Metallothionein induction in bivalves exposed to heavy metals in sediment of the Balamban Coast, Cebu, Philippines

This study investigates heavy metal bioaccumulation and metallothionein (MT) responses in bivalve mollusks, Dosinia histrio (Gmelin, 1791), Hiatula diphos (Linnaeus, 1771), and Septifer bilocularis (Linnaeus, 1758), collected seasonally along the Balamban coastline in Cebu, Philippines, to assess their potential as bioindicators for evaluating sediment contamination levels. Tissue and sediment samples were analyzed for copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb), and zinc (Zn) using flame atomic absorption spectrophotometry. The study also calculated biota-sediment accumulation factor, enrichment factors (EF), MT induction levels, and sediment pollution indices, including the geoaccumulation index, contamination factor, pollution load index (PLI), and potential ecological risk index. The results revealed that Zn and Cu were the predominant metals in mollusk tissues, while Cd and Pb levels were notably higher during the wet season, reflecting seasonal variability in metal bioavailability. The highest EF was recorded for Pb during the wet season (5.95), highlighting significant anthropogenic enrichment. The highest Zn accumulation (582±32.0 mg/kg) was observed in D. histrio during the wet season. Sediment Pb levels exceeded FAO/WHO safety thresholds in both seasons, while PLI values above 1 indicated considerable pollution, with Pb and Cd as major ecological risk contributors. These findings emphasize the health risks of consuming these mollusks, particularly during the wet season. Regular monitoring is recommended to mitigate environmental and public health impacts in the Balamban coastal area

Evaluation of using the hyperosmotic environment on the double-streptococcus (Streptococcus iniae/Lactococcus garvieae) vaccine efficacy by bath method in juvenile great sturgeon, Huso huso

In this study, the effectiveness of the double-streptococcus (Streptococcus iniae/Lactococcus garvieae) vaccine was evaluated in great sturgeon, Huso huso. The fish were divided into six experimental groups which included a group of fish vaccinated by injection method (Treatment 1), two-step vaccination in a hyperosmotic environment followed by a vaccine by immersion method (Treatment 2), two-step vaccination by immersion method (Treatment 3), vaccination in a hyper-osmotic environment followed by a one-step vaccine by immersion method (Treatment 4), one-step vaccinated fish group by immersion method (Treatment 5) and a control group. A total of 120 juvenile great sturgeon with an average weight of 27.4±1.7 g were divided into 12 tanks (two replicates for each group) and were reared and tested for two months. The fish in treatments 2 and 3 received the second step of the vaccine 21 days after the first vaccination. Based on the results, the serum total protein and immunoglobulin levels and white blood cell counts (WBC), as well as serum antibody titer against L. garvieae and S. iniae in vaccinated fish by the injection method, were recorded as higher in comparison to other treatments (P ? 0.05). On the other hand, the mentioned parameters for Treatments 2 and 3 were higher than those of the control group and Treatments 4 and 5. After the bacterial challenge, the control group had 80% mortality, while the lowest mortality rate belonged to the fish vaccinated by the injection method (with only 20% deaths). The fish that received two stages of vaccine by the immersion method had fewer casualties than the one-step vaccinated fish. According to the study's results, using a hyperosmotic solution (15 ppt NaCl) did not have a satisfactory effect on the vaccine efficacy in great sturgeon. Also, one-step vaccination by the bath method does not provide acceptable immunity for the mentioned bacteria in this fish. In conclusion, vaccination by the injection method is suggested as the best method of vaccination for juvenile great sturgeon

Pathogenic Vibrios associated with loose shell syndrome in mangrove crabs (Scylla spp.)

An emerging disease known as loose shell syndrome, with unknown etiology, impacts mangrove crab aquaculture in the Philippines. This study investigated the presence and characterized pathogenic Vibrio spp., which might be implicated in loose shell syndrome in mangrove crabs, Scylla spp. Five bacterial isolates associated with loose shell syndrome in mangrove crabs were obtained and purified. Polymerase chain reaction (PCR) amplification using Vibrio-specific primers identified one isolate carrying the hemolysin (vhh) virulence gene of Vibrio harveyi, which was later confirmed by sequencing of the 16S rRNA. The other non-Vibrio isolates were Proteus, Shewanella, and Stutzerimonas. This study provides valuable insights into the possible etiology of loose shell syndrome in mangrove crabs, contributing to a better understanding of whether the condition stems from bacterial, environmental, or a combination of both factors

Determination of some heavy metals in two macrophytes of Typha domingensis and Potamogeton pectinatus in Al-Shamiyah River, Iraq

