Reproductive dynamics of the tiger prawn Penaeus esculentus, and a comparison with P. semisulcatus, in the north-western Gulf of Carpentaria, Australia

1987 ◽  
Vol 38 (1) ◽  
pp. 91 ◽  
Author(s):  
PJ Crocos
Keyword(s):  
Egg Production ◽  
Reproductive Output ◽  
Size Range ◽  
Early Spring ◽  
Minimum Size ◽  
Late Winter ◽  
Limited Area ◽  
The North ◽  
Tiger Prawn ◽  
North Western

The reproductive cycle of female P. esculentus was investigated in the Groote Eylandt region of the Gulf of Carpentaria from August 1983 to March 1985. The minimum size at maturity for P. esculentus was 25 mm carapace length (CL), and 50% of the population were mature at 32 mm CL. The proportion of females which had mated increased sharply above 28 mm CL to a maximum of 80% inseminated in the size range 32-50 mm CL. An index of population egg production, calculated from female abundance, the proportion of females spawning and fecundity with size, was used as an indicator of reproductive output. Egg production tended to be spread throughout the year, but with eggs being produced most consistently in late winter and early spring. Spawning occurred in a limited area within the study area. A comparison of P. esculentus and P. semisulcatus showed that P. esculentus matures at a smaller size (50% at 32 mm CL) than P. semisulcatus (50% at 39 mm CL), fecundity is lower, spawning is nearer inshore and egg production is less strongly seasonal.

Reproductive dynamics of the grooved tiger prawn, Penaeus semisulcatus, in the north-western Gulf of Carpentaria, Australia

1987 ◽  
Vol 38 (1) ◽  
pp. 79 ◽  
Author(s):  
PJ Crocos
Keyword(s):  
Egg Production ◽  
Fishing Effort ◽  
Minimum Size ◽  
Limited Area ◽  
The North ◽  
Penaeus Semisulcatus ◽  
Spawning Stock ◽  
Tiger Prawn ◽  
A Minor ◽  
North Western

The reproductive cycle of female P. semisulcatus was investigated in the region north of Groote Eylandt in the Gulf of Carpentaria from August 1983 to March 1985. Approximately 1750 trawls were carried out over 21 monthly sampling cruises, and 13 748 females were examined. The minimum size at maturity was 29 mm carapace length (CL), and 50% of the population were mature at 39 mm CL. The proportion of females which had mated increased sharply above 34 mm CL with a maximum of 80% of females inseminated in the size range 38-54 mm CL. An index of population egg production, calculated from female abundance, the proportion of females spawning and fecundity according to size, was used as an indicator of reproductive output. Egg production was markedly seasonal, with a major spawning peak in August-September, and a minor one in February. Spawning occurred in a limited area within rhe study area. The spawning stock of P. semisulcatus is likely to be vulnerable to fishing pressure because the area and time of major spawning coincides with the major fishing effort in the region.

Leaf spot and dry rot of lettuce caused by Xanthomonas vitians (Brown) Dowson

1963 ◽  
Vol 14 (6) ◽  
pp. 778 ◽  
Author(s):  
DE Harrison
Keyword(s):  
Leaf Spot ◽  
Early Spring ◽  
Late Winter ◽  
Laboratory Studies ◽  
Dry Rot ◽  
Complete Destruction ◽  
Western Victoria ◽  
Valley Area ◽  
North Western

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves. The incidence of disease varied from about 10% up to practically complete destruction of some plantings. A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.

Lagrangian analysis of the northern polar vortex split in April 2020 during development of the Arctic ozone hole

2021 ◽  
Author(s):  
Jezabel Curbelo ◽  
Gang Chen ◽  
Carlos R. Mechoso
Keyword(s):  
Wave Train ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Early Spring ◽  
Ozone Hole ◽  
The Arctic ◽  
Late Winter ◽  
Lagrangian Analysis ◽  
The North ◽  
Vortex Split

<div>The evolution of the Northern Hemisphere stratosphere during late winter and early spring of 2020 was punctuated by outstanding events both in dynamics and tracer evolution. It provides an ideal case for study of the Lagrangian properties of the evolving flow and its connections with the troposphere. The events ranged from an episode of polar warming at upper levels in March, a polar vortex split into two cyclonic vortices at middle and lower levels in April, and a remarkably deep and persistent mass of ozone poor air within the westerly circulation throughout the period. The latter feature was particularly remarkable during 2020, which showed the lowest values of stratospheric ozone on record.</div><div> </div><div>We focus on the vortex split in April 2020 and we examine this split at middle as well as lower stratospheric levels, and the interactions that occurred between the resulting two vortices which determined the distribution of ozone among them. We also examine the connections among stratospheric and tropospheric events during the period.</div><div> </div><div>Our approach for analysis will be based on the application of Lagrangian tools to the flow field, based on following air parcels trajectories, examining barriers to the flow, and the activity and propagation of planetary waves. Our findings confirm the key role for the split played by a flow configuration with a polar hyperbolic trajectory and associated manifolds. A trajectory analysis illustrates the transport of ozone between the vortices during the split. We argue that these stratospheric events were linked to strong synoptic scale disturbances in the troposphere forming a wave train from the north Pacific to North America and Eurasia.</div><div><strong> </strong></div><div><strong>Reference:</strong><strong> </strong>J. Curbelo, G. Chen,  C. R. Mechoso. Multi-level analysis of the northern polar vortex split in April 2020 during development of the Arctic ozone hole. Earth and Space Science Open Archive. doi: 10.1002/essoar.10505516.1</div><div> </div><div><strong>Acknowledgements:</strong> NSF Grant AGS-1832842, RYC2018-025169 and EIN2019-103087.</div>

