فصلنامه بوم شناسی آبزیان
سال دوازدهم شماره 4 (پیاپی 47، بهار 1402)

One of the environmental problems of the Caspian Sea is the introduction of alien species, some of which have the property of biological adhesion, which cause problems for marine facilities and vessels. The aim of this study was to investigate the effects of the body material and anti-sticking paint of the floats on the settlement of the barnacle Amphibalanus improvisus in the southwestern Caspian Sea basin. A total of six types of paints (Pamchal, Runas, Rangin-zare, Skele, Bajak and Hempel) in two types of plates (fiberglass and shipbuilding steel) with dimensions of 10 x 10 cm were tested in the coast of Chabaksar, 2020-2021. They were tested with two unpainted surfaces and in general in 14 treatments each with 3 repetitions. In total, fiberglass surfaces performed better than steel surfaces in terms of reducing barnacle settlement and in terms of the above indicators between the two There was a significant difference in the page. In addition, the expected effectiveness of the colors with regard to the appearance color did not take place. The reason for the better performance of fiberglass was the presence of fine textures and hardness in steel plates. Also, the lack of regular effectiveness of the colors was due to the different effectiveness of the chemical compounds of the colors on the two levels. In conclusion, the color of the plates, which was affected by the chemical composition of the paints, can be effective in the final settlement of the adhesive organisms, and the fiberglass plates have less adhesion than steel.

The aims of the present study were to investigate the macrobenthos communities in the Caspian Sea and to investigate the pollution of this ecosystem based on the pollution indices ABC (Abundance Biomass Comparison), BC (Biotic Coefficient) and ABC curve in 2018 (autumn and winter) and 2019 (spring and summer). According to the results, polychaetes, crustaceans, and bivalvia formed the major groups of macrobenthos communities with 4, 11 and 1 species, respectively. The polychaetes (mainly Streblospio gynobranchiata) included about 70% of the total abundance and the group of bivalvia (Cerastoderma glucaum) included about 76-93% of the macrobenthos in all seasons except in spring. The mean values of the Shannon index and evenness indices were calculated as (1.56) and (0.55), respectively. The annual pollution (ABC) and BC indices were obtained as -3.1 and 2.7, respectively. These values along with characteristics of ABC curve indicate severe stress caused by pollution in the Caspian Sea ecosystem. In this study, the percentage abundance of the invasive species S. gynobranchiata in macrobenthos communities was 52%, which is about 10% decrease compared to 2009 and 2010. This decreasing trend can be considered as positive evidence in the improvement process of the ecosystem in this part of the food chain. However the continuity of recovery trend needs more time, no force by new stressors, proper management, and reduced pollutions into the ecosystem.

The water quality of Sheshroodbar River in Savadkooh was studied with population indices of benthic macroinvertebrates through sampling in 12 intervals at five stations in three replications, along with measuring some physicochemical parameters during 2014-2015. Among the invertebrates of the river (16 families from seven orders and six classes, n = 5230), aquatic insects larvae had the highest diversity. Significant differences were found between EPT and EPT/CHIR indices at different stations (p ≤ 0.05), but Shannon and Hilsenhoff indices were not significantly different among stations (p ≥ 0.05). Diptera at stations 1 and 2 and Diptera, Ephemeroptera, and Trichoptera at station 3 (n = 202, 256, & 282, respectively) showed the highest annual mean abundance. Mean annual frequency of orders was maximum for Haplotaxida, Tubificida, Lmbricida, Lumbriculida, Oligochaeta and Ephemeroptera at station 4, and for Trichoptera at station 5. The highest (12.3 ± 0.11) and the lowest (1.66 ± 0.24) annual averages of the Shannon-Wiener index were estimated for stations 1 and 4, respectively. The annual water quality was found to be very good (3.99 ± 0.18) to moderate (5.21 ± 0.21) from station 1 to station 3 (upstream to middle stations). Annual water quality was relatively poor (6.11 ± 0.34) downstream of station 4 while it was fairly good (4.55 ± 0.39) at station 5 due to the river self-purification. With changes and stresses of the river, increased and relatively decreased frequencies were observed in resistant and susceptible groups of the macroinvertebrates, respectively.

