engleski

The depth distribution of Oligochaeta (Annelida) assemblages in two barrage lakes

Freshwater oligochaetes have an important rolein aquatic ecosystem and food web functioning, as they are (in general) easily-caught and highly-nutritious prey for predatory invertebrates. They help transform energy resources that are not accessible to many invertebrate consumers, such as dead organicmatter in hypoxic and anoxic habitats, into viable biomass. Lake depth zones are characterized by different environmental factors influencing specific oligochaete assemblages. Profundal and sublittoral assemblages are usually affected by nutrient deposition and oxygen deficiency, while littoral communities are more exposed to hydromorphological pressures. We wanted to test how these oligochaete assemblages differ between zones of different nutrient deposition rates and environmental parameters. Our hypothesis was that most oligochaete species show clear preferences towards these zones which will result in very different assemblages among them. Sampling of the profundal and sublittoral zone was conducted with an Ekman sampler, while the littoral zone was sampled with benthos hand net in two barrage lakes –Brljan and Visovac. Kruskal–Wallis H test was used to determine differences in specific oligochaete species abundances with regard to depth zones. Bray-Curtis similarity and cluster analysis showed how oligochaete assemblages affiliate by depth zones rather than lake-system. Profundal assemblages of different lakes had similarity of 50%, while littoral assemblages had 40% similarity. Stylaria lacustris, Nais variabilisand N. pseudobtusashowed preferences towards littoral zone, Aulodrilus plurisetafor sublittoral zone, while Limnodrilus hoffmeisteriand Potamothrix heuscherishowed preference for profundal zone.

profundal, sublitoral, litoral

nije evidentirano