This study examined the vertical distributions of total phosphorus (TP) and phosphorus fractions, and the iron and organic matter, in the littoral sediment in a macrophyte-dominated, clearwater state in Lake Mogan between September 2005 and August 2006. Benthic macroinvertebrates and total bacteria in the sediment also were determined. No clear seasonal or depth-related (0-20 cm) patterns were found in sediment concentrations for the measured parameters. The phosphorus release was quantitatively very low, and a negative phosphorus release (-0.132 μg m -2 day -1 ) was measured during the summer months. The TP concentrations of the sediment samples ranged between 675.00 and 1463.80 μg g -1 dry weight (DW), and the trophic level of the lake was eutrophic. On average, inorganic phosphorus fractions comprised the largest fraction (63%), while organic-bound phosphorus (Org ≈ P) constituted 37% of the TP in Lake Mogan. The most important phosphorus-immobilizing factors are high iron content (14 200-47 750 μg g -1 DW), the sediment's clay content (47.80-51.80%), and an abundance of macrophytes at the sampling station. The low abundance of benthic macroinvertebrates (510-850 individuals m -2 ), which depend on sediments with high iron and low organic matter (5.42-13.30%), played a role in the sediment phosphorus retention. Although bacterial abundance in the surficial sediment appeared to be positively correlated to temperature, the overlying water did not experience anoxic conditions, supporting a state in which bacteria were able to retain phosphorus in their cell structures. Long-term changes in the sediments of Lake Mogan must be monitored lake. In order to optimize the management of the lake, and to determine the longevity of a clearwater state following management measures and continued external phosphorus loading, long-term changes in the sediments of Lake Morgan must be monitored.

To determine the effects of exposure to a mixture of formalin, malachite green and methylene blue (FMC) on the secondary stress indices, changes in glucose, phosphorus, calcium, magnesium, sodium, potassium and haematocrit were monitored in healthy Nile tilapia, Oreochromis niloticus L. Fish were exposed separately to varying concentrations of a mixture of formalin, malachite green and methylene blue (0.1, 0.5 and 1 p.p.m.) for 1, 10 and 60 min. In general, treatment of fish with FMC elicited marked elevations of plasma glucose. Plasma phosphorus levels dropped after FMC treatment. In fish exposed to FMC, calcium levels in general were lower than those of the controls. Magnesium levels were not influenced by FMC treatment. Plasma sodium and potassium levels showed an unclear pattern for differing FMC concentrations and exposure times. Haematocrit values were affected by FMC treatment.

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.