced two responses for the same feeding group: high toxicity for Daptonema fallax and low toxicity for two Theristus species (T. flevensis and T. modicus). The ecotoxicity of the Spirulina/chromium mixtures were lower than that of Spirulina alone, suggesting mutual neutralization between these two elements. The association between functional traits and taxonomic diversity showed that the effects of the mixtures were not additive and that one of the stressors camouflaged the effect of the other. Our findings should encourage the commercialization of chromium-enriched S. platensis owing to its lower ecotoxicity than Spirulina alone.

Agricultural activities often lead to nutrient enrichment and habitat modification in rivers, possibly altering macroinvertebrate assemblages and hence ecosystem functioning. For the sake of environmental management and conservation, therefore, assessing the impacts of agricultural activities becomes indispensable, especially when these activities are predicted to be intensified in the future. In this study, the plain river network in the Lake Chaohu Basin was chosen to examine how agricultural activities influence the functioning of rivers by assessing land use, water quality, habitat condition and macroinvertebrate assemblages, followed by calculating the macroinvertebrate-based multimetric index (MMI) to indicate overall ecosystem health of the rivers. We found that agricultural activities lowered the diversity of macroinvertebrates (e.g. total number of taxa and Simpson index) primarily due to elevated ammonium concentrations in water and reduced microhabitat types, thereby impairing the habitat integrity and nutrient cycling of rivers. The macroinvertebrate-based MMI was positively correlated with increasing habitat quality but negatively with increasing nutrient concentrations, suggesting its high reliability for indicating the impacts of agricultural activities, which was further substantiated by classification and regression tree (CART) analysis. We recommend analyzing macroinvertebrate assemblages using both multivariate and multimetric approaches to offer a more comprehensive evaluation of the impacts of agricultural activities on ecosystem health. Some environmental (CODMₙ, NH₄⁺-N and PO₄³⁻-P) and biological parameters (total number of taxa), however, can be used as good proxies for MMI, when time and resources for gathering information to develop MMI are limited.

At present, the majority of investigations concerning nanotoxicology in the nematode C. elegans address short-term effects. While this approach allows for the identification of uptake pathways, exposition and acute toxicity, nanoparticle-organism interactions that manifest later in the adult life of C. elegans are missed. Here we show that a microhabitat composed of liquid S-medium and live bacteria in microtiter wells prolongs C. elegans longevity and is optimally suited to monitor chronic eNP-effects over the entire life span (about 34 days) of the nematode. Silver (Ag) nanoparticles reduced C. elegans life span in concentrations ≥10 μg/mL, whereas nano ZnO and CeO₂ (1–160 μg/mL) had no effect on longevity. Monitoring of locomotion behaviors throughout the entire life span of C. elegans showed that Ag NPs accelerate the age-associated decline of swimming and increase of uncoordinated movements at concentrations of ≥10 μg/mL, whereas neuromuscular defects did not occur in response to ZnO and CeO₂ NPs. By means of a fluorescing reporter worm expressing tryptophan hydroxylase-1::DsRed Ag NP-induced behavioral defects were correlated to axonal protein aggregation and neurodegeneration in single serotonergic HSN as well as sensory ADF neurons. Notably, serotonergic ADF neurons represented a sensitive target for Ag NPs in comparison to GABAergic neurons that showed no signs of degeneration under the same conditions. We conclude that due to its analogy to the jellylike boom culture of C. elegans on microbe-rich rotting plant material liquid S-medium culture in spatially confined microtiter wells represents a relevant as well as practical tool for comparative identification of age-resolved nanoparticle effects and vulnerabilities in a significant target organism. Consistent with this, specifically middle-aged nematodes showed premature neuromuscular defects after Ag NP-exposure.

Central European mountain bogs, among the most valuable and threatened of habitats, were exposed to intensive human impact during the 20th century. We reconstructed the subrecent water chemistry and water-table depths using diatom based transfer functions calibrated from modern sampling. Herbarium Sphagnum specimens collected during the period 1918–1998 were used as a source of historic diatom samples. We classified samples into hummocks and hollows according to the identity of dominant Sphagnum species, to reduce bias caused by uneven sampling of particular microhabitats. Our results provide clear evidence for bog pollution by grazing during the period 1918–1947 and by undocumented aerial liming in the early 90-ies. We advocate use of herbarized epibryon as a source of information on subrecent conditions in recently polluted mires.

