Active and passive dispersal of Centroberyx affinis (Berycidae) and Gonorynchus greyi (Gonorynchidae) larvae on the Sydney shelf

Distributions of small and large larvae of Centroberyx affinis (Berycidae) and Gonorynchus greyi (Gonorynchidae) were examined along a shore-normal transect across the Sydney continental shelf, south-eastern Australia during January and April 1994. Both species were abundant, and 3016 individuals of C. affinis and 3184 individuals of G. greyi were taken. Distributions of small and large C. affinis reflected hydrographic variability and suggested passive dispersal. Previous observations of high year-class variability for this species may therefore reflect oceanographic variability during the larval stage. In contrast, the distributions of G. greyi only partially reflected hydrography and appeared to be influenced by larval behaviour at both sizes. Size distributions during each month indicated protracted spawning periods for both species. Spawning by C. affinis may have occurred over the inner shelf although the location was unclear because of the complexity of nearshore currents. Spawning by G. greyi probably occurred over the outer shelf. An increasing influence of larval behaviour with larval size on the distribution of G. greyi restricted larger individuals to the shelf break; this may have been a response to higher productivity in this region.

Download Full-text

Spawning dynamics of the eastern gemfish (Rexea solandri) in relation to regional oceanography in south-eastern Australia

Marine and Freshwater Research ◽

10.1071/mf00007 ◽

2001 ◽

Vol 52 (4) ◽

pp. 611 ◽

Cited By ~ 8

Author(s):

Jeremy D. Prince ◽

David A. Griffin

Keyword(s):

Continental Shelf ◽

Winter Season ◽

Shelf Break ◽

Sea Surface ◽

Mode Water ◽

Topographic Features ◽

Warm Core ◽

Eastern Australia ◽

Northern Edge ◽

Survival And Growth

Experienced fishers believe the winter aggregations of gemfish are influenced by the following: cold bottom currents from the south and east flowing up onto the shelf; the edge of warm-core eddies; and topographic features along the shelf break. These claims were tested through observations made at sea during industry surveys of the winter gemfish seasons 1996 –98, and the study of 250 m isotherm charts, sea surface temperature data, and historic catch data. The study generally confirmed the anecdotal information collected from the fishers. The first gemfish aggregations of the winter season often form on the southern edge of a warm-core eddy. Secondarily, aggregations tend to form around the northern edge of the warm-core eddy if it is interacting with the shelf break. Finally, gemfish aggregate around the point at which the main flow of the East Australian Current (EAC) detaches from the continental shelf. This timing and location apparently coincides with conditions conducive to the production of subsurface plumes of nutrient-rich deep Sub-Antarctic mode Water. These plumes lead to seasonal enhancement of phytoplankton growth along the edge of the continental shelf, which may offer the adaptive advantage of enhancing the survival and growth of larval gemfish.

Download Full-text

Sand and rhodolith-gravel entrainment on the mid- to outer-shelf under a western boundary current: Fraser Island continental shelf, eastern Australia

Marine Geology ◽

10.1016/0025-3227(96)83350-0 ◽

1996 ◽

Vol 129 (3-4) ◽

pp. 313-330 ◽

Cited By ~ 43

Author(s):

Peter T. Harris ◽

Yoshihiro Tsuji ◽

John F. Marshall ◽

Peter J. Davies ◽

Nobuyuki Honda ◽

...

Keyword(s):

Continental Shelf ◽

Western Boundary Current ◽

Outer Shelf ◽

Western Boundary ◽

Boundary Current ◽

Eastern Australia

Download Full-text

Benthic faunal assemblages and carbon supply along the continental shelf/shelf break-slope off Cape Hatteras, North Carolina

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/s0967-0645(02)00131-5 ◽

2002 ◽

Vol 49 (20) ◽

pp. 4599-4625 ◽

Cited By ~ 27

Author(s):

J.Y. Aller ◽

R.C. Aller ◽

M.A. Green

Keyword(s):

North Carolina ◽

Continental Shelf ◽

Shelf Break ◽

Faunal Assemblages ◽

Carbon Supply ◽

Cape Hatteras

Download Full-text

Density and body size of the larval stages of the invasive golden mussel (Limnoperna fortunei) in two neotropical rivers

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x2012005000006 ◽

2012 ◽

Vol 23 (3) ◽

pp. 282-292 ◽

Cited By ~ 4

Author(s):

Vivianne Eilers ◽

Márcia Divina de Oliveira ◽

Kennedy Francis Roche

Keyword(s):

