ASSESSMENT OF WATER CONTAMINATION IN FLUVIAL ECOSYSTEMS OF THE THRACE REGION (TURKEY) BY MEANS OF WATER QUALITY INDEX AND GEOGRAPHIC INFORMATION SYSTEM TECHNOLOGY

Aim of the study: Thrace Region is the most important geographical regions of Turkey in terms of agricultural and industrial production. Meriç – Ergene River Basin is the main watershed of this significant region and there are many streams feeding the basin. In the current research, water qualities of fluvial ecosystems of Thrace Region were evaluated by using some ecological and statistical indicators. Material and methods: For each water sample, 27 physical and chemical limnological parameters (EC, TDS, turbidity, NO3, NO2, SO4, F, COD, BOD5, As, Se, Cu, Zn, Cd, Sb, Ba, Pb, B, Na, Mg, Cr, Mn, Al, K, Ca, Fe, Ni) were analysed and all the investigated parameter values were used to develop the Water Quality Index (WQI). Furthermore, Cluster Analysis (CA) were applied to detected data in order to classify the investigated locations and also Geographic Information System (GIS) was used to provide a visual summary of contamination levels in the basin components. Results and conclusions: The results show quite high WQI coefficients of COD (20.773), Se (9.667) and BOD5 (9.216) parameters in fluvial components of Thrace Region. The WQI values of the fluvial habitats of Thrace Region ranged from 33.91 – 329.84 and Çorlu Stream and Ergene River were determined as the most contaminated fluvial ecosystems. According to the results of applied CA, 2 statistically significant clusters were formed, which were named as “High Contaminated Zones” and “Low Contaminated Zones”.

Longitudinal river zonation in the tropics: examples of fish and caddisflies from the endorheic Awash River, Ethiopia

Specific concepts of fluvial ecology are well studied in riverine ecosystems of the temperate zone but poorly investigated in the Afrotropical region. Hence, we examined the longitudinal zonation of fish and adult caddisfly (Trichoptera) assemblages in the endorheic Awash River (1,250 km in length), Ethiopia. We expected that species assemblages are structured along environmental gradients, reflecting the pattern of large-scale freshwater ecoregions. We applied multivariate statistical methods to test for differences in spatial species assemblage structure and identified characteristic taxa of the observed biocoenoses by indicator species analyses. Fish and caddisfly assemblages were clustered into highland and lowland communities, following the freshwater ecoregions, but separated by an ecotone with highest biodiversity. Moreover, the caddisfly results suggest separating the heterogeneous highlands into a forested and a deforested zone. Surprisingly, the Awash drainage is rather species-poor: only 11 fish (1 endemic, 2 introduced) and 28 caddisfly species (8 new records for Ethiopia) were recorded from the mainstem and its major tributaries. Nevertheless, specialized species characterize the highland forests, whereas the lowlands primarily host geographically widely distributed species. This study showed that a combined approach of fish and caddisflies is a suitable method for assessing regional characteristics of fluvial ecosystems in the tropics.

Defining Dry Rivers as the Most Extreme Type of Non-Perennial Fluvial Ecosystems

We define Dry Rivers as those whose usual habitat in space and time are dry channels where surface water may interrupt dry conditions for hours or a few days, primarily after heavy rainfall events that are variable in time and that usually lead to flash floods, disconnected from groundwater and thereby unable to harbor aquatic life. Conceptually, Dry Rivers would represent the extreme of the hydrological continuum of increased flow interruption that typically characterizes the non-perennial rivers, thus being preceded by intermittent and ephemeral rivers that usually support longer wet phases, respectively. This paper aims to show that Dry Rivers are ecosystems in their own right given their distinct structural and functional characteristics compared to other non-perennial rivers due to prevalence of terrestrial conditions. We firstly reviewed the variety of definitions used to refer to these non-perennial rivers featured by a predominant dry phase with the aim of contextualizing Dry Rivers. Secondly, we analyzed existing knowledge on distribution, geophysical and hydrological features, biota and biogeochemical attributes that characterize Dry Rivers. We explored the capacity of Dry Rivers to provide ecosystem services and described main aspects of anthropogenic threats, management challenges and the conservation of these ecosystems. We applied an integrative approach that incorporates to the limnological perspective the terrestrial view, useful to gain a better understanding of Dry Rivers. Finally, we drew main conclusions where major knowledge gaps and research needs are also outlined. With this paper, we ultimately expect to put value in Dry Rivers as non-perennial rivers with their own ecological identity with significant roles in the landscape, biodiversity and nutrient cycles, and society; thus worthy to be considered, especially in the face of exacerbated hydrological drying in many rivers across the world.

