Identification of pen shells (Bivalvia: Ostreida: Pinnidae) collected off northern Iloilo, Philippines using their morphological characters

This study describes morphological characteristics of pen shells collected along the coast of northern Iloilo, Philippines. A total of 380 pen shell individuals with intact shells and their adductor muscles were carefully examined and measured. Eleven species were studied, namely: Atrina pectinata (Linnaeus, 1767), Atrina inflata (Dillwyn, 1817), Atrina vexillum (Born, 1778), Atrina seminuda (Lamarck, 1819), Atrina rigida ([Lightfoot], 1786), Pinna bicolor Gmelin, 1791, Pinna atropurpurea Sowerby, 1825, Pinna deltodes Menke, 1843, Pinna muricata Linnaeus, 1758, Pinna incurva Gmelin, 1791, and Pinna nobilis Linnaeus, 1758. The species were identified based on the nine characteristics of the valve for the genus Pinna and eight for the genus Atrina. These characteristics were then correlated with their adductor muscles’ morphology. Analysis of variance revealed that the three most dominant species investigated under genus Atrina, namely Atrina pectinata, Atrina inflata, and Atrina vexillum, were found to be significantly different in the eight characters of the valve (P < 0.05). Moreover, three representative Pinna species, Pinna bicolor, Pinna atropurpurea, and Pinna deltodes, were significantly (P < 0.05) different based on shell width, dorsal posterior shell margin, sulcus width, and dorsal posterior margin to dorsal nacreous margin. The observed high correlation (P < 0.05) between adductor muscle properties and different shell length characteristics for five dominant species can be used as a predictor of growth and suggests that the increase in the size of adductor muscle correlates to the increase in the size of the mentioned shell characteristics. No previous study of this kind was conducted in the Philippines. This work provides relevant information for related biological research on other pen shell species and for the management of pen shell resources in northern Iloilo and, possibly, other regions in the world

Evaluation of the bioremediation potential of mud polychaete Marphysa sp. in aquaculture pond sediments

Organic enrichment from aquaculture could alter the chemical composition of the fishpond bottom by increasing the levels of organic matter (OM), sulfur (S), iron (Fe), and lower pH of the sediment. Polychaetes can contribute to the nutrient cycling and remediation of polluted sediment. A laboratory experiment was conducted to test the remediation potential of small and large mud polychaete Marphysa sp. introduced to two types of fishpond sediment. Initially, Sediment A had lower OM, S, Fe, and higher pH than Sediment B. After 30 days, in Sediment B, large polychaetes significantly decreased the OM level (27%) while both small and large polychaetes promoted significant decreases of S (71%) and Fe (70–73%) in both sediment types. The increase of sediment pH was promoted by the presence of polychaetes (0.53–0.69) although pH level in small polychaete was not significantly different with the no polychaete treatment. Regardless of polychaete treatment, the pH level of Sediment B (1.04 ± 0.10) was significantly improved than that of Sediment A (0.17 ± 0.02). In both sediments, large polychaetes (95%) had better survival rates than small polychaetes (73%). These findings reveal that large Marphysa sp. can significantly improve sediment quality by decreasing the levels of OM, S, and Fe and improve pH level to a more basic form without compromising its survival. Large polychaetes are recommended to be used as bioremediators of organically enriched aquaculture pond sediment.The first author is grateful to the Department of Science and Technology-Science Education Institute Accelerated Science and Technology Human Resource Development Program (DOST-SEI ASTHRDP) and UPV, Office of the Vice Chancellor for Research and Extension (OVCRE) for the scholarship and thesis grant, respectively. The authors are thankful to Vicente T. Balinas (statistician), the staff of Laboratory for Advanced Aquaculture Technology (LFAAT) and Polychaete Production Laboratory (Study Code FD-03-08 T) of SEAFDEC/AQD

Bacterial microbiota of hatchery-reared freshwater prawn Macrobrachium rosenbergii (de Man, 1879)

Quantitative and qualitative analyses of bacterial microbiota associated with hatchery of freshwater prawn Macrobrachium rosenbergii (de Man, 1879) were conducted over three larval cycles, along with important water quality parameters. Physicochemical parameters (temperature, DO, salinity, pH and total ammonia) of culture water were within the optimum level required for the hatchery phase of M. rosenbergii. Aerobic plate count (APC) (log10 CFU.mL-1) ranged from 4.2 ± 0.18–8.7 ± 0.01 in rearing water and (log10 CFU.g-1) 3.3 ± 0.12–9.1 ± 1.1 in eggs and larvae. Significant differences in APCs among larval stages were observed. Ten genera and 17 species were identified with the predominance of Gram-negative bacteria constituting 63 % of all isolates (n = 706). Acinetobacter baumannii, Acinetobacter lwoffii, Chryseobacterium indologenes, Enterobacter aerogenes, Enterobacter cloacae, Vibrio furnissii, Vibrio cholerae non-01, Plesiomonas shigelloides, Pseudomonas aeruginosa, Pseudomonas pseudoalcaligenes, Bacillus cereus, Staphylococcus haemolyticus, Staphylococcus warneri and Staphylococcus xylosus were predominantly present in culture water. These bacteria likewise dominated in eggs and larvae except for the absence of Ps. aeruginosa, Ps. pseudoalcaligenes, V. cholerae non-01, Staphylococcus epidermidis and Staph. xylosus in eggs, clearly indicating that resident bacteria in water affect the composition of bacteria in eggs and larvae. Some of these are opportunistic pathogens. Thus, control measures to reduce influx of pathogenic microbes in the system by maintaining good water quality and good farm management practices through disinfection of culture facilities, rearing water, Artemia cysts, the practice of good hygiene of personnel, regular water exchange and feed regulation among others and cautionary use of antibiotics can be adopted

Bacterial microbiota of hatchery-reared freshwater prawn Macrobrachium rosenbergii (De Man, 1879) and their pathogenicity

Quantitative and qualitative analyses of bacterial microbiota associated with hatchery of Macrobrachium rosenbergii (de Man, 1879) were conducted over three larval cycles, along with important water quality parameters. Physicochemical parameters (temperature, DO, salinity, pH, and total ammonia) of culture water were within the optimum level required for the hatchery phase of M. rosenbergii. Significant differences in aerobic plate count (APC) among larval stages were observed. Ten genera and 17 species were identified with the predominance of Gram-negative bacteria constituting 63 % of all isolates (n = 706). A total of 17 dominant bacterial isolates randomly selected from freshwater prawn larvae were screened for in vitro hemolysin activity using blood agar plate (BAP) medium with 5% sheep blood. Pathogenicity of the isolated bacterial strains was assessed through in vivo infection bioassay. Out of the 17 isolates tested, six isolates showed α – β zone of hemolysis on the BAP, i.e., Aeromonas caviae, Bacillus cereus, Plesiomonas shigelloides, Staphylococcus warneri, Vibrio cholerae non-01, and Vibrio furnissii, were used in the infection bioassay. The current data indicate that the six bacterial isolates tested, particularly B. cereus and V. cholerae non-01, are opportunistic pathogens capable of inducing disease epizootics, particularly in freshwater prawn hatcheries with suboptimal rearing water conditions. Thus, control measures to reduce the influx of pathogenic microbes in the system by maintaining good water quality and good farm management practices through disinfection of culture facilities, rearing water, and Artemia cysts, the practice of good hygiene of personnel, regular water exchange, and feed regulation, among others, and cautionary use of antibiotics, can be adopted