Coastal urbanization is leading to the accumulation of anthropogenic litter. Understanding the distribution and habitat use of litter by marine biota is important to predict how organisms will respond to anthropogenic changes. We assessed the density, distribution and composition of surface macro-litter (SML) in mangrove forests in Buenaventura (Colombia) and analysed how these microhabitats are used by marine biota. SML density ranged from 2 to 314 g m⁻² (0.22 to 35.5 items m⁻²), implying that mangrove forests surrounding Buenaventura city are among the most polluted coastal areas in the World. Biological assemblages colonizing SML differed according to position on the forest and litter type. The encroachment of SML in mangrove forest enables a seemingly transient colonization of resident and immigrant biota from intertidal rocky shores and subtidal hard bottoms. The successful colonization of SML poses questions regarding the potential for plastics or their leaching chemicals to transfer through food webs.

The Chagos Archipelago is geographically remote and isolated from most direct anthropogenic pressures. Here, we quantify the abundance and diversity of decapod crustaceans inhabiting dead coral colonies, representing a standardised microhabitat, across the Archipelago. Using morphological and molecular techniques we recorded 1868 decapods from 164 nominal species within 54 dead coral colonies, but total species estimates (Chao1 estimator) calculate at least 217 species. Galatheids were the most dominant taxa, though alpheids and hippolytids were also very abundant. 32% of species were rare, and 46% of species were found at only one atoll. This prevalence of rarer species has been reported in other cryptofauna studies, suggesting these assemblages maybe comprised of low-abundance species. This study provides the first estimate of diversity for reef cryptofauna in Chagos, which will serve as a useful baseline for global comparisons of coral reef biodiversity.

Ultraviolet (UV) radiation is a primary environmental stressor for marine species inhabiting intertidal pools. Thus, the use of microhabitats as refuges is key to protect organisms against this stressor. In this study, we compared the quality of rocky and algae as refuges for the intertidal fish Girella laevifrons exposed to UV radiation. Refuge quality was studied by evaluating oxygen consumption and weight gain in control and UV-exposed fish. Rocky-refuge fish consumed less oxygen and gained significantly more weight than algal-refuge fish. The obtained results support the importance of refuge quality on energetic balance of intertidal organisms, where energy can be differentially allocated towards key life processes such as protection/repair or growth. Energy trade-offs need to be considered in research concerning animals inhabiting stressful habitats.

Strong differences have been observed between the assemblages on artificial reefs and on natural hard-bottom habitats worldwide, but little is known about the mechanisms that cause contrasting biodiversity patterns. We examined the influence of spatial attributes in relation to both biogenic and topographic microhabitats, in the distribution and composition of intertidal species on both artificial and natural reefs. We found higher small-scale spatial heterogeneity on the natural reef compared with the study breakwater. Species richness and diversity were associated with a higher availability of crevices, rock pools and mussels in natural habitats. Spatial distribution of certain grazers corresponded well with the spatial structure of microhabitats. In contrast, the lack of microhabitats on the breakwater resulted in the absence of several grazers reflected in lower species richness. Biogenic and topographic microhabitats can have interactive effects providing niche opportunities for multiple species, explaining differences in species diversity between artificial versus natural reefs.

The illegal and destructive fishery of date mussels (i.e. the endolithic mollusc Lithophaga lithophaga) reduces the bio-physical complexity of Mediterranean rocky reefs and dramatically impacts biodiversity. Although date-mussel fishermen do not directly impact sea urchins, these echinoids dramatically increase in abundance on rocky reefs impacted by date-mussel fishery (DMF). The recovery of rocky reefs affected by DMF is hampered by the intense unselective grazing of sea urchins on benthic organisms. No evidence is available, however, about the mechanisms that cause the increase in the population density of sea urchins. I demonstrated here that DMF creates a new microhabitat, i.e. the holes left empty after date mussels are extracted, where small-sized sea urchins take refuge and escape predation. This study thus sheds light on a mechanism through which DMF may locally increase sea urchin population density, contributing to maintain the rocks bare on the long term.

The newly introduced polychaete Linopherus canariensis Langerhans, 1881 was found in the Lake of Faro (NE Sicily), during a study comparing the macrobenthos in artificial modules with a neighboring sandy bottom assemblage. Of a total of 4465 specimens, almost 6% showed morphological variation related to branchial turfs and mean body size. The sandy bottom exhibited an average density of 41.86indL⁻¹ and a wet biomass of 30.35mgL⁻¹, whereas the artificial substratum reached levels of 205.29indL⁻¹ and 318.44mgL⁻¹. The highest estimated immigration rate was 3.7indL⁻¹d⁻¹ (5.8mgL⁻¹d⁻¹). In the artificial microhabitat, 0.4% of the population showed mid-anterior fragmentation, with anterior- (2%), mid- (<1%) and posterior- (1%) regenerating lineages, which contributed significantly to the dispersion ability of this species. L. canariensis was a selective micro-deposit feeder, even under conditions of reduced sediments. Linopherus was found to be a new potential invader of stressed environments that is probably tied to the import of oysters.