Body Size ◽

Larval Stage ◽

Larval Density ◽

Limnoperna Fortunei ◽

Larval Size ◽

Larval Stages ◽

Positive Effects ◽

Paraguay River ◽

Body Sizes ◽

Golden Mussel

AIM: The present study involved an analysis of the monthly variations in the population densities and body sizes of the different stages of planktonic larvae of the invasive golden mussel (Limnoperna fortunei), in the rivers Paraguay and Miranda; METHODS: The study was carried out between February 2004 and January 2005. Monthly collection of the plankton samples was accompanied by physical, chemical and biological analyses of the water; RESULTS: The Miranda River presented higher values of calcium, pH, alkalinity, conductivity and total phosphorous. Larval density varied from 0-24 individuals.L-1 in the Paraguay River, with a peak in March of 2004, while in the Miranda River, densities varied between 0-9 individuals.L-1 with a peak in February of 2004. No larvae were encountered during the coldest months, May and June. No significant correlations were found between environmental variables and larval density in either river. Only the valved larval stages were recorded. The "D" and veliger forms were most abundant; umbonate larvae were rare in the Miranda River samples. Mean body sizes of "D", veliger and umbonate larval stages were, respectively, 111, 135 and 152 µm, in the Paraguay River, and 112, 134 and 154 µm in the Miranda River. Principal Components Analysis indicated positive relationships between "D" larval stage size and the ratio between inorganic and organic suspended solids, while negative relationships were found between larval size and calcium and chlorophyll-<img border=0 width=7 height=8 src="/img/revistas/alb/2012nahead/ALB_AOP_230307car01.jpg">; CONCLUSIONS: The larvae were recorded in the plankton during most of the year, with the exception of the two colder months. Neither densities nor larval stage body sizes were significantly different between the two rivers. Possible positive effects of food and calcium concentrations on body size were not recorded. This species may be adapted to grow in environments with elevated sediment concentrations.

Download Full-text

Stability of a buoyancy-driven coastal current at the shelf break

Journal of Fluid Mechanics ◽

10.1017/s0022112001006668 ◽

2002 ◽

Vol 452 ◽

pp. 97-121 ◽

Cited By ~ 16

Author(s):

C. CENEDESE ◽

P. F. LINDEN

Keyword(s):

Continental Shelf ◽

Continental Slope ◽

Unstable Mode ◽

Shelf Break ◽

Coastal Current ◽

Surface Currents ◽

Flat Bottom ◽

Vertical Boundary ◽

Axisymmetric Disturbances ◽

A Current

Buoyancy-driven surface currents were generated in the laboratory by releasing buoyant fluid from a source adjacent to a vertical boundary in a rotating container. Different bottom topographies that simulate both a continental slope and a continental ridge were introduced in the container. The topography modified the flow in comparison with the at bottom case where the current grew in width and depth until it became unstable once to non-axisymmetric disturbances. However, when topography was introduced a second instability of the buoyancy-driven current was observed. The most important parameter describing the flow is the ratio of continental shelf width W to the width L* of the current at the onset of the instability. The values of L* for the first instability, and L*−W for the second instability were not influenced by the topography and were 2–6 times the Rossby radius. Thus, the parameter describing the flow can be expressed as the ratio of the width of the continental shelf to the Rossby radius. When this ratio is larger than 2–6 the second instability was observed on the current front. A continental ridge allowed the disturbance to grow to larger amplitude with formation of eddies and fronts, while a gentle continental slope reduced the growth rate and amplitude of the most unstable mode, when compared to the continental ridge topography. When present, eddies did not separate from the main current, and remained near the shelf break. On the other hand, for the largest values of the Rossby radius the first instability was suppressed and the flow was observed to remain stable. A small but significant variation was found in the wavelength of the first instability, which was smaller for a current over topography than over a flat bottom.

Download Full-text

Use of Larval Size, Instead of Larval Stage, to Study the Ecology of a Stomatopod Crustacean Oratosquilla oratoria

Fisheries Science ◽

10.2331/fishsci.61.165 ◽

1995 ◽

Vol 61 (1) ◽

pp. 165-166 ◽

Cited By ~ 2

Author(s):

Tatsuo Hamano ◽

Takashi Kikkawa ◽

Shunshiro Ueno ◽

Ken-Ichi Hayashi

Keyword(s):

Larval Stage ◽

Larval Size ◽

Oratosquilla Oratoria

Download Full-text

Upper ocean stratification and sea ice growth rates during the summer-fall transition, as revealed by Elephant seal foraging in the Adélie Depression, East Antarctica

