set 2: ocean warming & coastal change

why has there been a worldwide coral decline

• human activity results in lower abundance

• less diversity leads to less structural complexity etc

points from Hughes T.P

• measured changes in percentage cover of coral and percentage cover of seaweed

• across 20 years it massively declined from 60% coverage to 10% coverage

• this was replaced by an increase in algal cover

• reef has undergone a phase shift

what is a phase shift

when a reef goes from being dominated by one thing to being dominated by another

what are the driving factor of coral cover decline in the GBR

• crown of thorns starfish and cyclones

• climate change and heat stress

what are the three brand categories of human disturbances on reefs

• fishing

• coastal development

• biological disturbances

how was the limited number of scientists and funding to monitor all reefs combated

• Gregor Hodgson developed reef check

• training amateur diver volunteers to do assessments of the reefs

• suggestion that the reefs around more human activity were in a poorer state

what is coral bleaching

• is the visible loss of the microscopic algae that inhabits the coral

• the symptom of the breakdown in the symbiosis caused by temperature stress

when was the first global mass bleaching

1998

explain the recent GCMRN report

• black line: sea surface temperature for coral reefs around the world

• red vertical lines: thermal anomalies - annual temperature was higher than normal

• big shaded blue areas are confidence intervals

• coral cover between 1975 and 1995 was relatively stable

  • however big confidence intervals and dat amounts prior to 1995 were slim

• after 1998 there is a sharp decline

  • big spike in temperature (black line), and thermal anomalies

  • el-nino year

  • mass coral bleaching

  • confidence intervals get smaller due to increased monitoring and surveys

• within 10 years coral cover increases again and recovers to pre 1998

• 2010

  • second mass coral bleaching event

  • thermal anomalies and temperature spike

  • small confidence intervals

  • decrease in coral cover

• a continued period of continued heat stress from 2012/13 - 2019

  • highest heat spike

  • big decline

  • small confidence intervals