The concentrations of heavy metals in water, sediments, and aquatic organisms, including aquatic plants, needs to be estimated and analyzed, because metals can continuously move from one trophic level to another. The present study aimed to evaluate the contamination of the two aquatic plants of Typha domingensis and Potamogeton pectinatus in the Al-Shamiyah River in Al-Diwaniyah, Iraq, with heavy metals of copper, manganese, cadmium, lead, zinc, and chromium. The concentrations of heavy metals in T. domingensis were as follows: Cu: 24.56-76.40, Mn: 174.47-642.97, Cd: 0.70-23.58, Pb: 1.84-127.75, Zn:  2.70-150.14, and Cr: 1.34-35.26 ?g/g dry weight. The concentrations of these metals in P. pectinatus were as follows: Cu: 16.59-348.72, Mn: 299.74-642.84, Cd: 1.51-34.75, Pb: 1.72-30.44, Zn: 30.57-152.59, and Cr: 1.15-34.99 ?g/g dry weight. The results highlight the role of these two large aquatic plants as monitoring tools for heavy metals pollution as well as the rehabilitation of the aquatic habitats

Development of “red head” in shrimp: Analysis of possible causes and product appearance quality

The development of red coloration in the hepatopancreas of shrimp is a complex issue in the industry that is often linked to poor culture and harvest management, particularly in relation to inefficient temperature settings during harvesting and processing. Despite strict adherence to temperature management protocols, the introduction of Litopenaeus vannamei to marine shrimp farms has resulted in red discoloration in the hepatopancreas, known as discolored or ruptured hepatopancreas (RDHP). This condition is caused by the oxidation of carotenoids in protein compounds, resulting in the formation of a multi-macromolecular complex, crustacyanin, in the hepatopancreas and cephalothorax regions. Although RDHP is harmless to consumers and has no direct correlation with microbial spoilage, it negatively affects the sensory aspects and visual quality of the product. To avoid such issues, various options are available, including different storage and processing techniques, as well as keeping the product cold using ice, which is the most commonly used method. Understanding the causes, processes, and consequences of red head is crucial for preventing such problems and preserving the product's good appearance. Accordingly, the current review aims to gather and present the most up-to-date information on red head in a concise and comprehensible manner

Green mussel (Perna viridis) culture in recirculating aquaculture system: A performance evaluation from Cox's Bazar, Bangladesh

This research assesses the growth performance of green mussels, Perna viridis, cultivated in a Recirculating Aquaculture System (RAS) in Cox’s Bazar, Bangladesh. Mussels were cultivated under three distinct treatments (T1, T2, and T3), with variations in key environmental parameters recorded from stocking to harvesting. T2 demonstrated the greatest ultimate weight (55.55±0.21 g), length (10.45±0.10 cm), and width (3.51±0.06 cm), followed by T1, while T3 revealed the least growth performance (50.5±0.09 g, 9.07±0.06 cm, and 3.59±0.06 cm, respectively). The water quality parameters remained within an acceptable range, with temperatures ranging from 26.9±0.59 to 32.2±0.83°C, pH levels varying between 7.10±1.16 and 7.92±2.75, and dissolved oxygen levels ranging from 4.62±0.28 to 5.31±0.31 ppm. Ammonia and nitrite concentrations were also lowest in T2 (0.01±0.01 mg/L and 0.05±0.02 mg/L, respectively), suggesting better water quality management. The findings indicate that RAS provides a controlled environment conducive to mussel growth, with T2 conditions being the most optimal. This research highlights the practicality of incorporating RAS into green mussel cultivation as a viable alternative to traditional methods in Bangladesh

Production performance of cladoceran Moina micrura fed Pleurotus florida mushroom byproducts

Cladoceran Moina micrura is an important live food organism in aquaculture. It provides essential nutrients such as proteins, lipids, and amino acids for fish and crustacean larvae. The composition of their diet primarily influences their growth and reproduction. The spent mushroom substrate (SMS), mushroom stalk waste (MSW), and mushroom fruiting body (MFB) have the potential to serve as an alternative food source due to their nutrient content. However, their efficiency in supporting M. micrura production remains unclear. Therefore, this study aimed to evaluate the effects of Pleurotus florida mushroom byproducts on the life history and population dynamics of M. micrura. A controlled experiment was conducted using different diets provided at 1000, 500, and 250 mg/L concentrations. The positive control was provided with baker’s yeast, while the negative control was provided with tap water without feed. Selected life history variables were measured to assess the production performance. The results showed that M. micrura fed 1000, 500, and 250 mg/L of SMS, as well as 500 mg/L of MSW and MFB, exhibited better production and longevity. The findings suggest that SMS and MSW have the potential to be alternative food sources in M. micrura production. Moreover, the high cost of MFB makes it less practical for large-scale use