Ocean Science ◽

10.5194/os-7-185-2011 ◽

2011 ◽

Vol 7 (2) ◽

pp. 185-202 ◽

Cited By ~ 19

Author(s):

G. D. Williams ◽

M. Hindell ◽

M.-N. Houssais ◽

T. Tamura ◽

I. C. Field

Keyword(s):

Sea Ice ◽

Continental Shelf ◽

Mixed Layer ◽

Growth Rates ◽

Shelf Break ◽

Upper Ocean ◽

Ocean Stratification ◽

Glacier Tongue ◽

Ice Growth ◽

Continental Shelf Break

Abstract. Southern elephant seals (Mirounga leonina), fitted with Conductivity-Temperature-Depth sensors at Macquarie Island in January 2005 and 2010, collected unique oceanographic observations of the Adélie and George V Land continental shelf (140–148° E) during the summer-fall transition (late February through April). This is a key region of dense shelf water formation from enhanced sea ice growth/brine rejection in the local coastal polynyas. In 2005, two seals occupied the continental shelf break near the grounded icebergs at the northern end of the Mertz Glacier Tongue for several weeks from the end of February. One of the seals migrated west to the Dibble Ice Tongue, apparently utilising the Antarctic Slope Front current near the continental shelf break. In 2010, immediately after that year's calving of the Mertz Glacier Tongue, two seals migrated to the same region but penetrated much further southwest across the Adélie Depression and sampled the Commonwealth Bay polynya from March through April. Here we present observations of the regional oceanography during the summer-fall transition, in particular (i) the zonal distribution of modified Circumpolar Deep Water exchange across the shelf break, (ii) the upper ocean stratification across the Adélie Depression, including alongside iceberg C-28 that calved from the Mertz Glacier and (iii) the convective overturning of the deep remnant seasonal mixed layer in Commonwealth Bay from sea ice growth. Heat and freshwater budgets to 200–300 m are used to estimate the ocean heat content (400→50 MJ m−2), flux (50–200 W m−2 loss) and sea ice growth rates (maximum of 7.5–12.5 cm day−1). Mean seal-derived sea ice growth rates were within the range of satellite-derived estimates from 1992–2007 using ERA-Interim data. We speculate that the continuous foraging by the seals within Commonwealth Bay during the summer/fall transition was due to favorable feeding conditions resulting from the convective overturning of the deep seasonal mixed layer and chlorophyll maximum that is a reported feature of this location.

Download Full-text

Mesoscale, tidal and seasonal/interannual drivers of the Weddell Sea overturning circulation

Journal of Physical Oceanography ◽

10.1175/jpo-d-20-0320.1 ◽

2021 ◽

Keyword(s):

Continental Shelf ◽

Shelf Break ◽

Weddell Sea ◽

Global Ocean ◽

Mean Flow ◽

Ice Shelf ◽

Overturning Circulation ◽

Global Circulation ◽

Interannual Fluctuations ◽

Continental Shelf Break

Abstract The Weddell Sea supplies 40–50% of the Antarctic BottomWaters that fill the global ocean abyss, and therefore exerts significant influence over global circulation and climate. Previous studies have identified a range of different processes that may contribute to dense shelf water (DSW) formation and export on the southern Weddell Sea continental shelf. However, the relative importance of these processes has not been quantified, which hampers prioritization of observational deployments and development of model parameterizations in this region. In this study a high-resolution (1/12°) regional model of the southern Weddell Sea is used to quantify the overturning circulation and decompose it into contributions due to multi-annual mean flows, seasonal/interannual variability, tides, and other sub-monthly variability. It is shown that tides primarily influence the overturning by changing the melt rate of the Filchner-Ronne Ice Shelf (FRIS). The resulting ~0.2 Sv decrease in DSW transport is comparable to the magnitude of the overturning in the FRIS cavity, but small compared to DSW export across the continental shelf break. Seasonal/interannual fluctuations exert a modest influence on the overturning circulation due to the relatively short (8-year) analysis period. Analysis of the transient energy budget indicates that the non-tidal, sub-monthly variability is primarily baroclinically-generated eddies associated with dense overflows. These eddies play a comparable role to the mean flow in exporting dense shelf waters across the continental shelf break, and account for 100% of the transfer of heat onto the continental shelf. The eddy component of the overturning is sensitive to model resolution, decreasing by a factor of ~2 as the horizontal grid spacing is refined from 1/3° to 1/12°.

Download Full-text