International Journal of Aquatic Biology
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Stock assessment of the marine ornamental Vagabond Butterflyfish Chaetodon vagabundus Linnaeus, 1758 (Pisces, Chaetodontidae) and the Indo-Pacific sergeant Abudefduf vaigiensis (Quoy & Gaimard, 1825) from Iligan Bay, Southern Philippines
No full textThe success of fisheries depends critically on the state of the fish stocks. In this study, a total of 1,188 fish individuals belonging to two species of Abudefduf vaigiensis (711), Chaetodon vagabundus (477) were investigated based on the samples collected from the waters of Iligan Bay, Southern Philippines. Population parameters were assessed using length-frequency data with FiSAT II software. The results showed positive correlations between length and weight. The values of b significantly (P<0.000) increased from 2.55 in C. vagabundus to 2.82 in A. vaigiensis. The growth and mortality parameters asymptotic length (L?), annual growth rate (K), annual total mortality (Z), natural mortality (M), fishing mortality (F) and exploitation rate (E) were 15.75 cm, 0.430, 1.60, 1.24, 0.28 and 0.18 for A. vaigiensis and 14.70 cm, 0.700, 2.60, 1.73, 1.09 and 0.39 for C. vagabundus, respectively. A bimodal recruitment pattern of unequal strength was observed for both species. The result of the virtual population analysis (VPA) routine showed that most of the small and young fish were prone to natural losses, while bigger fish were mostly caught by the fisherman. Finally, the maximum sustainable yield (Emax) for the two species was higher than the exploitation level, indicating that these two ornamental reef fishes were in good condition in Iligan Bay
Drought and flood footprint: An environmental analysis of plant biodiversity changes in Al-Hawizeh Marsh, Iraq
No full textThis study aimed to assess environmental changes and degradation in Al-Hawizeh Marsh-Umm al-Naaj Pond, southern Iraq, from 2017 to 2023, focusing on plant diversity and its response to variations in rainfall, flooding, and water quality. It compared the wet season (2018/2019) with the severe drought season (2022/2023). Field surveys and data on the region's rainfall patterns showed a sharp annual variation. The 2018/2019 season recorded 413.6 mm of annual rainfall, resulting in complete flooding of the marsh (100% in the spring). In contrast, the drought seasons (2020/2021) saw rainfall of no more than 31.2 mm. The drought became more severe in the 2022/2023 season, as the AL-Hawizeh Marshes in Misan were flooded by only 5% of the area that could be flooded. The reduced freshwater releases associated with the drought led to a significant deterioration in water quality. In 2023, chloride (Cl) ion concentrations nearly doubled, and TDS and EC values ??increased significantly compared to 2018. The most severe impact of drought was on vegetation cover, where a radical ecological shift occurred between 2018 and 2023. In 2018, aquatic plants dominated (70%) of plant diversity. By 2023, this ratio had reversed, with terrestrial plants comprising (73%) of plant diversity, and 16 terrestrial plant species of Iraqi flora were recorded for the first time in the marshlands. The study confirms that climatic fluctuations, represented by the annual variation in rainfall, are the main determining factor for water levels in the marshes, and that periods of severe drought led to widespread structural deterioration in the region’s ecosystem, increased salinity, water pollution, and a complete shift in plant biodiversity towards terrestrial and halophyte species
Population dynamics of three Epinephelus groupers in the Sulawesi Sea, Indonesia
Full text linkGroupers of the genus Epinephelus play important roles in coastal ecosystems and small-scale fisheries. Market demand has driven intensive exploitation, threatening stock status and coastal community livelihoods if these valuable fisheries are poorly managed. This research on grouper population dynamics in Kwandang Bay, on the Sulawesi Sea coast of Gorontalo Province, Sulawesi, Indonesia, focused on three Epinephelus species: E. fasciatus, E. faveatus, and E. ongus. The mean length at first maturity (Lm50) was estimated using the Spearman-Karber formula, and population dynamics parameters were estimated through Response Surface Analysis using the ELEFAN I suite in FISAT II. Catches of all three species were dominated by juveniles with total length TL < Lm50. The respective asymptotic lengths (TL?) for E. fasciatus, E. faveatus, and E. ongus were 47.52, 53.50, and 52 cm, with von Bertalanffy growth coefficient K values of 0.49. 0.54 and 0.53, respectively. Natural and fishing mortality estimates were 1.01/year-1 and 1.23/year-1 for E. fasciatus, 1.05/year-1 and 2.00/year-1 for E. faveatus, and 1.04/year-1 and 2.44/year-1 for E. ongus. The Beverton and Holt yield per recruit analysis indicates overexploitation with respective exploitation rates (E) of 0.55/year-1, 0.66/year-1, and 0.70/year-1, all exceeding Emax = 0.37/year-1. Recommendations include setting minimum legal size limits (above 25 cm for E. fasciatus and E. faveatus, 26 cm for E. ongus), as well as reductions in fishing effort of 31% for E. fasciatus, 42% for E. faveatus, and 46% for E. ongus.
