Marine Biodiversity in Temperate Western Australia: Multi-Taxon Surveys of Minden and Roe Reefs

Abstract

A growing body of evidence indicates that temperate marine ecosystems are being tropicalised due to the poleward extension of tropical species. Such climate mediated changes in species distribution patterns have the potential to profoundly alter temperate communities, as this advance can serve to push temperate taxa, many of which are southern Australian endemics, southward. These changes can lead to cascading effects for the biodiversity and function of coastal ecosystems, including contraction of ranges/habitats of sensitive cool water species. Hence there is growing concern for the future of Australia's temperate marine biodiversity. Here we examine the diversity and abundance of marine flora and fauna at two reefs near Perth's metropolitan area-Minden Reef and Roe Reef. We report the presence of 427 species of marine flora and fauna from eight taxon groups occurring in the Perth metropolitan area; at least three species of which appear to be new to science. Our data also extends the known range of 15 species, and in numerous instances, thousands of kilometres south from the Kimberley or Pilbara and verifies that tropicalisation of reef communities in the Perth metropolitan area is occurring. We report the presence of 24 species endemic to southwest Australia that may be at risk of range contractions with continued ocean warming. The results of these surveys add to our knowledge of local nearshore marine environments in the Perth metropolitan area and support the growing body of evidence that indicates a diverse and regionally significant marine fauna occurs in temperate Western Australia. Regular, repeated survey work across seasons is important in order to thoroughly document the status of marine biodiversity in this significant transition zone.

Refugia under threat: Mass bleaching of coral assemblages in high‐latitude eastern Australia

“…Unfortunately, high‐latitude regions are predicted to experience greater heat stress than the tropics over the coming decades (Hobday & Pecl, ; Wu et al, ), which is likely to result in increasingly frequent and intense regional bleaching events (Heron, Maynard, van Hooidonk, & Eakin, ; van Hooidonk, Maynard, & Planes, ; van Hooidonk et al, ). However, unlike their tropical counterparts, poleward range shifts and/or expansions are unlikely for many high‐latitude coral species because suitable habitats are progressively unavailable toward the poles, such as along the high‐latitude east coast of Australia and South Africa (Harriott & Banks, ; Schleyer et al, ; but see, Booth & Sears, ; Greenstein & Pandolfi, ; Richards et al, ). Similar to other flora and fauna (Jablonski, ; Parmesan, ), many high‐latitude corals may therefore contract their geographic ranges and be more prone to extinction as their habitats become unsuitable under climate change and/or they are unable to compete with incoming vagrant species.…”

A Victorian emigrant: first observation and range extension of the nudibranch Tenellia catachroma (Burn, 1963) in Western Australia (Mollusca: Gastropoda)

“…In southern Australia, both the east and west coasts are vulnerable to marine climate change, with southward shifts in distribution a likely outcome (Przeslawski et al 2008;Beger et al 2014;Richards et al 2016). Several recent range extensions have been reported for sea slugs on the east coast and these may be attributed to a combination of increased survey effort and shifts in distribution in response to ocean warming (Nimbs et al 2015;, 2017.…”

“…It is possible, however, that an intermittent supply of temperate species larvae can be delivered in summer by the inshore, northflowing Capes counter-current (Pearce & Pattiaratchi 1999) (Figure 3). Richards et al (2016) discussed the presence of poleward range shifts in a variety of taxa into southern WA and increasing tropicalisation driven by rising (Pearce 2014). The observation of a temperate taxon not only 2000 km west of its previously known western range limit at Barker Rocks, SA, but also a further 300 km equatorward illustrates the complexity of spatio-temporal factors associated with change in marine ecosystems and indicates that northern range shifts in temperate species can occur even in the presence of warming.…”

The Cardiidae (Mollusca: Bivalvia) of tropical northern Australia: A synthesis of taxonomy, biodiversity and biogeography with the description of four new species

“…Southward penetration of this current is annually variable, but when strong can carry larvae and thus taxa from more northerly waters southward (via the Indonesian Through Flow or ITF that then connects with the Holloway and Leeuwin currents in WA). This can extend penetration of the northern IWP fauna along the WA coast seasonally (Wilson and Allen 1987, Richards et al 2016, Wilson 2016.…”