Density and diversity of the desert Arthropoda of Qatar

Abstract

Density and diversity of arthropods were studied at different habitats of the Qatari desert. Diurnal sampling was conducted at two seasons of the year, the end of the dry season, at the beginning of autumn (October) in 1995-1996, and in spring (April) in 1996-1997. The habitats selected included land-depressions (roda), sand dunes (nijyan) and salt mud flats (sabkha). Variations in macroclimate were apparent in the records of air temperature, relative humidity, soil surface temperature and wind speed. Soil characteristics (texture, moisture content, organic content and salt content) were found to affect plant biomass and consequently the occurrence and distribution of the arhropods. Arthropods represented the major animal taxon in all the localities studied, and members of the class Insecta were dominant both in density and in diversity. Insect diversity was highest in the sand-dune locality while a higher density was recorded in land depressions. Salt-mud flats sustained the lowest density and diversity. Soil arthropod fauna was richer in land depression samples collected from Rodat Um Alamad in April 1996. Temporary rain pools in Rodat Alkaraana investigated in April 1996, supported a variety of aquatic arthropod species. This indicates that the Qatari desert, though comparatively small, embodies distinct localised habitats. These support diverse assemblages of arhropods which constitute the bulk of the animal biomass. The role played by arthropods in the structure and functions of the desert is most probably considerable in the overall balance of this delicate ecosystem.