16S rRNA revealed a low rate of maternal genetic variations in Cyprinus carpio Linnaeus, 1758 across the southern Caspian Sea
Full text linkGenetic diversity surveys are informative and practical tools in aquaculture and restocking programs. With its maternal inheritance, mtDNA provides direct information about the available source of genetic variations in the female brood stock. The present study investigated the maternal genetic diversity of the Caspian common carp, Cyprinus carpio, and the farmed common carp across the southern Caspian Sea using direct sequencing of 571 bp fragment of 16S rRNA. A number of eight haplotypes were identified, with an average of Hd = 0.55. A low level of population differentiation was recognized with the overall Fst = 0.01, indicating an assumption of the shared ancestry in C. carpio in the southern Caspian Sea. Among different regions, Anzali population was observed to be a more unique stock of common carp across the southern Caspian Sea basin. Hence, considering Anzali as a separate population is highly recommended to enrich the genetic diversity and avoid the population structure breakdown in C. carpio. The obtained results during the present study can be useful in the ongoing restocking activities of C. carpio along the southern Caspian Sea. Furthermore, rehabilitation of the main rivers to provide the natural breeding of anadromous fish species such as C. carpio should be considered for their future conservation
Growth patterns, sex maturation stages, and fatty acid profiling of hatchery-cultured male short-finned eel (Anguilla Bicolor) in relation to the reproduction index under different hormonal treatments
No full textThis study investigated the effects of different hormonal treatments on growth performance, maturation, and fatty acid composition in hatchery-cultured male short-finned eel (Anguilla bicolor). A total of 12 individuals were subjected to four treatments — control (no hormone), Human Chorionic Gonadotropin (HCG), pituitary gland extract (PG), and Ovaprim (OVP) — over 100 days. Growth patterns were assessed through morphometric measurements and allometric analysis, while reproductive development was evaluated using gonadosomatic index (GSI), hepatosomatic index (HSI), histological characteristics, and steroid hormone profiling (11-ketotestosterone and estradiol). Fatty acid composition was determined using gas chromatography (GC). The HCG treatment significantly enhanced gonadal development (GSI = 4.36±0.21, P<0.001) and elevated 11-KT levels, promoting advanced spermatogenesis, as further evidenced by histological analysis. However, the HCG-injected eel showed lower body weight gain and a weaker length-weight correlation, indicating a shift in energy allocation toward reproduction. Meanwhile, the OVP-injected eel exhibited balanced growth with strong weight-length relationships (R² = 0.94) and the highest monounsaturated fatty acid (MUFA) levels. PG-injected eel, however, demonstrated moderate effects on reproductive and growth indices. Fatty acid profiling revealed that HCG increased polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (DHA), which corresponded with higher spermatozoa abundance. These results show that HCG can effectively induce sexual maturation in male short-finned eels, although it may reduce somatic growth. The varied responses to hormone treatments suggest the potential for enhancing breeding strategies in eel aquaculture through more precise hormonal management
Ecological responses of pen shell, Atrina lischkeana, and ark shell, Scapharca kagoshimensis, to sediment characteristics in a temperate tidal flat
No full textTo investigate the ecological responses of pen shells and ark shells to sediment characteristics in a temperate tidal flat in Japan, field surveys were conducted during spring low tides. Bivalve distributions were recorded, and sediment samples were collected from 32 sites. Regression analyses were performed to examine the relationships between bivalve density and sediment parameters, including mean grain size (Md?), mud layer thickness, moisture content, mud content, and loss on ignition (LOI) at 600°C and 800°C. Pen shells showed significant negative correlations with Md?, mud layer thickness, moisture content, mud content, and LOI at 600°C, but a positive correlation with LOI at 800°C. In contrast, ark shells were positively correlated only with Md? and mud content, with no significant associations with other parameters. These patterns were further supported by correlation matrix analysis and principal component analysis. Overall, the results suggest that pen shells exhibit selective habitat preferences, favoring sandy sediments with low mud content and high coarse shell material. In contrast, ark shells demonstrate broader ecological tolerance to sediment variation, resulting in a wider distribution
Do lunar cycles affect molting of mud crabs Scylla olivacea reared in a closed recirculation system?
