Biogeographic patterns in the Australian chondrichthyan fauna

Abstract

The major biogeographic structure and affinities of the Australian chondrichthyan fauna were investigated at both interregional and intraregional scales and comparisons made with adjacent bioregions. Faunal lists were compiled from six geographical regions with species from these regions assigned to distributional classes and broad habitat categories. Australian species were further classified on provincial and bathomic structure following bioregionalization outputs from regional marine planning. About 40% of the world's chondrichthyan fauna occurs in Indo-Australasia (482 species) of which 323 species are found in Australian seas. The tropical Australian component, of which c. 46% of taxa are regional endemics, is most similar to faunas of Indonesia, New Guinea and New Caledonia. The temperate Australian component is most similar to New Zealand and Antarctica with about half of its species endemic. Highest levels of Australian endemism exist in bathomes of the outer continental shelf and upper slope. A relatively high proportion of regional endemism (57% of species) on the slope in the poorly surveyed but species-rich Solanderian unit is probably due to high levels of large-scale habitat complexity in the Coral Sea. The richness of demersal assemblages on the continental shelf and slope appears to be largely related to the spatial complexity of the region and the level of exploration. Much lower diversity off Antarctica is consistent with the pattern in teleosts. The complex chondrichthyan fauna of Australia is confirmed as being amongst the richest of the mega-diverse Indo-West Pacific Ocean. Species-level compositions of regional faunas across Indo-Australasia differ markedly because of moderate to high levels of intraregional speciation. Faunal assemblages in Australian marine provinces and bathomes differ from each other, supporting a broader pattern for fishes that underpins a marine planning framework for the region.

Size, sex and seasonal patterns in the assemblage of Carcharhiniformes in a sub‐tropical bay

“…Sub‐tropical regions encompass many inshore waters adjacent to large human populations. Within Australia, these waters are known to support a high diversity of sharks (Last & White, 2011), but there is a lack of basic ecological knowledge for many species. This study examined Carcharhiniformes in Moreton Bay in southern Queensland.…”

Identification of Rays through DNA Barcoding: An Application for Ecologists

“…The central Indo-Pacific is a major centre of origin and radiation of stingrays [19] and within this region, the Indo-Australian archipelago contains 30% of all species of sharks and rays worldwide [11], [24], including many species of tropical rays. Rays are exploited directly or indirectly in commercial fisheries; however, detailed data on landings and by-catch are often lacking.…”

Zoogeography of Elasmobranchs in the Colombian Pacific Ocean and Caribbean Sea

“…This number of endemic species is particularly low if compared to the Australia biogeographic region (Last & Yearsley, 2002;Last & White, 2011).…”

“…Another possible cause of lower elasmobranch species richness in the Pacific compared with other regions of the world (Last & White, 2011) is that smaller benthic sharks (such as the Orectolobiformes), that contribute substantially to Indo-Pacific diversity, have not been able to reach the Pacific oceanic islands (Springer, 1982).The strength of this East Pacific Barrier in elasmobranch dispersion has been observed in the species richness of Australasia (Last & Yearsley, 2002) and the TEP, where even highly vagile species such as Manta birostris have restricted gene flow between these areas (Clark, 2002), and only very few shark species (e.g. Carcharhinus albimarginatus, C. galapagensis, Triaenodon obesus) have an amphi-Pacific distribution (Robertson & Allen, 2008).…”

“…Despite the high diversity of elasmobranchs (more than 465 species of sharks and 539 batoids), grouped in 178 genera and 51 families (Nelson, 2006;White & Last, 2012;Dulvy et al, 2014), there are few zoogeographical studies carried out in this group, and most are focused on the order Rajiformes (Ishihara, 1991;Last & Yearsley, 2002;Musick et al, 2004;Last & White, 2011). Elasmobranchs are distributed in all the world oceans, from the poles to tropical waters, and from the surface to over 3,000 m depth.…”