Biodiversity assessment: selecting sampling techniques to access anuran diversity in grassland ecosystems

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.

The Program for Biodiversity Research in Brazil: The role of regional networks for biodiversity knowledge, dissemination, and conservation

“…Researchers have also undertaken studies of environmental impacts of extensive infrastructure programs (Bobrowiec & Tavares 2017), fire ecology (e.g. Fadini & Lima 2012), island biogeography and metapopulation dynamics (Carvalho et al 2008, Cintra et al 2013, methods in ecology (Norris et al 2014, Madalozzo et al 2017, Fontana et al 2018, population ecology (Brigatti et al 2016, Ferreira et al 2016, population genetics and phylogeography (Collevatti et al 2014, Melo et al 2016, Vitorino et al 2016 PPBio has produced several books about the ecology of Brazilian ecosystems and identification guides for specific groups of funga, fauna, and flora (e.g. Costa et al 2011, Baccaro et al 2015, Iop et al 2016, Peixoto et al 2016.…”

The advertisement calls of Brazilian anurans: Historical review, current knowledge and future directions

“…The development of acoustic methodologies for biodiversity appraisal has been substantial in the last years [ 25 , 93 ]. The use of automatic sound recorders for acoustic monitoring terrestrial and aquatic environments is a relatively recent technique and has been applied on a large scale in many recent studies [ 94 ].…”

“…Besides being an efficient and non-invasive technique, passive acoustic monitoring enables simultaneous sampling at several scales in time and space, with reduced observer biases and animal disturbances [ 64 ]. Although there are methods to circumvent the need of knowledge about all species occurring in habitats with high diversity [ 79 , 80 ], information about the species-specific calls provides a more powerful and cost effective tool for the study of communities [ 25 ], and for monitoring of populations over the years in the light of global change [ 24 , 95 ] or other major evolutionary trends such as effects of introduced species [ 96 ]. Due to the relevance of bioacoustics in anuran species delimitation, the deposit of recorded calls in sound libraries may also facilitate the taxonomic studies [ 16 , 28 ].…”

“…Thereby, bioacoustic information has been particularly relevant in studies of behaviour [ 17 ], ecology [ 20 ], evolution [ 21 , 22 ], conservation [ 23 ], thermal biology in light of climate change [ 24 ], biodiversity inventory (passive acoustic monitoring; [ 25 ]), and is becoming a suitable tool for studies on taxonomy (integrative taxonomy; see [ 14 , 26 ]). Since call is a particularly powerful premating isolation mechanism, it has been used as an undisputed means for species delimitation [ 14 ].…”

Annual and daily patterns of calling activity in male Scinax fuscomarginatus (Anura: Hylidae) from Central Brazil

“…The automated recording of acoustic signals (or Automated Digital Recording, ADR) has become increasingly popular in recent years for the surveying of anurans (Dorcas et al 2009, Sugai et al 2018. Although this technique does not allow the researcher to detect some important aspects of anuran reproduction (e.g., the presence of non-calling females and egg masses), it can provide valuable information on the presence of a particular species and detect interspecific variability in occurrence patterns (Bridges andDorcas 2000, Schalk andSaenz 2016), as well as reducing considerably sampling effort in the field (Hsu et al 2005, Madalozzo et al 2017. The principal advantage of this technique is that it permits the collection of data continuously over prolonged periods, that is, a number of consecutive days, as well as the possibility of implementing automatic species identification procedures (Acevedo and Villanueva-Rivera 2006).…”