Several water (dissolved oxygen, pH, ammonia-nitrogen, nitrite-nitrogen, nitratenitrogen, total phosphorus and orthophosphate) and sediment (organic matter, total nitrogen, organic carbon and phosphorus) quality parameters, as well as benthic macroinvertebrate communities were investigated monthly between May 2007 and November 2007 at a rainbow trout farm located on one of the sources of the Sakarya River in Central Anatolia. Water and sediment samples were collected from three stations, i. e., the inlet of the farm, which was a karst spring-originated pond, the outlet of the farm, and a location 200 m from the outlet of the trout farm, which has a capacity of 30 t annually. These water quality parameters were compared to the acceptable effluent limits proposed for trout farming in different countries. Ammonia-nitrogen, total phosphorus and orthophosphate were found to be higher than the acceptable effluent limits during the study period. Sediment quality parameters were also found to be higher than those at the inlet of the farm. The benthic macroinvertebrate community consisted of only Gastropoda (Limnaedae, Planorbidae, Neritidae and Pleuroceridae). Almost identical organism groups were observed at the three stations, and the highest abundance was found at the outlet of the farm during the study. Finally, as an indicator of damage to the environment, the biodiversity indices were generally measured at levels below 1 in all stations.

Turkey's inland water ecosystem consists of 33 rivers (177.714 miles), 200 natural lakes (906.118 ha), 159 reservoirs (342.377 ha) and 750 ponds (15.500 ha). Sedimentological studies conducted on inland water ecosystems during the last 15 years in Turkey can be categorized into two main topics. The first group of studies is concerned with heavy metal levels in sediment, with especial reference to the interaction between water, sediment and aquatic organisms. Additionally, the studies in question deal with the potential impacts of heavy metal concentrations on the ecosystem. The second group of studies is concerned with the role of eutrophication in the sediment as a result of serious contamination of inland water ecosystems. It is known that the sediment can directly influence the nutrient level in standing inland waters such as lakes and ponds by way of internal nutrient loading. In this context, studies regarding sediment, overlying water, sediment pore water and nutrient release from the sediment should be emphasized as these are important steps with respect to the eutrophication process. By keeping these studies in mind, the researcher in this study compiled and analyzed studies dealing with inland water ecosystems with differing nutrient levels and uses, including for drinking water, in Turkey's drainage basins. In addition, field and laboratory studies regarding nutrient release from sediment into Turkey's inland water ecosystems were evaluated in light of lake management practices.

The aim of this study was to quantitatively determine the phosphorus fractional composition of the eutrophicated West Pond sediment using vertical and seasonal changes (positive-upwards and/or negative-downwards) in the phosphorus cycling across the sediment-water, and to examine the most effective potential fraction or fractions on phosphorus release and the pond's eutrophication process. In this study, mean release values of phosphorus in depths and months representing the seasons (April, July, October, January) varied between 9.19 (January, 0-5 cm) and 119.08 µg m -2 d -1 (October, 0-5 cm) in West Pond sediment which supplies water to the Sakaryabaşı Fish Culture and Research Station. The mean negative phosphorus release dependent on months and depths were estimated as 1.25 µg m -2 d -1 (July, 5-10 cm) and 46.45 µg m -2 d -1 (October, 10-15 cm). The distribution of phosphorus fractions in the pond sediment: total organically bound phosphorus fraction (Org≈P) > calcium bound phosphorus fraction (Ca≈P)> carbonate bound phosphorus fraction (CO 3 ≈P) > iron + aluminum bound phosphorus fraction (Fe+Al≈P). In line with research findings the negative phosphorus release dependent on months and depths have revealed quantitatively that West Pond sediment is a sink not a source in terms of phosphorus. In the light of this, conservation of the aquatic macrophytes, role in preventing/suppressing the dissolved inorganic phosphorus release from sediment to overlying water, suggested as the best management technique of West Pond.

No abstract

Mogan Lake, a popular recreation area, is under the pressure of intense urban-industrial pollution, therefore some management strategies included occasional macrophyte harvesting, diverting running water into the lake to accelerate the improvement of its water, and dredging have been in progressing since 1995. This study was conducted on sediment and overlying water samples collected in April, July and October 2015 and January 2016 from Mogan Lake. The outstanding data for this study is presented as: i) detection of the sediment chemical composition and estimation of sediment phosphorus mobility, ii) comparison of the current status of the lake's eutrophication regarding phosphorus mobility with data from earlier studies regarding the common station. The research data has revealed i) sediment TP concentrations ranged from 620.00 µgP gDW -1 , to 1047.50 µgP gDW -1 while TN concentrations were between 3250.00 µg gDW -1 and 6325.00 µg gDW -1 . Sediment TOC concentrations ranged between 58850.00 µg gDW -1 and 79675.00 µg gDW -1 . Sediment iron content and loss on ignition values were determined as 1.608-3.415 mg gDW -1 and 9.05-20.94 %, respectively. The rank order of phosphorus fractions were evaluated as Ca≈P>Org≈P>CO 3 ≈P>Fe+Al≈P. ii) the phosphorus release values from the sediment (0.1754 -1.1249 mg P m -2 d -1 ) were higher than the earlier studies findings. Phosphorus release in the lake has increased over the past ten years but still remains at a generally low level together with some management activities in Mogan Lake, therefore, instead of the internal P source future research should focus on external sources. In shallow eutrophic systems such as Mogan Lake, sediments having phosphorus accumulation depends on deep interactions with principally antropogenic external sources. In conclusion the primary goal is to determine the adsorption capacity of the sediment in order to estimate the critical internal phosphorus load and the second goal should be to apply a sustainable monitoring program.