Composition, Abundance and Diversity Indices of Zooplankton in Lake Alau, Borno State Nigeria

The occurrence and abundance of zooplankton in lake Alau were documented during the rainy and dry seasons (July, 2012 to April, 2013) in station A, B, C, D and E respectively. The sampling was done in the morning before 8:00am on monthly basis. Pour-through method was used to collect the samples and analysed. A total of ten species belonging to four families were identified. The research reveals that seasonal population abundance and species composition of zooplankton envisaged Brachionidae (59.52%) as the dominant specie, followed by Asplanchidae (22.22%) Cladocera (10.76%) and Copepoda (7.50%). Throughout the study period, five species of rotifers, three species of Cladocera and two species of Copepoda were identified. Not all of the identified species were found in all the five stations, thus indicating that depth play a vital role in their vertical migration. Shannon-Weiner index showed that station A (2.021) and B (2.016) have high species diversity index compared to station C, D, and E (1.888, 1.894 and 1.875) respectively. Equitability index revealed that all the stations were within 0.908 to 0.963 ranged. Simpson’s index shows that station C (0.170) has the highest diversity index while station A and B had the same value of 0.151 as the least. Lake Alau is fairly rich in terms of zooplankton population and abundance. The presence of typical zooplankton species, notwithstanding other limnological features strongly suggests that the water body is maintaining an Oligo-mesotrophic status. More intensive study of the zooplankton species in West African arid region lakes will lead to the documentation of other species and wider distribution of many others than those that were recorded in the current study. This will lead to