bluuebunny/crossref_metadata_2025 huggingface dataset:
An ageing methodology, growth parameters and estimates of mortality for hake (Merluccius australis) from around the South Island, New Zealand
Authors: Horn Peter L.
Published: August 2004

A method is described to determine the age of hake by counting zones in
sectioned otoliths. The technique was validated to age 1 years from the
progression of modes in length–frequency distributions, and for ages 2
years onwards by examining the state of otolith margins from fish sampled
regularly over a one-year period. von Bertalanffy growth parameters are
estimated for hake on the Campbell Plateau and Stewart–Snares shelf, on
the Chatham Rise, and off the west coast of the South Island. Hake grow
rapidly for about five years, but growth is slight after about 12 years.
Female fish have a significantly faster rate of growth than males. A value
forM of 0·20–0·25 is proposed.
Differences in growth rates and population age distributions imply that there
are at least two stocks of hake in New Zealand waters, with fish off the west
coast of the South Island being distinct from those on the Campbell Plateau
and Chatham Rise.
Estuaries to salt lakes: Holocene transformation of the estuarine ecosystems of south-western Australia
Authors: Hodgkin Ernest P. , Hesp Patrick
Published: August 2004

When the estuaries of south-western Australia were first flooded by the
Holocene marine transgression about 7000 years before present (BP), most were
enclosed by limestone barrier dunes. Coastal sand drift built bars and
flood-tide deltas in the narrow entrances, but until about 3500 years BP the
estuaries remained tidal-dominated systems with a diverse
marine–estuarine fauna. Now the bars/deltas so obstruct the small
tides that estuary water is fresh in winter and marine to hypersaline in
summer; the estuaries are river-flow-dominated systems and the ecosystems are
characterised by a restricted euryhaline estuarine biota. Some estuaries are
still permanently open, their bars/deltas never
close, and some are seasonally open, their bars open
with river flow in winter and close in summer. Other estuaries are
normally closed, their bars remain closed for several
years and break with episodic flood flow, or are
permanently closed coastal salt lakes with bars that
never or rarely break: they can become grossly hypersaline and may dry up
altogether. An hypothesis to explain this Holocene transformation of the
estuaries attributes it principally to sedimentary processes in an environment
where river flow is highly seasonal, tides are microtidal, there was a fall in
sea level, and there are differences in the volume and periodicity of flow and
the degree of shelter to the entrances from the prevailing south-west winds
and swell.
Variability of directional spectra of wind-generated waves, studied by means of wave staff arrays
Authors: Babanin Alexander V. , Soloviev Yuri P.
Published: August 2004

Parameterization of the directional distribution of the wave energy obtained
by means of arrays of wave probes is suggested. The parameterization
encompasses a wide frequency band both above and below the peak frequency as
well as a broad range of wave ages. The parameterization is developed for the
integral width of the directional spectrum, which does not depend on a
specific form of the approximating function. The width of the directional
distribution depends on the stage of wave development and relative frequency.
The narrowest directional spectra are observable, on average, 5% below
the peak frequency. Above that frequency, the width of the directional
spectrum increases as the frequency rises, and the rate of widening does not
depend on the wave age. On the forward face of the spectrum, the rate of
widening of the directional distributions towards low frequencies depends
strongly on the stage of wave development and, at early stages, the
directional spectra in this range are unchangeable. In general, the
directional distributions of wave energy become narrower as the waves develop.
Coral bleaching and elevated sea-water temperature in Milne Bay Province, Papua New Guinea, 1996
Authors: Davies Jocelyn M. , Dunne Richard P. , Brown Barbara E.
Published: August 2004

A coral bleaching event began in February 1996 on reefs in Milne Bay Province,
Papua New Guinea. Corals were affected on the shallow fringing reef and to
water depths of greater than 20 m on the reef slope. Bleaching was extensive
and in the survey area 54% of all corals were bleached. Branching
corals (particularly Acropora and
Pocillopora) were more severely affected than massive
species. Bleaching occurred at the time of the annual maximum monthly sea
temperature when long-term sea temperature data sets recorded an anomaly of
+ 1.29°C. Analysis of the anomalies over the previous 40 years shows
a positive trend of 0.09°C per decade.
Physiological responses of seagrasses used to identify anthropogenic nutrient inputs
Authors: Udy James W. , Dennison William C.
Published: August 2004

Fertilization experiments have established that seagrass growth in Moreton Bay
can be limited by the supply of both N and P. In the present study,
morphological and physiological characteristics (canopy height, shoot density,
biomass, growth, tissue nutrient content, amino acid concentrations and
δ15N ratios) of
Zostera capricorni Aschers. in Moreton Bay, close to and
distant from nutrient sources, were compared.
Z. capricorni at the four sites close to nutrient
sources (sewage, septic or prawn-farm effluent, or river discharge), had
physiological characteristics representative of high nutrient availability and
at the five sites distant from nutrient sources had physiological
characteristics representative of low nutrient availability. Differences in
sediment nutrient concentrations
(NH4+ and
PO43- ), seagrass morphology and
growth were not related to proximity to nutrient sources. However, the
nutrient content of the seagrasses and their amino acid concentrations were
consistently higher at sites close to a nutrient source. The amino acids
glutamine and asparagine were the most responsive to elevated nutrient
availability, and δ15N values of seagrasses
reflected the source of N rather than the nutrient load. These results
demonstrate that physiological characteristics of seagrasses can be used to
identify the nutrient load and source affecting marine ecosystems.
Squalene content in livers from deep-sea sharks caught in Canary Island waters
Authors: Hernández-Pérez Margarita , Gallego Rosa M. Rabanal , Alayón Pedro J. Pascual , Hernández Alberto Brito
Published: August 2004

