TRENDS IN AQUATIC ECOLOGY Biodiversity analyses: are aquatic ecologists doing any better and differently than terrestrial ecologists? Tadeu Siqueira • Luis Mauricio Bini • Sidinei Magela Thomaz • Diego Fontaneto Received: 22 July 2014 / Revised: 30 September 2014 / Accepted: 4 October 2014 Ó Springer International Publishing Switzerland 2014 Abstract Species richness is a key variable in biodiversity analyses, being often analyzed as either a response or an explanatory variable. We addressed whether biodiversity studies conducted in aquatic habitats (including both freshwater and marine habi- tats) differed substantially from those conducted in terrestrial habitats. Using a systematic literature search, we show that aquatic and terrestrial ecologists use species richness predominantly as a response variable. However, the number of studies in terrestrial systems was greater than the number of studies in aquatic habitats. The amount of variance in species richness explained by the statistical models was similar—around 59%. The frequency of citation was also similar between terrestrial and aquatic studies. The sample sizes of studies conducted in aquatic habitats were significantly lower than those of studies conducted in terrestrial habitats. Both aquatic and terrestrial ecologists tend to use a large number of explanatory variables to model species richness. We conclude that the differences between the ways aquatic and terrestrial ecologists conduct biodiversity studies were not substantial; their impacts on the scientific community were similar; and there is a need to increase the focus on theory-driven analyses. We recommend that research efforts on the mechanisms underlying species richness variation in aquatic sys- tems should be intensified. Keywords Coefficient of determination Á Cross- ecosystem analysis Á Bibliometrics Á Species richness Introduction It has been clear for many years that biodiversity can and should be studied considering different levels of the biological hierarchy (from genes to ecosystems; Noss, 1990). Among these levels, species richness (usually defined as the number of species of a specific taxonomic group in a specific area) is a key variable in Guest editor: Koen Martens / Emerging Trends in Aquatic Ecology T. Siqueira Departamento de Ecologia, Instituto de Biocie ˆncias, UNESP - Universidade Estadual Paulista, Rio Claro, Brazil e-mail: tsiqueira@rc.unesp.br L. M. Bini Laborato ´rio de Ecologia Teo ´rica e Sı ´ntese, Universidade Federal de Goia ´s, Campus Samambaia, Goia ˆnia, GO CEP 74001-970, Brazil S. M. Thomaz Nupelia, Universidade Estadual de Maringa ´, PEA-UEM, Av. Colombo, 5790, Maringa ´, PR CEP 87020-900, Brazil D. Fontaneto (&) CNR Institute of Ecosystem Study (ISE), Largo Tonolli 50, 28922 Verbania, Pallanza, Italy e-mail: d.fontaneto@ise.cnr.it 123 Hydrobiologia DOI 10.1007/s10750-014-2071-6