In a “voyage of discovery” on
the outer continental shelf and continental slope, WA Museum staff
have discovered several new records and range extensions of mollusc
species, as well as possible undescribed (new) species. Such examples
include the first record of a Conus species in Australia and a
range extension and rare live specimen of Austroharpa wilsoni Rehder,
1973.
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Major Achievements and Findings from
SRFME
Some of the achievements of
SRFME and key scientific outcomes and findings arising from the
research programs in the following areas;
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Collaboration and Capability
- CSIRO and the Western Australian government invested $10 million
each into the SRFME initiative and coinvestment by SRFME’s
collaborators added approximately $2.3 million more into SRFME
research projects.
- SRFME funded a total of over $2.8 million to 32 projects
under its SRFME Collaborative Research Program to Western Australian
research organisations in addition to the 3 SRFME Core Projects
conducted by CSIRO.
- SRFME has increased Western Australia’s marine research
capability by increasing CSIRO’s permanent WA based marine
science staff complement from 4 to 25.
- SRFME has facilitated the training of 12 PhD students, many
of whom have already graduated and found employment in WA universities
and state government agencies or won overseas postdoctoral fellowships.
- SRFME established collaborative partnerships involving 10
different research organisations across the state and commonwealth
governments and the university sector.
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Events and Conferences
- SRFME held six well attended marine science symposia presenting
the results of its research regularly to a wide audience.
- SRFME organised and hosted the First International Whale
Shark Conference in Perth in May 2005. Delegates from 23 countries
attended and the conference proceedings has been accepted for
publication as a special issue of the journal Fisheries Research.
- SRFME helped fund the Twelfth International Marine Biological
Workshop held in Esperance in February 2003. The outcomes of
this workshop have produced a two volume proceedings containing
29 scientific papers on the marine flora and fauna of Esperance
region.
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Publications
- Projects funded wholly or in part by SRFME have so far
generated 140 publications (see publications).
- A set of 23 scientific papers about the Leeuwin current and
its eddies have been submitted for publication in a special issue
of the international journal Deep Sea Research II. This special
issue has been edited by SRFME scientists.
Awards
- SRFME was awarded the CSIRO Go for Growth
Award 2004 “For
the successful promotion and implementation of a new direction
in strategic environmental marine science in Western Australia.”
- Tony Koslow was awarded an international prize; the Don
McAllister Medal for Marine Conservation for contributions
to the conservation of deepwater coral environments.
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Marine Science
Data
- SRFME has produced an on-line interactive data and model
output interrogation tool which has been distributed to Western
Australia’s state government
natural resource management agencies.
- SRFME has provided one of the most detailed spatial and temporal
studies of IOPs (inherent optical property) and AOPs (apparent
optical property), for any marine area in Australia. This dataset
will provide an excellent base for refining the standard algorithms
of the current ocean colour sensors for use in southern Western
Australia, thus providing an important tool for scientists and
managers of this marine environment.
Climate impacts
- SRFME has produced a high resolution climatology for temperature,
salinity, nitrate, phosphate, silicate and oxygen off the Western
Australian coast. From this climatology, the Leeuwin Current,
the South Australian Current, and the Zeehan Current off western
Tasmania are found to be joined into the longest eastern boundary
current (5,500 km) in the world during the austral winter, which
has an important effect on poleward transport of tropical biota
along the west to south coast of Australia.
- BLUElink ReAnalysis (BRAN), is a global physical model, and
has been run from 1992 to 2004, with 10 km resolution off the
WA coast. These data sets provide valuable insights into climate-scale
influences on the shelf and coastal dynamics, in particular as
boundary conditions for SRFME modelling.
Sea-Level
- SRFME has quantified the nature of the linear relationship
between the Fremantle sea level and the strength of the Leeuwin
Current, with 7.5 cm of sea level corresponding to 1 million
m3s-1 of flow. These results justify the wide use of the Fremantle
sea level as an index for the Leeuwin Current.