The content of liver oil from deep-sea sharks caught in Canary waters was
examined to ascertain whether the species studied might be a source of
commercially valuable squalene. Sixty-three sharks caught at depths of
600–2100 m represented seven species:
Centroscymnus coelolepis,
Centroscymnus cryptacanthus,
Centrophorus squamosus,
Centrophorus lusitanicus,
Deania histricosa,
Deania profundorum and
Etmopterus princeps. The relative weight of the liver
ranged from 15% to 26% of total body weight and
59–82% of the liver wet weight was oil. The major lipid classes
were hydrocarbons (45–77% in liver oil), as is typical of most
deep-water sharks. High concentrations of squalene in the livers
(27–61% of liver wet weight) suggested that sharks caught in deep
waters off the Canary Islands could be a rich source of squalene.
Resumen. Se ha examinado el contenido de aceite en hígado de tiburones
capturados en aguas profundas de Canarias, con el fin de comprobar si las
especies estudiadas pueden constituir una fuente valiosa de escualeno a nivel
comercial. Para ello fueron analizados 63 ejemplares de siete especies de
tiburón capturadas a una profundidad entre 600 y 2100 m:
Centroscymnus coelolepis,
Centroscymnus cryptacanthus,
Centrophorus squamosus,
Centrophorus lusitanicus,
Deania histricosa,
Deania profundorum y
Etmopterus princeps. El peso de los hígados
supone el 15–26% del peso total de tiburón y el
59–82% del peso de hígado es aceite. Los lípidos
que se encuentran en mayor proporción (45–77% en aceite)
fueron identificados como hidrocarburos, lo cual es típico en la
mayoría de los tiburones de profundidad. Los hígados contienen
altas concentraciones de escualeno (27–61% en peso de
hígado) indicando que efectivamente los tiburones capturados en aguas
profundas de Canarias pueden ser una buena fuente de escualeno.
The puerulus of the spotted spiny lobster, Panulirus guttatus (Latreille 1804) (Crustacea: Decapoda)
Authors: Lyons W. G. , Hunt J. H.
Published: August 2004

The puerulus of Panulirus guttatus is described from
specimens collected at Florida reefs. Preliminary examination by scanning
electron microscopy of the spatulate antennal tip of a
P. guttatus puerulus revealed no qualitative features
different than those previously described for the tapered antennal tip of
P. cygnus. The unique combination of morphological
characters of the P. guttatus puerulus requires minor
adjustment to a recently proposed evolutionary classification of
Panulirus based on pueruli.
Influence of wind on water levels and lagoonriver exchange in the River Murray, Australia
Authors: Webster Ian T. , Maier Holger , Burch Michael , Baker Peter
Published: August 2004

This paper examines river water levels and water exchange between the river
and an adjacent lagoon at a site on the River Murray about 150 km from its
discharge point into Lake Alexandrina. Riverine water levels at the site
underwent significant fluctuations (~ 0·3 m) which appeared to be
mainly associated with fluctuations in the N–S component of wind rather
than with discharge.
The lagoon studied was connected by a channel to the river. The measured flow
through the channel was almost always out and had an average rate over the 30
days of the study which was large enough to empty the lagoon in 9 days. It is
hypothesized that the replenishment flow to the lagoon occurred as a seeping
flow through the bank separating the lagoon from the river. Successful
comparisons between measurements and computer simulations of river water level
and of the flow through the channel confirmed that it was the wind stress
acting on the surface that mediated variations in riverine water levels and
the exchange between river and lagoon.
Seasonal changes in organic constituents in leaves of nine mangrove species
Authors: Basak U. C. , Das A. B. , Das P.
Published: August 2004

Seasonal variations in protein, polyphenol and tannin concentrations in leaves
of nine mangrove species of Rhizophoraceae
(Bruguiera cylindrica,
B. gymnorrhiza, B. parviflora,
B. sexangula, Ceriops decandra,
C. tagal, Kandelia candel,
Rhizophora apiculataandR. mucronata)
are reported. Mean protein concentration varied from 0.108 g
g-1 dry wt in B. cylindrica to
0.231 g g-1 dry wt in
B. sexangula; mean polyphenol concentration ranged from
0.111 g g-1 dry wt in B. sexangula
to 0.488 g g-1 dry wt in
C. decandra, and mean tannin concentration from 0.088 g
g -1 dry wt in B. parviflora to
0.408 g g-1 dry wt in
B. sexangula. Concentrations of these organic
constituents in leaf tissues were highest during the rainy season:
Bruguiera sexangula had the highest concentration of
protein (0.291 g g-1 dry wt) and tannin (0.441 g
g-1 dry wt) and C. decandra the
highest concentration of polyphenols (0.528 g g-1 dry
wt). Significant variation in organic constituents was observed among the
species in different seasons and protein concentration was negatively
correlated with polyphenols and tannin.
Experimental manipulations of the biomass of introduced carp (Cyprinus carpio) in billabongs. II. Impacts on benthic properties and processes1
Authors: Robertson A. I. , Healey M. R. , King A. J.
Published: August 2004

