Reports of visible algal blooms have increased in New South Wales (NSW) coastal waters since 1990. Our three-year, multi-disciplinary study assessed the relative importance of natural and anthropogenic nutrients on the development of phytoplankton blooms in the waters between Port Stephens and Jervis Bay. The hinterland of this region accommodates 85% of the population of the 6.5 million inhabitants of New South Wales, Australia. Three deepwater outfalls represented the principal, continuous, anthropogenic nutrient source with nitrogen mainly in the bioavailable form of ammonia. Sewage effluent typically remained submerged especially during the spring-summer period when algal blooms occur most frequently. On average, coastal catchments contributed relatively small loads of nutrients except during major flood events because extensive estuaries tend to buffer nutrient fluxes to the ocean. Episodic slope water intrusions were the principal source of nitrogen (nitrate) to coastal waters especially during spring and summer. Phytoplankton blooms appeared to occur in response to slope water intrusions irrespective of proximity to other major nutrient sources. A new understanding of mechanisms of slope water intrusion emerged from model simulations and direct observations. A major upwelling event in January 1998, towards the end of the 1997/98 El Niño period, demonstrated the importance of large scale slope water intrusions on the development of algal blooms. Although natural upwelling/uplifting was found to be the principal driver for major algal blooms, it is possible that more subtle impacts of anthropogenic nutrients may be masked by ‘natural’ variability including that due to the El Niño Southern Oscillation.

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References

Andersen, D. M.
1995
. “
Toxic red tides and harmful algal blooms: a practical challenge in coastal oceanography
”. In
Rev. Geophysics, Suppl. U.S. National Report to the Int. Union of Geodesy and Geophysics. 1991-1994
1189
1200
.
ANZECC (Australian and New Zealand Environment and Conservation Council)
.
1992
.
Australian Water Quality Guidelines for Fresh and Marine Waters
Australia
Ajani, P. A., Hallegreaff, G. M. and Pritchard, T. R.
2001a
.
Historic overview of Algal blooms in marine and estuarine waters of New South Wales
.
Australia, Proc. Linn. Soc. NSW
,
123
:
1
22
.
Ajani, P. A., Lee, R. S., Pritchard, T. R. and Krogh, M.
2001b
.
Phytoplankton patterns at CSIRO's long-term coastal station off Sydney
.
Journal Coastal Res.
,
34
:
60
73
.
Bothner, M. H., Takada, H., Knight, I. T., Hill, R. T., Butman, B., Farrington, J. W., Colwell, R. R. and Grassle, J. F.
1994
.
Sewage contamination in sediments beneath a deep-ocean dump site off New York
.
Marine Environmental Research
,
33
:
43
59
.
Broadie, J.
1995
. “
The problem of nutrients and eutrophication in the Australian marine environment.
”. In
State of the Marine Environment Report for Australia Technical Annex 2
, Edited by: Zann, L. P. and Sutton, D. C.
1
29
.
Great Barrier Reef Marine Park Authority Report to Department of Environment Sport and Territories
.
Buskey, E. J.
1995
.
Growth and bioluminescence of Noctilltica scintillans on varying algal diets
.
J. Plankton Res.
,
17
:
29
40
.
Cresswell, G.
1994
.
Nutrient enrichment of the Sydney continental shelf
.
Aust. J. Mar. Freshwater Res.
,
45
:
677
691
.
Diener, D. R., Fuller, S. C., Lissner, A., Haydock, C. L., Maurer, D., Robertson, G. and Gerlinger, T.
1995
.
Spatial and temporal patterns of the infaunal community near a major ocean outfall in Southern California
.
Mar. Pollut. Bull.
,
30
:
861
878
.
Ferraro, S. P. and Cole, F. A.
1991
.
Taxonomic level and sample size sufficient for assessing impacts on the Southern California Bight macrobenthos
.
Marine Ecology Progress Series
,
67
:
251
262
.
Gibbs, M. T., Marchesiello, P. and Middleton, J. H.
1997
.
Nutrient enrichment of Jervis Bay during the massive 1992 coccolithophorid bloom
.
Mar. Freshwater Res.
,
48
:
473
478
.
Gibbs, M. T., Middleton, J. H. and Marchesiello, P.
1998
.
Baroclinic responses of Sydney Shelf Waters to Local Wind and Deep Ocean Forcing
.
Journal of Physical Oceanography
,
28
:
178
190
.
Gonzalez, H., Pomares, M., Ramirez, M. and Torres, I.
1999
.
Heavy metals in organisms and sediments from the discharge zone of the submarine sewage outfall of Havana City, Cuba
.