- A SRFME project has found that since 1991, the annual sea level
has increased at a rate of 5 mm per annum, a rate more than 3
times the trend over the previous 100 years
- The “Boxing Day tsunami” was captured by the tide
gauge at SRFME Station A. A sharp rise in pressure of 0.3 db,
equivalent to a 0.3 m rise in sea-level, occurred at about 1500
on 26 December 2004. Sea-level oscillations with a period of
about 1 hour persisted for another two days.
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Currents
- SRFME has quantified the annual and ENSO-related interannual
variations of the Leeuwin current. The average flow rate of the
Leeuwin Current is about 3.4 x 106 m3s-1. The strength of the
current varies by about a factor of 2 over the year, being weakest
in summer, when it is opposed by southerly winds, and strongest
in winter. It is also about 40% stronger during a La Nina year
than during an El Nino year.
- SRFME has shown that, inshore, in water depths around 20 m,
currents follow the wind direction, principally north in the
summer and south in the winter, with the water speed close to
3% of the wind speed. At 100 m depth, surface waters tend to
follow the wind direction, while waters below 50 m flow south
under the influence of the Leeuwin Current. Water temperatures
are warmer inshore during the summer but, during the winter the
Leeuwin Current keeps the offshore water warmer. In 100 m, the
surface water is about 2 ºC warmer than the bottom, but
the water is well-mixed during the winter.
- SRFME wave and sediment modelling, calibrated against measurements,
suggest that the wave climate in southern coastal waters is sufficient
to keep inshore sand mobile for most (>60%) of the time, with
an increase in winter.
- SRFME found that wave amplitude diminishes rapidly across reef
platforms typical of southwestern Australia, with measurements
at Marmion showing 1/3 reduction within 1500 m.
- SRFME has shown how eddies form south of the Abrolhos Islands
(29ºS)
from meanders of the Leeuwin Current. The eddies are more intense
when the Leeuwin Current is flowing strongest, in the winter
and in La Nina years. Warm-core eddies drift from the shelf offshore
and may persist for months. The eddy drift carries a volume of
water roughly equivalent to flushing the southern shelf twice
per year. The eddy-induced cross-shelf transport of productive
water from the shelf to the open ocean may influence the western
rock lobster recruitment process. The relationship between enhanced
Leeuwin flow and eddy activity on shelf productivity may explain
the positive correlation between Leeuwin flow and recruitment
to the western rock lobster.
- The late-autumn and early-winter bloom appears to be at least
partially explained by enhanced vertical mixing, and the transport,
by eddies, of nutrient-rich water from the shelf. Both of these
mechanisms have been demonstrated by simplified, 1-dimensional
biogeochemical modelling and fully 3-d modelling. From satellite
data, the offshore flux of phytoplankton biomass by warm-core
eddies is estimated as equivalent to about 4 ×105 tonnes
of carbon per year.
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Ocean temperature
- SRFME has calculated that the water temperature at coastal
stations off WA rose by around 0.017 ºC per year over the
last 50 years, consistent with the global temperature rise attributed
to climate change. At the same time, salinity off the WA coast
has also increased. There is also a clear suggestion of a lengthening
warm season.
Biophysical Oceanography
- The first detailed temporal study of biophysical oceanographic
dynamics across the Perth continental shelf has revealed a marked
contrast between summer and winter plankton dynamics. Low productivity
and a deep chlorophyll maximum layer were observed in summer
when the upper water column was strongly stratified. Increased
Leeuwin flow and eddy activity in late autumn/early winter were
associated with enhanced nutrient input to the upper mixed layer,
a peak in primary production, increased phytoplankton concentrations
and a shoaling of the chlorophyll maximum layer. Distinct onshore/offshore
assemblages were found for all major pelagic groups: phytoplankton,
microzooplankton, mesoplankton and ichthyoplankton.
- In a comparative study to map the larval abundance and health,
and ecosystem structure of two eddies off the west coast of WA,
a downwelling (“death-trap”) eddy,
possibly dominated by N-fixation, and an upwelling (“nursery”)
eddy, possibly dominated by upwelled nitrate, were discovered.
The results from this work will be published in a special issue
of Deep Sea Research.
- A new method was developed to assess, simultaneously, the grazing
of micro- and mesozooplankton on phytoplankton assemblages.