Two billabongs on the floodplain of the Murrumbidgee River, Australia, were
partitioned in half with impermeable plastic barriers and the biomass of carp
was manipulated to establish high- and low-carp biomass treatments in each
billabong. Measurements of benthic variables (rates of particle settlement,
biofilm development, sediment respiration, macrophyte detritus decomposition,
sediment solid-phase nutrient concentrations and benthic algal biomass) were
performed over four months from summer to winter 1995. Rates of particle
settlement were greater in the high-carp treatment of each billabong
throughout the experiment. High carp biomass had a negative impact on the
autotrophic component of the biofilm developing on wood blocks placed at
different heights above the sediment surface but the mechanism responsible
differed between billabongs. Sediment oxygen demand became greater in the
presence of a higher biomass of carp during the experiment but time courses
differed between billabongs. Manipulations of carp biomass did not influence
algal biomass on the sediment surface, the rate of decomposition of macrophyte
detritus or sediment solid-phase nutrients or nutrient ratios. The impact of
carp on benthic and surficial processes was significant but the mechanisms of
change differed between billabongs.
Keeping the fish in ‘fish and chips’: research and management of the Western Australian shark fishery
Authors: Simpfendorfer Colin , Donohue Kevin
Published: August 2004

The shark fishery in the southern half of Western Australia fishery began in
1941 and developed slowly until the mid 1970s when the fishery began to expand
rapidly. A management plan incorporating limited entry, gear specifications
and effort controls was introduced in 1988 in response to concerns about the
status of the stocks. Research has focused on the assessment of stocks, and
has involved the collection of catch-and-effort data since 1975, and tactical
research projects to gather data on biology; this has allowed the
implementation of stock assessment, modelling and forecasting techniques. The
fishing industry is involved in the development of the research projects and
in the decision-making process of management. This, together with regular
reporting of research results, assists in maintaining industry support and
acceptance of results. A potential disadvantage of the involvement of industry
is the delay in implementation that may be caused by the complexity of the
system of consultation or by the conflict between regulation of the fishery
and the present livelihood of fishers. However, this is minimized by the
creation of clear quantitative targets for management.
Effects of cyanide on corals in relation to cyanide fishing on reefs
Authors: Jones Ross J. , Steven Andrew L.
Published: August 2004

Small fragments of the zooxanthellate corals
Pocillopora damicornis and
Porites lichen were subjected to a range of cyanide
concentrations for various times (i.e. to various cyanide doses). Doses
encompassed those likely to be experienced by corals as a result of various
cyanide fishing practices. Following the highest doses, corals died; after
medium doses, they lost their zooxanthellae (symbiotic algae) resulting in a
discolouration or ‘bleaching’; and after the lowest doses they
lost zooxanthellae but not in sufficient numbers to cause noticeable
discolouration. Respiratory rates of P. damicornis were
inhibited by 10–90% following exposure to cyanide but recovered
to pre-exposure levels within 1–2 h after transfer to clean sea water.
Age and growth of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in Queensland east-coast waters with implications for stock structure
Authors: Begg Gavin A. , Sellin Michelle J.
Published: August 2004

Age and growth of school mackerel
(Scomberomorus queenslandicus) and spotted mackerel
(S. munroi) in east-coast waters, Queensland, Australia
(16˚S to 28˚S), were determined to provide population parameters
required for stock assessment and fisheries management. Female school mackerel
(L∞ = 651 mm,
K = 0.59,
t0 = –1.41) were
estimated to grow to a greater asymptotic length, but at a slower rate, than
males (L∞ = 628 mm,
K = 0.71,
t0 = –1.26). Growth
patterns of school mackerel differed between geographic regions and suggested
the existence of separate stocks throughout the east-coast distribution. In
contrast, female spotted mackerel
(L∞ = 849 mm,
K = 0.46,
t0 = –1.54) were
estimated to reach a greater asymptotic length at a faster rate than males
(L∞ = 768 mm,
K = 0.23,
t0 = –4.33). There
was no difference in growth between spotted mackerel from different regions,
suggesting that there is a single stock along the Queensland east coast.
Identification of school and spotted mackerel populations in Queensland
east-coast waters will enable the species to be managed on the basis of stock
structure across this range.
Optical properties of ocean waters in the vicinity of the Chatham Rise, South Pacific Ocean
Authors: Shooter David , Davies-Colley Robert J. , Kirk John T. O. , Schwarz Anne-Maree
Published: August 2004

Apparent optical properties of the water at 21 ocean stations in the South
Pacific, east of New Zealand in the vicinity of the Chatham Rise, have been
studied. Spectral irradiance attenuation and reflectance, and PAR irradiance
attenuation, were measured in Sub-tropical and Sub-antarctic water masses, in
the Sub-tropical Convergence zone between them, and in coastal waters. The
waters studied are considered to be predominantly Jerlov optical types II and
III. Anomalous features at wavelengths above 590 nm in the spectra of
reflectance and of the vertical attenuation coefficient for upward irradiance
were attributed predominantly to Raman emission with a contribution from
chlorophyll fluorescence at longer wavelengths.
Keystone coleopterans? Colonization by wood-feeding elmids of experimentally immersed woods in south-eastern Australia
Authors: McKie B. G. L. , Cranston P. S.
Published: August 2004