The biology of Harveyella mirabilis (Cryptonemiales, Rhodophyceae). IV. Life history and phenology

1976 ◽  
Vol 54 (3-4) ◽  
pp. 281-292 ◽  
Author(s):  
Lynda J. Goff ◽  
Kathleen Cole
Keyword(s):  
Water Temperature ◽  
Seawater Temperature ◽  
Environmental Parameters ◽  
Late Summer ◽  
Early Spring ◽  
Day Length ◽  
Late Winter ◽  
Temperature Sensitive ◽  
The North ◽  
The North Pacific

A 20-month field study of the reproductive biology of the parasitic red alga Harveyella mirabilis was undertaken to investigate the effects of environmental parameters on the reproductive periodicity of Harveyella in the intertidal habitat. In the northeast Pacific, tetraspores have been observed in the late winter - early spring; apparently they are produced in response to increased available sunlight and water temperature. Gametogenesis appears to be temperature sensitive; it occurs between a narrow temperature range (9–11 °C). Carpospores are produced in the late summer when both water temperature and day length reach a peak. The phenology of H. mirabilis in the North Atlantic differs from that which is observed in the North Pacific in the timing of gametogenesis and carposporogenesis. The significance of this is discussed in relation to the possible effects of differences in seawater temperature on gametogenesis.

scholarly journals Spawning location of Norway pout (Trisopterus esmarkii Nilsson) in the North Sea

2012 ◽  
Vol 69 (8) ◽  
pp. 1338-1346 ◽  
Author(s):  
Richard D. M. Nash ◽  
Peter J. Wright ◽  
Iveta Matejusova ◽  
Stefan Petev Dimitrov ◽  
Martha O'Sullivan ◽  
...  
Keyword(s):  
North Sea ◽  
Size Range ◽  
Northern Region ◽  
Stage I ◽  
The South ◽  
The North ◽  
Spawning Areas ◽  
The North Sea ◽  
Merlangius Merlangus ◽  
North Western

Abstract Nash, R. D. M., Wright, P. J., Matejusova, I., Dimitrov, S. P., O'Sullivan, M., Augley, J., and Höffle, H. 2012. Spawning location of Norway pout (Trisopterus esmarkii Nilsson) in the North Sea. – ICES Journal of Marine Science, 69: . The northern region of the North Sea (56–62°N) was sampled in February/March 2009 for eggs and in May 2010 for larvae. To aid in the identification of Norway pout stage I eggs and distinguish them from other ‘cod-like’ eggs, a Taq-Man probe was designed for this species and used here. Stage I Norway pout egg diameters collected from the field were in the range 1.03–1.28 mm and largely overlapped with the size range determined for whiting (Merlangius merlangus). The distribution of Norway pout stage I eggs in 2009 revealed the distribution of spawning in the North Sea and showed that it was similar to the distribution of 2 + Norway pout taken during the International Bottom Trawl Surveys (IBTS) over the same period covering the whole North Sea. The larvae sampled in 2010 were largely in the same area; however, larger larvae occurred to the south-east of the survey area, suggesting advection of young stages from the principal spawning areas in the north-western North Sea to the south-east and toward the Skagerrak.

Some Life History Aspects of the Rock Crab, Cancer irroratus, in the Gulf of Maine

1972 ◽  
Vol 29 (10) ◽  
pp. 1479-1482 ◽  
Author(s):  
Jay S. Krouse
Keyword(s):  
Life History ◽  
Sexual Maturity ◽  
Size Range ◽  
Gulf Of Maine ◽  
Carapace Width ◽  
Early Spring ◽  
Late Winter ◽  
Early Winter ◽  
Cancer Irroratus ◽  
Rock Crab

Rock crabs, Cancer irroratus, were caught in wire lobster traps from 1968 through 1971 at Boothbay Harbor and in 1969 at Casco Bay, Maine. Females dominated the annual catches (except in Casco Bay) and width classes from 61 to 90 mm; while males were predominant above this size range. Rock crabs from Casco Bay were heavier at a given width than those from Boothbay Harbor. Soft-shelled females were caught mostly in the fall, while soft-shelled males appeared most frequently in late winter and early spring. The occurrence of newly berried females suggested that spawning (egg extrusion) took place in late fall and early winter, and hatching occurred in spring. Most female crabs attained sexual maturity between 70–80 mm carapace width, but a few matured at widths less than 70 mm.

scholarly journals Seasonal changes in basking shark vertical space use in the north-east Atlantic

