Assessment of the ecological status of the shallow Lake Neor (Iran) using a macroinvertebrate community structure

Abstract

Macroinvertebrates play a key role in freshwater lentic and lotic ecosystems. Lake Neor, located in the northwest of Iran (37° 55′ to 38° 1′ 45), 2700m above sea level, is one of the lakes with little information available regarding the limnological data. Therefore, the present study was planned and conducted during a period of one year focusing on macroinvertebrate fauna and assemblage. Sampling was done monthly at four sites from August 2008 to July 2009. Altogether, a total of 11 species belonging to three phyla, seven classes, 10 orders and 10 families were identified, indicating a low diversity. From these species, eight are recorded for the first time from this lake and from the country, including Pisidium supinum, Fossaria humilis, Stagnicola catascopium, Quistadrilus multisetosus, Stylodrilus herngianus, Mooreobdella fervida, Podura aquatica, Dasycorixa hybrida. From these species, Gammarus fasciatus, Pisidium supinum and Quistadrilus multisetosus were dominant, constituting 49%, 43% and 5% of the total benthic fauna respectively. Two predominant species, Gammarus fasciatus and Pisidium supinum, are indicator species that are sensitive to eutrophic conditions, reflecting the oligo-mesotrophic character of the lake. Dissolved oxygen, temperature, TOM and habitat homogeneity seemed to be the main environmental factors affecting the community structure of macroinvertebrate fauna in this lake. At present, in this shallow water body with an average depth of 3 and a maximum of 5 meters, the annual water level fluctuation is around 1 to 2 meters during the period of using water for agricultural purposes. These annually high water level fluctuations would result in an increase in nutrient recycling and nutrient release to the water column, which in turn might affect the trophic status of the lake. Hence, the present situation of the lake, mainly its trophic regime, clearly shows the need for developing a management and monitoring plan. © 2010 WIT Press.