Response of the peroxisomal ascorbate peroxidase (pAPX) gene in aquatic plants, Hydrilla verticillata and Lemna minor, to cadmium, lead, and nickel stress

In plants, the pAPX gene is an important enzyme that breaks down hydrogen peroxide into hydrogen peroxide and oxygen, lowering the level of oxidative stress. This study aimed to determine how the pAPX gene in Hydrilla verticillata and Limna minor react to heavy metal stress. Different concentrations of cadmium (0.5, 2, and 4 ppm), lead (0.5, 5, and 10 ppm), and nickel (1, 5, and 10 ppm) were used in addition to the control. Genefold was measured. The treatment with Cadmium slowed plant growth significantly more than treatments with lead and nickel, and it also caused a greater accumulation of the pAPX gene. The nickel treatment was significant in increasing by a factor of more than one other metal (Cd and Pb). The fold change showed increased values in all cadmium, lead, and nickel treatments compared to the control. The recorded value of nickel was higher than that of lead, followed by cadmium. The conclusion was that nickel significantly enhanced the response to gene expression. These results can provide a deeper understanding of the role of the pAPX gene in protecting plants from oxidative stress caused by heavy metals. O2 lowers the levels of oxidative stress

Fermented calamansi (Citrus microcarpa) waste as a functional feed additive: Nutritional, antioxidant, and anti-nutritional insights for tilapia (Oreocrhromis sp.)

This study investigates the potential of fermented calamansi, Citrus macrocarpa, waste powder (FCWP), as a sustainable feed additive for tilapia (Oreochromis sp.). Calamansi waste, a byproduct of citrus processing, is often discarded, contributing to environmental pollution. To address this issue, the waste was repurposed as a fish feed additive through fermentation, which enhances nutrient content and bioavailability while reducing anti-nutritional factors. Fermentation trials were conducted with varying molasses concentrations (0, 5, 10, 15, and 20%) and durations (0, 14, and 28 days). The results revealed improved proximate composition (protein: 6.85-10.17%, fiber: 4.96-20.30%, fat: 2.49-3.95%, ash: 5.84-9.02%, carbohydrates: 62.87-77%) and antioxidant activity (TPC: 4.46-12.34 mg GAE/g, TFC: 0.56-1.56 mg catechin/g, DPPH: 5.68-41.57%) while reducing anti-nutritional factors (phytate: 0.06-0.067%, tannin: 11.25-23.97 mg TAE/g), with fermentation optimized at 5% molasses, 28 days. A 30-day feeding trial evaluated the effects of FCWP (0 and 3% inclusion levels) on tilapia growth performance, survival, water quality, gut microbiota, and stress tolerance. The results showed significant improvements in weight gain, specific growth rate (SGR), survival rate, and resilience to osmotic stress in the FCWP-fed group, with no adverse effects on water quality or gut microbiota. FCWP demonstrates potential as a cost-effective and sustainable alternative to conventional feed additives in aquaculture, enhancing fish growth and health while addressing environmental concerns by converting agricultural waste into valuable resources

Recent advances and challenges in the industrial-scale production of probiotics in aquaculture

Abstract: Probiotics have emerged as a transformative solution for improving health, growth, and disease resistance in aquaculture, offering a sustainable alternative to conventional practices. This review focuses on updates and advancements in the industrial-scale production of probiotics for aquaculture, emphasizing their significance in fostering eco-friendly aquaculture systems. The development of probiotics tailored for aquaculture has seen substantial progress, with species like Bacillus, Lactobacillus, and Saccharomyces dominating the market due to their proven benefits. Emerging technologies are revolutionizing industrial production, including large-scale fermentation techniques designed to enhance yield and maintain viability, alongside innovative microencapsulation methods that improve the stability and shelf-life of probiotic formulations. Advances in quality control and standardization are also enabling the production of high-quality, consistent products, meeting both industry demands and regulatory standards. However, industrial production is not without its challenges. Technical issues, such as optimizing strains for mass production and ensuring their functionality under diverse aquaculture conditions, remain critical hurdles. Economic and regulatory barriers, including high production costs and stringent compliance requirements, further complicate large-scale implementation. Despite these challenges, the sector holds immense potential, with emerging opportunities in strain optimization and integrative approaches using biofloc systems and advanced feed formulations. This review highlights the ongoing evolution of industrial probiotic production and underscores the need for multidisciplinary collaboration to address existing barriers. By leveraging technological innovations and fostering industry-academia partnerships, aquaculture can achieve more sustainable and efficient practices, paving the way for the broader application of probiotics on an industrial scale