Macroinvertebrates on immersed woods in streams in montane south-eastern
Australia respond to differences in wood taxa, according to a 4-month
colonization study of experimentally positioned sticks. Xylophagous elmids
(Coleoptera : Elmidae) strongly preferred local native
Eucalyptus over other types of wood including non-native
softer timbers (Pinus and Alnus).
Where gouging elmids were abundant (in native forest streams with native
riparian vegetation), immersed Eucalyptus wood supported
high abundances of other macroinvertebrates; in their absence (in open
grassland streams), Eucalyptus supported few other
macroinvertebrates. Macroinvertebrate-gouged channels were present
disproportionately on Eucalyptus sticks relative to
other wood species. It is proposed that xylophagous elmid beetles are the
principal macroinvertebrate modifiers of wood in these south-eastern
Australian streams, where their gouging of channels increases surface area,
thereby facilitating colonization by other macroinvertebrates and
wood-decaying microorganisms and fungi.
Effects of predation on the size structure of the gastropod Salinator solida (Martens) populations at Towra Point, NSW, Australia
Authors: Roach A. C.
Published: August 2004

The pulmonate gastropod Salinator solida inhabits
intertidal mangrove and saltmarsh communities throughout New South Wales.
Studies at Towra Point and elsewhere have consistently found that the mean
size and range of size/age classes increases with height on shore. Afield
experiment was undertaken to test the hypothesis that predation was
responsible for reductions in the mean size of individuals
inS. solida populations in the upper mangrove forest.
Twelve months after the establishment of fenced plots, there were
significantly more individuals in the fenced plots than in unfenced or
partially fenced control plots; the number of snails in the 4.1–8.0 mm
and > 8.1 mm size classes had increased in the fenced plots but not in the
control plots. The results suggest that predation is a major factor
determining variation in population size structure by acting to significantly
reduce the abundance of adults in the upper mangrove forest.
Mysids and environmental monitoring: a case for their use in estuaries
Authors: Roast S. D. , Thompson R. S. , Widdows B , J. , Jones M. B.
Published: August 2004

Mysids (Crustacea : Mysidacea) are ubiquitous members of the permanent,
endemic hyperbenthic fauna of estuarine and other coastal ecosystems. They
often occur in high numbers and their ecological importance, particularly
their role in food chains as a link between the benthic and pelagic systems,
is becoming increasingly apparent. In general, mysids are omnivores, feeding
on detritus, zooplankton and phytoplankton, and they contribute up to
40% of the standing stock of omnivores in some systems. In estuaries,
specific mysid faunas often occur in discrete zones, usually as a result of
different salinity tolerances, although responses to turbidity and water flow
also determine mysid distributions. Many mysids are particularly sensitive to
chemical contaminants as illustrated by their relatively low 96-h
LC50 values. Due to this sensitivity, the United States
Environmental Protection Agency promotes the use of
Americamysis ( Mysidopsis) bahia for laboratory toxicity
testing; however, there is growing interest in the use of local, endemic
species rather than the standard American mysid. At Plymouth, novel and
sensitive techniques are being developed for assessing sublethal responses to
toxicants by use of the northern European estuarine mysid
Neomysis integer. This paper summarizes the ecological
role of mysids in estuaries and describes their potential for use for
estuarine environmental monitoring.
Macroalgal recruitment in artificially disturbed areas: interactive effects of temporal and spatial scale
Authors: Emmerson Louise M. , Collings Gregory J.
Published: August 2004

The effect of the surrounding community and spatial extent of disturbance on
recruitment was investigated in a mixed stand (dominated by large brown algae
of the order Fucales) on a subtidal rocky platform in South Australia. In
particular, survival and growth of Cystophora and
Sargassum recruits on natural substratum were examined
in artificially cleared areas of three sizes (30 × 30 cm, 60 × 60
cm and 100 × 100 cm). Abundance and growth of recruits was monitored for
6 months at both the edge and the centre of the clearances. The influence of
clearance size and position within a clearance on the abundance of recruits
changes with time. Initially, the size of clearance was most important, with
larger clearances supporting denser stands of recruits. However, after 143
days, position within the clearance became important, with greater mortality
at the edges than at the centre. The large residual values associated with the
analysis were evidence of the variability of the interactions within this
community. The results demonstrate the importance of the consideration of
spatial and temporal scales, and particularly the position within a disturbed
area, in recruitment studies.
Life history and population dynamics of the exotic snail Potamopyrgus antipodarum (Prosobranchia : Hydrobiidae) in Lake Purrumbete, Victoria, Australia
Authors: Schreiber E. S. G. , Glaister A. , Quinn G. P. , Lake P. S.
Published: August 2004

The density, population size-structure, and fecundity of the exotic snail
Potamopyrgus antipodarum are described, for a period of
two years, on two shores subject to different levels of disturbance in Lake
Purrumbete. The population dynamics of
Potamopyrgus antipodarum showed the same seasonal
pattern in the numbers of embryos carried per individual female in both years,
but seasonal patterns in density and potential reproductive output of the
population differed between shores. Densities of
Potamopyrgus antipodarum were high, with a trend for
highest densities to occur in spring and summer. The population consisted
almost entirely of females, which is indicative of a parthenogenic mode of
reproduction. Fecundity was high, with the number of embryos carried per
female peaking in spring. In summer, the population was dominated by small
individuals, but some small snails were present at all times of the year.
Potamopyrgus antipodarum was found to be a very
successful invader of Lake Purrumbete, with high densities, high fecundity,
parthenogenesis and the presence of embryos throughout the year contributing
to this success.
Nitrate applications to control phosphorus release from sediments of a shallow eutrophic estuary: an experimental evaluation
Authors: McAuliffe T. F. , Lukatelich R. J. , McComb A. J. , Qiu S.
Published: August 2004