- A rare protist (radiolarian Coelodiceras
spinosum) was caught
in a sediment trap placed within an upwelling eddy in 2003, and
has only been identified in six locations globally, three of
which are in the Southern Hemisphere. A total of 12 specimens
have been identified and its description has not been updated
since the original publication by V. Haecker in 1909.
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Marine fauna
- At the Kingston Reef Sanctuary area on Rottnest Island, the
population of rock lobster greater than minimum legal size has
been shown to be more than ten times greater than in areas outside
the sanctuary subjected to recreational fishing. Significant
differences in the abundances and biomass of target and by-catch
fish species (eg. Dhufish and Breaksea Cod) were also found between
the sanctuary and adjacent areas open to fishing. Fish predation
on grazing invertebrates such as urchins and snails was higher
where fishing has reduced fish numbers. However, these differences
do not presently appear strong enough to lead to the creation
of “barren grounds” such as those that occur
on other coasts in Australia and elsewhere worldwide.
- In a SRFME project on the
biodiversity of marine fauna on the central west coast, four
species of the isopod family Sphaeromatidae collected in this
study have not before been recorded in Western Australia. Extended
species ranges have been determined for nine species of echinoderms
found in the area: seven northwards from the Fremantle/Rottnest
area and two southwards from Dongara and Shark Bay.
- In a “voyage of discovery” on the outer continental
shelf and continental slope, WA Museum staff have discovered
several new records and range extensions of mollusc species,
as well as possible undescribed (new) species. These await investigation
and confirmation. Such examples include the first record of a
Conus species in Australia and a range extension
and rare live specimen of Austroharpa wilsoni Rehder, 1973.
Marine flora
- Signficant progress has been made towards the ‘Seagrass
Epiphyte Interactive Key’, by John Huisman. This is a
list of known seagrass epiphytes (over 200 species) which will
take the form of a interactive identification key on CD.
- SRFME scientists John Huisman, Julia Phillips and C Parker
produced a 72 page booklet which is an illustrated guide entitled
Marine Plants of the Perth Region.
- An introduced isopod species Sphaeroma
serratum was found in
high densities in the Jurien Bay marina.
- A new species of macroalgae, named Sargassum
kendrickii was described by N. Goldberg
and J. Huisman, and named after SRFME researcher and Sargassum
expert from UWA, Dr Gary Kendrick.
- The extremely rare red alga Gelidiella
ramellosa (Kützing)
Feldmann & Hamel
was found in SRFME specimens collected off Perth. This species
was originally described from collections made over 150 years
ago from Western Australia, and has not been found in the region
since that time.
- In a pilot study, a seagrass species, Amphibolis
griffithii and its epiphytes responded rapidly to severe,
short-term reductions in light availability but the shoot – and
meadow – scale responses allow the plant to respond rapidly to
improved light conditions after a short period of time. This
work will allow us to better predict and manage the responses
of seagrass meadows to the effects of dredging.
- The structure of reef algal communities in eastern Geographe
Bay, as well as their seasonal cycles, was found to differ strongly
from that of other parts of the west coast, mainly as a consequence
of seasonal sediment and detritus re-suspension.
- Modelling of wave climate at Jurien Bay indicated that almost
75% of the variation in species diversity of algae could be explained
by the strength of the wave exposure. This has implications for
the creation of representative systems of marine protected areas,
as well as for understanding the impacts of climate change and
climate variation in the region.
- SRFME has described several characteristic algal community
types and shown that some habitat types are much more important
and widespread than previously thought. Many reefs are a patchwork
of different algal communities, rather than being dominated by
kelp forests. These findings may have important implications
for our understanding of how reef ecosystems function.
- SRFME has characterised reef algal and invertebrate communities
at sites from Jurien Bay to Cape Naturaliste. The character of
these communities is largely similar along this gradient, justifying
their inclusion in a single bioregion, but important differences
were described at smaller scales.
- The role and importance of reef algae in marine food webs was
shown to be disproportionately higher than that of seagrass.
Importantly, because algae can be dislodged and drift many kilometres
from their reef of origin, reefs can provide very important food
subsidies for distant seagrass and sand habitats.
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