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

Abstract

The effects of ectoparasites on larvae of the clingfish Gobiesox marmoratus were evaluated at the dietary and morphometric levels. The larvae and ectoparasites were collected by nearshore plankton samplings during October, November and December 2013 off El Quisco Bay, central Chile. The standardized abundance of total larvae and those ectoparasitized larvae (PL) was positively related and high parasite prevalence was found throughout the sampling period (up to 38%). Geometric morphometrics analyses indicate main changes in the shape through early ontogeny and subtle but significant variations between PL and non-parasitized larvae (NPL). Prey composition varied between PL and NPL; small size (<6 mm standard length, L ) parasitized larval G. marmoratus ate mostly gastropod larvae, whereas small non-parasitized specimens ate mainly cirripede nauplii. All larger (>8 mm L ), pre-settlement stages parasitized by Trifur and, or Caligus copepods had content in their gut, suggesting that ectoparasites did not diminish prey capture in host with larger size. Morphometric and dietary changes occurring during larval development were decoupled, both for PL and NPL. The maintenance of a slender, more hydrodynamic body through pelagic development and the ingestion of less-mobile prey in PL suggests non-lethal effects of ectoparasitism on rocky-reef fish larvae.

Modelling seasonal patterns of larval fish parasitism in two northern nearshore areas in the Humboldt Current System

“…Studies of copepods parasitizing fish larvae around the world are scarce. However, a few studies have reported parasitic larvae of the family Pennellidae on larval fish belonging to different families 4,5,7 . Our study adds more data to the record of such ectoparasites; this work documented ectoparasitic pennellid larvae (Trifur sp.)…”

“…Parasites in fish larvae could have detrimental impacts on the nutritional and immune response as well as mechanic effects can be caused by parasites via their own body weight 11 . All of these levels could affect the larval growth prior to settlement in fish species 7 . In our study, positive correlations between parasite size and larval fish size were recorded in A. crinitus, G. marmoratus, and Myxodes sp., reflecting that, at least in northern latitudes of the HCS, ectoparasites infest the larval fish species early in the planktonic larval stage, and both grow together until the larval copepod detaches and looks for its next host, suggesting that there are no lethal or detrimental effects on fish larvae survival.…”

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.…”

“…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 ., ).…”

“…Adults have carnivorous habits, mainly preying on amphipods, crustacean decapods, molluscs and fish (Muñoz & Ojeda, ; Pardo‐Gandarillas et al ., ). Similarly, larvae feed on cirriped nauplii and gastropod larvae (Jahnsen‐Guzmán et al ., ). Using larval stages of this crypto‐benthic littoral fish as a species model, we tested the hypothesis that feeding habits of fish larvae will vary during the lunar cycle and that feeding success and selectivity will increase during full moon.…”