Photo Credit: Courtesy of University of Auckland |
A unique record at the University of Auckland's Leigh marine lab shows dramatic change in the Hauraki Gulf.
A thermometer dipped in a bucket of sea water on New Year’s Day in 1967 began a unique record which shows the dramatic intensification of warming in the Hauraki Gulf.
Sea-surface readings at the Leigh Marine Laboratory north of Auckland since that time indicate the “unprecedented nature of recent marine heatwaves,” according to Dr Nick Shears of the University of Auckland, Waipapa Taumata Rau.
The number of marine heatwave days and their cumulative intensity has increased sharply since 2012, Shears and his co-authors write in a paper published in the New Zealand Journal of Marine and Freshwater Research.
In past decades, some years had no heatwaves, but that hasn’t happened since 2012. Sponges `melting,’ becoming detached from rocks and dying, along with seaweed and kelp die-offs, are among temperature effects.
Especially warm autumns and winters have likely facilitated an increase in subtropical and tropical species such as the long-spined sea urchin Centrostephanus rodgersii, a voracious herbivore which can lay waste to deep reef environments.