Mar. Pollut. Bull.
,
38
:
1048
1051
.
Hahn, S. D., Rochford, D. J. and Godfrey, J. S.
1977
.
Long term variability of oceanographic data at the Port Hacking 50-metre station
.
Aust. J. Mar. Freshwater Res.
,
28
:
57
66
.
Hallegraeff, G. M. and Reid, D. D.
1986
.
Phytoplankton species successions and their hydrological environment at a coastal station off Sydney
.
Aust. J. Mar. Freshwater Res.
,
37
:
361
377
.
Humphrey, G. F.
1960
. “
The concentration of planktonic pigments in Australian waters
”. In
CSIRO (Commonwealth Scientific & Industrial Research Organisation)
,
Division of Fisheries and Oceanography Technical Paper No. 9
Jeffrey, S. W. and Hallegraeff, G. M.
1990
. “
Phytoplankton Ecology of Australasian Waters.
”. In
Biology of Marine Plants
, Edited by: Clayton, M. N and King, R. J.
310
348
.
Longman Cheshire
:
Melbourne
.
Lee, L. H. W. and Cheung, V.
1990
.
Generalised Lagrangian model for buoyant jets in a current
.
Proc. ASCE, JnI Env. Eng.
,
116
(
6
):
1085
1106
.
Lee, R. S. and Pritchard, T. R.
1996
. “
Dispersion of effluent from Sydney's new deepwater outfalls Part 1: ocean processes.
”. In
Mixing Processes in Estuaries and Coastal Seas
, Edited by: Pattiaratchi, C.
430
438
.
Washington
:
American Geophysical Union
.
Lee, R. S. and Pritchard, T. R.
Extreme Discharges into the Coastal Ocean: A Case Study of August 1998 Flooding on the Hawkesbury and Hunter Rivers
.
Pacific Coasts and Ports '99 Proceedings
.
Perth.
pp.
341
346
.
W.A.
Lee, R. S., Ajani, P. A., Pritchard, T. R. and Black, K. P.
2001a
.
Resolving climatic variance in the context of retropective phytoplankton investigations off the east coast of Australia
.
Journal Coastal Res.
,
34
:
74
86
.
Lee, R. S., Ajani, P. A., Wallace, S., Pritchard, T. R. and Black, K. P.
2001b
.
Anomalous upwelling along Australia's east coast
.
Journal Coastal Res.
,
34
:
96
109
.
Lord, D. A.
February
1994
. “
Coastal eutrophication: prevention is better than cure
”. In
The Perth Coastal Water Study
,
February
,
22
27
.
Water
.
1994
Lund, J. W., Kipling, C. and Le Cren, E. D.
1958
.
An inverted microscope method of estimating algal numbers and the statistical basis of estimations by counting
.
Hydrobiologia
,
11
:
143
170
.
McClean-Padman, J. and Padman, L.
1991
.
Summer upwelling on the Sydney inner continental shelf: the relative roles of local wind forcing and mesoscale eddy encroachment
.
Continental Shelf Research
,
11
(
4
):
321
345
.
Middleton, J. H., Cox, D. and Tate, P.
1996
.
The Oceanography of the Sydney Region
.
Mar. Pollut. Bull.
,
33
:
124
131
.
Murray, S. and Slithers, I. M.
1999
.
Population ecology of Noctiluca scintillans Macartney, a red-tide-forming dinoflagellate
.
Mar. Freshwater Res.
,
50
:
243
252
.
Newell, B. S.
1966
.
Seasonal changes in the hydrological and biological environments off Port Hacking, Sydney Aust
.
J. Mar. Freshwater Res.
,
17
:
77
91
.
Oke, P. R. and Middleton, J. H.
2000
.
Topographically Induced Upwelling off Eastern Australia
.
Journal of Physical Oceanography
,
30
(
3
):
512
531
.
Oke, P. R. and Middleton, J. H.
2001
.
Nutrient enrichment off Port Stephens: the role of the East Australian Current
.
Continental Shelf Research
,
21
(6-7)
:
587
606
.
Pan, Y. and Subba Rao, D. V.
1997
.
Impacts of Domestic Sewage Effluent on Phytoplankton from Bedford Basin
.
Eastern Canada. Mar. Pollut. Bull.
,
34
:
1001
1005
.
Parsons, T. R., Takahashi, M. and Margrave, B.
1977
.
Biological Oceanographic Processes
, Second edition,
Oxford
:
Pergamon Press
.
Partridge, I. J., ed.
1994
.
Will It Rain? The effects of the Southern Oscillation and El Niño on Australia
, Second edition,
Brisbane
:
Queensland Department of Primary Industries
.
