Abundance and behavioural ecology of the blenny <em>Ophioblennius trinitatis</em> (Teleostei: Blenniidae) at an oceanic archipelago of Brazil (Atlantic)

Abstract

Summary: Local patterns of fish density, microhabitat use, feeding behaviour, bite rate, territory area and agonistic interactions were recorded for Ophioblennius trinitatis at an oceanic archipelago (southwestern Atlantic). Rugosity, number of crevices and benthic diversity positively predicted the distribution of O. trinitatis. Turf algae was the preferred food item at all sites, but given its high availability inside and outside territory boundaries, it did not seem to be a limiting factor on the density of this blenny, as opposed to substrate heterogeneity. Bite rate was higher in the afternoon and for smaller individuals (juveniles). Territory size showed local variation and, although larger territories may be an effect of density-dependent conditions (more available space in low-density areas), we propose that individuals expand territories to compensate for residing in areas of lower quality (i.e. of low structural complexity). Larger individuals defended larger territories and residents responded differently to intruders, with higher rates of agonistic interactions towards potential competitors. Higher agonistic rates were also observed in larger territories and at low-complexity sites.Keywords: behaviour; Blennidae; Brazil; density; territory; microhabitat. La abundancia y la ecología del comportamiento del blenny Ophioblennius trinitatis (Teleostei: Blenniidae) en un archipiélago oceánico de Brasil (Atlántico) Resumen: En este trabajo se han estudiado las pautas en la densidad, la utilización del micro hábitat, el comportamiento alimentario, las tasas de mordisqueo, la superficie del territorio y las interacciones agonísticas de Ophioblennius trinitatis en un archipiélago oceánico del SO Atlántico. Los mejores predictores de la distribución de O. trinitatis fueron la rugosidad, el número de grietas y la diversidad bentónica. El turf algal es el alimento preferido de este pez en todos los lugares, pero dada su elevada disponibilidad, dentro y fuera de los territorios, no pareció ser un factor limitante para este blénido como lo fue la heterogeneidad del substrato. La tasa de mordisqueo resultó ser más elevada entre los peces pequeños (juveniles) y especialmente por la tarde. La superficie del territorio presentó notables variaciones locales y, a pesar de que los territorios mayores pueden ser el resultado de un efecto denso-dependiente (al haber más espacio disponible en la zonas con densidades bajas), proponemos que los individuos expanden su territorio para compensar la baja calidad ambiental de ciertas zonas (una baja complejidad estructural). Los ejemplares mayores defendían territorios más extensos y respondían de manera diferente ante los intrusos, con una mayor tasa de interacciones agonísticas hacia los potenciales intrusos. Las interacciones agonísticas también fueron más elevadas en los territorios más amplios y con una baja complejidad.Palabras clave: comportamiento; Blennidae; densidad; territorio; micro hábitat.

Predicting the effects of body size, temperature and diet on animal feeding rates

“…The genus is distributed across all tropical and subtropical Atlantic marine provinces, and each of the five species is endemic to a single province, with the exception of one species found in both southwestern Atlantic (SWA) and the Gulf of Guinea (Lastrucci et al., 2018). Species in this genus are an ideal model to study feeding activity because they inhabit shallow reefs, are easy to observe and follow continuously, and are distributed along a range of environmental temperatures and reef types (Medeiros et al., 2014; Nursall, 1977).…”

“…Species in this genus are an ideal model to study feeding activity because they inhabit shallow reefs, are easy to observe and follow continuously, and are distributed along a range of environmental temperatures and reef types (Medeiros et al, 2014;Nursall, 1977).…”

“…Algae, plastic and other materials were less important, and possibly reflected accidental ingestion. Detritus is a common component found in the algal matrix, which is the main substratum in most rocky and coral reefs (Aued et al, 2018;Wilson et al, 2003) and is the preferential foraging ground of Ophioblennius (Medeiros et al, 2014).…”

“…By virtue of being an energy‐intake rate, bite rates are expected to scale with individual body mass (Barneche et al., 2009; Medeiros et al., 2014). For example, studies focusing on terrestrial mammals (Pelletier & Festa‐Bianchet, 2004), marine iguanas (Wikelski & Carbone, 2004) and reef fishes (Barneche et al., 2009; Floeter et al., 2005; Medeiros et al., 2014) suggested that bite rates scale negatively with increasing body size.…”

“…By virtue of being an energy‐intake rate, bite rates are expected to scale with individual body mass (Barneche et al., 2009; Medeiros et al., 2014). For example, studies focusing on terrestrial mammals (Pelletier & Festa‐Bianchet, 2004), marine iguanas (Wikelski & Carbone, 2004) and reef fishes (Barneche et al., 2009; Floeter et al., 2005; Medeiros et al., 2014) suggested that bite rates scale negatively with increasing body size. These are at odds with the size scaling of consumption rates, which are positive and can be either hypo‐ or hyper‐allometric depending on the dimensions of the preying environment (Pawar et al., 2012).…”