Seaweed is a rich source of natural antioxidants. There are large populations of Ulva and Sargassum on the southern coasts of Iran. In this study, populations of green alga U. fasciata Delile and brown alga S. vulgare C. Agardh were collected from Bushehr coasts in winter and spring, and their total phenols and flavonoids were evaluated. Various extracts of these species were prepared and their antioxidant activities were investigated by ABTS and DPPH methods. The results showed that S. vulgare had the highest phenols and the lowest flavonoids contents in spring at 0.62±0.065 and 0.83±0.088 mg g-1 of algae, respectively, and U. fasciata contained the highest flavonoids and the lowest phenols in winter (1.65±0.21 and 0.28±0.04 mg g-1 of algae, respectively. In all extracts, S. vulgare showed higher antioxidant activity than U. fasciata. Both species did not show significant differences in antioxidant activity in winter and spring. The 80% ethanolic, methanolic and boiling water extracts showed higher antioxidant properties than the pure ethanolic, methanolic and distilled water extracts, respectively. The highest and the lowest antioxidant activities were mostly observed in the acidic and ethanolic extracts, respectively. The results will greatly help in the selection and application of algae in the food and pharmaceutical industries.

Streptococcus iniae and Lactococcus garvieae bacteria are among the most important fish pathogens. The aim of this study was to determine antimicrobial resistance patterns of S. iniae and L. garvieae isolated from diseased rainbow trout. With respect to outbreak of disease, the survey was carried out in warm seasons using 100 rainbow trout fish with clinical symptoms of disease. Bacteria were cultured from Kidney tissue of fish using standard methods. The antibiotic resistance pattern of strains was studied based on CLSI protocol. The results of the research showed that S. iniae isolates were more sensitive to enrofloxacin, florfenicol, erythromycin and lincospectin, and more resistant to sulfamethoxazole-trimethoprim, tetracycline, fosfomycin, ampicillin, lincomycin and flemequine, respectively. Furthermore, L. garvieae isolates were more sensitive to erythromycin, enrofloxacin, florfenicol, flemequine and lincospectin, and more resistant to sulfamethoxazole-trimethoprim, fosfomycin, tetracycline and ampicillin.

Human activities are the main cause of river pollution that continuously affect the water quality of the rivers. In this study, the population structure of macroinvertebrates was investigated as a biological indicator for water quality in the Khorram-rud River. For this purpose, a number of 4 stations were selected and some physicochemical parameters along with macroinvertebrates sampling were done monthly for 12 months (December 2018- November 2019) in each station. Totally 26 families in 14 orders of macroinvertebrates with the domination of families Chironomidae, Baetidae, and Tricorythidae, respectively were found. The results of physicochemical factors showed that the lowest and highest water temperatures recorded were 8.66 ± 0.57 in December and 23.66 ± 0.57 in July, respectively, the maximum average dissolved oxygen in March 5.83 ± 0.28 mg/l  in the station (1), and the minimum was 0/00 mg/l in a station(4). pH value recorded with a minimum of 6 ± 0.86 in January and a maximum of 8 ± 0/00 in June. The average change of nitrite in different stations showed a slight fluctuation but was higher than the allowable limit in all stations. The highest amount of nitrate in a station (3) in June was 36.66 ± 5.77 and the lowest in a station (1) in December recorded as 2 ± 0/00 mg/l. The seasonal variations in density of macroinvertebrates indicate the maximum density in autumn and the minimum density in winter. The results based on (BMWP, ASPT) and richness and diversity indices (Shannon-Weiner, Margalef) indicated that the Khorram-rud river water is in the contaminated water class.

The purpose of this study was to examine the secondary production of the dominant species of the Acartiidae family in the Arvandrud estuary. Specimens were sampled monthly for one year, at eight stations from December 2018 to November 2019. Sampling was conducted with a 300 µm mesh size plankton net and a 45-cm-diameter mouth. Environmental parameters such as temperature, salinity, dissolved oxygen, depth, and water turbidity were measured monthly. Five species belonging to the Acartiidae family were identified, including Acartia pcifica, A. fossae, A. danae, A. faoenis, and A. ambionesis. Due to the highest percentage of frequency for A. pacifica (107± 40 ind.m-3), and because of its presence in most months and stations, it was known as a dominant species. The measurement of the total length of A. pacifica showed that the length of this species along the Arvandrud River has relatively similar values. The average length measured in station 2 has the highest value (0.122±0.016) of the total length. Biomass changes in this species showed the highest amount of biomass in spring (1.24 mg of carbon per cubic meter) and the lowest amount in autumn (0.46 grams of carbon per cubic meter). Secondary production of dominant species was obtained at 0.99 mg C.day-1 during the summer and at 0.25 mg C.day-1 in the autumn. According to the Pearson correlation, there was no significant correlation between identified species abundance and larval abundance at different stations.