14 – Plankton
143
example, at the edge of the continental shelf upwelling
events are common and 10 m to 20 m deep ‘wedges’ of
cool water move along the bottom over the shelf and
under lighter warmer shelf waters. Different planktonic assemblages may be found above and below the
thermocline in these water masses. In addition, some
plankton will concentrate in and around the thermocline. Freshwater plumes will also cause vertical stratification and variation in abundance of plankton with
depth.
Interactions between plankton and oceanography
are studied intensively, but the behaviour of plankton
also has a role. Some plankton will meet in convergences,
but will maintain their position for the purposes of reproduction (e.g. Appendicularia and jellyfishes). The
larvae of prawns, crabs and fishes regulate depth at different stages of their deve lopment and this has major
consequences for transport. For example west Australian lobster larvae (Palinurus ornatis) are transported into
the Indian Ocean at the surface and migrate to deeper
water later in development for transport back toward
the Australian coastline.
N PLANKTON AND CLIMATE CHANGE
It is well known that physical forcing, through changes
in climatic conditions, has a great influence on planktonic assemblages. Phytoplankton has a major role in
the recycling of global CO 2 . For this reason, anything
deleterious that happens to phytoplankton will have a
cascade effect through the entire food chain. Pelagic
ecosystems are well known for trophic cascades and it
is generally assumed that nutrient supply and subsequent growth of phytoplankton will result in ‘bottomup’ control of the whole food chain. Top-down effects
are also possible where predators remove zooplankton grazers, relieving grazing pressure on phytoplankton and resulting in an increase in phytoplankton
biomass. Changes can happen very quickly in the
plankton. Long term plankton records in the northern
hemisphere have demonstrated that the warming of
waters has resulted in substantial changes in planktonic assemblages and there is great concern how this
will affect higher trophic groups and the survival of
larval forms. The impact of global change on plankton
of the GBR will be greatest due to changes in conditions that include: temperature, availability of nutrients (e.g. upwelling and runoff) and change in pH
(that can affect plankton with carbonate skeletons; i.e.
coccolithophores). On the GBR, it is expected that
changes over the next 50 years are likely to be patchy
by region (e.g. central section v. southern section).
ADDITIONAL READING
Biological oceanography
Furnas, M. J., and Mitchell, A. W. (1996). Nutrient
inputs to the central Great Barrier Reef (Australia)
from subsurface intrusions of Coral Sea waters: a
two dimensional displacement model. Continental
Shelf Research 16, 1127–1148.
Genin, A. (2004). Biophysical coupling in the formation
of zooplankton and fish aggregations over abrupt
topographies. Journal of Marine Systems 50, 3–20.
Mann, K. H., and Lazier, J. R. N. (2003). ‘Dynamics of
Marine Ecosystems: Biological-physical Interactions
in the Ocean.’ (Blackwell: Oxford.)
Identification of plankton
Boltovskoy, D. (1999). ‘South Atlantic Zooplankton.’
(Backhuys Publishers: Leiden.)
Dakin, W. J., and Colefax, A. N. (1940). ‘The Plankton
of the Australian Coastal Waters off New South
Wales. Part I.’ (Australian Publishing Company Ltd:
Sydney.)
Graham, L. E., and Wilcox, L. W. (2000). ‘Algae.’
(Prentice Hall: New Jersey.)
Leis, J. M., and Carson-Ewart, M. (2000). ‘The Larvae of
Indo-Pacific Coastal Fishes.’ (Brill: Leiden.)
Newell, G. E., and Newell, R. C. (1977). ‘Marine
Plankton: A Practical Guide.’ (Hutchinson: Essex.)
Todd, C. D., and Laverick, M. S. (1991). ‘Coastal Marine
Zooplankton: A Practical Guide for Students.’
(Cambridge University Press, Cambridge.)
143
example, at the edge of the continental shelf upwelling
events are common and 10 m to 20 m deep ‘wedges’ of
cool water move along the bottom over the shelf and
under lighter warmer shelf waters. Different planktonic assemblages may be found above and below the
thermocline in these water masses. In addition, some
plankton will concentrate in and around the thermocline. Freshwater plumes will also cause vertical stratification and variation in abundance of plankton with
depth.
Interactions between plankton and oceanography
are studied intensively, but the behaviour of plankton
also has a role. Some plankton will meet in convergences,
but will maintain their position for the purposes of reproduction (e.g. Appendicularia and jellyfishes). The
larvae of prawns, crabs and fishes regulate depth at different stages of their deve lopment and this has major
consequences for transport. For example west Australian lobster larvae (Palinurus ornatis) are transported into
the Indian Ocean at the surface and migrate to deeper
water later in development for transport back toward
the Australian coastline.
N PLANKTON AND CLIMATE CHANGE
It is well known that physical forcing, through changes
in climatic conditions, has a great influence on planktonic assemblages. Phytoplankton has a major role in
the recycling of global CO 2 . For this reason, anything
deleterious that happens to phytoplankton will have a
cascade effect through the entire food chain. Pelagic
ecosystems are well known for trophic cascades and it
is generally assumed that nutrient supply and subsequent growth of phytoplankton will result in ‘bottomup’ control of the whole food chain. Top-down effects
are also possible where predators remove zooplankton grazers, relieving grazing pressure on phytoplankton and resulting in an increase in phytoplankton
biomass. Changes can happen very quickly in the
plankton. Long term plankton records in the northern
hemisphere have demonstrated that the warming of
waters has resulted in substantial changes in planktonic assemblages and there is great concern how this
will affect higher trophic groups and the survival of
larval forms. The impact of global change on plankton
of the GBR will be greatest due to changes in conditions that include: temperature, availability of nutrients (e.g. upwelling and runoff) and change in pH
(that can affect plankton with carbonate skeletons; i.e.
coccolithophores). On the GBR, it is expected that
changes over the next 50 years are likely to be patchy
by region (e.g. central section v. southern section).
ADDITIONAL READING
Biological oceanography
Furnas, M. J., and Mitchell, A. W. (1996). Nutrient
inputs to the central Great Barrier Reef (Australia)
from subsurface intrusions of Coral Sea waters: a
two dimensional displacement model. Continental
Shelf Research 16, 1127–1148.
Genin, A. (2004). Biophysical coupling in the formation
of zooplankton and fish aggregations over abrupt
topographies. Journal of Marine Systems 50, 3–20.
Mann, K. H., and Lazier, J. R. N. (2003). ‘Dynamics of
Marine Ecosystems: Biological-physical Interactions
in the Ocean.’ (Blackwell: Oxford.)
Identification of plankton
Boltovskoy, D. (1999). ‘South Atlantic Zooplankton.’
(Backhuys Publishers: Leiden.)
Dakin, W. J., and Colefax, A. N. (1940). ‘The Plankton
of the Australian Coastal Waters off New South
Wales. Part I.’ (Australian Publishing Company Ltd:
Sydney.)
Graham, L. E., and Wilcox, L. W. (2000). ‘Algae.’
(Prentice Hall: New Jersey.)
Leis, J. M., and Carson-Ewart, M. (2000). ‘The Larvae of
Indo-Pacific Coastal Fishes.’ (Brill: Leiden.)
Newell, G. E., and Newell, R. C. (1977). ‘Marine
Plankton: A Practical Guide.’ (Hutchinson: Essex.)
Todd, C. D., and Laverick, M. S. (1991). ‘Coastal Marine
Zooplankton: A Practical Guide for Students.’
(Cambridge University Press, Cambridge.)