Oral Presentation Australian Society for Fish Biology Conference 2017

Climate-mediated changes to the distribution and density of reef fishes family pomacentridae in south-western australia (#125)

Tanika C Shalders 1 , Benjamin J Saunders 1 , Euan S Harvey 1 , Scott Bennett 1
  1. Environment & Agriculture, Curtin University, Perth, WA, Australia

Changes in climate are leading to latitudinal shifts in the geographical distribution and abundance of many fish species. These shifts may be driven by both discrete and gradual climatic events, the effects of which are cumulative in nature. This study focuses on the abundance distributions of four species of Pomacentrid (Pomacentrus milleri, Parma occidentalis, Parma mccullochi, and Parma victoriae) on shallow complex rocky reefs located on Western Australia’s temperate coastline. These species use similar algal habitats. However, they differ in sea-surface temperature requirements and therefore have differing population distributions. Diver operated stereo-video surveys were used to investigate changes in the distribution patterns of these Pomacentrid species between 2006 and 2015. The abundance of the warmer water affiliated species P. milleri and P. occidentalis increased in the north of the survey area, from Jurien Bay to Port Gregory. The abundance of P. victoriae, a cooler water species, decreased at Albany, while the cosmopolitan species P. mccullochi showed similar distribution and abundance patterns in 2006 and 2015. The cumulative effects of an extreme temperature event (2 – 4°C warming over >10 weeks) across the survey area in early 2011 and gradual sea temperature warming has led to significant changes in the algal composition of south-western Australian reefs. The loss of Ecklonia radiata, and subsequent increase in turfing algae is likely to be a key factor in the changes of P. milleri and P. occidentalis distribution and abundance.