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UCT RESEARCH REPORT 2012
The Air We Breathe
One of BASICS’s projects looked at bromoform – a chemical
compound found in the air above the sea surface produced
by marine plants. Most bromoform is produced naturally
and readily crosses the sea
‐
air boundary into the marine-
boundary layer. Once in the atmosphere, bromoform is
broken down by light energy into bromine radicals, which
destroy ozone in the lower and upper troposphere.
Research Projects
Monitoring Marine Species
Over the past two decades, several marine species
have changed their distributions in waters off the South
African coast. One of the species that has moved
its population centres is the commercially
important
rock lobster (
Jasus lalandii
), which has decreased in
abundance on the West Coast and increased on the
South Coast, east of Cape Hangklip. The reasons for
the shift are not fully understood, but are probably
linked to changes in environmental conditions.
Brett Kuyper and colleagues developed a simple, cost-
effective method to detect and quantify bromoform
in environmental air samples. They then measured
bromoform concentrations at the Cape Point Global
Atmospheric Watch station. These concentrations
were found to be 5–7 times greater than in most other
studies, although they fell within the range reported
for similar marine environments.
The high concentrations are probably caused by the
extensive kelp beds that occur in close proximity to the
measuring station, although a possible anthropogenic
influence from the nearby urban areas of Cape Town
could not be excluded. This project is funded by
ICEMASA and Ma
‐
Re.
Postdoctoral research fellow Dr Laura Blamey and
colleagues applied three different statistical methods
to environmental and biological data sets to try and
identify what factors might have contributed to the
shifts. They found that rock
lobsters grew much more
slowly from the mid-1980s and progressively moved
eastward during the early
to mid-1990s, at a time when
summer winds strengthened and coastal upwelling
was very variable.
From the mid
to
late 1990s there were fewer Bank
Cormorants (which eat rock lobsters) on the West
Coast and more on the South
‐W
est coast, probably in
response to the movement of their prey. Rock lobsters
eat sea urchins, so increased numbers of rock lobsters
on the South Coast have also caused sea urchins to
virtually disappear. In turn, sea urchins provided shelter
from predators for juvenile abalone, and when the
sea urchins disappeared many more juvenile abalone
were eaten, impacting the adult populations at a time
when they were being affected by uncontrolled illegal
fishing. The results of this research are part of the
effort under Ma
‐
Re BASICS to develop environmental
indicators to act as early warning signals for long-
term ecosystem
‐
scale changes. This project is funded
through the SARChI Research Chair in Marine Ecology
and Fisheries, and BASICS.
Brett Kuyper and the Applied Marine Science
master’s students at the South African Weather
Services.
Postdoctoral research fellow Dr Laura Blamey.