Paerl, H.
1997
.
Coastal eutrophication and harmful algal blooms: Importance of atmospheric deposition and groundwater as “new" nitrogen and other nutrient sources
.
Limnology and Oceanography
,
42
(
5
):
1154
1165
.
Pearson, T-H. and Rosenberg, R.
1978
.
Macrobenthic succession in relation to organic enrichment and pollution of the marine environment
.
Oceanography and Marine Biology Annual Review
,
16
:
229
311
.
Pelley, J.
1998
.
‘Is Coastal Eutrophication Out of Control?’
.
Environmental Science and Technology, October
,
1998
:
462
466
.
Pritchard, T. R.
1997
.
Environmental Performance of Sydney's Deepwater Outfalls
.
Journal Australian Water and Wastewater Association
,
24
:
29
34
.
Pritchard, T. R., Lee, R. S. and Davison, A.
1996
. “
Dispersion of effluent from Sydney's new deepwater outfalls Part 2: Observations of Plume Behaviour Winter and Summer Examples.
”. In
Mixing Processes in Estuaries and Coastal Seas
, Edited by: Pattiaratchi, C.
439
452
.
Washington
:
American Geophysical Union
.
Pritchard, T., Lee, R. and Ajani, P.
Anthropogenic and oceanic nutrients in NSW's dynamic coastal waters and their effect on phytoplankton populations
.
14th Australian Coastal and Ocean Engineering Conference and the 7th Australasian Port and Harbour Conference--Coasts and Ports
.
1999
. pp.
537
543
.
Pritchard, T. R., Lee, R. S., Rendell, P. and Ajani, P.
2001
.
How do ocean outfalls affect nutrient patterns in coastal waters of New South Wales, Australia?
.
Journal Coastal Res.
,
34
:
87
95
.
Rendell, P. S. and Pritchard, T. R.
1996
.
Physicochemical Conditions in Coastal Waters off Sydney, Central NSW, Australia
.
Mar. Pollut. Bull.
,
33
:
132
139
.
Rochford, D. J.
1984
.
Nitrates in eastern Australian coastal waters
.
Aust. J. Mar. Freshwater Res.
,
35
:
385
397
.
Rochford, D. J.
1975
.
Nutrient enrichment of East Australian coastal waters. 2. Laurieton upwelling
.
Aust. J. Mar. Freshwater Res.
,
26
(
2
):
233
243
.
Merz, Sinclair Knight.
1997
.
Nutrient Discharges from Estuaries
,
NSW EPA (New South Wales Environmental Protection Agency)
.
Smayda, T. J.
1997
.
Harmful algal blooms: Their ecophysiology and general relevance to phytoplanklon blooms in the sea
.
Limnol. Oceanogr.
,
42
(
5
):
1137
1153
.
Smayda, T. J. and White, A. W.
1990
. “
Has there been a global expansion of Algal blooms? If so, is there a connection with human activities?
”. In
Toxic Marine Phytoplankton
, Edited by: Graneli, E.
516
517
.
Elsevier Pub. Co. Inc.
.
Smith, S. D. A.
1996
.
The Effects of Domestic Sewage on Marine Communities at Coffs Harbour, New South Wales, Australia
.
Mar. Pollut. Bull.
,
33
:
309
316
.
Sprintall, J., Roemmich, D., Stanton, B. and Bailey, R.
1995
.
Regional climate variability and ocean heat transport in the southwest Pacific Ocean
.
Jour. Geophys. Res.
,
100
(C8)
:
15865
15871
.
Sydney Water
.
1996
. “
Environmental Indicators Monitoring Report & Special Objectives Statement
”. In
Sydney Water Annual Environment Report Auxiliary volume
,
Sydney Water Corp.
.
Taylor, F. J. R.
1990
. “
Red tides, brown tides and other harmful algal blooms: The view into the 1990's.
”. In
Toxic Marine Phytoplankton
, Edited by: Graneli, E.
527
533
.
Elsevier Pub. Co. Inc.
.
Tranter, D. J., Carpenter, D. J. and Leech, G. S.
1986
.
The coastal enrichment effect of the East Australian Current eddy field
.
Deep-sea Res.
,
33
:
1705
1728
.
Wolanski, E. and Collis, P.
1976
.
Aspects of Aquatic Ecology of the Hawkesbury River. 1
.
Hydrodynamic Processes, Aust. J. Mar. Freshwater Research
,
Zann, L.
1995
.
Our Sea, Our future. Major findings of the state of the Marine Environment report for Australia
,
2000
Great Barrier Reef Marine Park Authority (Australia) for Ocean Rescue
.