. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 396 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 7. Mean and ranges of maximum and minimum depth distribution of the most abundant species and barren sites. UDL = upper depth hmit, LDL = lower depth hmit. The mean values are calculated on the number of sample sites; thus they represent weighted centres of distribution and not average positions between upper and lower limits. I-IV on the upper border demarcate species grouped between gradient changes in the curve of mean values. taxa within various latitu
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 396 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 7. Mean and ranges of maximum and minimum depth distribution of the most abundant species and barren sites. UDL = upper depth hmit, LDL = lower depth hmit. The mean values are calculated on the number of sample sites; thus they represent weighted centres of distribution and not average positions between upper and lower limits. I-IV on the upper border demarcate species grouped between gradient changes in the curve of mean values. taxa within various latitudinal sectors. A more comprehensive analysis has been carried out, and is summarized in Figures 8 and 9. These represent projections of abundance values (as smoothed percentages of the total fauna) on to across-shelf (depth), and along- shelf (latitudinal) axes, respectively. A plan of the distribution of dominant taxa (> 20% total fauna) on the shelf and slope (Fig. 10) was constructed using Figures 8 and 9, and additional depth/abundance profiles computed at intervals of 5° latitude. A simple calcu- lation of regional dominance gives the following abundances in order of rank: areas north of 24°S — Palmoconcha walvisbaiensis = 32 per cent, Cytherella namibensis = 21 per cent; south of 24°S — Pseudokeijella lepralioides = 36 per cent, Ruggieria cytheropter- oides = 22 per cent, Bensonia knysnaensis knysnaensis = 6 per cent; in water > 500 m — Henryhowella melobesioides = 43 per cent. The inner-outer-shelf region (0-300 m) is dominated by three species (Fig. 10). North of 23°S, Palmoconcha walvisbaiensis occurs on its own but, south of 25°S, is replaced, respectively, by Bensonia k. knysnaensis on the inner shelf and Pseudokeijella. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original South Africa
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
