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Nanoplastics in Aquatic Ecosystems: Toxicological Risks and Emerging Bacterial Strategies for Biodegradation

Naoplastics, defined as particles smaller than 1000 nm, are an emerging pollutant of increasing concern in aquatic environments. Their small size and high surface-area-to-volume ratio confer high reactivity and a strong capacity to adsorb other environmental contaminants, positioning them as a significant ecological risk, particularly for aquatic ecosystems, seafood safety, and fisheries productivity. In aquaculture systems, nanoplastics can accumulate in the tissues of economically valuable species like shrimp and shellfish, posing potential threats to food safety and trade viability. This review synthesizes current understanding of nanoplastics sources, properties, and toxicological mechanisms, with emphasis on their biological impact across multiple trophic levels. Particular focus is given to their interactions with fish and aquatic invertebrates, as well as their size-dependent toxicity and complex environmental behaviors. The review also explores microbial and enzymatic strategies for nanoplastics detection and biodegradation, highlighting bacterial species capable of producing key enzymes such as PETase and laccase. Additionally, biofilms are discussed as potential modulators of nanoplastics fate, influencing aggregation, transport, and biodegradability. Despite growing research interest, microbial approaches remain largely experimental. Critical challenges persist in detection standardization, in situ validation, and the characterization of degradation pathways. This review outlines emerging opportunities in microbial biotechnology and offers a roadmap for advancing nanoplastics research through interdisciplinary research in aquatic toxicology, microbiology, and sustainable fisheries.

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Microsatellites in Aquaculture Genetics: Foundations, Applications, and Future Directions for Sustainable Breeding

Aquaculture continues to expand globally every year to meet the nutritional needs across the world, but the sustainability of this industry is largely dependent on genetic diversity and breeding practices. This review explores the role of microsatellite markers (SSRs) in aquaculture genetics, and their applications in determining genetic diversity, monitoring inbreeding, and guiding selective breeding programs. It also examines practices such as broodstock selection and ecological influence on genetic differentiation and geneflow. With their high polymorphism and codominant inheritance: microsatellites can be used in parentage analysis, studying population structure and linkage mapping. Applications span diverse taxa; from shrimp and sturgeon to oysters and sea otters; demonstrating their versatility in both conservation and production contexts. Marker-Assisted Selection (MAS) and Quantitative Trait Loci (QTL) mapping are discussed as key strategies for improving traits such as growth, disease resistance, and reproductive efficiency. Despite their advantages, SSRs are also not without limitations. Limitations including genotyping errors, homoplasy, and reduced functional relevance compared to SNPs. However, recent advances in next-generation sequencing (NGS) have significantly enhanced the efficiency of SSR marker discovery, enabling large-scale development even in species lacking extensive genomic resources. When integrated with single nucleotide polymorphisms (SNPs) and genomic selection frameworks, these tools are expected to improve breeding precision and support the global harmonization of marker panels. The synergistic usage of SSRs, SNPs and functional genomics can pave the way to a new era of precision aquaculture that promotes high productivity and long-term sustainability.

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Evaluation of hybridization and spawning ground between Amphiprion ocellaris and Amphiprion ocellaris var.

The main objective of this study was to develop clownfish with specific body colors through hybridization experiments with Amphiprion ocellaris (female) and A. ocellaris var. (male). The experiment also investigated artificial pairing behavior, choice of artificial ovaries, spawning rates, and juvenile morphology. Four types of artificial spawning substrates-smooth tiles (A), rough tiles (B), ceramic flower pots (C), and plastic PVC pipes (P)-were placed in breeding tanks. A total of 12 pairs of broodstock were observed over a period of 16-months to monitor pairing behavior, spawning conditions, and willingness to choose spawning grounds. The results showed that B and C had a higher number of eggs, whereas no spawning was observed in A and P. The average number of eggs laid was 303 ± 0.27 on B and 332 ± 0.57 on C, with no significant difference between the two. These findings suggest that rough tiles and ceramic pots are more suitable spawning substrates than smooth tiles and PVC pipes for A. ocellaris breeding under artificial conditions. The body color of the juvenile fish is different from that of the parents. It has an orange-red chest, a brown body, and a three-white stripe pattern.

