Volume 50 (2021): Issue 4 (December 2021)

The presented research was conducted in 2018–2019 in the Peshawar Valley, Pakistan, to study for the first time the effect of water quality on the spatial distribution of charophytes. A total of six taxa of charophytes were found at 41 sites in the Peshawar Valley along the banks of seven rivers, 16 streams and two wetlands: Chara braunii C.C.Gmelin, C. connivens Salzmann ex A. Braun, C. contraria A. Braun ex Kützing, C. globularis Thuiller, C. vulgaris Linnaeus, and Nitellopsis obtusa (Desvaux) J. Groves. Chara vulgaris was the most abundant species, followed by C. globularis, and C. contraria. Water pH, electrical conductivity (EC), total dissolved solids (TDS), salinity and dissolved oxygen (DO) were within the permissible limits for Pakistan, while water temperature, oxidation reduction potential (ORP) and resistivity showed deviations. Canonical Correspondence Analysis (CCA) revealed that DO affected Chara vulgaris, pH and resistivity affected C. braunii, C. connivens and C. globularis, temperature and ORP affected C. contraria and Nitellopsis obtusa. Furthermore, CCA showed that TDS, EC, and salinity had no effect on the spatial distribution of Chara contraria, C. vulgaris and Nitellopsis obtusa. Chara contraria and Nitellopsis obtusa should be protected under VU (Vulnerable) status (IUCN) along with their habitats.

The permanganate index (PI), oil and grease (O&G), and 17 polycyclic aromatic hydrocarbons (PAHs) were analyzed in surface sediment and water samples collected at 13 sites along the western coast of Suez Bay (SB). PI and O&G in the SB coastal seawater ranged from 9.6 mg O₂ l⁻¹ and 17.0 mg l⁻¹ to 16.0 mg O₂ l⁻¹ and 37.0 mg l⁻¹, respectively. The level of polycyclic aromatic hydrocarbons (PAH) in water and sediment in the SB offshore area was determined by gas chromatography/flame ionization detection. The concentration ranged from 0.574 to 16873.2 ng g⁻¹ in the sediment and 0.502 to 43.540 ng l⁻¹ in water. The collected data were compared with values reported in the literature. The possible source and origin of pollution was also assessed based on the determined relative PAH levels at the study sites, the ratio of low molecular mass PAHs (LPAHs) to high molecular mass PAHs (HPAHs), and molecular indices of samples.

Ten monoclonal microalgal cultures were obtained from several Tunisian inland water bodies, and their dichloromethane and methanolic extracts were screened for antibacterial, antileishmanial, and antioxidant properties, as well as phycobiliprotein production capacity. Cylindrospermopsis raciborskii has been shown to synthesize high levels of phycocyanin and may be an effective alternative source to other sources used for commercial production of phycocyanin. Chroococcus sp. and Leptolyngbya sp1. exhibited the strongest radical scavenging activity against DPPH (IC₅₀ = 212.15 and 263.91 μg ml⁻¹, respectively), indicating their promising potential for use as new effective and non-toxic antioxidants. Furthermore, Dunaliella sp. showed an interesting antileishmanial activity against the pathogens Leishmania infantum and Leishmania major (IC₅₀ = 151 and 284 μg ml⁻¹, respectively), thus representing a good candidate for use against cutaneous and visceral leishmaniasis in Tunisia, a country endemic to these diseases where thousands of new cases are registered every year. These results suggest that the strains of microalgae featured in this work have the potential to serve as natural alternative, safe and sustainable sources of high value-added products that could be used to improve the final biomass value.

The study deals with the growth pattern, mortality, and reproduction of common sole, Solea solea (Linneaus, 1758), from the Sea of Marmara (Turkey). A total of 580 fish specimens were sampled monthly from October 2017 to September 2018. The total length of all sampled individuals ranged from 11.1 to 29.5 cm, corresponding to ages from 1 to 3 years. The length–weight relationship was expressed as W = 0.022 TL^2.6838, where the slope indicated negative allometric growth. Growth parameters were L_∞ = 33.7 cm, k = 0.48, and t₀ = −0.18 for all samples. A seasonally oscillating growth model, indicating the amplitude of oscillations, revealed an important seasonal growth pattern. Total, natural, and fishing mortality rates were calculated as 1.42, 0.47, and 1.01, respectively. The exploitation ratio (E = 0.68) indicates that the fishing pressure on the common sole in the Sea of Marmara was high. The sex ratio (♀/♂) was 1.18. The gonadosomatic index (GSI) for females showed that two main spawning seasons were observed: one in spring (May) and one in autumn (September–October). Sizes at the onset of sexual maturity were estimated for both females and males at 21.6 and 18.6 cm, respectively.

The ecological risk resulting from the accumulation of some heavy metals in the sediments of Iskenderun Bay was assessed using the following measures: enrichment and contamination factor, pollution load index (PLI), and potential ecological risk index (RI). The concentrations of the studied heavy metals were in the following order: Fe > Ni > Mn > Cr > Zn > Cu > As > Pb > Cd > Hg. Ni and As had the highest EF values. This situation is most likely due to the presence of iron, pesticide, and fertilizer plants in the region. According to the United States Environmental Protection Agency, Ni, As, Mn, and Cr may have harmful effects on faunal communities in sediments. According to the RI, Site 4 was more contaminated and toxic than the other seven study sites, with “moderate” ecological risk. Pearson’s correlation coefficient was determined by multivariate methods – cluster and principal component analysis. As can be inferred from the RI values, the potential toxic effect of As and Ni in the sediments is moderate.

