Determination of heavy metal (Cr, Zn, Cd and Pb) concentrations in water, sediment and benthos of the Gorgan Bay (Golestan province, Iran)

The coastal area of the Caspian Sea and Gorgan Bay are important ecosystems receiving discharge from their tributaries. In this study, concentration of lead (Pb), cadmium (Cd), zinc (Zn) and chromium (Cr) was seasonally determined at 8 sampling points during 2009-2010. Water samples were collected from the sampling stations and transferred to laboratory in polyethylene containers, whereas, sediment and benthic fauna samples were collected using a Van Veen grab. The levels of heavy metals were determined by atomic absorption spectroscopy method. Results showed that range of Pb, Cd, Cr and Zn in the water samples were 80-123, 61-97, 63-87 and 82-120 ppb, respectively and their ranges in the sediment samples were 479-1072, 98-293, 102-622 and 937-1577 ppb, respectively. The range of Pb, Cd, Cr and Zn in the benthos samples were 95-132, 59-110, 26-58 and 103-155 ppb, respectively. Zn and Pb were the most concentrate metals in all samples. Likewise, sediment had the highest heavy metal content amongst the samples. This study demonstrated that the level of metals in the environment is increasing, bringing a serious warning to industries and threat of man-made contamination, which can be restricted and a necessity to control ecosystem and food-chain pollution

Age structure and growth rate of (Squalius cephalus Linnaeus, 1758) in Tuji tributary from Talar River, Mazandaran Province

A structure and growth pattern of Squalius cephalus (Linnaeus, 1758) in Tuji tributary of Talar River, Mazandaran Province, was studied during the period from August 2008 till August 2009. In total, 298 fish were caught by electrofishing and fixed in 10% formalin. The weight and length of fish were measured and the age was determinated by scallometric method. The age data showed that fishes were between 0+ to 4+ age groups. Pauli`s applied growth pattern showed a positive alometric for male and female and total fish and a negative isometric for unmature fishes. The average instantaneous growth rate of European Chub showed that the age groups 2+ and 3+ with 1.1 had the fastest growth compare to 3+ and 4+ age groups with 0.89. Condition factor of specimens showed that the highest one with 1.58 (r2 = 0.983) belong to females and the lowest with 1.17 (r2 = 0.901) belong to unmature fishes. The total sex ratio (123 males to 115 females) showed no significant differences between them

Some biological parameters of Silver Crucian carp, Carassius auratus, in the international wetlands of Alma-Gol and Ala-Gol (Golestan Province, Iran)

In the present study, age, growth and reproduction of Carassius auratus were investigated in the Alma-Gol and Ala-Gol (northern Iran) from September 2000 to August 2002. Among the total of 1450 specimens, the estimated ages ranged from 0+ to 8+ years. C. auratus showed an allometric growth, negatively in Alma-Gol and positively in Ala-Gol. The von Bertalanffy growth curves were fitted to mean total lengths at age, resulted as Ltmales=183.33(1-e^-0.31(t+1.05)) and Ltfemale=245.66(1-e^-0.19(t+1.21)) for Alma-Gol population and Ltmale=224.79(1-e^-0.24(t+0.83)) and Ltfemale=242.80(1-e^-0.23(t+0.80)) for Ala-Gol population. The value of φ' index varied from 9.25 to 9.51. The unbalanced sex ratio of males to females was 1:10 and 1:12.7 in Alma-Gol and Ala-Gol, respectively. The reproductive period for this species in these particular areas was February, March and April and the maximum recorded GSI was 2.19 and 2.17 for males and 10.37 and 10.49 for females in Alma-Gol and Ala-Gol, respectively. The linear relationship between absolute fecundity and total weight was more suitable for expressing the fecundity-weight relationship for both populations as estimated: Fec.Alma-Gol= 4120.56+ 62.62W and Fec.Ala-Gol= 3832.83+ 68.67W

Age, growth and some biological characteristics of Silver bream (Blicca bjoerkna L., 1758) (Cyprinidae) from Aras Dam Lake in Northwest of Iran

We collected Silver bream Blicca bjoerkna from March to July 2013 from Aras Dam Lake (North-west of Iran) and investigated its age, size, and some biological characteristics. The maximum age was 5+ years. The total length and weight of specimens ranged 137-278 mm and 26-247 g for male and 134-282 mm and 26-289 g for female, respectively. Length-weight relationship was estimated as W = 1E-06TL3.44 for females, W = 1E-06TL3.45 for males and W = 1E-06TL3.44 for the sexes combined. Sex ratio was 1:1.42 in favor of males. The growth model was positive allometric for males, females and sexes combined. The calculated maximum condition factor was 0.34 in male and 0.37 in female. The most frequent age classes in the samples were 2+ years for males and females

An investigation into the age and origin of Suranga in the foothills of the Western Ghats of India