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Applications of plasma technology in aquaculture: antimicrobial effects, nitrogen removal, and toxicological implications of plasma-activated water

This study investigates the antimicrobial, nitrogen removal, and toxicity effects of plasma-activated water (PAW) in aquaculture systems. Plasma-activated water was generated using an atmospheric plasma system, which demonstrated potent antimicrobial activity against a range of aquatic pathogens. The bactericidal efficacy was primarily attributed to the synergistic effects of high oxidation-reduction potential (ORP) and low pH, with full pathogen inhibition observed after 5 to 10 minutes of plasma treatment. Oxygen PAW exhibited antimicrobial activity, albeit with lower potency, and showed significant improvements in the degradation of nitrogenous compounds without causing the accumulation of nitrite-N. Notably, atmospheric PAW resulted in the accumulation of nitrite-N, particularly in environments with atmospheric nitrogen, which can present challenges in nitrogen-sensitive aquaculture systems. Toxicity assessments revealed that atmospheric PAW caused 100% mortality in giant freshwater prawns within 2 h, primarily due to elevated nitrite-N levels. In contrast, oxygen PAW showed significantly lower toxicity, especially in seawater, and was deemed relatively safe for marine species such as orange-spotted grouper and white shrimp juveniles. However, oxygen PAW still induced high mortality in giant freshwater prawns, suggesting that plasma treatment remains highly toxic to certain freshwater organisms. These findings highlight the potential of oxygen PAW for nitrogen compound removal and safer application in aquaculture systems, while atmospheric PAW requires careful consideration due to its toxicity.

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Acute toxicity of sulfides and toluene to tilapia (Oreochromis sp.), white shrimp (Penaeus vannamei), and hard clam (Meretrix lusoria)

This study evaluated the acute toxicity of sulfide and toluene to three aquaculture species: tilapia (Oreochromis sp.), white shrimp (Penaeus vannamei), and hard clam (Meretrix lusoria). The experimental protocol was modified from the standard toxicity testing procedure for common carp under static conditions (NIEA B904.13B). The results demonstrated that both sulfide and toluene induced mortality in all three species. Based on 96-h median lethal concentration (LC_(50)) values, the LC_(50) of sulfide and toluene for tilapia were 7.11 mg L^(-1) and 35.03 mg L^(-1), respectively; for white shrimp, 6.24 mg L^(-1) and 28.90 mg L^(-1), respectively; and for hard clam, 3.74 mg L^(-1) and 12.47 mg L^(-1), respectively. Among the tested species, hard clam exhibited the highest sensitivity (lowest tolerance) to both sulfide and toluene, whereas tilapia demonstrated the greatest tolerance.

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Reproductive traits, larval development, and optimal rearing conditions for red-nosed shrimp (Caridina gracilirostris)

This study investigated the reproductive performance, larval development, and optimal environmental conditions for the successful aquaculture of red-nosed shrimp (Caridina gracilirostris). Fecundity was positively correlated with female body size, with an average of 244 eggs per female and an estimated hatching rate of 64.18%. Larvae exhibited high mortality in freshwater, whereas salinities of 5-20 psu significantly enhanced survival, with 10 psu yielding the highest metamorphosis rate (52.02%). Temperature also influenced development time, with larvae at 27-30 °C reaching the postlarval stage more rapidly than those at 24 °C. Detailed morphological observations revealed a six-stage zoeal development, culminating in metamorphosis by day 17. Postlarvae exhibited rapid growth in the first 28 days, followed by slower growth until reaching 3.17 cm at day 84. Crucially, the timing of freshwater acclimation post-metamorphosis significantly influenced survival; transferring postlarvae at 30 days post-metamorphosis (2 cm length) resulted in a significantly higher survival rate (66.7%) compared to earlier transfers. These findings offer valuable insights for optimizing breeding and hatchery practices in ornamental shrimp aquaculture.

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A new species of Terapon from shallow waters of the Red Sea coast off Saudi Arabia (Centrarchiformes, Terapontidae)

A new species of the grunter genus Terapon is described based on two adult fish collected in the Red Sea off Yanbu, western Saudi Arabia, while several other individuals are recorded from Egyptian waters based on photographs. The new species can be separated from its most similar congeneric species, the Indo-West Pacific Terapon jarbua, in having a relatively more slender body, its depth 3.6-3.7 times in SL; the fourth dorsal-fin spine 1.2-1.3 times longer than the third; cycloid scales on the anterior portion of the nape, the chest region and the bases of the pectoral fins; the second body stripe dipping well below the lateral line beneath the base of the spinous dorsal fin; the origins of the pelvic and anal fins 1.9-2.0 times farther apart than the pelvic-fin length; and other body proportions and otolith morphology.

