Sampling efforts necessary to achieve regional fish diversity inventory
Not only the OTU accumulation curves and their asymptotes provide diversity estimates, they also provide crucial insights into the sampling effort needed to achieve a more complete census. Here, using the asymptote on the OTU accumulation curve for all fish species (Fig. 4a), we found that our 92 cumulated samples (representing 0.2 m3) achieved up to 63.5% of the potential fish OTU diversity in the Bird’s Head Peninsula (Fig. 6). To collect 90% of this regional fish diversity, we should have filtered seawater in 735 samples so 8 times the effort of our sampling campaign, representing an aggregated sampled water volume of 1.5 m3. This sampling effort would reach 1,883 samples (an aggregated water volume of 3.8 m3) to collect 95% of the regional fish OTU richness (Fig. 6).
On average across fish families, our sampling effort achieved the detection of 77.1% (± 14.9 SD) of OTUs predicted by the asymptote of the accumulation curve with a variation among families ranging from 42.2% (Muraenidae) and 47.5% (Gobiidae) to 93.9% (Balistidae) (Fig. 6). The sampling effort needed to achieve 90% of the asymptotic number of OTUs in the region varied greatly among families, ranging from 37 samples for Chaetodontidae to 494 samples for Gobiidae, with a mean of 164 samples (± 123 SD). The estimated additional sampling effort to reach 95% from 90% of the OTU richness ranged from 20 more samples (Tetraodontidae) to 593 more samples (Gobiidae).