Temporal Prediction of Paralytic Shellfish Toxins in the Mussel Mytilus galloprovincialis Using a LSTM Neural Network Model from Environmental Data

Paralytic shellfish toxins (PSTs) are produced mainly by Alexandrium catenella (formerly A. tamarense). Since 2000, the National Institute of Fisheries Science (NIFS) has been providing information on PST outbreaks in Korean coastal waters at one- or two-week intervals. However, a daily forecast is essential for immediate responses to PST outbreaks. This study aimed to predict the outbreak timing of PSTs in the mussel Mytilus galloprovincialis in Jinhae Bay and along the Geoje coast in the southern coast of the Korea Peninsula. We used a long-short-term memory (LSTM) neural network model for temporal prediction of PST outbreaks from environmental data, such as water temperature (WT), tidal height, and salinity, measured at the Geojedo, Gadeokdo, and Masan tidal stations from 2006 to 2020. We found that PST outbreaks is gradually accelerated during the three years from 2018 to 2020. Because the in-situ environmental measurements had many missing data throughout the time span, we applied LSTM for gap-filling of the environmental measurements. We trained and tested the LSTM models with different combinations of environmental factors and the ground truth timing data of PST outbreaks for 5479 days as input and output. The LSTM model trained from only WT had the highest accuracy (0.9) and lowest false-alarm rate. The LSTM-based temporal prediction model may be useful as a monitoring system of PSP outbreaks in the coastal waters of southern Korean.

Biological Effects of Non-ionizing Electromagnetic Fields to 27 GHz on Sperm Quality of Mytilus galloprovincialis

Recently, a rising use of wireless internet technologies has been demonstrated. The devices which use these technologies emit a considerable amount of electromagnetic radiation (EMFs) which could interact with the male reproductive system. The aim of this study was to investigate in vitro influence of electromagnetic fields a 27 GHz on sperm quality in Mytilus galloprovincialis. The experiments were conducted with a no commercial high gain pyramidal horn antenna. Sperm samples, taken from sexually mature males of M. galloprovincialis, were placed in seawater. Once evaluated the number and quality of spermatozoa, sperm cells were exposed to electromagnetic fields. The effect of exposure was evaluated after 10, 20, 30 and 40 minutes with light microscope and using Eosin test. All the samples were performed in triplicate and statistical analysis was carried out by one-way ANOVA test. A significative decrease (30%) in sperm motility was ob-served after 10 minutes of exposure and after 30 minutes all sperms were immobile and not vital. The measurement of the Oxidation Reduction Potential (sORP), which evaluates the oxidative damage on spermatozoa, shows how the exposure to 27 GHz has increased the oxidant amount compared to the control groups. This study provides useful data on potential ecological impact of the EMFs on aquatic animals, that currently are poor investigated.

Morphological, Gene, and Hormonal Changes in Gonads and In-Creased Micrococcal Nuclease Accessibility of Sperm Chromatin Induced by Mercury

Mercury is one of the most dangerous environmental pollutants. In this work, we analysed the effects of exposure of Mytilus galloprovincialis to 1, 10 and 100 pM HgCl2 for 24 h on the gonadal morphology and on the expression level of three stress genes: mt10, hsp70 and πgst. In this tissue we also evaluated the level of steroidogenic enzymes 3β-HSD and 17β-HSD and the expression of PL protein genes. Finally, we determined difference in sperm chromatin accessibility to micrococcal nuclease. We found alterations in gonadal morphology especially after exposure to 10 and 100 pM HgCl2 and hypo-expression of the three stress genes, particularly for hsp70. Furthermore, decreased labelling with both 3β-HSD and 17β-HSD antibodies was observed following exposure to 1 and 10 pM HgCl2 and complete absence at 100 pM HgCl2 exposure. Gonads of mussels exposed to all HgCl2 doses showed decreased expression of PL protein genes especially for PLIII. Finally, micrococcal nuclease digestions showed that all doses of HgCl2 exposure resulted in increased sperm chromatin accessibility to this enzyme, indicative of improper sperm chromatin structure. All of these changes provide preliminary data of the potential toxicity of mercury on the reproductive health of this mussel.

