International Journal of Aquatic Biology

Effect of temperature and pH on primary metabolic and biomass productivity culture in Euglena sp.

2023-01-04T06:29:29+00:00

Euglena is a microalga with the potential to be used as a renewable energy source. The biofuel-making potential is present in Euglena species biomass's proteins, lipids, and carbohydrates. Therefore, optimizing microalgal growth under various physiological conditions is crucial to obtaining more biomass. In this study, Euglena sp. was cultivated on medium Cramer-Myers (CM) and subjected to various temperatures and acidities. Euglena sp. cultures were optimized at different pH levels, including 2.5, 3.5, and 5.5, and at 29 and 32°C. Then, treatments were evaluated on the culture's pace of cell development, total biomass, and amount of carbohydrates, protein, and lipids. Based on the results, Euglena sp. at pH 5.5 and 29°C had the optimal growth rate, biomass, carbohydrate, protein, and fat content compared to the other treatments. In a pH 5.5 at 29°C, the average biomass was 0.382±0.173 g/L, and the resulting concentrations of protein, carbohydrates, and lipids of 0.288±0.12, 0.201±0.052, and 0.182±0.083 g/L, respectively.

New insights on the seasonal trend of Goniodoridella picoensis (Paz-Sedano, Ortigosa & Pola, 2017) along the central-eastern coast of Sicily: A possible warning of its expansion and establishment in the Mediterranean Sea?

2024-01-29T09:59:22+00:00

Goniodoridella picoensis is a nudibranch species originally described from Pico Island (Azores, Atlantic Ocean). After its description, the reports of this species suddenly increased in a short timeframe, leading to two main hypotheses: one that it is native to the entire Atlanto-Mediterranean region, the other that it is a non-indigenous species that entered the Mediterranean from the Atlantic Ocean. The present study explored the seasonal trend of G. picoensis along the central-eastern coast of Sicily to understand whether this species is non-indigenous and its possible pattern of spread and establishment in that area. To carry out this research, a photographic visual census activity through scuba dives was performed in four sites with different anthropogenic pressures (Ognina, Santa Maria La Scala, Scalo Pennisi, and Acque Fredde) throughout three years (from 2021 to 2023). A similar seasonal trend was found in all the sites. The number of individuals of this species started to increase in the autumn months, maintained or rose during the spring, and throughout the summer months underwent a sharp decline. The negative correlation between the temperature and the number of specimens also evidenced this seasonal trend. Indeed, even if this species can tolerate a wide temperature range, it would seem to prefer lower temperatures, like those of the winter-spring months, when there is a higher availability of food supply. The sites with the highest number of specimens were Scalo Pennisi and Acque Fredde, probably both because of the higher natural conditions compared to the other sites and because of the influence of tidal currents of the Strait of Messina and the upwelling currents of the Ionian Sea, which might act as a veliger conveyor belt. Overall, from 2021 to 2023, an increase in assemblages’ size was observed in all the sites. Moreover, the breeding activity was documented between 2022 and 2023. Considering the above, G. picoensis is most likely a non-indigenous species coming from the Atlantic Ocean. The collected data reflect that this species has settled in these study areas in the last years and indicate that G. picoensis is establishing stable populations there. Indeed, the probability that this species is Atlanto-Mediterranean and has been so far overlooked seems unlikely, not only due to the intense research in the Mediterranean area but also for the conspicuousness of this species.

Heavy metal concentration in the muscle tissues of selected commercially important fishes and health risk assessment in Tubay, Agusan del Norte, Philippines

2024-11-06T04:27:21+00:00

Caraga Region is a hub for nickel-iron mining operations in Tubay, Agusan del Norte. Two notable mining companies are currently operating—San Roque Metal Inc. (SRMI) and Agata Mining Venture Inc. (AMVI). Three heavy metals, namely mercury (Hg), lead (Pb), and chromium (Cr), were analyzed from the muscle tissues of commercially important fishes, and a health risk assessment for human consumers was conducted. Heavy metal concentrations were determined using cold vapor atomic absorption spectrometry (AAS) for Hg and Flame AAS for Pb and Cr. Levels of heavy metals at various stations fall within FAO's approved maximum permitted limits, except for Cheilinus trilobatus, which exhibits elevated levels of Pb with a concentration of 6.21 mg/kg fresh weight in Lawigan. The highest fish consumption was observed in Binuangan (2.70 g/person/day), while the lowest was in La Fraternidad (1.15 g/person/day). Health risk indicators for environmental risk assessment revealed potential risk values surpassing the reference dose. The estimated daily intake (EWI) surpassed acceptable levels in C. trilobatus, while the Target Hazard Quotient (THQ) for Cr and the Total THQ exceeded one for most fish species.These findings underscore the critical need for ongoing research to thoroughly investigate and monitor fishery commodities, including water and sediments, ultimately safeguarding the people's welfare, considering the active operation of mining companies in the area.

