MEPS 367:283-293 (2008)  -  doi:10.3354/meps07511

Nested sampling: an improved visual-census technique for studying reef fish assemblages

Carolina V. Minte-Vera1, Rodrigo Leão de Moura2,3,*, Ronaldo B. Francini-Filho2,3

1NUPELIA - Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura, Universidade Estadual de Maringá, Av. Colombo 5790, Bloco H-90, 87020-900 Maringá PR, Brazil
2Programa Marinho, Conservation International Brasil, Rua das Palmeiras, 451 Centro, 45900-000 Caravelas BA, Brazil
3Grupo de Pesquisas em Recifes de Corais e Mudanças Globais, Universidade Federal da Bahia, Rua Caetano Moura 123,
40210-340 Salvador BA, Brazil
*Corresponding author. Email:

ABSTRACT: Our aim was to devise visual sampling protocols to estimate densities in a morphologically and behaviorally diverse assemblage of reef fishes. The focus was on a design that is cost-effective and produces relatively accurate and precise density estimates for the largest number of species. We evaluated the 2 most widely used shapes of sampling units (strip transects and stationary cylinders) of several dimensions on a fringing reef at Fernando de Noronha Archipelago, tropical West Atlantic. Small sampling units produced the best density estimates for small fishes, while large ones produced the best estimates for large fishes, regardless of sampling unit shape. The sampling unit with the lowest cost was the stationary cylinder. We further compared accuracy and precision of density and richness estimates from several combinations of stationary cylinders and fish size. A simple improvement in stationary censuses, i.e. a sampling unit composed of 2 nested cylinders (2 m and 4 m radii, respectively), enhanced the accuracy and precision of estimates. Counts of small fish (≤10 cm) were made in the smaller cylinder and counts of larger fish (>10 cm) were made in the larger. Such nested cylinders reduce the bias towards large and conspicuous species and allow for separate density estimates for adults and juveniles of large species.


KEY WORDS: Visual census · Sampling · Reef fishes · Biodiversity · Community structure


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Cite this article as: Minte-Vera CV, de Moura RL, Francini-Filho RB (2008) Nested sampling: an improved visual-census technique for studying reef fish assemblages. Mar Ecol Prog Ser 367:283-293

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