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Effects of temperature and salinity on coral ciliate disease

In recent years, environmental changes have led to significant fluctuations in seawater temperature and salinity, resulting in stress responses in corals. This study investigates the identity of ciliates found in coral farms and examines the effects of temperature and salinity on their proliferation to assess potential threats to coral reef sustainability. Experimental conditions included four temperature treatments (21°C, 24°C, 27°C, and 31°C) and four salinity levels (15, 25, 35, and 40 psu). The ciliate species identified in this study was Scuticociliatia sp. Proliferation rates at 21°C, 24°C, and 27°C increased significantly after 48 hours, with the highest density observed at 72 h at 24°C, followed by a gradual decline after 96 h. Ciliates were unable to tolerate the high temperature of 31°C, reaching peak density at 24 h, after which the proliferation rate declined. High salinity initially suppressed ciliate proliferation, but exponential growth was observed after 24 h of acclimation. Optimal proliferation occurred under low-salinity conditions at 15 psu.

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Utilizing Lipidomics to Optimize PUFA Profiles in Mixed Microalgal Diets for Enhancing Larval Survival of Sexy Shrimp (Thor amboinensis)

The sexy shrimp (Thor amboinensis) is a popular ornamental species known for its distinctive posture, white markings, rapid growth, and social behavior. Despite its appeal, the breeding and larval survival of T. amboinensis are not well understood. This study provided an insights into the optimal dietary requirements for improving larval survival, focusing on the fatty acid composition analyzed using lipidomics. Six microalgal diets-Isochrysis galbana (IG), Nannochloropsis oculata (NO), Tetraselmis chui (TC), and Chaetoceros muelleri (CM), both individually and in combinations I. galbana + N. oculata (IG+NO) and I. galbana + C. muelleri (IG+CM) were test over 28 days. We identified that the mixed IC diet resulted in a significantly higher larval survivals (150.33 ± 2.52 larvae) and supported complete development through all eight zoeal stages. In contrast, diets of NO or TC alone led to severe mortality and incomplete development. The lipidomic profiling of fatty acids revealed that elevated levels of C22:5n-6 and total polyunsaturated fatty acids (PUFAs) were crucial for enhancing larval survival. These findings highlighted the value of lipidomics in identifying PUFA-rich diets, particularly the combination of IG and CM, as essential for supporting the survival and development of sexy shrimp larvae. This study offered a breakthrough for optimizing dietary formulations in the successful captive breeding of this species.

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Optimized Sterilization and Plant Growth Regulators Regime for the Micropropagation of Echinodorus sp. 'Small Bear'

Echinodorus sp. 'Small Bear' is a compact, slow-growing ornamental aquatic plant that is commercially available and widely recognized as one of the most popular red leaf Echinodorus cultivars. This study aimed to establish an efficient micropropagation protocol for large-scale production of Echinodorus sp. 'Small Bear' by optimizing explant sterilization, shoot and root induction, and acclimatization conditions. The most effective sterilization treatment was a two-step process consisting of a 30-second pretreatment in 75% ethanol followed by immersion in 2.0% sodium hypochlorite for 30 minutes, yielding 80.0 ± 8.2% asepsis. Shoot proliferation occurred exclusively on full-strength MS medium supplemented with 4.0 mg/L 6-benzylaminopurine (BAP) and 0.4 mg/L 1-naphthaleneacetic acid (NAA), achieving a 100.0 ± 0.0% proliferation rate and an average of 21.3 ± 4.0 leaves per explant. Root induction was most effective on half-strength MS medium containing 0.2 mg/L BAP and 1.0 mg/L NAA, resulting in 43.0 ± 2.0 roots per explant. However, the longest roots (4.59 ± 0.17 cm) were obtained with 0.2 mg/L BAP and 0.1 mg/L NAA. During acclimatization, all substrates tested-Aqua Soil, silica sand, and their 1:1 mixture-supported 100.0 ± 0.0% survival. However, visual assessment indicated that plantlets grown in Aqua Soil exhibited the healthiest growth and leaf coloration. These findings support the commercial potential of this cultivar-specific micropropagation protocol for the mass production of Echinodorus sp. 'Small Bear'.