Marine and Freshwater Research
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Cơ quản chủ quản: CSIRO Publishing , CSIRO,
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Ecology, Evolution, Behavior and SystematicsOceanographyAquatic ScienceEcology
Các bài báo tiêu biểu
Climate change, coral bleaching and the future of the world's coral reefs Sea temperatures in many tropical regions have increased by almost 1°C
over the past 100 years, and are currently increasing at ~1–2°C
per century. Coral bleaching occurs when the thermal tolerance of corals and
their photosynthetic symbionts (zooxanthellae) is exceeded. Mass coral
bleaching has occurred in association with episodes of elevated sea
temperatures over the past 20 years and involves the loss of the zooxanthellae
following chronic photoinhibition. Mass bleaching has resulted in significant
losses of live coral in many parts of the world. This paper considers the
biochemical, physiological and ecological perspectives of coral bleaching. It
also uses the outputs of four runs from three models of global climate change
which simulate changes in sea temperature and hence how the frequency and
intensity of bleaching events will change over the next 100 years. The results
suggest that the thermal tolerances of reef-building corals are likely to be
exceeded every year within the next few decades. Events as severe as the 1998
event, the worst on record, are likely to become commonplace within 20 years.
Most information suggests that the capacity for acclimation by corals has
already been exceeded, and that adaptation will be too slow to avert a decline
in the quality of the world’s reefs. The rapidity of the changes that
are predicted indicates a major problem for tropical marine ecosystems and
suggests that unrestrained warming cannot occur without the loss and
degradation of coral reefs on a global scale.
- 1999
Effects of climate change on fish reproduction and early life history stages
Seasonal change in temperature has a profound effect on reproduction in fish. Increasing temperatures cue reproductive development in spring-spawning species, and falling temperatures stimulate reproduction in autumn-spawners. Elevated temperatures truncate spring spawning, and delay autumn spawning. Temperature increases will affect reproduction, but the nature of these effects will depend on the period and amplitude of the increase and range from phase-shifting of spawning to complete inhibition of reproduction. This latter effect will be most marked in species that are constrained in their capacity to shift geographic range. Studies from a range of taxa, habitats and temperature ranges all show inhibitory effects of elevated temperature albeit about different environmental set points. The effects are generated through the endocrine system, particularly through the inhibition of ovarian oestrogen production. Larval fishes are usually more sensitive than adults to environmental fluctuations, and might be especially vulnerable to climate change. In addition to direct effects on embryonic duration and egg survival, temperature also influences size at hatching, developmental rate, pelagic larval duration and survival. A companion effect of marine climate change is ocean acidification, which may pose a significant threat through its capacity to alter larval behaviour and impair sensory capabilities. This in turn impacts on population replenishment and connectivity patterns of marine fishes.
Tập 62 Số 9 - Trang 1015 - 2011
Carbon in catchments: connecting terrestrial carbon losses with aquatic metabolism
For a majority of aquatic ecosystems, respiration (R)
exceeds autochthonous gross primary production (GPP). These systems have
negative net ecosystem production
([NEP]=[GPP]–R) and
ratios of [GPP]/R of <1. This net
heterotrophy can be sustained only if aquatic respiration is subsidized by
organic inputs from the catchment. Such subsidies imply that organic materials
that escaped decomposition in the terrestrial environment must become
susceptible to decomposition in the linked aquatic environment.
Using a moderate-sized catchment in North America, the Hudson River (catchment
area 33500 km2), evidence is presented for the magnitude
of net heterotrophy. All approaches (CO2 gas flux;
O2 gas flux; budget and gradient of dissolved organic C;
and the summed components of primary production and respiration within the
ecosystem) indicate that system respiration exceeds gross primary production
by ~200 g C m-2 year-1. Highly
14C-depleted C of ancient terrestrial origin
(1000–5000 years old) may be an important source of labile organic
matter to this riverine system and support this excess respiration. The
mechanisms by which organic matter is preserved for centuries to millennia in
terrestrial soils and decomposed in a matter of weeks in a river connect
modern riverine metabolism to historical terrestrial conditions.
