Feeding variations and shape changes of a temperate reef clingfish during its early ontogeny

Abstract

The majority of rocky reef fishes have complex life cycles, involving transition from a pelagic to a benthic environment. This means that as they grow, their morphology, behaviour and feeding habits must change. Therefore, shape changes occurring during early development of these fishes will be related to diet changes. The clingfish Sicyases sanguineus was selected for this study, because it displays a noticeable variation in shape from pelagic larvae to juvenile stage, and it is expected that diet composition will change as well. The pattern of shape changes was studied using geometric morphometrics. A set of 9 landmarks were digitized in 159 larval and juvenile fish and the same specimens were used for gut content analysis. Allometric growth was most prominent early in the ontogeny, from 4 to 12 mm. Morphology changed from a thin and hydrodynamic shape to a more robust and deeper body prior to settlement. The diet of the clingfish during larval stages showed preferences for a variety of copepod stages. As individual grows the ingested prey volume increases, but not the number and width of prey. A partial least square analysis showed low covariance between shape changes and diet composition changes in prey number and volume, suggesting that the two processes were temporally decoupled. The biggest shape changes, a lengthening of the visceral cavity and a flattening of the head, occurred up to 12 mm standard length, while the largest feeding differentiation, shifting from copepods to microalgae, occurred after 16 mm. Results suggest that shape changes precede trophic changes in this clingfish species during the transition from a pelagic to a benthic habitat.

Lunar influences in the diet habits and selectivity of larval clingfish Gobiesox marmoratus

“…It is important to notice the difference in the diet of larval G. marmoratus with the sympatric clingfish Sicyases sanguineus Müller & Troschel 1843, even when both species have similar body shape prior to 7 mm L N (Bernal‐Durán et al ., ). While small larval G. marmoratus ingest larval gastropods, invertebrate eggs (this study) and cirriped nauplii (Jahnsen‐Guzmán et al ., ), larvae of S. sanguineus ate mostly copepod nauplii and eggs (Bernal‐Durán & Landaeta, ). This suggests resource partitioning between both sympatric species during their pelagic stages.…”

“…Larvae were not corrected for shrinkage. Only preflexion larvae were selected to avoid or reduce confounding effects of the ontogenetic variability in the diet described in other clingfish species during larval development (Bernal‐Durán & Landaeta, ). Larvae with ectoparasites were not considered in this study because they may affect larval diet (Jahnsen‐Guzmán et al ., ).…”

Parasitic copepods affect morphospace and diet of larvae of a temperate reef fish

“…), using TpsDig 2·17 (http://life.bio.sunysb.edu/morph). This landmark configuration explains well the changes in morphospace of fish larvae (Ponton et al ., ; Zavala‐Muñoz et al ., ) and particularly G. marmoratus larvae (Bernal‐Durán & Landaeta, ; Bernal‐Durán et al ., ). Shape information was extracted from the landmark coordinates with a generalized Procrustes analysis (Dryden & Mardia, ), using MorphoJ 1·05f (Klingenberg, ; http://www.flywings.org.uk/morphoj_page.htm).…”

Sharing morphospaces: early ontogenetic shape changes in two clingfish larvae (Pisces: Gobiesocidae) from the south‐east Pacific Ocean

“…This study did not examine subadult or adult specimens and these could have potentially influenced the results. Bernal‐Durán & Landaeta () found that allometric growth occurred early in the ontogeny of S. sanguineus (between 4 and 12 mm L S ). Above this size, there was little change in body shape.…”

“…Gobiesox marmoratus inhabits boulder fields, is carnivorous (Muñoz & Ojeda, ; Pardo‐Gandarillas et al ., ), has a hatching size of 2·6 mm and a growth rate of 0·24 mm day −1 (Contreras et al ., ) and reaches a maximum length of 16 cm. Sicyases sanguineus inhabits the upper intertidal zone; is omnivorous (Paine & Palmer, ; Muñoz & Ojeda, ; Bernal‐Durán & Landaeta, ); has a hatching size larger than 3 mm and a growth rate of 0·14 mm day −1 (Contreras et al ., ); and reaches a maximum length of 30 cm, which is exceptionally large for members of this family (Briggs, ). The third species, T. chilensis , is distributed in northern Chile and has an herbivorous diet (Berrios & Vargas, ); no information about larvae of this species is available in the literature.…”