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Kizilirmak River has been used as Ankara’s drinking water source for approximately 1.5 years. Therefore, this region’s water, sediment, and fish samples are measured for detecting the heavy metals. This is important for the current situation as well as the future in terms of potential impact. The amount of heavy metals in drinking water should be within the limited values; otherwise, the accumulation of heavy metals will cause many problems to living organisms. Especially high levels of arsenic, cadmium, nickel, mercury, etc. are very dangerous to freshwater ecosystems as for human if the water is being use as drinking water. In this study, water, sediment samples, muscle, and gills of three fish species (Capoeta tinca, Capoeta capoeta, Leuciscus cephalus) were analyzed for the presence of heavy metals such as (Al, Fe, As, Cd, Ni, Mn, Se, Si) to determine present accumulation levels and possible toxic effect. The accumulation pattern of heavy metals in the water, sediment, and fish tissue follows the sequence: Si > Fe > Al > Mn > As > Ni > Se > Cd, Fe > Al > Mn > Ni > As > Se > Cd, and Fe > Al > Mn > As > Ni > Si > Cd. In addition, the detected concentrations of heavy metals in the Kizilirmak and Delice Rivers are compared with other heavy metal studies in the other main rivers and lakes in Turkey.

The seasonal occurrence of medicinal leeches was studied at two lakes in the Black Sea coastland of north-western Turkey. The number of leeches attracted by a collector per hour was taken as an indicator for population density. Leeches were most abundant in May/June, and were almost absent during the cold season (November – March). Leeches with a weight of less than 1 g occurred principally between July and October with a peak in July. It is thought that these individuals represent newly hatched leeches. Although both study areas are close to each other, significant differences were found in respect to mean leech size and the seasonal frequency of leeches (both total number and certain age classes). It is suggested that leech biology is greatly dependent on factors such as microclimate and the availability of hosts, and no general conclusions on phenology can be drawn. There is therefore no scientific basis for restricting commercial leech collecting to certain months of the year.

A survey of all the major potential habitats in western Turkey showed that medicinal leeches, Hirudo medicinalis L., are widely distributed over the country and are not rare. They occur in practically all suitable habitats and the only region where they were found to be absent is that of the large river deltas in the south of the country (Cukurova deltas, Goksu delta). There may be zoogeographic reasons for this (Taurus mountains barrier). The application of a semi-quantitative survey method using collecting efficiency (number of leeches collected per hour by a single person) allowed a rapid assessment to be made of its status in a large number of wetlands. Leech density varied considerably from wetland to wetland, and the results enabled a ranking of the Turkish wetlands to be made according to their importance for medicinal leeches. Taking both the leech density and the size of leech habitats into account, the largest populations were identified on the Black Sea coast (Kizilirmak delta, Yesilirmak delta and Karagol Marshes near Sinop) and in inner and south-west Anatolia (Eber Golu, Karamik and Sultan Marshes). Commercial exploitation for the pharmaceutical industry and for other purposes takes place at only a few places and does not appear to affect the population seriously. However, many populations are threatened by the draining of their habitats.