2019 ◽  
Vol 166 (10) ◽  
Author(s):  
P. D. Doherty ◽  
J. M. Baxter ◽  
B. J. Godley ◽  
R. T. Graham ◽  
G. Hall ◽  
...  
Keyword(s):  
Satellite Telemetry ◽  
Space Use ◽  
Marine Species ◽  
Early Spring ◽  
Conservation Strategies ◽  
Late Winter ◽  
East Atlantic ◽  
Vertical Movements ◽  
North East ◽  
The North

Abstract Mobile marine species can exhibit vast movements both horizontally and vertically. Spatial analysis of vertical movements may help improve an understanding of the processes that influence space use. Previously, vertical space use of basking sharks (Cetorhinus maximus) in the north-east Atlantic described movements largely within waters of the continental shelf during summer and autumn months, with few records of detailed vertical behaviour during winter. We use archival satellite telemetry data from 32 basking sharks (12 females, 6 males, and 14 of unknown sex measuring 4–5 m (n = 6), 5–6 m (n = 10), 6–7 m (n = 7), 7–8 m (n = 8), and 8–9 m (n = 1) estimated total length) tracked over 4 years (2012–2015). The satellite tags provided depth and temperature data for a cumulative 4489 days (mean 140 ± 97 days per shark, range 10–292 days) to describe vertical space use and thermal range of basking sharks in the north-east Atlantic. Basking sharks exhibit seasonality in vertical space use, revealing repeated ‘yo-yo’ movement behaviour with periods of occupancy at depths greater than 1000 m in late winter/early spring. Describing seasonal vertical space use in marine megavertebrates can increase knowledge of movements throughout their environment including physiological and morphological constraints to movement, nutrient transfer, and overlap with anthropogenic threats to inform future conservation strategies.

Deep-water red coral from the island of Sardinia (north-western Mediterranean): a local example of sustainable management

2013 ◽  
Vol 64 (8) ◽  
pp. 706 ◽  
Author(s):  
Maria Cristina Follesa ◽  
Rita Cannas ◽  
Alessandro Cau ◽  
Claudia Pedoni ◽  
Paola Pesci ◽  
...  
Keyword(s):  
Maximum Yield ◽  
Maximum Size ◽  
Management Plan ◽  
Western Mediterranean ◽  
Minimum Size ◽  
Western Coast ◽  
Basal Diameter ◽  
The North ◽  
Red Coral ◽  
North Western

Since 1979, red coral harvesting in Sardinia has been regulated by regional laws. The regulations, including a minimum take size of 10-mm basal diameter, were imposed to limit and control harvesting. Our study indicated that >75% of the red coral colonies harvested in 2007–08 in the north-western coast were above the legal minimum size for exploitation. Moreover, extensive surveys with remotely operated vehicles allowed us to document the real structure of wild populations. Large colonies (>10 mm) represented a big portion of the population (~38% of the total), suggesting that harvesting effort did not affect yet the maximum size of colonies. All these results seem to be confirmed by the application of the model of Beverton and Holt. This model shows that the fishery of red coral in Sardinia reaches its maximum yield at an age at first capture of 20 years, an age significantly lower than the average age of 30 years calculated for the colonies actually harvested in the Sardinian coast. Our data confirmed that the measures enacted in the Sardinian regulations provide for an adequate management of this resource and, in addition, can represent a guideline for other countries that still lack a valid management plan.

scholarly journals Winter and early spring assemblages of ladybird beetles (Coleoptera: Coccinellidae) in two forest habitats in suburban area of Warsaw, central Poland

2016 ◽  
Vol 14 (3) ◽  
pp. 115-129 ◽  
Author(s):  
Karolina Bodzon ◽  
Piotr Ceryngier
Keyword(s):  
Deciduous Forest ◽  
Mixed Forest ◽  
Coccinella Septempunctata ◽  
Forest Litter ◽  
Early Spring ◽  
The North ◽  
Ladybird Beetles ◽  
Clitostethus Arcuatus ◽  
North Western ◽  
Forest Habitats

In March and April of 2014 and 2015, overwintering and post-overwintering assemblages of ladybird beetles were investigated in deciduous (Tilio-Carpinetum) and mixed forest (Querco roboris-Pinetum) patches in a forest complex on the north-western periphery of Warsaw. March samples were collected by sifting forest litter with an entomological sieve, while in April, ladybirds were collected from the vegetation using sweeping net and beating sheet. In both years, mean densities of ladybirds found in March in the two forest types were low, not exceeding 2 individuals/m2. Seven ladybird species were found overwintering in the litter of the deciduous forest and four in that of the mixed forest. Propylea quatuordecimpunctata was the most abundant in both habitats in 2014, while in 2015 in the litter of the deciduous forest Vibidia duodecimguttata predominated. In April, 15 species were recorded in the deciduous forest and 7 in the mixed forest. Scymnus ferrugatus predominated in the former plant community and P. quatuordecimpunctata and Coccinella septempunctata in the latter. Several of the recorded species, such as Clitostethus arcuatus, Scymnus femoralis and S. abietis, have rarely been reported from Poland.

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