Island ecosystems have attracted the attention of scientists since the early days of science because of their formation and biodiversity. Despite their abundant freshwater resources, data on freshwater diversity of Gökçeada are incomplete, especially for macroinvertebrates. This study was conducted in a wide range of freshwater ecosystems on Gökçeada between May 2016 and September 2018. Sampling of macroinvertebrates was performed using a hand net from 34 pre-selected sampling sites on the island. A total of 78 aquatic macroinvertebrate taxa were found, 46 of which are new records for the island. The most common species during the study were Gammarus komareki and Bythinella gokceadaensis with a frequency of 25.93%, followed by Tubifex tubifex, Gammarus sp. and Caenis sp. with a frequency of 22.22%. Endemic and invasive species on the island were assessed according to their presence and frequency values. Based on the results of the current study and previous data, it can be concluded that Gökçeada is characterized by a remarkable species diversity compared to aquatic macroinvertebrates on other Aegean islands.

Otolith phenotypic variability was analyzed in the Caucasian bleak (Alburnus escherichii) from the Selevir Reservoir in Turkey. Utricular (lapillus) and lagenar (asteriscus) otoliths were removed, while distinguishing between left and right otoliths. All otoliths were photographed on the distal (for asterisci) and dorsal surface (for lapilli) using a Leica DF295 digital camera. Otolith morphometrics were measured to the nearest 0.001 mm using Leica Imaging Software. Linear and nonlinear (power) models were applied to determine the relationships between otolith measurements and total length of fish individuals. Two length classes (Class I: 6.7–10.9 cm L_t; Class II: 11.0–15.0 cm L_t) were established to analyze the shape of otoliths. The Form Factor, Circularity, Roundness, Rectangularity, Aspect Ratio and Ellipticity were used to analyze the shape of otoliths. A standardized model was used to remove the effect of size on otolith measurements. Multivariate analysis was performed to detect differences in otolith shape variation. The results of discriminant function analysis showed that 79.9% of A. escherichii specimens were correctly classified by length classes. In this study, intraspecific variation of asteriscus and lapillus otoliths in A. escherichii is reported for the first time. The results of this study provide the first comprehensive data on otolith shape analysis and the relationship between otolith morphometrics and total length in the Caucasian bleak.

The study was conducted between July 2018 and May 2020 to compare seasonal changes in growth parameters of the Mediterranean mussel (Mytilus galloprovincialis) at different depths in two different areas of the Northeastern Mediterranean Sea (Aegean Sea). In a preliminary study, mussels were placed in cages at different depths of an artificial reef (AR – shipwreck) and natural reef (NR). Temperature, salinity, pH, and dissolved oxygen were determined seasonally at both sites at a depth of 37 m (deepwater) and 25 m (midwater). Linear increases in length and width of mussels at the AR site were recorded, while no consistent changes were observed for mussels at the NR. There was negative correlation between the specific growth rate (SGR) and salinity (r² = 0.5098) and temperature (r² = 0.1470) at the AR site. Negative correlations were also recorded between pH and the commercial condition index (CCI) at both the AR (r² = 0.3869) and NR (r² = 0.3600) sites. Our findings show that depth had a significant effect (p < 0.05) on the CCI of mussels at the NR site, while its effect was insignificant for this index at the AR site (p > 0.05). This study indicates that natural reefs provide more suitable conditions for the growth of Mediterranean mussels than shipwrecks used as artificial reefs.

Risk perception and risk responses of Greek mussel farmers are important for understanding their risk behavior and the likely success of different risk mitigation strategies. This allows policy makers and actuarial companies to decide what risk management products to offer to address specific types of risks.

Results from an empirical survey showed that ex-farm prices and health/disability status of farmers are perceived as the most important sources of risk.

Risk management decisions were strongly influenced by the attitudes of mussel farmers rather than their socioeconomic status or perception of risk sources.

Financial reserves and an alternative source of stable income are both preferred by mussel farmers as risk management strategies, while optimizing farm management to produce at the lowest possible cost is commonly practiced to eliminate losses. Farmers recommend that for certain types of risks that lead to total losses, e.g. anoxia, tsunamis, harmful algal blooms (HABs), insurance contracts should be provided by the public sector, as in similar situations in agriculture. For other needs, customized insurance contracts should be provided by the actuarial market.

Biological Traits Analysis (BTA) was used to investigate the functional structure of marine macrobenthic communities along the Samsun Shelf Area (SSA). Benthic samples were collected seasonally from five different locations and at four different depths using a Van Veen grab sampler. Macrofaunal communities distributed in the SSA were assessed using 10 biological traits to identify characteristic traits for each depth and location. It was found that variability of benthic ecosystem functions in the SSA was driven by biological traits such as maximum size, living habit, sediment position, feeding mode and type of reproductive behavior. Bivalves, polychaetes and crustaceans of small to medium size, biodepositing, burying themselves in the sediment (burrowers) and feeding in suspension were relatively more abundant at depths of 0–60 m. However, the biomass of Amphiura, Abra, Papillicardium and some polychaetes characterized by medium to large sizes, diffusive mixing, free living and feeding on deposit and subsurface deposit showed higher values at depths below 60 m. In general, it is concluded that the functional structure of the benthic infauna in the SSA has adapted to physical disturbance, and communities distributed in this area consist mainly of taxa resistant to mechanical pressure.