Concentration and distribution of macrominerals in tissues of Mediterranean mussel Mytilus galloprovincialis exposed to Cd and Cd-mixtures

Marine ecosystems are under great pressure due to heavy metals pollution, and mussels remain an important knowledge source in this regard. In this study, Mediterranean mussels (Mytilus galloprovincialis) were exposed for 7 days to Cd and three Cd-mixtures (Cd+Pb, Cd+Cu and Cd+Pb+Cu). The accumulation and tissue distribution of inorganic elements (Ca, K, Mg, Na, P and S, macrominerals) that are usually not taken into consideration in field studies on in bioassays were evaluated. Regarding concentration, the element which differed the most with respect to the control group was K, while Mg was the only one which showed no significant statistical difference with the control group. The group exposed to ternary mixture was the one in which there were more alterations in concentration and distribution of these macrominerals with respect to control, whereas in the group exposed to single Cd no significant differences in the concentration of these inorganic elements were found. The concentration and distribution of macrominerals in the compartments studied (digestive gland, gill and remaining soft tissues) is susceptible to the presence of Cd and heavy metal Cd-mixtures, with percentages of changes until 28.7%. Study results suggest that macrominerals composition in mussel tissues could be useful in studies of heavy metal contamination in marine ecosystems.

CONTROL OF POTENTIAL MUSSEL RECRUITMENT TAKING INTO ACCOUNT SOME ENVIRONMENTAL PARAMETERS IN SEVASTOPOL ESTUARINE ZONE

In 2020-2021, potential recruitment of the mussel Mytilus galloprovincialis was measured in Sevastopol estuarine waters with regard to temperature, salinity, and pH in three depth horizons 1–3, 7, and 11 m. Compared to the previous annual period in 2021, spring mussel recruitment at all depth horizons in-creased by an order of magnitude. This increase was preceded by a mild winter. Also in 2021, a decrease in salinity and an increase in the vertical variability of the thermohaline structure of water were observed. The obtained data may indirectly indicate the improvement of environmental conditions for mussel productivity increase in 2021. The necessity of improving the method of the control for mussel recruit-ment related to possible vertical migrations of its post-larvae is shown.

Mussel Shells, a Valuable Calcium Resource for the Pharmaceutical Industry

(1) Background: The mussel (Mytilus edulis, Mytilus galloprovincialis) is the most widespread lamellibranch mollusk, being fished on all coasts of the European seas. Mussels are also widely grown in Japan, China, and Spain, especially for food purposes. This paper shows an original technique for mussel shell processing for preparation of calcium salts, such as calcium levulinate. This process involves synthesis of calcium levulinate by treatment of Mytilus galloprovincialis shells with levulinic acid. The advantage of mussel shell utilization results in more straightforward qualitative composition. Thus, the weight of the mineral component lies with calcium carbonate, which can be used for extraction of pharmaceutical preparations. (2) Methods: Shell powder was first deproteinized by calcination, then the mineral part was treated with levulinic acid. The problem of shells generally resulting from the industrialization of marine molluscs creates enough shortcomings, if one only mentions storage and handling. One of the solutions proposed by us is the capitalization of calcium from shells in the pharmaceutical industry. (3) Results: The toxicity of calcium levulinate synthesized from the mussel shells was evaluated by the method known in the scientific literature as the Constantinescu phytobiological method (using wheat kernels, Triticum vulgare Mill). Acute toxicity of calcium levulinate was evaluated; the experiments showed the low toxicity of calcium levulinate. (4) Conclusion: The experimental results highlighted calcium as the predominant element in the composition of mussel shells, which strengthens the argument of capitalizing the shells as an important natural source of calcium.