Effects of nitrate on phosphate release from sediments of a eutrophic estuary
were investigated under laboratory conditions, using reconstituted
sediment–water cores. Application of nitrate (5–100 mg
L-1 NO3-N) increased redox
potential near the sediment–water interface from –200 mV to about
200 mV during 25 days of incubation. The effective concentration of nitrate
differed between sediments, reflecting differences in sediment properties,
particularly bioavailable carbon. Reduced phosphate after nitrate application
is attributed mainly to: (1) increased iron (III)
binding near the sediment–water interface; and (2)
increased dissolved oxygen in the water column due to lowered oxygen demand,
with increased oxidation of ferrous iron and substances binding soluble
reactive phosphate. High nitrate concentrations (50 and 100 mg
L-1 NO3-N) did not persist through
a 155-day incubation, suggesting that without carbon limitation added nitrate
will eventually be consumed by microbial activity, and increased phosphate
release may occur. Nitrate application directly into the surface sediment
increased nitrate consumption, and so was less effective than application to
the water column. Frequent resuspension increased dissolved oxygen
concentration, so reduced nitrate consumption and lowered concentration of
soluble reactive phosphate.
Feasibility studies on mangrove Avicennia marina cultivation below ground level along the bank of a dug-out pond
Authors: Anwahi Abdulrazzaq , Zarouni Mohamed Abdel Rahim Al , Janahi Ahmed Al , Cherian Thomas
Published: August 2004

The feasibility of cultivating grey mangrove A. marina
on the bank of a dug-out pond at 2.25 m below ground level ~500 m inland at
Umm Al Qaiwain, United Arab Emirates, has been studied. A seedling emergence
of 74% to 84% was observed within 10 days of sowing 796 seeds
(propagules). Average values of shoot height, number of leaves and number of
branches decreased with distance from the water line. Growth rates of the
seedlings were reasonably good (0.19–0.26 cm
day-1).
Feeding technique, critical size and size preference of Jasus edwardsii fed cultured and wild mussels
Authors: James Philip J. , Tong Lennard J.
Published: August 2004

This paper describes a technique used by juvenile red rock lobsters,
Jasus edwardsii, 20–70 mm carapace length, to open
and feed on live mussels. This technique appears to be an innate behaviour.
The maximum or critical size (shell length) of cultured and wild
Mytilus galloprovincialis, and cultured
Perna canaliculus, which
J. edwardsiiis capable of opening, is strongly
correlated with lobster carapace length. Jasus edwardsii
is capable of opening significantly larger cultured than wild
M. galloprovincialis; this is a reflection of the
differences in shell morphology between wild and cultured mussels, and the
vulnerability of different shapes to the opening technique employed. In
replacement experiments, the greatest numbers of mussels were eaten from the
smallest mussel sizes (6–20 mm shell length), whereas the greatest
amount of dry flesh weight was consumed from the middle mussel sizes
(11–40 mm shell length) for all three mussel types. Dry-weight
consumption was considered the most appropriate indicator of preference, the
amount of mussel flesh consumed being more relevant to a rock lobster farmer
than the numbers of mussels eaten. The preferred mussel size was approximately
half the critical size. The application of these results to rock lobster
farming is discussed.
Population structure, demography and life tables of Avicennia marina (Forssk.) Vierh. at sites on the eastern and western coasts of the United Arab Emirates
Authors: ElAmry Mamdouh
Published: August 2004

In this 3-year study, an attempt was made to establish life tables and
population structure models at four sites of the only mangrove species
recorded for the area, Avicennia marina. Some of the
sites showed clumped patterns of distribution, there were regular patterns of
distribution on the east coast and random patterns on the west coast. The
population flux reflected different growth-stage capacities at the selected
sites. Survivorship curves were Type I (probability of death increasing with
age) for all populations except for one record of Type III (probability of
death decreasing with age) on the east coast. The data suggest that
A. marina is not endangered in this region, despite the
arid conditions.
Recent advances in mangrove studies using remote sensing data
Authors: Blasco F. , Gauquelin T. , Rasolofoharinoro M. , Denis J. , Aizpuru M. , Caldairou V.
Published: August 2004

This paper summarizes present capabilities in studying mangrove vegetation
from space. There is no standard image processing method that can be applied
for the identification and delineation of coastal ecosystems. From a spectral
point of view, it is practically impossible to characterize each of the sixty
species of trees and shrubs that constitute the mangroves of the world.
Nevertheless, some possibilities exist to map at global and at local scales
mangrove areas from satellite products, combining several space data sets,
interpretation of aerial photographs and ground surveys.
The monitoring of mangroves can be considered as operational at a local level
using remote sensing techniques, whereas monitoring of these ecosystems at
global or at regional levels has not yet been achieved.
Diel feeding and prey selection of three size classes of shortfinned eel (Anguilla australis) in New Zealand
Authors: Sagar P. M. , Glova G. J.
Published: August 2004

