Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 27: 1687 -1696. Published March 8, 2010.
Microhabitat preference, diversity and ecology of aquatic mites in a municipal stream in the Niger Delta
Francis O. Arimoro
*Department of Animal and Environmental Biology, Delta State University, P.M.B. 1, Abraka, Nigeria.
Correspondence e-mail : fransarimoro@yahoo.com
ABSTRACT
Objective: Information on water mite assemblages from afrotropical streams is scanty. This study investigates aspects of the ecology of the aquatic mites of the Orogodo River, Niger Delta, Nigeria.
Methodology and results: The study was carried out between January and June 2006. Water samples and aquatic mites were collected from four different microhabitats in Orogodo River, analyzed and studied. The water at the site of sampling was slightly acidic at pH 5.8 - 7.4, water temperature ranged from 24.6 to 33.7oC, dissolved oxygen 6.6 - 8.4mg/l and Biochemical Oxygen demand (BOD) 1.9 - 4.0mg/l. These parameters fluctuated within the normal range suitable for habitation of macroinvertebrates intolerant to organic pollution. A survey of different microhabitats in the stream revealed that water mites were widely distributed but relatively less abundant. A total of 386 mites belonging to five species in five families were recorded. Arrenurus damkoehleri and Piona africana were the dominant mites with the latter being the most ubiquitous species recovered from all microhabitats studied. Encentridophorus was the least abundant, recovered only from litter in riffle. Based on the ecological requirements, the mites fell into three groups namely, helocrene, rheocrenes and limnocrene. The number and diversity of mites were found to be more abundant in the macrophytes and riffle microhabitats compared to other microhabitats as indicated by the rather high Simpson dominance (0.755) recorded for the pool. Typical standing water dwellers represented only a small fraction of the species sampled. A principal component analysis clearly grouped the various mite species with the microhabitat having the greatest influence on their distribution.
Conclusion and application of findings: This study has elucidated the general paucity of aquatic mites in afrotropical streams with only five species recorded. Water mites were more common in macrophytes, possibly as a result of their association with plants for shelter and food. From an earlier investigation in this river, aquatic mites were only recorded from the present site of sampling as opposed to other stations of the river affected by organic pollution indicating that this group of organisms could be incorporated as indicator organisms for biomonitoring programmes especially in the afrotropical region.
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