Assessing the Toxicity of Lagocephalus sceleratus Pufferfish from the Southeastern Aegean Sea and the Relationship of Tetrodotoxin with Gonadal Hormones.

Given the dramatic increase in the L. sceleratus population in the southeastern Aegean Sea, there is growing interest in assessing the toxicity of this pufferfish and the factors controlling its tetrodotoxin (TTX) content. In the present study, liver, gonads, muscle and skin of 37 L. sceleratus specimens collected during May and June 2021 from the island of Rhodes, Greece, were subjected to multi-analyte profiling using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to quantitate TTX and evaluate whether this biotoxin interrelates with hormones. TTX and its analogues 4-epiTTX, 11-deoxyTTX, 11-norTTX-6-ol, 4,9-anhydroTTX and 5,11/6,11-dideoxyTTX were detected in all tissue types. Liver and gonads were the most toxic tissues, with the highest TTX concentrations being observed in the ovaries of female specimens. Only 22% of the analyzed muscle samples were non-toxic according to the Japanese toxicity threshold (2.2 µg TTX eq g-1), confirming the high poisoning risk from the inadvertent consumption of this species. Four steroid hormones (i.e., cortisol, testosterone, androstenedione and ß-estradiol) and the gonadotropin-releasing hormone (GnRH) were detected in the gonads. Androstenedione dominated in female specimens, while GnRH was more abundant in males. A positive correlation of TTX and its analogues with ß-estradiol was observed. However, a model incorporating sex rather than ß-estradiol as the independent variable proven to be more efficient in predicting TTX concentration, implying that other sex-related characteristics are more important than specific hormone-regulated processes.

Comparative Chemical Profiling and Antimicrobial/Anticancer Evaluation of Extracts from Farmed versus Wild Agelas oroides and Sarcotragus foetidus Sponges.

Marine sponges are highly efficient in removing organic pollutants and their cultivation, adjacent to fish farms, is increasingly considered as a strategy for improving seawater quality. Moreover, these invertebrates produce a plethora of bioactive metabolites, which could translate into an extra profit for the aquaculture sector. Here, we investigated the chemical profile and bioactivity of two Mediterranean species (i.e., Agelas oroides and Sarcotragus foetidus) and we assessed whether cultivated sponges differed substantially from their wild counterparts. Metabolomic analysis of crude sponge extracts revealed species-specific chemical patterns, with A. oroides and S. foetidus dominated by alkaloids and lipids, respectively. More importantly, farmed and wild explants of each species demonstrated similar chemical fingerprints, with the majority of the metabolites showing modest differences on a sponge mass-normalized basis. Furthermore, farmed sponge extracts presented similar or slightly lower antibacterial activity against methicillin-resistant Staphylococcus aureus, compared to the extracts resulting from wild sponges. Anticancer assays against human colorectal carcinoma cells (HCT-116) revealed marginally active extracts from both wild and farmed S. foetidus populations. Our study highlights that, besides mitigating organic pollution in fish aquaculture, sponge farming can serve as a valuable resource of biomolecules, with promising potential in pharmaceutical and biomedical applications.

Uptake of aquaculture-related dissolved organic pollutants by marine sponges: Kinetics and mechanistic insights from a laboratory study.

Besides the release of organic matter from uneaten feed and fish excreta, a considerable amount of deleterious chemicals may also end up into the marine environment from intensive aquaculture. A fraction of these pollutants remains freely dissolved and pose a threat to marine life due to increased bioavailability. Given the filter-feeding ability of sponges, we investigated the capacity of four ubiquitous Mediterranean species (Agelas oroides, Axinella cannabina, Chondrosia reniformis and Sarcotragus foetidus) in removing aquaculture-related dissolved organic pollutants. These included individual chemicals belonging to antibiotics (i.e., oxytetracycline), antifouling biocides (i.e., diuron and Irgarol 1051) and polycyclic aromatic hydrocarbons (i.e., 2,6-dimethylnapththalene, phenanthrene). The uptake of pollutants was assessed in vitro by exposing small sponge explants to each chemical for a period of 8 h. Additional "cleanup" experiments were performed for complex mixtures mimicking the dissolved organic material encountered in fish farms, such as filtrates of fish feed and excreta. All sponges exhibited a pronounced preference for lipophilic pollutants and a strong positive correlation was revealed between clearance rate and substrate hydrophobicity. Our best filter-feeder (i.e., A. oroides) was able to clear 10.0 ± 1.3 mL of seawater per hour and per gram of sponge, when exposed to 2,6-dimethylnapththalene. Active pumping was found to be the predominant mechanism dictating the assimilation of dissolved pollutants in all sponge species, as it was 3-10 times faster than pollutants' passive adsorption on sponges' pinacoderm. Additionally, the uptaken pollutants were shown to be strongly retained by sponges and they were hardly released back to seawater as a result of desorption or sponge excretory mechanisms. Our study corroborates that sponges are highly efficient in uptaking dissolved organic compounds and it offers new insights into the kinetics and mechanisms ruling this process.