Benthic diatoms species richness had been analyzed based on materials collected in 1996–2009 at 8 near shore locations of SW Crimea. Totally 93 stations were sampled on sandy-muddy substrate within depth range 6–48 m. At total, 433 diatom species were found by results of cell calculations in Goryaev chamber and microscoping of permanent slides. Prognostic estimation of the expected diatom species richness (S_exp) was performed by application of 4 estimators (Jack-knife-1 & 2, Chao-2 and Karakassis-S_∞). The statistical assessment of the estimators’ results accuracy and evaluation of optimal ratio between minimal sampling efforts and maximal information about diatom species richness at the certain sampling location were conducted. The estimation accuracy of the S_exp is increased proportionally to sampling efforts. Magnitude of S_exp, resulted by estimator S_∞, displayed the most similar values to the really observed species number (S_obs). Overestimation of S_obs values (not more than 10–13%) was found under consideration of 12–15 samples or less, and slightly underestimation (3–5%) when number of samples exceeds 40–43. The other estimators gave large overestimated results of the expected species richness (Chao – from 21 to 70% higher than S_obs, Jack-knife – 23–58%), calculated by randomization for increasing row of all samples. Based on relative error (RE) and squared relative deviation (SRD) the estimators’ accuracy depending on biotopes peculiarities and sampling efforts was evaluated. It was shown, all estimators give overestimated results of the S_exp (1.3 to 1.8 times) under consideration of few samples (4–6). Under extension of station number up to 15–20, Chao and Jack-knife estimators give decreasing of the RE and SRD values. Estimator S_∞ quite precisely evaluates parameter S_exp after the first 7-8 permutated samples. The parameters of generalized log-dependence between number of samples (1 to 93) and ratio (%) of species richness, totally registered in near shore water areas of SW Crimea (433 spp.) were determined. Detection of about 50% of all species registered in SW Crimea on sandy/muddy substrates within 5-45 m depth range is required consideration of not less than 10 randomized stations. Similarly, revelation of 67% of total species richness is necessary to study not less than 20 stations, and 80% ones – about 40 stations (on assumption the equal probability of any species presence in samples). Application of this dependence can be recommended for prognostic evaluation of percent share of diatom species richness in relation to different sampling efforts under exploring of ecologically similar and earlier not studied coastal areas of the Black Sea.

Keywords: benthic diatoms, species richness, estimators, species-accumulation curves, Black Sea

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