Analysis of niche characteristics of phytoplankton functional groups in fluvial ecosystems

Assigning species to functional response groups in phytoplankton ecology reduces the number of functional units, which helps understand the processes that shape diversity and functioning of planktonic assemblages. Although the concept has become widespread in recent years, numerical characterization of the groups’ positions in the niche space remained a challenging task. Using a large river phytoplankton dataset, we characterized the functional groups (FGs) of phytoplankton by their niche position and niche breadth in the niche space defined by the relevant environmental variables using the Outlying Main Index approach. The niche space has been defined primarily by trophic-related (nutrients) and river size-related variables (water residence time, discharge). Although we hypothesized that FGs with central niche position would have wide, while those with marginal niche position have narrow niche breadth, these have not been corroborated by the results. Rather, FGs occurred both with central niche position and intermediate breadth, as well as with marginal niche position and wide breadth. Niche position of several FGs was different from that suggested by their known habitat templates in lakes. Furthermore, we found no significant relationship between niche position and niche breadth, suggesting that the occurrence of FGs in rivers is simultaneously influenced by both niche characteristics.

Estimation of Temperature Recovery Distance and the Influence of Heat Pump Discharge on Fluvial Ecosystems

Temperature differences between the atmosphere and river water allow rivers to be used as a hydrothermal energy source. River-water heat pump systems are a relatively non-invasive renewable energy source; however, effluent discharged from the heat pump can cause downstream temperature changes which may impact sensitive fluvial ecosystems. The temperature change associated with heat pump discharge in a river reach was examined using the heat transfer equation in a previous study, but not using models. There were also no studies on the impact of temperature change due to heat pump discharge on river ecosystem elements such as endangered fishes. Therefore, in this study, the water temperature recovery distance of effluent was estimated for a river section in the Han River Basin, Korea, using the heat transfer equation and the Environmental Fluid Dynamic Code (EFDC) model. The water temperature recovery distance was estimated to be 9.7 km using the heat transfer equation and 5 km using the EFDC model in summer. It was also estimated to be 4.5 km using the heat transfer equation and 6.7 km using the EFDC model in winter. Results showed that the water temperature recovery distance results estimated by the heat transfer equation had greater variation than the EFDC model. The water temperature recovery distance could also be used as an objective indicator to decide the reuse of downstream river water. Furthermore, as the river system was found to support an endangered fish species that is sensitive to water environment changes, care should be taken to exclude the habitats of protected species affected by water temperatures within water temperature recovery distance.

Estimation of Temperature Recovery Distance and the Influence of Heat Pump Discharge on Fluvial Ecosystems

Temperature differences between the atmosphere and river water allow rivers to be used as a hydrothermal energy source. The river-water heat pump system is a relatively non-invasive renewable energy source; however, effluent discharged from the heat pump can cause downstream temperature changes which may impact sensitive fluvial ecosystems. In this study, the water temperature recovery distance of the effluent was estimated for a river section in the Han River Basin, Korea, using the heat transfer equation and the Environmental Fluid Dynamic Code (EFDC) model. Results showed that, compared to the EFDC model, the heat transfer equation tended to overestimate the water temperature recovery distance due to its simplified assumptions. The water temperature recovery distance could also be used as an objective indicator to decide the reuse of downstream river water. Furthermore, as the river system was found to support an endangered fish species that is sensitive to water environment changes, care should be taken to exclude the habitats of protected species affected by water temperatures within water temperature recovery distance.

First record of plastic ingestion by an important commercial native fish (Prochilodus lineatus) in the middle Tietê River basin, Southeast Brazil

This is the first study to report the plastic ingestion by Prochilodus lineatus in Brazilian fluvial ecosystems. We examined 32 individuals collected in two contrasting lotic environments: the highly polluted Tietê River and its much less degraded tributary, Peixe River. Most individuals, 71.88%, contained plastic in their digestive tract, with averages of 3.26 and 9.37 particles per individual in the tributary and main river, respectively. The blue color was predominant among the observed plastic particles and size ranged from 0.18 to 12.35 mm. Plastic ingestion must be accidental, predominantly, since the species has an iliophagous eating habit. As this species is regionally the most important fishery resource, potential adverse effects of this type of contamination may be transferred to human consuming populations. Mitigation measures against pollution are urgent in the Tietê River basin.