The Turiec River drains four geomorphological units with contrasting bedrock geology, including crystalline, carbonate, and volcanic rocks, within a small basin. We analysed differences in beta diversity of macroinvertebrate communities using qualitative and quantitative data and evaluated species preferences across sites. Because bedrock influences water chemistry, we examined whether geological site classification corresponded to environmental similarity based on water quality, altitude and flow velocity. Hierarchical clustering revealed a mismatch between mapped geology and measured environmental conditions, resulting in a reclassification into crystalline‑like, carbonate‑like and volcanic‑like groups. Canonical analysis of principal coordinates showed that calcium concentration and flow velocity significantly influenced species distribution under the environmental classification, whereas only flow velocity was significant under the geological classification. Multivariate homogeneity tests indicated significant differences in abundance and richness of Trichoptera, and consequently in total and EPT communities, between crystalline‑like and volcanic‑like groups. No significant differences were detected among sites classified solely by bedrock geology, although several taxa were associated with the mineral gradient. Beyond group-level patterns, our study also revealed several ecologically and biogeographically distinctive species responses that are rarely observable in larger or less heterogeneous catchments. These results demonstrate that bedrock affects macroinvertebrate communities indirectly through its influence on water chemistry, which may not align with geological boundaries. In geologically complex mountain regions, environmental reclassification based on water chemistry and hydraulics is therefore essential to avoid biased interpretations of biodiversity patterns and to support more reliable ecological assessment and management.
This study examined spatial and seasonal variation in bacterial communities in coastal and offshore waters of Visakhapatnam, northeastern Bay of Bengal, using 16S rRNA gene amplicon sequencing. Eight seawater samples representing surface and bottom waters at two stations were collected during the pre-monsoon and post-monsoon periods, alongside measurements of hydrographic and physicochemical parameters. Pseudomonadota dominated the sampled communities, while differences in the relative abundances of Bacteroidota, Actinomycetota and other taxa were observed across samples. Bray–Curtis analysis and PERMANOVA indicated a significant difference in community composition between the coastal and offshore stations (R2 = 0.47, p = 0.03), whereas depth and season were not significant at the community level. Coastal samples showed higher observed richness and mean Shannon diversity than offshore samples in this dataset. PICRUSt2-based predictions indicated potential for chemoheterotrophy and other carbon-, nitrogen- and sulfur-associated functions, with variation among samples. These predictions represent inferred functional potential rather than direct evidence of gene expression, metabolic activity or biogeochemical process rates. Interpretation is constrained by the limited spatial and temporal coverage and the use of only two sampling stations. The findings provide a preliminary baseline for bacterial community composition in the sampled waters and support further investigation using broader sampling and direct functional measurements.
This study investigates the variability of phytoplankton characteristics—namely species richness, and Shannon diversity index—as well as Reynolds functional group (RFG) attributes, including composition, total biovolume of the species classified within those groups, and RFG richness, across 16 predefined lake types. The analysis is based on data collected from 70 lentic systems in Türkey during the spring, summer, and autumn seasons between 2017 and 2019. Patterns of variation and similarity in both lake types and individual lentic systems were evaluated in relation to type descriptors (altitude, latitude, longitude, lake depth, surface area, and geological features-alkalinity) and additional environmental parameters. The results of the multivariate analyses revealed that the 16 lake types differed from one another in terms of RFG composition, phytoplankton biovolume, dominant RFGs, species richness, the Shannon index, and RFG richness. In addition, while typological descriptors such as surface area, lake depth, alkalinity, and spatial factors played a key role in distinguishing typologies based on their composition of RFGs and dominant RFGs, the environmental parameters, such as electrical conductivity, also had an impact. Despite similarities in RFGs composition and the distribution of dominant RFGs among systems within the same lake type, the presence of significant differences underscores the importance of local environmental conditions. These findings suggest that incorporating supplementary descriptors—especially electrical conductivity—may enhance the accuracy of phytoplankton-based classification of lentic ecosystems in Türkiye.
Land use has emerged as a key driver for anthropogenic impacts on stream ecosystems. Given the small and semi-isolated nature of the Kapıdağ Peninsula, we hypothesized that land-use patterns would be directly reflected in diatom metacommunity structure. To test this, we evaluated the effects of land use and environmental variables on diatom composition and diversity across 19 stream sites, and further examined whether estuarine proximity and micro-scale salinity variations influence community structure. Multivariate analyses, including Heat Maps, TWINSPAN, Redundancy Analysis (RDA), and Variation Partitioning Analysis (VPA), revealed that agricultural land use significantly altered water chemistry—particularly soluble silica (Si), salinity (SAL), and sulphate ( SO_4 )—compared to forested areas. These changes were strongly associated with shifts in diatom species composition. Notably, increasing SO_4 concentrations were linked to higher species richness and diversity. In contrast, while macro-scale SAL levels at estuarine sites did not differ from upstream sections—indicating limited direct seawater intrusion—RDA forward selection identified SAL as a significant environmental filter shaping specific tolerant assemblages at lower reaches. Among the 18 diatom indices evaluated, DESCY demonstrated the highest performance in reflecting ecological status, based on its strong alignment with environmental gradients and indicator species distribution. Overall, our findings highlight land use as a primary determinant of environmental variability and diatom community dynamics in semi-isolated systems, emphasizing its critical role in ecological assessment frameworks.
Microplastic pollution has been widely studied across diverse environmental matrices; however, knowledge gaps persist regarding the source-specific characterisation of fishing-related plastics. This study investigates the bioaccumulation and biochemical effects of microplastics derived from boat-building Fibreglass Reinforced Plastic (FRP-MPs) in Oreochromis niloticus (Nile tilapia). Fish were exposed to different concentrations of virgin and weathered FRP-MPs via dietary intake for 120 days. Growth parameters, feed conversion ratio, faecal egestion, microplastic leaching from feed, bioaccumulation in tissues, biochemical and haematological changes were assessed. Growth performance and feed conversion were significantly affected only at higher concentration (p<0.05). The highest MPs accumulation occurred in the gut (61.2 particles/g), followed by the skin (11.1 particles/g). Muscle tissue (0.55 particles/g) showed minimal retention. Faecal egestion of MPs increased with exposure concentration (1.4–47.33 particles/g). Tissue-specific responses showed altered carbonyl, amine, and silicate profiles, with pronounced changes in the liver and a marked loss of amino and benzenoid groups in the gills, while muscle tissue retained silicates but exhibited a loss of carbonyl and amide groups, as revealed by FTIR. MPs affected antioxidant enzyme activity (catalase and superoxide dismutase) and elevated hepatic biomarker enzyme levels (alanine aminotransferase and aspartate aminotransferase) across various organs. Haematological parameters such as Red Blood Cell (RBC), White Blood Cell (WBC), Packed Cell Volume (PCV), Haemoglobin (HGB), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH), and Plateletcrit (PCT) showed significant differences between the groups fed with weathered and virgin FRP-MPs. This study reports the first evidence of FRP-derived MPs bioaccumulation and physiological alterations in fish, offering critical baseline data for understanding the ecological implications and the urgency for policy requirements.
