How well do single samples reflect rotifer species diversity? A test based on interannual variation of rotifer communities in Big Bend National Park (Texas, USA)

Abstract

Studies of rotifer community composition and dynamics often rely on limited sampling regimes.To determine how well species richness is reflected in these studies, we examined interannual variation of rotifer species richness and monogonont community structure from 10 aquatic systems comprising four habitat types-springs, rock pools (tinajas), former cattle tanks, and artificial ponds-in Big Bend National Park (Texas, USA). Planktonic, littoral, and benthic samples were collected from all sites at about the same date for each of five summers (2001)(2002)(2003)(2004)(2005). Our survey yielded 15 monogonont families including 30 genera and 84 species. Two bdelloid taxa also were designated. Species richness varied widely among these four habitats: range, 1-32; mean (±1 SD), 11.2 ± 8.0. Total Species richness in the habitats also varied considerably: springs (54 taxa) > artificial ponds (35 taxa) > tinajas (19 taxa) > cattle tanks (15 taxa). Sessile species comprised &13% of the taxa in our samples. Species turnover indices (STI) of these systems indicate low overall relatedness: mean (±1 S.D.) = 85.2 ± 7.1%. The relative frequency of encounter of most taxa in the four systems was low, with 79 taxa (&92%) having values 2.0%. Singleton rates were quite high, ranging from 46.7 to 71.4%, with an overall mean &65.1%. Most importantly, we found that both species richness and STI varied considerably among habitat type. Species richness varied by 2-10· between consecutive years and STI ranged from 64 to 89% over the entire study. Our results indicate that rotifer community composition fluctuates greatly over time, and that rotifer community structure may be more labile than is generally believed. Species richness and thus biodiversity may be dramatically underestimated using single sampling or short-term strategies that are often employed in studies of zooplankton community structure.Keywords Biodiversity Á Chihuahuan Desert Á Index of faunal originality Á Invertebrate Á Relative frequency of encounter Á Singleton rate Á Species turnover index Á Sørensen index

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“…Such a reorganised phenomenon at regional level may hint towards a Complex Adaptive System within the metacommunity (Figure 1). Walsh et al (2007) found surprisingly high species richness in the arid ephemeral pond systems which fits our finding about Site 2 exhibiting substantial zooplankton richness, although being temporary in nature. Wallace (2002) opined that rotiferan species abundance can differ markedly and unfortunately, even short term sampling schedules can miss the details of population peaks.…”

“…Values of "j" were mostly high for pairwise combinations of the sub-sites belonging to the Site 1 during monsoon and pre-monsoon in contrast to those during post-monsoon. Walsh et al (2007) (Jurine, 1820) MnB composition of G-II showed maximum similarity with G-PB during monsoon (C N = 0.582) due to overflow, in contrast to post monsoon, when connectivity was disrupted. This suggests that simple connectivity may render similar species assimilations for nearest subsites only and is not sufficient to homogenise the composition of entire water body.…”

“…However, there were some species which did not exhibit any such preference, inferring that the rest were common to the region. It may be true that the existence of a rotifer in any particular place is not determined by the processes of dispersal, colonization, and establishment, but rather that the habitat selects which organisms thrive (Walsh et al, 2007). Contrarily, some species are known to have high habitat selectivity (Kaya et al 2010).…”

Temperature and salinity as interacting drivers of species richness of planktonic rotifers in Turkish continental waters

“…Species composition is highly affected by sampling site for continental zooplankton (Shaw & Kelso 1992;Walsh et al 2007). Samples within the same water body generally tend to be more similar to each other than samples between water bodies.…”

Consistent, long-term change in rotifer community composition across four Polish lakes

“…These metrics have also been used extensively in freshwater systems (Dumont & Segers, 1996;Arnott et al, 1998;Muirhead et al, 2006;Walsh et al, 2007;Kuczyńska-Kippen, 2007). However, few studies have explored biodiversity variation at different temporal and spatial scales (but see Arnott et al, 1998).…”