Copepods are the most abundant organisms in marine zooplankton and the primary components of the food chain. They are hotspots for highly adaptable microorganisms, which are pivotal in biogeochemical cycles. The microbiome, encompassing microorganisms within and surrounding marine planktonic organisms, holds considerable potential for biotechnological advancements. Despite marine microbiome research interests expanding, our understanding of the ecological interactions between microbiome and copepods remains limited. This review intends to give an overview of the recent studies regarding the microbiome associated with marine copepods, with particular focus on the diversity of bacteria and fungi. The significance of copepod-associated microbiomes in different contexts, such as aquaculture and biodegradation processes, was evaluated. The ability of the microbiome to mitigate harmful bacterial growth in cultured organisms was also explored. The microbiome associated with copepods has demonstrated efficacy in reducing the proliferation of detrimental bacteria in aquaculture, paving the way for the commercial utilization of natural zooplankton in fish rearing. Additionally, copepod-associated microbiomes may play a role in addressing marine environmental challenges, such as the bioremediation of polluted marine matrices. Overall, this review represents a basis for investigating intricate copepod-associated microbiomes and their diverse applications, enhancing our comprehension of the ecological and evolutionary significance of marine microbiomes.

Zinc environmental levels are increasing due to human activities, posing a threat to ecosystems and human health. Therefore, new tools able to remediate Zn contamination in freshwater are highly recommended. Specimens of Dreissena polymorpha (zebra mussel) were exposed for 48 h and 7 days to a wide range of ZnCl₂ nominal concentrations (1–10–50–100 mg/L), including those environmentally relevant. Cellulose-based nanosponges (CNS) were also tested to assess their safety and suitability for Zn removal from freshwater. Zebra mussels were exposed to 50 mg/L ZnCl₂ alone or incubated with 1.25 g/L of CNS (2 h) and then removed by filtration. The effect of Zn decontamination induced by CNS has been verified by the acute toxicity bioassay Microtox^®. DNA primary damage was investigated by the Comet assay; micronuclei frequency and nuclear morphological alterations were assessed by Cytome assay in mussels’ haemocytes. The results confirmed the genotoxic effect of ZnCl₂ in zebra mussel haemocytes at 48 h and 7-day exposure time. Zinc concentrations were measured in CNS, suggesting that cellulose-based nanosponges were able to remove Zn(II) by reducing its levels in exposure waters and soft tissues of D. polymorpha in agreement with the observed restoration of genetic damage exerted by zinc exposure alone.

The use of marine invertebrates in ecotoxicology is important for an integrated approach which takes into consideration physiological responses and chemical levels in environmental matrices. Standard protocols have been developed and organisms belonging to different trophic levels are needed as model organisms to evaluate toxicant bioavailability and assess their impact on marine biota. The calanoid copepod Acartia tonsa is commonly used in ecotoxicology due to its widespread distribution and well-studied biology. However, different strains coming from various geographical areas are available, and possible variations in physiological characteristics raise concerns about the comparability of ecotoxicological results. This study compares the life cycle assessment and sensitivity of Adriatic and Baltic strains of A. tonsa exposed to nickel (Ni²⁺) in standardized acute and semi-chronic tests. Life cycle assessments revealed differences in egg production, egg-hatching success, and naupliar viability between the strains. The acute toxicity test demonstrated the significantly higher sensitivity of Adriatic strain nauplii to Ni²⁺ compared to the Baltic strain, whereas the semi-chronic test showed no significant difference in sensitivity between the strains. These findings suggest that while strain-specific differences exist in different geographical populations, responses to toxicants are not significantly different. Particularly, the semi-chronic assessments with both A. tonsa strains emphasized the robustness of this species as a model organism in ecotoxicology.

The use of eco-friendly engineered nanomaterials represents a recent solution for an effective and safe treatment of contaminated dredging sludge. In this study, an eco-designed engineered material based on cross-linked nanocellulose (CNS) was applied for the first time to decontaminate a real matrix from heavy metals (namely Zn, Ni, Cu, and Fe) and other undesired elements (mainly Ba and As) in a lab-scale study, with the aim to design a safe solution for the remediation of contaminated matrices. Contaminated freshwater sludge was treated with CNS coupled with a filtering fine-mesh net, and the obtained waters were tested for acute and sublethal toxicity. In order to check the safety of the proposed treatment system, toxicity tests were conducted by exposing the bacterium Aliivibrio fischeri and the crustacean Heterocypris incongruens, while subtoxicity biomarkers such as lysosomal membrane stability, genetic, and chromosomal damage assessment were performed on the freshwater bivalve Dreissena polymorpha. Dredging sludge was found to be genotoxic, and such genotoxicity was mitigated by the combined use of CNS and a filtering fine-mesh net. Chemical analyses confirmed the results by highlighting the abetment of target contaminants, indicating the present model as a promising tool in freshwater sludge nanoremediation.

This study investigates the effect of different microalgae diets on the microbiomes associated with the marine copepod Acartia tonsa. Copepods were fed with two different mixed-diet compositions: (i) Isochrysis galbana (ISO) and Rhinomonas reticulata (RHI)—(ISO + RHI) and (ii) ISO and Rhodomonas baltica (RHO)—(ISO + RHO). 16S rDNA metabarcoding and comparative statistic have been adopted to study microbial diversity associated with algae and copepods. Diversity index, taxonomic profiling, and statistically significant taxa differential abundances were evaluated with reference to the different algal and copepod microbiomes. Results showed that the different feeding regimes shape different copepod microbial communities. The abundance of Vermiphilaceae, OM190, KI89A_clade, Cyanobium_PCC-6307, and Cyclobacteriaceae increased in copepod microbiomes independently by the feeding regimes. On the other hand, Tistlia sp., Bradymonadales, and Alteromonadaceae were differentially enriched in copepod microbiomes in relation to the different feeding regimes. Differences in the microbial community composition between ISO + RHI and ISO + RHO were observed, suggesting that the specific algal diet plays a pivotal role in shaping microbiome structure.

Copepods are widely recognized as biologically superior live prey for many marine fish larvae, yet their routine large-scale production remains a major bottleneck in aquaculture. Within this context, the harpacticoid genus Tigriopus has attracted increasing attention because it combines broad environmental tolerance, ease of culture, and promising nutritional and biotechnological value. This review critically examines the current state of knowledge on the genus Tigriopus, with particular emphasis on its aquaculture relevance, while integrating the biological, ecological and ecotoxicological framework needed to interpret the specific case of the Mediterranean species T. fulvus. The available literature shows that in aquaculture, the potential of this copepod genus is supported by complementary evidence across species. T. californicus currently provides the strongest proof of concept for pilot-scale biomass production and biochemical valorization, particularly as a source of omega-3- and astaxanthin-rich biomass. T. japonicus contributes most clearly to culture optimization and live-feed application, especially with respect to feeding performance and stocking-density effects. Tigriopus fulvus, in contrast, remains an earlier-stage but credible Mediterranean candidate, showing promising diet-dependent naupliar production and survival, although its culture technology is still underdeveloped. Overall, Tigriopus should be regarded as a genus of growing relevance for aquaculture, not only as live prey but also as a potential source of functional biomass. Future progress will depend on improved mass-culture methods, feeding optimization, harvesting efficiency, and a comparative species-level framework linking biological traits to specific aquaculture applications.