International Journal of Aquatic Biology
Volume:7 Issue: 6, Dec 2019

This study aimed to describe the post-seminal development, evaluate how the available water, light and temperature influence seed germination and to describe the vegetative propagation by selecting one of the collected plants of Pistia stratiotes . The plant material was collected in a tributary of the Rio Igaraçu, Parnaíba, Piauí State, Brazil. A botanical description of the species was made using individuals collected in the study area. For the germination tests, a total of 1400 seeds were harvested and three experiments were conducted, varying the amount of available water, light and temperature. The results showed that the highest percentage of germination is occurred with seeds pre-washed with distilled water, sown on filter paper with abundant water (enough to form a sheet of water) and exposed to alternating light at an average temperature of 37°C. Germination began on the fourth day after sowing, marked by the appearance of the cataphyll. After 22 days, the seedling stage was completed. Vegetative propagation of this species is efficient and fast. In 50 days, a total of 134 new vegetative shoots were recorded in just one individual. The results showed that the germination rate is related to the amount of light and temperature.

The current study was carried out on Okpara Stream in Northern Benin to evaluate the demographic factors with inferences on fisheries status of five dominant fish species, which were sampled monthly intervals for 18 months. Asymptotic length (L∞) ranged from 36.23 cm ( Brycinus macrolepidotus ) to 18.8 cm ( Hemichromis fasciatus ). Growth rates (K) varied between 1.6 yr-1 and 0.66 yr-1 with growth performance index (Φ’) ranging from 2.4 to 3.1. Theoretical age at length zero (t0) varied -0.95 year for Marcusenius senegalensis to -0.59 year for Shilbe intermedius . Except for B. macolepidotus , total mortalities were higher than 2 year-1 and length at first capture (L50) ranged 7.72-12.09 cm. Marcusenius senegalensis and S. intermed ius showed one annual peak of recruitment, whereas H. fasciatus , Oreochromis niloticus and B. macrolepidotus displayed two peaks. The results indicated that the stocks of these five species were underexploited. However, the low length at first capture (L50) recorded for some species, requires the implementation of early fisheries management scheme to assure a sustainable exploitation of these fishes.

Biological features including sex ratio, length-frequency distributions (LFDs), size at sexual maturity, spawning season, length-weight relationships (LWRs) and condition factor of Chanda nama were studied in the Old Brahmaputra River, Bangladesh. There was no significant difference in sex ratio. LFDs indicated no significant differences in size between the sexes. Size at sexual maturity was estimated at ~3.0 cm standard length. Monthly variations in gonadosomatic index indicate that the main spawning season is from July to August. The LWRs showed isometric growth in males and positive allometric growth in females. Fulton’s condition factor varied in both sexes and was attributed to variations in GSI with maturity. The findings of this study will be helpful to formulate conservation and management strategies of C. nama population in the Old Brahmaputra River and surrounding ecosystems.

Yellowfin tuna, Thunnus a lbacares , are the most important ecological and economic fishes in the Persian Gulf. In recent decades, their populations have faced overfishing, environmental problems and climate change. In this study, using some environmental variables affecting the habitat of tuna fish, i.e. sea surface temperature at night and day, reflection of 645 nm wavelength as a water turbidity, angstrom view of aerosol 443 to 965 nm, aerosol optic thickness at 869 nm, organic and inorganic particle carbon, photosynthetic active radiation, absorption by phytoplankton at 443 nm and chlorophylla concentration from 2002 to 2018, on the spatial distribution of yellow-fin tuna has been modelled by fuzzy rule-based classification. Over the years, the variables had different degrees of importance in the models. There was a great variation in the spatial distribution of the species from year to year.

This study aimed to determine the chemical composition of Thymus vulgaris , Origanum majorana and Ziziphora clinopodioides and evaluate the antimicrobial properties of their combined essential oils i.e. T.o.z 50% T.v, 25% O.m and 25% Z.c; t.O.z = 25% T.v, 50% O.m and 25% Z.c and t.o.Z = 25% T.v, 25% O.m and 50% Z.c, against A e r o m o n a s H y d r o p h il a (in vitro). The compositions of the herbal essential oils were determined using gas chromatography–mass spectrometry (GC-MS) and the antimicrobial effects was conducted using agar-disc diffusion method, determination of MIC and MBC, and bacterial growth curves determination based on OD at 600 nm. The main compounds were Thymol (40.60%) and Limonene (15.98%) for T. vulgaris , Carvacrol (57.86%) and Thymol (13.54%) as the major compounds in O. magorana . Regarding Z. clinopodiodes , α-pinene (22.6%) and Carvacrol (21.1%) represented the major constituents. Base on the disc-diffusion results, t.O.z showed the best inhibition zone (26 mm). The inhibitory activity and bactericidal effect of t.O.z, unveiled by the MIC and MBC values, was clearly the highest between all combined herbal oils. Regarding the bacterial growth curves, the combined essential oils exhibited significant differences in all tested concentrations. The t.O.z was the most effective between the three tested combined oils at different temperature that cannot affect herbal oil performance. As conclusion, we suggested that the mixing of herbal oils with growth media was delaying exponential phase starting in the bacterial growth curves.

The current study was performed to ascertain the biochemical and physiological impact of cerium oxide (CeO2) on freshwater fish C i r r h i n u s m r i g a l a , which are widely consumed. Biochemical, neurochemical and physiological modifications were evaluated and LC50 of CeO2 was found to be 22 ppm, observed for 24 h. Further 1/10th of the LC50 concentration of CeO2 (2.2 ppm) was used for short term investigation at 96 h. The results demonstrate an increase in physiological levels of serum lactate dehydrogenase (LDH), aspartate transaminase (AST) and alanine transaminase (ALT) compared to control groups. Studies revealed variations in oxidative stress markers with a significant reduction in the serum superoxide dismutase (SOD) and catalase (CAT) activities and an increase in malondialdehyde (MDA). The study reported the increase in brain glutamate concentrations indicating possible brain tissue damage. The above analysis highlights the potential toxicological impact of CeO2 on freshwater fish and their ecosystem.

In this study, the feeding habits of Bigeye Houndshark,
Iago omanensis , a typical deep water shark, were examined in the Gulf of Oman by analyzing of stomach contents. In addition, the effects of sex and seasons (spring and summer) on its feeding habits were evaluated. Bigeye Houndshark diet consists of mostly teleost fishes, and to a lower extent on crustaneans, molluscs and sea snakes. The great importance of teleost in the diet of Bigeye Houndshark may be due to the fact that teleosts are the dominant in terms of biomass and abundance in the area where Bigeye Houndshark exist, allowing them to exploit food resources available in the environment. No significant differences were found between sexes and seasons. This species occupy high trophic position within the food webs. These results present new data that will allow us to understand the role of Bigeye Houndshark in the deep water of Gulf of Oman to effect of fishing activity on its population dynamics in the future.

Fish species introduction into the Mediterranean Sea is constantly increasing, and this is what worries biologists especially after the arrival of poisonous species. In this paper, Synanceia verrucosa is recorded for the first time in the Syrian marine waters, filling the gap of its distributions between north and south of the eastern Mediterranean.