A comparative study of photography and mud excavation methods for estimating population density, sex ratio, body size, and claw size of the fiddler crab Austruca perplexa (Brachyura, Ocypodidae)

2024-11-06T05:58:00+00:00

Though fiddler crabs are considered ecosystem engineers in mangroves, accurately estimating their density, sex ratio, and body sizes is challenging. The conventional method of mud excavation is frequently employed to estimate these parameters, yet it proves destructive because it destroys crab burrows and stresses the crabs. In this study, we compared a non-destructive photography method with the mud excavation method in a fiddler crab, Austruca perplexa, population in southern Thailand. Ten 0.25 m² quadrats were fixed, and 4 photographs of the crabs inside each quadrat were taken. Subsequently, the mud within the quadrat was excavated to 30 cm, and all crabs were collected. Parameters such as crab numbers, sexes, body sizes, male handedness (right/left major claws), and male major claw sizes were estimated. Afterward, the photographs were processed in GIMP (GNU Image Manipulation Program) to estimate the same parameters. These parameters were then compared between the two methods. We observed that the photography method was as effective as the mud excavation method in measuring most parameters, except female density, which was higher in the mud excavation method. This study reveals that the photography method could be used effectively instead of the mud excavation method in estimating several population parameters in fiddler crabs while acknowledging its limitation in accurately estimating female density.

Evaluation of physiochemical parameters of the Third River South Iraq

2024-08-22T07:34:46+00:00

Our study focuses on the physicochemical properties of the Third River in South Iraq and its suitability for irrigation. We collected samples from six stations along the river, each 10 km apart, to assess water quality parameters, viz. temperature, pH, total hardness, and electrical conductivity. Our results highlight seasonal variations and the influence of upstream industrial activities and regional agricultural practices on water quality. We interpret these findings in the context of international irrigation water quality standards and discuss their potential effects on soil health. Importantly, we provide practical recommendations for water management strategies that can be implemented to optimize the Third River for sustainable agriculture in South Iraq.

Male reproductive evidence for the importance of gastropods as a sentinel species from Libong Island, Thailand

2024-04-07T01:34:27+00:00

A unique marine productive ecosystem of the seagrass beds on Thailand’s Libong has been identified, which may raise environmental concerns. However, limited data on the health status of marine animals, especially gastropods, as a good sentinel species, has been found. Therefore, the present study provides a detailed observation of the male reproductive health and spermatogenesis of three gastropod species, including Polinices mammilla, Cerithidea cingulata, and Nerita balteata as sentinel species, which are investigated using morphology and histological methods. All samples were collected randomly from seagrass areas with healthy and unhealthy conditions in April 2021. The samples’ male gonads were then investigated using histological methods. The results indicate that the species shared testicular structure and spermatogenesis in different stages (spermatogonium to spermatozoa). Additionally, their spermatogenic stages were not significantly different in size and diameter. Consequently, the structure of brown cells was common and distributed among the spermatogenic stages. Brown cells have been reported in animals that are under stress or unhealthy, such as in seagrass areas with unhealthy conditions. These results suggest that environmental and seagrass loss and the threatened seagrass habitats on Libong Island may impact aquatic animal health, necessitating long-term monitoring in further studies.