Benthic macroinvertebrates and three size classes of shortfinned eel
(Anguilla australis, Anguillidae) were sampled in a
lowland New Zealand stream over a 24-h period in summer to investigate diel
feeding periodicity and prey selection. Fish of all three size classes fed
mostly from post-dusk to dawn, with larger fish tending to consume a greater
proportion of their prey during night-time. The number of prey taxa consumed
increased with increasing size of fish. Prey selection indices indicated that:
(1) the smallest eels (80–100 mm total length, TL)
preferentially consumed ostracods (Crustacea) and larvae of Chironomidae
(Diptera) and Psilochorema sp. (free-living
Trichoptera); (2) medium-sized eels (101–199 mm
TL) preferred larvae of Chironomidae, and Costachorema
sp., Hydrobiosis sp. and
Psilochorema sp.; and (3) large
eels (200–300 mm TL) preferred ostracods,
Psilochorema sp. and
Hudsonema amabilis (cased Trichoptera). Eels of all size
classes showed selection for soft-bodied or easily broken prey over those with
hard cases which would have been more difficult to digest. There was
considerable overlap in the diets of medium and large eels. Differences in the
timing of feeding between the three size classes of eel are explained in terms
of microhabitat use; differences in diet are explained in terms of prey size,
and are also related to eel size.
Effect of light intensity on feeding of striped trumpeter Latris lineata larvae
Authors: Pankhurst Patricia M. , Hilder Pollyanna E.
Published: August 2004

This study investigates the influence of light intensity on feeding of striped
trumpeter larvae, correlating feeding responses with changes in morphology of
the retina during growth. A pigmented single-cone retina had differentiated
one day before first feeding, and rod precursor cells and double cones were
visible in the retina on the 23rd, and 25th day after hatching, respectively.
Feeding performance at four light intensities (0, 1, 30, 150 and 700 lux),
revealed that striped trumpeter larvae are primarily dependent on vision, a
light-dependent behaviour, to feed. The youngest larvae tested (15, 18 and 19
days of age) showed a poor feeding response at 1 lux (range
2–10%), but a 98–100% feeding response at 30, 50 and
700 lux. By 28 days of age, feeding behaviour had changed significantly, with
52% of fish now feeding at 1 lux, 100% of fish feeding at the
intermediate light intensities of 30 and 150 lux, and only 62% of fish
feeding at 700 lux. The apparent increased photopic sensitivity in 28-day-old
fish may reflect increased areas for photon capture provided by double cones,
or may reflect ontogenetic changes in cone spectral sensitivity.
Colonization by lake benthos of hard substrata in the water column versus on the bottom
Authors: Quinn G. P. , Lake P. S. , Schreiber E. S. G.
Published: August 2004

Little work has been done on colonization by lake benthos, particularly onto
hard substrata. This study experimentally compared the rates of colonization
of hard substrata (bricks) in a lake by benthic macroinvertebrates from two
sources — the water column and the bottom. Colonization onto bricks (as
mimics of stones) placed on the bottom of the lake was compared with
colonization onto bricks suspended in the water column, where they could not
be reached by crawling fauna. Almost all taxa colonizing bottom bricks also
colonized suspended bricks, including taxa usually considered benthic (e.g.
gastropods, mites, oligochaetes and planarians). Water-column samples
confirmed the presence of these taxa in open water. These results suggest that
many benthic animals in lakes may move through the water column more readily
than previously considered; constant movement by lake benthos may be in
response to shortage of resources.
Exploitation and movements of yellowfin tuna (Thunnus albacares) and bigeye tuna (T. obesus) tagged in the north-western Coral Sea
Authors: Hampton John , Gunn John
Published: August 2004

Yellowfin tuna (Thunnus albacares) and bigeye tuna
(T. obesus) were tagged and released in the
north-western Coral Sea off northern Queensland in 1991 and 1992. Over the
next five years, recaptures were reported by Australian longline vessels based
in Cairns and fishing in the release area, and by industrial tuna fleets
fishing in the adjacent western Pacific region, thus demonstrating clear links
between the tuna stocks in these areas. Some southerly movements of yellowfin,
in particular, further suggested links with stocks supporting the longline
fishery in the south-eastern Australian Fishing Zone.
Bigeye tuna tag returns and catch per unit effort by Cairns-based longliners
showed a strong seasonal signal, peaking in mid year. Yellowfin tag-return
data displayed a similar, but weaker, seasonal pattern. The data were analysed
by use of tag-attrition models with seasonally variable catchability and with
two assumptions regarding changes in targeting of the two species by
longliners during the study. Under both assumptions, the local exploitation
rates for yellowfin are low: about 0.07 in 1996. For bigeye, the local
exploitation rate in 1996 may have been as high as 0.30, warranting a cautious
approach to further fishery expansion in this area.
Hormone-induced spawning and development of artificially reared larvae of the West Australian dhufish, Glaucosoma hebraicum (Glaucosomatidae)
Authors: Pironet Françoise N. , Neira Francisco J.
Published: August 2004

