Indicator: CO-44 Marine chlorophyll concentration

Data

Changes in marine chlorophyll concentrations would ideally be measured by ocean colour analysis around the coastline of the continent and in estuarine waterways.

Unfortunately, no continent-wide data are available to provide an overall summary of either the general Chlorophyll condition of Australian coastal waters, or even on the incidence, extent, duration or severity of algal blooms. There are no ongoing systematic monitoring programs across subregions that compare and track changes over time.

In Antarctica, satellite data have shown significant ecosystem-level effects of exposure to ultraviolet B (UVB) radiation. This occurred below a threshold stratospheric ozone concentration of 300 Dobson Units (DU), reducing the seasonal increase of chlorophyll by around 60 per cent at less than 300 DU. Inhibition occurs over time scales greater than one day, suggesting this is due to indirect effects of exposure to enhanced UVB radiation.

Source: Robinson SA, Turnbull JD and Lovelock CE 2005, Impact of changes in natural ultraviolet radiation on pigment composition, physiological and morphological characteristics of the Antarctic moss, Grimma antarctici.

What the data mean

No data on marine chlorophyll variations in Australian waters are available but the data from Antarctica suggest that stratospheric ozone depletion can disrupt marine chlorophyll production. This in turn has the potential to affect both other organisms which depend on marine vegetation for food or habitat, and the capacity of the oceans to absorb carbon dioxide from the atmosphere.

Data Limitations

No data available.

Issues for which this is an indicator and why

Coasts and Oceans — Condition of the ocean and coastal waters - Condition of marine vegetation 

Changes in ocean colour mapped across the continent could give a broad indication of changes in marine chlorophyll and therefore of the condition of marine plant life at the continental level.

Coasts and Oceans — Condition of the ocean and coastal waters - Climatic and carbon dioxide factors 

Changes in marine chlorophyll would be indicative of changes in the ocean’s capacity to absorb carbon dioxide.

Other indicators for this issue:

Coasts and Oceans — Direct pressure of human activities on coasts and oceans - Direct pressure of coastal activities (other than shipping and fishing) 

Excesses of some marine plants, such as algae, are indicative of excess nutrients in the water. Algal blooms may in turn place pressure on other marine life by blocking off sunlight from the surface and preventing oxygenation through photosynthesis. Bacteria breeding in dead algae can also deoxygenate water. In the absence of continental data on actual occurrences of algal blooms, continental information on ocean colour in areas close to coastal areas of intensive human activity could serve as an indicator of areas suffering or at risk of algal blooms

Other indicators for this issue:

Coasts and Oceans — Contributions and pressures between the coasts and oceans and the atmosphere - Climate and carbon dioxide 

Condition of marine plant life is a primary determinant of the ocean’s capacity to act as a greenhouse sink, and therefore of the contributions and pressures operating between the ocean and the atmosphere.

Other indicators for this issue:

Coasts and Oceans — Contributions and pressures between the coasts and oceans and the atmosphere - Ozone depletion 

Marine plant life, especially phytoplankton, is especially vulnerable to UV radiation. A change in health of phytoplankton, combined with an increase in UV radiation at the surface, could be indicative of increased pressure from ozone depletion.

Other indicators for this issue:

Biodiversity — Species, habitats and ecological communities - Condition of marine biodiversity: Condition of marine vegetation 

The health of marine plant life is essential to the health of marine biodiversity more broadly. A change in ocean colour or number of reported algal blooms could be indicative of a change in the condition of marine plant life.

Biodiversity — Pressures on biodiversity - Climate variability 

The capacity of marine plant life to absorb atmospheric carbon and release oxygen is an indirect indicator for the pressure of greenhouse gases on the atmosphere and thus for climate change.

Other indicators for this issue:

Biodiversity — Pressures on biodiversity - Pressures on marine biodiversity: Pressures on coasts and oceans arising from multiple causes 

The full range of human activities involving the coasts and oceans can impact on the condition of marine plant life.

Other indicators for this issue:

Biodiversity — Pressures on biodiversity - Pressures on marine biodiversity: pressures of coastal activities 

A range of coastal activities result in pollution which has the potential to impact on coastal and marine vegetation.

Other indicators for this issue:

Atmosphere — Climate variability and change - Greenhouse 

Marine carbon helps to absorb atmospheric carbon. Changes in marine carbon levels could signal a reduced or increased capacity for the oceans to absorb greenhouse gases from the atmosphere.

Other indicators for this issue:

Further Information