Molecular identification of two tilapia species of the genus Oreochromis from Shat Alarab River

2024-09-09T21:26:26+00:00

In the current study, the two species of Tilapia, including Oreochromis niloticus and O. aureus, collected from Shat Alarab River in the Basrah region, South of Iraq, were identified using the nuclear sox3 gene to confirm their genetic matching. They have been recorded since 2007 in the middle part of Shat Alarab River, Iraq based on morphometric characters; however, there is no evidence to prove how these two species were introduced into the Iraqi inland waters. After collection, morphological characteristics of specimens, including meristic measurement, were counted to identify the two species. Then, their phylogenetic relationship with other available genes from different geographical regions was constructed using maximum likelihood and neighbor-joining algorithms. The results revealed that both species did not belong to a common ancestor. Furthermore, the results confirmed that Scan4ab existed in O. niloticus, but it was not found in O. aureus, showing they are probably not taxonomically related.

Growth pattern variability in invasive non-indigenous mosquitofish Gambusia holbrooki (Girard, 1859) from southern Caspian basin, Iran

2024-09-28T05:48:37+00:00

The study was conducted to determine the allometry variability of mosquitofish based on 10987 specimens collected from 11 localities in the southern Caspian Sea basin in summer 2021. The estimated b-values range from 2.414 for males from the coastal lagoon of Gorgan Bay to 3.911 for the population from the Sorkhroud River. In the basin, the overall mean of the b coefficient was 3.190±0.413. The growth patterns of most considered groups were positive allometric. The form factor a_3.0 indicated that body shapes were different between the areas.

Temporal and spatial fluctuations of some heavy metals and silica in Tigris River water, downstream of Belad city, Iraq

2024-06-03T07:36:13+00:00

This study was designed to assess the concentrations of six elements of zinc, cadmium, lead, nickel, aluminum, and total silica (SiO₂) in Tigris River water downstream of Belad city and evaluate their temporal and spatial fluctuations. For this purpose, water samples were collected monthly, and four sampling sites were chosen and sampled during 2022. According to the results, the average concentrations of all metals in the water were within the permissible range by Iraqi river standards. Only aluminum slightly crossed the allowed levels during the study. In addition, the values of metals varied spatially and increased longitudinally. Generally, the concentrations of metals in the Tigris before Baghdad's Province entrance were parallel with many global rivers and increased steadily toward the downstream. Elevated Al concentrations are discussed regarding the river region's features and the sedimentation method.

The effect of the ethanolic extract of Tetraselmis suecica microalgae isolated from the Persian Gulf on the expression of BAX/BCL-2 genes in the Hela cervical cancer cell line

2024-12-07T09:51:38+00:00

Marine organisms produce a variety of compounds with medicinal activities, including anticancer effects. This study aimed to investigate the effect of the ethanolic extract of Tetraselmis suecica algae isolated from the Persian Gulf on the expression level of BAX/BCL-2 genes in the Hela cervical cancer cell line. The ethanolic extract was obtained from T. suecica, and then, using the IC50 formula, the best extract concentration was obtained. MTT, Annexin V-FITC, and Real-time PCR tests were performed to investigate the effect of T. suecica microalgae extract on cytotoxicity, apoptosis, and expression of BAX/BCL-2 genes. Tetraselmis suecica extract significantly decreased the survival rate, increased apoptosis, increased the expression of the pro-apoptotic BAX gene, and reduced the expression of the anti-apoptotic BCL-2 gene in the Hela cell line. The results showed that the ethanolic extract of T. suecica microalgae may be helpful in the management of cervical cancer.

Effects of aquatic plants on reducing salinity and cation concentrations in different types of water

2024-07-12T08:52:41+00:00

The efficiency of some aquatic plants, i.e., Azolla filicoides, Ceratophyllum demersum, and Lemna minor, in reducing electrical conductivity (ECs) and some cations were studied in a laboratory experiment with three filter sizes (300, 400, and 500 cm³) for each plant and type of water. Two sources of water samples were collected: Shatt al-Arab (EC 7 dS m^-1) and Shatt al-Basrah water, collected on October 5, 2022 (EC 60 dS m^-1), and February 20, 2022 (EC 43 dS m^-1 adjusted to 20 dS m^-1), respectively. Filtered water was kept in plastic containers while the EC and cations reduction efficiencies were calculated. Based on the results, Azolla had the highest reduction efficiency among the filters, followed by Ceratophyllum and duckweed for the filter size equal to 500 cm³. The other filter sizes were less efficient than those with a volume equal to 500 cm³ or greater. The different sizes showed varying abilities in reduction, all less than those of the 500 cm³ size.