Microhabitats and ecomorphology of coral- and coral rock-associated gobiid fish (Teleostei: Gobiidae) in the northern Red Sea

Abstract

Twenty‐one coral‐ and coral rock‐associated gobiid fish species were examined in the Gulf of Aqaba, northern Red Sea in autumn 2003 and spring 2004. They represent the seven genera Bryaninops, Eviota, Gobiodon, Paragobiodon, Pleurosicya, Priolepis and Trimma. All species showed clear spatial niche segregation. Branching corals of the genus Acropora were obligatorily inhabited by Gobiodon spp., while Paragobiodon echinocephalus was restricted to Stylophora pistillata. Three Bryaninops species showed species‐specific associations with Acropora spp., Millepora dichotoma and Cirripathes sp. Most of the five Eviota species had weak associations with live corals but frequented coral rock. Among the genus Pleurosicya, two species were encountered. Pleurosicya micheli frequented massive scleractinian corals, while P. prognatha occupied various species of Acropora. Priolepis semidoliata was only occasionally observed on coral rock. Weak associations with scleractinian corals were documented in Trimma avidori and T. mendelssohni, both of which inhabit coral rock. Principal component and cluster analyses showed several morphological features to be important ecomorphological traits. Gobiid species inhabiting encrusting or massive corals have a more depressed body than species in branching corals. Eye size was well correlated with preferred water depth, especially in the coral‐associated species. A typical gobiid feature – the pelvic disc – was found in very different character states, and corresponded to preferred microhabitats. A well‐developed suctorial pelvic disc was typical for obligate coral‐dwellers.

Microhabitat specialisation and ecological consequences for coral gobies of the genus Gobiodon in the Gulf of Aqaba, northern Red Sea

“…Due to their small body size and the high structural variation among hard corals, these fishes can potentially occupy a broad range of microhabitats (Munday et al 1997). Coral-associated species belong to the genera Gobiodon, Paragobiodon, Bryaninops, or Pleurosicya (Herler 2007). Although these fishes are difficult to study, detailed ecological studies on their habitat preferences hold the key to understanding the population dynamics, distribution and evolution of small reef fishes with strong habitat fidelity (Kuwamura et al 1994, Munday et al 1997, 2001, especially for species associated with living hosts.…”

Microhabitat characteristics influence shape and size of coral-associated fishes

“…Some gobies of the genus Gobiodon have evolved a highly laterally compressed body in adaptation to their lives in Acropora corals, but shapes differ significantly among species (Herler 2007). One of the most compressed species, G. histrio, grows relatively long and exhibits a larger lateral body display compared to congeneric species (Herler & Hilgers 2005, Herler 2007) but can still move easily among the interbranches of its host coral.…”

“…One of the most compressed species, G. histrio, grows relatively long and exhibits a larger lateral body display compared to congeneric species (Herler & Hilgers 2005, Herler 2007) but can still move easily among the interbranches of its host coral. G. rivulatus, a space competitor of G. histrio, has evolved a different shape to live within the same but also in several other coral species not used by G. histrio (Dirnwöber & Herler 2007).…”

“…The form and function of an organism are thus expected to reflect specialization to its preferred microhabitat. Accordingly, coral-associated fishes that live within 3-dimensional structures often evolve a compressed (laterally flattened) body shape, while those living on the surface of massive or flat corals tend to have a highly depressed (dorso-ventrally flattened) body shape (Herler 2007).…”

“…These adaptations have enabled them to exploit many small-scaled microhabitats, including the reefbuilding corals themselves. Coral architecture creates variation in the physical environment, providing a broad variety of living space for coral-associated organisms, including the space between coral branches (Munday & Jones 1998, Herler 2007. Key parameters that physically constrain the size, growth and shape of coral inhabitants are branching form and colony interbranch distance (Munday 2001, Vytopil & Willis 2001.…”