Feeding patterns in eastern tropical Pacific blennioid fishes (Teleostei: Tripterygiidae, Labrisomidae, Chaenopsidae, Blenniidae)

Abstract

In terms of species number (47) and numerical abundance, blennioids are the most important primary resident rocky reef fishes in the Gulf of California, Mexico. We present the feeding patterns of the 34 most abundant species of blennioid fishes, 8 of which are Gulf endemics. A total of 2,144 specimens were sampled at 51 anaesthetic stations in 9 areas throughout the Gulf. Four feeding guilds were distinguished: 1) The majority (29 of 34 species) are microcarnivores exhibiting a number of different feeding strategies (ambush and stalking predators, active foragers, pickers, etc.). The more important prey categories were mobile invertebrates, and to some extent also sedentary fauna. Algae were of no importance for most of the latter species. 2) Hypsoblennius brevipinnis and H. gentilis are two omnivorous species, browsing mainly on sessile items including 52% and 13% (Vol.) algae in their diets. 3) Entomacrodus chiostictus and Ophioblennius steindachneri are herbivores, grazing on fine algae. 4) Plagiotremus azaleus specializes in cropping mucus and scales from the body surface of other fishes.Crustaceans account for 58.6% of the total volume of prey items in the 34 species investigated. Benthic amphipods were most important and made up 26% of the total volume of all prey items.Cluster analysis of percentage volumetric data using Squared Euclidian Distance and Horn's Index of Overlap produced distinct subgroups which coarsely reflected taxonomic grouping.The species are separated either by their geographic ranges, habitat and microhabitat preferences, feeding, or a combination thereof. Only rarely do sympatric species significantly overlap in diet.Trophic diversity as measured by the Shannon-index provides a tool for distinguishing: 1) specialists (6 species) from 2) low diversity feeders (18 species) and 3) high diversity generalists (10 species). Two different types of specialists can be distinguished: those which feed on the same items as the generalists but utilize only a very restricted prey spectrum (Stathmonotus sinuscalifornici and the chaenopsids Chaenopsis alepidota and Emblemaria hypacanthus). A second group of specialists (Entomacrodus chiostictus and Ophioblennius steindachneri as well as Plagiotremus azaleus) feed on items not utilized by any of the generalists.There is some evidence that high diversity generalists are numerically more abundant than the other trophic groups.In the labrisomids and blenniids a phylogenetic trend from microcarnivory towards feeding on sessile items appears to be expressed.

Dieta e comportamento alimentar de Malacoctenus delalandii (Perciformes: Labrisomidae)

“…Também para uma espécie da família Labrisomidae, endêmica das ilhas Galápagos, Dialommus fuscus, Nieder (2001) confirmou o hábito carnívoro e encontrou principalmente decápodes e copépodes, além de anfípodes, isópodes e poliquetas no conteúdo estomacal. Kotrschal & Thomson (1986), analisando o conteúdo estomacal de cinco espécies do gênero Malacoctenus encontrou anfípodes, caranguejos anomura e braquiúra, poliquetas errantes e Caprellidea.…”

“…Embora tenha sido encontrada uma freqüência de ocorrência nos estômagos de 31% de algas calcárias e também de 31% de algas verdes, tal fato não as caracteriza como item acessório, pois são ingeridas acidentalmente no momento que a espécie captura os invertebrados que forrageiam sobre as algas e assim, não fazem parte diretamente do hábito alimentar do peixe (Linkowski et al 1983, Kotrschal & Thomson 1986, Santos 2005.…”

“…Habita os interstícios da porção rasa de costões rochosos, recifes de corais, bancos de algas e de areia, ocorrendo no Oceano Atlântico Ocidental, de Belize até Santa Catarina, e utiliza pequenos invertebrados em sua dieta, principalmente crustáceos (Hostim-Silva et al 2006). Há alguns trabalhos que descrevem a composição da dieta de Malacoctenus, indicando um predomínio de crustáceos, particularmente decápodes (anomuros e braquiúros), anfípodes e isópodes, embora poliquetos e gastrópodes também sejam itens alimentares comumente utilizados (Cervigón 1966, Almeida 1972, Kotrschal & Thomson 1986, Zamprogno 1989, Sabino 1992, Santos 2005 Pôde-se verificar que no conteúdo estomacal da espécie foram encontrados invertebrados com dimensões e hábitos muito varianômico possível, utilizando-se chaves específicas e consultando-se especialistas.…”

Ontogeny of microhabitat use and two-step recruitment in a specialist reef fish, the Browncheek Blenny (Chaenopsidae)

“…This may be related to predation intensity at this site or to reduced availability of passing plankton in the protected waters of Bahia San Carlos where strong currents were rare. The relative success of these two feeding strategies and the types of prey consumed were not assessed, but this ontogenetic shift in feeding strategy of the Browncheek Blenny may contribute to it having the highest observed feeding diversity among 34 Gulf of California blennioid species (Kotrschal and Thompson 1986). …”

“…Though they have historically been underrepresented in reef diversity and biomass studies (due to their small size and difficulty in field identification), cryptobenthic fishes are significant contributors to reef microcarnivory and detritivory (Kotrschal and Thompson 1986;Depczynski and Bellwood 2003) and constitute a significant portion of reef fish biodiversity (Smith-Vaniz et al 2006). Many of these less conspicuous specialists almost certainly follow a similar ''two-step'' recruitment path, but few data are available documenting this transition Gonçalves and Faria 2009).…”