ZOOPLANKTON AND ESTUARINE RELICT (BENTHIC) FAUNA IN LAKE MZINGAZI, A FRESHWATER COASTAL LAKE OF NATAL

SUMMARY

Lake Mzingazi, a natural, undisturbed freshwater coastal lake in the heart of the Richards Bay municipal area, is threatened by rapid urban and industrial growth. The previously unrecorded composition and distribution of zooplankton in the lake was studied during 1979 as part of an overall limnological investigation of this important water resource. Both the zooplankton and the water chemistry showed that the lake was not an enriched system. Throughout the lake the zooplankton was dominated by the Copepoda. The presence of relict estuarine crustaceans such as Grandidierella ligno-rum, Gastvosaccus brevifissura,? Lanocira gardineri and Apseudes digitalis suggests some historical link with the marine environment. The unique character of the lake was manifested in the paucity of Cladocera and the abundance of submerged and emergent aquatic plants in the system. Anomalies in the structure of the zooplankton community emphasized the unusual ecology of this lake.

KEYWORDS:

• Lake Mzingazi
• freshwater coastal lake
• zooplankton
• phytoplankton
• relict estuarine fauna
• aquatic macrophytes
• nutrients