Evaluating detectability of freshwater fish assemblages in tropical streams: is hand-seining sufficient?

A. Deacon, Rajindra Mahabir, Devan Inderlall, Indar W. Ramnarine, Anne E. Magurran

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Unprecedented threats to natural ecosystems mean that accurate quantification of biodiversity is a priority, particularly in the tropics which are underrepresented in monitoring schemes. Data from a freshwater fish assemblage in Trinidad were used to evaluate the effectiveness of hand-seining as a survey method in tropical streams. We uncovered large differences in species detectability when hand-seining was used alone, in comparison with when hand-seining and electrofishing were used together. The addition of electrofishing increased the number of individuals caught threefold, and increased the biomass fivefold. Some species were never detected using hand-seining, resulting in significant underestimates of species richness; rarefaction curves suggest that even when hand-seining effort increases, species richness is still underestimated. Diversity indices (Shannon and Simpson index) reveal that diversity was also significantly lower for hand-seined samples. Furthermore, the results of multivariate analyses investigating assemblage structure also differed significantly depending on whether they were based on hand-seined data alone, or a combination of hand-seining and electrofishing. Despite the extra equipment and maintenance required, these findings underline the value of including electrofishing when sampling tropical freshwater streams.
Original languageEnglish
Pages (from-to)839-849
Number of pages11
JournalEnvironmental Biology of Fishes
Volume100
Issue number7
Early online date1 Jun 2017
DOIs
Publication statusPublished - Jul 2017

Keywords

  • Trinidad
  • Electrofishing
  • Alpha diversity
  • Detectability
  • Species richness
  • Sampling methods
  • Gear bias

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