Hormone-induced spawning of the West Australian dhufish,
Glaucosoma hebraicum (Glaucosomatidae) is reported, and
the artificially-reared eggs and larvae are described. Hormones tested were
hCG, Ovaprim and LHRH analogue, the last both as implants and in a saline
solution. Late-stage fertilized eggs are spherical (960–1200 µm),
possess a pigmented oil globule (210–273 µm) anteriorly on the
unsegmented yolk, and hatch in about 32 hours at ~23˚C. Newly hatched
larvae (1.75–2.10 mm) have a prominent yolk sac which is resorbed after
3.3 days. The mouth becomes functional from Day 3, first feeding occurs from
Day 3.5 and the inflated gas bladder is first observed from Day 4.3. Larvae
examined (1.75–8.13 mm) have a moderately deep body, 24–25
myomeres, early-forming pelvic fins that are heavily pigmented by the
postflexion stage, small to moderate head spination, no gap between anus and
anal-fin origin, and a distinct pattern of pigmentation. Notochord flexion
occurs between 3.42 (15 days) and 4.83 mm (25 days), and the transition to the
juvenile stage starts from ~8 mm (45–46 days). Comparisons with taxa
with similar larvae show that Glaucosoma larvae share
some similarities with pempherid larvae, although the evidence is not
sufficient to strengthen the view that both groups are closely related.
Trace metal concentrations in livers and kidneys of sea turtles from south-eastern Queensland, Australia
Authors: Pople A. R. , Gordon A. N. , Ng J.
Published: August 2004

The concentrations of some or all of arsenic (As), cadmium (Cd), mercury (Hg),
selenium (Se) and zinc (Zn) were determined in the livers and kidneys of 50
stranded sea turtles (38 Chelonia mydas, eight
Caretta caretta, three
Eretmochelys imbricata, one
Lepidochelys olivacea) from the Moreton Bay region of
south-eastern Queensland, Australia. Concentrations of Cd, Se and Zn in the
kidney tended to decrease with age, whereas concentrations of Zn in the liver
tended to increase. Concentrations of Cd in all sea turtle species
(1.7–75.9 µg g-1 wet weight) were amongst
the highest recorded for marine vertebrates globally. Although there was no
obvious association between metal concentrations and particular diseases in
C. mydas, the high concentrations of Cd found in edible
turtle tissues may pose a threat to the health of indigenous people whose diet
includes C. mydas.
Light absorption and scattering by ocean waters in the vicinity of the Chatham Rise, South Pacific Ocean
Authors: Shooter David , Davies-Colley Robert J. , Kirk John T. O.
Published: August 2004

Inherent optical properties, namely spectral absorption coefficients of
soluble and filterable (Millipore 0.22 µm) particulate constituents, and
beam attenuation coefficients, have been measured at 19 stations east of New
Zealand, in the vicinity of the Chatham Rise. In-water spectroradiometer
irradiance measurements were used to test a recent algorithm for the
estimation of spectral absorption coefficients. The results suggest that the
algorithm worked from the near-UV through the blue and green parts of the
spectrum up to wavelengths at which Raman emission became significant (>590
nm). Comparison with spectroradiometrically derived absorption suggests that
calculations of absorption spectra from spectrophotometer measurements of
yellow substance and particulate matter captured on filters are biased by use
of a published empirical relationship for the ‘path amplification’
factor. However, scattering coefficients obtained from the spectroradiometer
data by using the algorithm were in reasonable agreement with those obtained
from transmissometry and spectrophotometric data.
Age determination and growth of the smalltail shark, Carcharhinus porosus, from northern Brazil
Authors: Lessa Rosangela , Santana Francisco Marcante
Published: August 2004

Age and growth of C. porosus was estimated from
seasonally formed marks in vertebrae of 504 specimens (30.0–101.0 cm
total length), and from length–frequency data from 1128 individuals
(29.4–120.5 cm). Estimated von Bertalanffy growth parameters were: from
observed length-at-age, L∞
125.1 cm, K 0.101 year-1 and
t0 –2.89 year; from
back-calculated lengths, L∞
136.4 cm, K 0.077 year-1,
t0 –3.27 year; and from
length–frequency analysis,
L∞ 131.0,
K 0.080 and
t0 –3.40. Growth did not
differ significantly between sexes. Males and females were mature at 71.0 and
70.0 cm, respectively, corresponding to 6 years old. The largest shark aged
from vertebrae was a 12-year-old female (101.0 cm). Growth rates calculated
from mean observed lengths were 7.0 cm year-1 for the
first four years and 4.0 cm year-1 after maturity.
Lee’s phenomenon was not apparent. The annulus forms from September to
January. Parameters derived from back-calculated lengths were considered to
best describe growth. Like most carcharhinids,
C. porosus follows the general pattern of K-selected
species, exhibiting slow growth, late maturity and low fecundity.
Resumo. A idade e o crescimento de
C. porosus foram estimados a partir de marcas sazonais
em vértebras de 504 indivíduos (30.0–101.0 cm comprimento
total) e através de distribuição de
freqÜências de comprimentos de 1128 indivíduos
(29.4–120.5 cm). Os parâmetros de von Bertalanffy obtidos com
comprimentos observados na captura foram:
L∞ 125.1 cm,
K 0.101 ano –1 e
t0 –2.89 anos; com
comprimentos retrocalculados:
L∞ 136.4 cm,
K 0.077 ano-1,
t0 –3.27 anos, e da
distribuição de freqÜências de comprimentos
obteve-se: L∞ 131.0 cm,
K 0.080 ano-1 e
t0 –3.40. O crescimento
não difere entre sexos. Machos e fêmeas são maduras com 71
e 70 cm, respectivamente, correspondendo a idade de 6 anos. O maior
espécime cuja idade foi estimada das vértebras tinha 12 anos
(101.0 cm). As taxas de crescimento calculadas dos comprimentos médios
observados foram 7.0 cm ano-1 para os primeiros quatro
anos e 4.0 cm ano-1 após a maturidade. O
fenômeno de Lee não ocorreu. O anel se forma entre setembro e
janeiro. Os parâmetros obtidos do retroclculo descreveram melhor o
crescimento. Como muitos carcharhinideos, C. porosus
segue o padrão das espécies da seleção K, exibindo
crescimento lento, maturidade tardia e baixa fecundidade.
Phyllochron in Wheat as Affected by Photoperiod Under Two Temperature Regimes
Authors: Slafer Gustavo A. , Rawson H. M.
Published: August 2004

