Habitat specialisation and the distribution and abundance of coral-dwelling gobies

Abstract

Many fishes on coral reefs are known to associate with particula~ microhabitats If these associations help determine population dynamics then w e would expect (1) a close assoclation between the abundances of these fishes and the abundances of the most frequently used mlcrohabitats and (2) changes in the abundance of microhabitats would result in a corresponding change In fish population sizes We examined habitat associations among obligate coral-dwelling g o b~e s (genus Goblodon) and then investigated relationships between the spatial and temporal ava~labillty of habitats and the abundances of Goblodon species among locations and anlong zoncs on the leef at Lizard Island (Great Barrler Reef) Out of a total of 11 Acropora species found to be used by Gobiodon, each specic3s of Goblodon occupied 1 01 2 species of Acropora significantly more often than expected from the availability of these corals on the reef Across reef zones, the abundance of most species of Gobiodon was closely correlated with the abundance of coral species most frequently inhabited However, the abundance of 1 species G a x~l l a r~s .iiras not conelated with the availability of most frequently used corals aci oss reef zones or among locations Foi G axlllarls the1 efoi e factors other than habitat availab~lity weie more important In determining differences In abundance among zones and locations Also corielations between the abundance of 2 species, G histrlo and G quinquestrigatus, and the coral species they most frequently used was less cons~stent anlong locations than among zones This suggests that the relative importance of habitat availability in determining the abundance of these species of Goblodon is reduced at the spatial scale of locations around Lizard Island The population dynamics of Gob~odon during this study were closely linked to the population dynamics of host corals Because of a crown of thorns starfish (Acanthaster plancl) outbreak the abundance of corals declined in paiticular reef zones Cor~esponding with t h~s loss of h a b~t a t was a decline in Goblodon abundance This study demonstrated that the abundance of habitat specialised fishes can be closely correlated with the spatlal and temporal availab~lity of suitable habitats among and w~t h i n reefs

Coral decline threatens fish biodiversity in marine reserves

“…In the past, there has been a dichotomy of opinion over how closely fish communities are linked to their habitat, with some information indicating a high degree of variability that is independent of habitat change (9)(10)(11)(12)(13)(14) and other data showing that coral-specialists clearly suffer when coral cover is reduced (13)(14)(15)(16)(17). Here we ask the following questions.…”

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

“…Males of these chaenopsids are constrained to make the ontogenetic transition to occupy the specialized microhabitat of shelters because these are sites of egg deposition and defense (Hastings 1986). Finally, similar to other specialists (Munday et al 1997), reliance on such a specific biologically derived microhabitat for reproduction could put this and related species at risk if ongoing global change affects the distribution or growth of test-building invertebrates (Doney et al 2009), even before it affects the Browncheek Blenny directly.…”

Growth trades off with habitat specialization

“…These goby species were classified as either habitat specialists or habitat generalists based on the total number of coral species they occupy at this location in proportion to their availability, or more frequently than expected by chance, compared with the number they either avoided (used less than expected based on availability) or did not use at all (Munday et al 1997; table 1). The range of coral species used by the specialist species is nested within the range occupied by the generalists (Munday et al 1997). Such nesting of resource use facilitates a very reliable estimate of specialization (Futuyma & Moreno 1988).…”

“…(Munday et al 1997); growth rates of gobies in these two hosts can vary substantially (Munday 2001) and they are the most morphologically divergent of the coral species (Veron 2000) used by these gobies. Growth rates of Gobiodon spp.…”

“…We investigated under field conditions, trade-offs with specialization among four species of coral-dwelling gobies that vary widely in their degree of habitat specialization (Munday et al 1997;table 1). Specifically, we tested for growth trade-offs in two habitat-specialized and two habitat-generalized goby species in two species of coral host.…”