This document is the Accepted Manuscript version. The final publication is available at Springer via: https://doi.org/10.1007/s12685-015-0125-yThis paper presents the evidence for determining the age and origin of suranga irrigation found mainly in southern Karnataka and northern Kerala in the foothills of the Western Ghats of south India. It draws on on-going research that has attempted to use an interdisciplinary approach to date the system using Indian Archives, British and Portuguese colonial archives, etymology, oral testimony archaeology, phenology and palaeo dating techniques. The results from this study put the origins of the system at around 1900–1940 CE. These results are compared with the current academic discourse that supports the view that the system originates from ancient Persia and qanat technology, because of the long established trade links with Persia and the Arabian Peninsula in the Malabar region. We argue that a new ‘origin discourse’ should be framed around these much more recent dates. The methodological constraints behind both theories are discussed throughout to enable the reader to appreciate the limitations of both arguments.Peer reviewedFinal Accepted Versio

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

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 a3.0 indicated that body shapes were different between the areas

Benthic community structure in the Gorgan Bay (Southeast of the Caspian Sea, Iran): Correlation to water physiochemical factors and heavy metal concentration of sediment

Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae), Arthropods (Pontogammaridae, Balanidae and Chironomidae) and Mollusks (Cardiidae and Scrobicularidae). Lumbriculidae (413 individuals m-2, corresponding to 18.7%) and Cardiidae (55.2 g m-2, corresponding to 82.4%) had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show unsimilar relationship with heavy metal concentration

Growth and mortality parameters of Caspian kutum, Rutilus kutum, in southern Caspian Sea

The Caspian Kutum, Rutilus frisii, is one of the endemic and most important commercial cyprinid species in the southern Caspian Sea. A detailed study on growth and mortality parameters of this species was conducted based on 700 samples collected from commercial catches of beach seining in Guilan and Mazanderan provinces during fishing season 2017-2018. Females were dominated in both studied populations. Size frequency distributions showed significant variation among same sexes and between different sexes. The different WLRs were observed, positive allometric in Mazanderan, and negative allometric in Guilan. There were significant differences in growth parameters between sexes, females were of much greater asymptotic length than males, while the male fish had a higher growth rate and attained a smaller theoretical L∞ size than females. The theoretical maximum length (L∞) was larger than the maximum one recorded during sampling. Based on the Bhattacharya method, the Caspian kutum from Guilan fishing grounds was more diverse, and included nine cohorts, while the population from Mazanderan Province showed only six cohorts. The linearized catch curve based on age composition data showed that total mortality rates (Z) are 1.32 year-1 and 0.63 year-1 for males and females of Guilan, respectively, that of males in Mazanderan is 1.04 year-1 and of females 0.86 year-1. The natural mortality rates (M) were 0.48 year-1 for males and 0.26 year-1 females in Guilan, and was found to be as 0.26 year-1 and 0.45 year-1 for males and females of Caspian kutum caught in Mazanderan. The exploitation ratio (E) was found to be higher than 0.5 for both sexes from Guilan, and to be lower than the expected optimum level of exploitation in Caspian kutum males and females caught in Mazanderan

Life history characteristics of a potential invasive Ponto-Caspian goby, Neogobius fluviatilis in natural lakes from its native range (Black Sea region of Turkey)

To fill the gap in and provide baseline knowledge for developing increased understandings of the factors driving the invasiveness of the Ponto-Caspian gobiid Neogobius fluviatilis, their life history traits (as somatic growth and reproduction) were studied in three natural freshwater lakes in its native range. These populations were characterised by slow somatic growth rates, being the slowest reported across all of their native and non-native ranges. Ages were recorded to seven years old. Across the three lakes, there was considerable variability in their sex ratios and reproductive traits (including length at maturity and fecundity at length and age), revealing considerable inter-population variability. These data thus suggest N. fluviatilis has considerable plasticity in the expression of their life history traits, with this plasticity argued as a key factor in facilitating their ability to establish and invade new waters following introductions

Assessment of aquatic ecosystem health in Gorgan Bay based on biotic indices

The relationship between spatial patterns of macrobenthic community characteristics and environmental conditions (dissolved oxygen, temperature, salinity, organic matter content and sediment particle size) was studied at 12 stations in Gorgan Bay (South Caspian Sea, Iran), seasonally in 2017. A total of 8803 individuals belonging to 11 families and 11 species were identified. Three species of polychaeta including Streblospio gynobranchiata, Tubificidae and Hediste diversicolor were the most dominant group in terms of abundance, making up 79.3% of all specimens. The highest density (4733 ind m-2) was observed at St. 1 while the lowest (1166 ind m-2) at St. 9. Biotic indices (i.e. AMBI, BOPA and BENTIX) were used to determine the quality of the bay. Gorgan bay is divided into two distinct zones (eastern and western regions) based on MDS analysis and ecological status. Generally, eastern part of the bay revealed the lowest abundance and biodiversity of macrobenthos. Our results suggest the effect of sediment particle size and TOM as significant parameters on distribution of macrobenthic community in Gorgan bay, South Caspian Sea