Tập 52 Số 1 - Trang 101 - 2001
Why otoliths? Insights from inner ear physiology and fisheries biology
Otoliths are of interest to investigators from several disciplines including systematics, auditory neuroscience, and fisheries. However, there is often very little sharing of information or ideas about otoliths across disciplines despite similarities in the questions raised by different groups of investigators. A major purpose of this paper is to present otolith-related questions common to all disciplines and then demonstrate that the issues are not only similar but also that more frequent interactions would be mutually beneficial. Because otoliths evolved as part of the inner ear to serve the senses of balance and hearing, we first discuss the basic structure of the ear. We then raise several questions that deal with the structure and patterns of otolith morphology and how changes in otoliths with fish age affect hearing and balance. More specifically, we ask about the significance of otolith size and how this might affect ear function; the growth of otoliths and how hearing and balance may or may not change with growth; the significance of different otolith shapes with respect to ear function; the functional significance of otoliths that do not contact the complete sensory epithelium; and why teleost fishes have otoliths and not the otoconia found in virtually all other extant vertebrates.
Tập 56 Số 5 - Trang 497 - 2005
Sources, sinks and transformations of organic carbon in Australian floodplain rivers
This paper reviews research on fluxes of carbon in Australian floodplain
rivers. Except where cover is absent, and in-stream gross primary production
is >1 gC m–2 day–1
and ratios of production to respiration are >1, riparian sources dominate
carbon pools in catchment streams. On floodplains, primary production by river
red gum (Eucalyptus camaldulensis) forests is ~600
gC m–2 year–1. Total
primary production by aquatic macrophytes and biofilms in floodplain wetlands
is >2500 gC m–2
year–1 and >620 gC
m–2 year–1,
respectively. Large pools of particulate organic carbon (POC) exist on
floodplains as litter (>500 gC m–2) and coarse
woody debris (~6 kgC m–2). Floods may release
50 gDOC m–2 from leaf litter. Export of this DOC
(dissolved organic carbon) may be substantial relative to autochthonous
production in river channels. Sediments deposited on floodplains during large
floods represent a substantial sink of riverine POC (up to 280 gC
m–2). Bacteria are responsible for rapid
decomposition of DOC and POC in floodplain wetlands (sediment respiration and
methanogenesis, both ~1 gC m–2
day–1). Flow and its interaction with
geomorphology control carbon fluxes in rivers. Decreased inputs of floodplain
carbon, following river regulation and physical disturbances to catchments and
floodplains, may have resulted in many Australian rivers being dominated by
algal production.
- 1999
Studies on southern Australian abalone (genus Haliotis). I. Ecology of five sympatric species Five species of abalone occur along the southern Australian coastline; of these three species, Haliotis laevigata Donovan, Haliotis roei Gray, and Haliotis ruber Leach, are of commercial importance; the other two species are Haliotis cyclobates Peron and Haliotis scalaris Leach. The habitat, movement, feeding behaviour, food, and ecological relationships with predators were studied for each species at three study sites. Each species of abalone occupies a distinctive microhabitat. H. cyclobates lives in calm-water places associated with communities of the seagrass Posidonia australis and the razor shell Pinna dolobrata; H. laevigata lives on open rock adjacent to sand in moderate to rough water localities; H. ruber prefers caves in calm- to rough-water localities; H. roei occurs in narrow crevices in the upper sublittoral on rough-water coasts ; H. scalaris is an under-boulder or crevice-living species. All species are sedentary, but may make local movements in search of food. Several species may occur in a given habitat but there is little microhabitat overlap. The seasonal variation in food eaten by each species is described. All species show preference for red algae and reject most species of brown algae, subsisting predominantly on red algae and seagrasses according to the possibilities of the habitat. H. laevigata feeds mainly on algal drift and H. roei is substantially a grazing species. The other species feed on algal drift or graze opportunistically. Water movement is an important environmental factor affecting the feeding of those species which feed on algal drift. H. laevigata and H. ruber feed best in conditions of moderate water movement but poorly if the water is too calm or too rough. Water movement elicits a characteristic feeding response in these species. The predators of abalone include fish, crabs, molluscs, and starfish; their interaction with abalone is discussed. Crevices, caves, and cavities under boulders provide a refuge in space from predators for H. roei, H. ruber, and H. scalaris and juveniles of other species, which appear to be confined to these places, except for nocturnal feeding excursions, by the activity of their predators. The adults of the different species differ from each other in their dependence on water movement, their preference for open or cryptic sites such as crevices or caves for resting, their size and their methods of feeding. These differences between the species, taken together, ensure that there will be very little overlap between them in the sorts of places that they seek to live in or their behaviour in seeking food; in those cases where food-seeking behaviour is similar, interspecific competition would seem to be negligible because food is abundant. Predation would seem to have been more important than interspecific competition as the selective pressure that established and maintains these differences between the species.