Full text linkMud crabs grow through molting, a process during which they become highly vulnerable to predation. This makes molting management crucial in crab aquaculture, including practices utilizing crab boxes. Environmental factors such as lunar cycles influence molting in natural habitats. However, research is limited to molting in controlled environments with closed recirculation systems that offer environmental stability, water resource efficiency, and precise feed management. This study investigated the effects of the lunar phase on the molting stages of mud crabs reared in a closed recirculation system. A total of 40 Scylla olivacea specimens were reared for three months to observe molting patterns across eight lunar phases: new moon (NM), waxing crescent (WXC), first quarter (FQ), waxing gibbous (WXG), full moon (FM), waning gibbous (WG), last quarter (LQ), and waning crescent (WNC). Overall, 77.5% of crabs were molted during the study period. No molting occurred during the WXC, WXG, WNC, and WG phases. Molting prevalence was higher during FM (22.5±2.5%) and NM (20±2.9%) phases compared to FQ (17.5±1.4%) and LQ (17.5±1.4%). Post-molting weight gain was 31.7±5.9 (NM), 32.2±4.4 (FQ), 31.2±5.9 (FM), and 27±3.2 (LQ), while carapace width (CW) increased by 9.0±1.6 (NM), 8.5±1.3 (FQ), 9.5±2.4 (FM), and 8.2±1.77 mm (LQ), respectively. The results showed molting frequency and growth did not differ significantly between lunar phases NM, FQ, FM and LQ. In closed recirculation aquaculture systems where natural fluctuations such as tidal changes were eliminated, molting remained associated with the lunar cycle, suggesting the persistence of instincts and circadian rhythms in mud crabs in controlled environments. This study provides valuable insights for mud crab farmers, particularly for optimizing productivity by understanding the influence of lunar phases on molting in closed recirculation systems
Converting agricultural and fisheries waste into high-value products: Utilization of pea meal and shrimp protein hydrolysate as feed components for Nile Tilapia (Oreochromis niloticus)
Full text linkThis study aims to characterize pea meal and shrimp protein hydrolysate as alternative protein ingredients, replacing soybean meal (SBM) in tilapia feed. The presence of protease inhibitors and the in vitro digestion were evaluated for both raw and extruded pea meals, while the characteristics of shrimp protein hydrolysate were also studied. The nutritional quality of alternative ingredients was assessed to formulate a diet that meets tilapia juveniles’ requirements, and its preliminary effects on growth were evaluated. Extrusion significantly reduced the inhibitory effect of pea meal on tilapia proteases (from 5.4 to 1.9%). In vitro, protein digestion of extruded pea meal (7.8±1.35%) did not differ from the control treatment with fish meal (11.8±1.94%). Additionally, shrimp protein hydrolysate presented 41.6±2.91% of DPPH radical scavenging activity. Tilapia fed a diet including 25% extruded pea meal and 10% shrimp protein hydrolysate, replacing soybean meal, presented comparable growth indicators to those exposed to the control diet. All the results in this study demonstrate that it is possible to include these ingredients derived from industrial waste in tilapia diets, improving the quality of the feed without affecting its performance
Response of the peroxisomal ascorbate peroxidase (pAPX) gene in aquatic plants, Hydrilla verticillata and Lemna minor, to cadmium, lead, and nickel stress
Full text linkIn 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
New records of two rare crabs of Nursia plicata (Herbst, 1803) and Trichia indica (Sankarankutty, 1968) (Crustacea: Decapoda: Brachyura) from the Gujarat coast, India
Full text linkIn the present study, two rare brachyuran crabs were caught from the intertidal zone of Kachchh and identified for the first time from Gujarat, India. The first species, Nursia plicata (Herbst, 1803), previously known from the Indo-West Pacific region and the Indian coastline (Maharashtra, Tamil Nadu, and Orissa), is reported here for the first time from the Gujarat waters. The second species, Trichia indica (Sankarankutty, 1968), was originally described from a single female specimen collected from Sri Lanka. Later, it was only known from the locality of Thailand. This specimen represents the third global record of this species, marking the first report of this species and genus from the Indian coast. Detailed morphological descriptions, habitat, and present distribution status are provided for their biogeographic range