In this paper we describe the effects of photoperiod (9, 12, 15, 17, 19 and 21
h) and temperature (21/17 and 16/12°C) on rate of leaf appearance
and phyllochron in two spring wheats, a semi-winter wheat, and a winter wheat.
Under long photoperiods only, all leaves on the main culm of a cultivar
emerged at a common rate within a temperature regime, so it was acceptable to
assign a specific phyllochron to leaves irrespective of their level of
insertion. Increased temperature significantly decreased phyllochron, but the
degree of this effect differed between cultivars. As photoperiod was shortened
below the optimum, phyllochron lengthened marginally and similarly in all
varieties (by approximately 0.1 days per hour change in photoperiod). For very
short photoperiods this was true only for the first six leaves, whilst for
leaves at higher insertions there was a major effect of reducing photoperiod
on lengthening phyllochron. The actual daylength required for producing this
major effect on phyllochron was cultivar-dependent. These results suggest
that, when making predictions of heading date using phyllochron, it may not be
acceptable to assume that leaf number and time are always linearly related at
shorter photoperiods, particularly when considering leaves at higher
insertions.
Cortical Intracellular Electrical Potential in Roots of Unstressed and Stressed Sunflower Seedlings. II. Radial Profiles and Oscillations
Authors: Cortes P. M.
Published: August 2004

Various models have been proposed to explain how plants can extract water from
dry soil against a gradient in water potential. According to one model, it is
hypothesised that water uptake from dry soil is associated with a radial
gradient in the intracellular electrical potential
(Ec) of root cortical cells such
that the potential in the outer cells is relatively hyperpolarised. As a
partial test of this model, a microelectrode was used to measure radial
profiles of Ec in intact roots of
sunflower (Helianthus annuus) seedlings. The seedlings
were subjected to either a control (unstressed) or one of two stress
treatments. Water stress was rapidly imposed and relieved by lowering and
raising the level of nutrient solution in a tank which contained all the
seedling roots except the lateral root in which
Ec was measured. There was a
gradient in Ec in roots of
unstressed plants with the potential of the outer cortical cells being
relatively depolarised. The imposition of stress shifted the gradient in
accordance with the hypothesis. Increasing the magnitude of the osmotic
potential of the solution perfusing the measured portion of a lateral root of
a stressed seedling resulted in a discontinuity in the profile between the
second and third cortical layers. The gradients in the profile of
Ec indicate there is a limitation
in intercellular electrical coupling and the appearance of a discontinuity may
indicate a decrease in coupling. Three types of occasional, spontaneous
oscillations in Ec are
characterised. One type of oscillation may be additional evidence that the
electrical coupling between the cortical cell layers is variable and depends
on the transport and status of water in the roots.
Seed Germination Model for Eucalyptus delegatensis Provenances Germinating under Conditions of Variable Temperature and Water Potential
Authors: Battaglia M.
Published: August 2004

This paper develops a population-based threshold model to describe the
combined action of sub- and supra-optimal temperatures, water stress and the
release of dormancy by cool-moist stratification on the germination of seeds
of Eucalyptus delegatensis R.T. Baker. Separate models
were fitted for seed samples collected from five climatically differing
regions. The model presumes that the time to germination of a given seed
fraction is inversely proportional to the difference between the actual level
of a given germination factor and the factor threshold. The model then assumes
that variation in this factor threshold within a seed population as a whole
can be characterised by a normal, or log-normal, distribution. By using
physiological time rather than clock time as a metric, the model was extended
to describe germination under varying conditions in the field.
A number of applications of the model were demonstrated. The correlation of
model parameters with regional climate was tested and it was concluded that
site temperature affected both the mean and variation in base population
sensitivities to stratification-dose but that site rainfall affected only the
mean base population sensitivity to water stress with all populations having a
common variance. Examination of the model parameters relating to the release
of dormancy indicated that the increased germination rate associated with
stratification could be accounted for by progress towards germination made at
stratifying temperatures. Finally, the model was used to examine the
fundamental regeneration niche of E. delegatensis and it
was concluded that abundant germination in the field could only be expected
when the soil water potential is above –0.4 MPa and temperatures exceed
7.5°C.
The model is presented as a flexible framework that allows for the prediction
of field germination and as a useful tool for exploring seed germination
processes, and the fundamental regeneration niche of the species. The
modelling framework is easily modified to include additional factors and
factor interactions applicable to other situations and species.