Biodiversity assessment: selecting sampling techniques to access anuran diversity in grassland ecosystems
B. Madalozzo A C , T. G. Santos B , M. B. Santos A , C. Both A and S. Cechin A
+ Author Affiliations
- Author Affiliations
A Programa de Pós-Graduação em Biodiversidade Animal, Departamento de Ecologia e Evolução, Universidade Federal de Santa Maria, Av. Roraima n° 1000, Camobi, RS 97105-900, Santa Maria, Rio Grande do Sul, Brazil.
B Universidade Federal do Pampa, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
C Corresponding author. Email: bmadal@gmail.com
Wildlife Research 44(1) 78-91 https://doi.org/10.1071/WR16086
Submitted: 16 May 2016 Accepted: 20 January 2017 Published: 3 March 2017
Abstract
Context: Species richness is a relevant diversity component of community ecology and many standardised techniques are available for data estimations. However, each technique is appropriate to a few environment types and has its own sampling biases. Thus, it is necessary to test the effectiveness of traditional and heterodox sampling techniques in different habitat types, especially for highly diverse taxonomic groups, such as anurans.
Aims: We present a comparison based on species richness and detection between the following techniques: acoustic survey with visual encounter of adults (ASVE), automated digital recorders (ADR) and dip net survey of larvae (DSL). We sought to determine: (1) the most efficient sampling technique to survey species richness in ponds of grasslands habitats; and (2) whether efficiency is related to the particular life history traits of species.
Methods: During 2014 and 2015, we sampled 47 ponds distributed in vulnerable Brazilian grassland areas using ASVE, ADR and DSL. Anuran species were surveyed across two seasons that coincide with the peak of anuran breeding activity in the region.
Key results: Species richness recorded by ADR and ASVE was higher when compared with DSL. In terms of combined utilisation, ADR with DSL was as efficient as using all techniques together. However, species detection differed among sampling techniques. ADR had the higher percentage of species that were sampled exclusively in at least one breeding pond and DSL detected two species that were not detected by the other techniques.
Conclusions: Our findings suggest that ADR includes most species whose males call for only a few hours during the night or day, and DSL exclusively detects ‘explosive breeders’, incorporating a wide range of life history traits. ASVE becomes unnecessary since it does not include specific variations of species’ calling behaviour. It is susceptible to a discrepancy of survey data among observers and potentially causes a human disturbance effect in the estimated data.
Implications: We strongly recommended the use of ADR rather than ASVE, and we recommended DSL as a supplementary technique for population monitoring and surveys in grassland areas. We encourage researchers to include ADR and DSL in future works to survey biologic data outside of the short sampling event for which ASVE is commonly utilised, thereby improving the interpretation of biological patterns.
Additional keywords: amphibians, automated recorders, breeding ponds, calling males, survey methods, tadpoles.
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