Tập 24 Số 3 - Trang 217 - 1973
Hydrodynamics of a tidal creek-mangrove swamp system. A mathematical model is proposed for the movement of water and sediments in Coral Creek. a tidal creek surrounded by thickly vegetated mangrove wamps in Missionary Bay at the northern end of Hinchinbrook Island, northern Queensland. It is shown that a net down-stream longitudinal current through mangrove swamps exists and is responsible for rapidly carrying away organic detritus (e.g. fallen tree leaves) to the ocean, thereby enhancing the export of nutrients from mangrove swamps. The asymmetry between ebb and flood currents contributes to the maintenance of a deep self-sustaining drainage channel. even in the presence of a large sediment input from surrounding coastal waters. The size and geometry of the drainage channel are related to vegetation density in mangrove swamps. Evapotranspiration from mangroves in Coral Creek is responsible for the existence of a longitudinal salinity gradient. The evapotranspiration rate could be as large as 3 cm,'day. Residual currents are clockwise in Missionary Bay and explain the overall patterns of scour and deposition in the bay.
Tập 31 Số 4 - Trang 431 - 1980
Potential effects of climate change on Australian estuaries and fish utilising estuaries: a review Estuaries are especially vulnerable to the impacts of climate change because changes in climatic and hydrologic variables that influence freshwater and marine systems will also affect estuaries. We review potential impacts of climate change on Australian estuaries and their fish. Geographic differences are likely because southern Australian climates are predicted to become warmer and drier, whereas northern regions may see increased precipitation. Environmental factors, including salinity gradients, suspended sediment, dissolved oxygen and nutrient concentrations, will be influenced by changing freshwater input and other climate variables. Potential impacts will vary depending on the geomorphology of the estuary and the level of build-up of sand bars across estuarine entrances. Changes to estuarine fish assemblages will depend on associated changes to salinity and estuarine-mouth morphology. Marine migrants may be severely affected by closure of estuarine mouths, depending on whether species ‘must’ use estuarine habitat and the level of migratory v. resident individuals. Depending on how fish in coastal waters locate estuaries, there may be reduced cues associated with estuarine mouths, particularly in southern Australia, potentially influencing abundance. In summary, climate change is expected to have major consequences for Australian estuaries and associated fish, although the nature of impacts will show significant regional variation.
Tập 62 Số 9 - Trang 1115 - 2011
Dinoflagellates in the Australian Region. In this paper, the taxonomy of the dinoflagellates found in Australian
waters is given, and the species concept as applied to the group is discussed.
It is suggested that the Linnaean species concept cannot be strictly applied to
a group which has, as a whole, no known sexual process and of which the vast
majority of forms has not been cultivated.
The seasonal variation and fluctuations of dinoflagellates in Australian
waters are considered. It is found that, as usual, the greatest number of
species occurs in warmer waters.
Dinoflagellates are regarded as excellent indicators of water masses, and
in one example, i.e. west of Tasmania, subtropical dinoflagellates led to the
postulation of a subtropical current flowing east from Cape Leeuwin to King
I. This has recently been confirmed by the finding of warm-water turtles on
the west coast of Tasmania.
Dinoflagellates are not as important as diatoms or tropical blue-green
algae in productivity, except on rare occasions, but do serve as food for certain
groups, e.g. salps, tintinnids, etc. Some are halophytic, some holozoic, and some
facultative.
No single factor or set of factors can be adduced to explain dinoflagellate
maxima. There is some evidence of a rhythm, which may be tidal, in Goniaulas
digitale and also in G. catenella.
Tập 5 Số 2 - Trang 171 - 1954
Coral assemblages and physico-chemical characteristics of the Whitsunday Islands: evidence of recent community changes
Benthic communities were assessed and 22 environmental variables were
monitored at seven leeward localities (L1ŒL7) in the Whitsunday Islands,
Queensland, Australia. L1 was near the Proserpine and O’Connell river
mouths and L7 ~80 km north of the river mouths. Distinct physico
Œchemical and biological gradients were evident. Sparse scleractinian
coral communities, dominated by faviids, Montipora spp.
and encrusting Porites colonies, were present at L1, L2
and L3, whereas diverse reef-building communities, dominated by
Acropora spp., were more common at and beyond L4. The
number of coral recruits (age <6 months) did not differ significantly among
localities, suggesting that coral recruitment was near random and that the
environment shapes the adult community from those recruits. The study
demonstrates strong negative relationships between chlorophyll
a and the following: percentage coral cover, coral
species richness and coral abundance. The reef-building capacities of the
coral communities and the extent of Holocene reef development were
inconsistent at L2 and L3, which is interpreted as a sign of anthropogenic
effects.
Tập 50 Số 5 - Trang 427 - 1999