Seasonal Migration Patterns of Postlarval and Juvenile Banana Prawns, Penaeus merguiensis de Man, in the Major Rivers of the Gulf of Carpentaria, Australia

1979 ◽  
Vol 30 (2) ◽  
pp. 143 ◽  
Author(s):  
DJ Staples
Keyword(s):  
Seasonal Pattern ◽  
Temporal Distribution ◽  
Major Change ◽  
Seasonal Migration ◽  
Geographical Differences ◽  
Monsoon Period ◽  
Migration Patterns ◽  
North West ◽  
The North ◽  
Two Generations

Samples of juvenile P. merguiensis taken from 20 major rivers around the Gulf of Carpentaria from 1970 to 1973 showed that the Gulf could be divided into four major areas, each characterized by its own seasonal pattern of postlarval immigration and emigration of juveniles. The main nursery areas for the Gulf, however, are the rivers along the east and south-east coasts (Cape Keerweer to Mornington Island) and the majority of prawns migrate from these rivers during the north-west monsoon period (November to February); the main recruitment into the commercial fishery, there- fore, occurs during a relatively confined period each year. Additional sampling in 1976-77 showed that although there have been recent changes in the temporal distribution of adult prawns as a result of increased fishing pressure, no major change in the temporal pattern of postlarval immigration has resulted. An hypothesis is presented in which the observed geographical differences in the seasonal migration patterns are explained with reference to a basic pattern involving two generations of P. merguiensis each year.

scholarly journals The rise and fall of dialects in northern elephant seals

2018 ◽  
Vol 285 (1892) ◽  
pp. 20182176 ◽  
Author(s):  
Caroline Casey ◽  
Colleen Reichmuth ◽  
Daniel P. Costa ◽  
Burney Le Boeuf
Keyword(s):  
Mammalian Species ◽  
Structural Complexity ◽  
Mirounga Angustirostris ◽  
Geographical Differences ◽  
Migration Patterns ◽  
Elephant Seals ◽  
The North ◽  
Vocal Behaviour ◽  
Northern Elephant Seals ◽  
The North Pacific

Vocal dialects are fundamental to our understanding of the transmission of social behaviours between individuals and populations, however few accounts trace this phenomenon among mammals over time. Northern elephant seals ( Mirounga angustirostris ) provide a rare opportunity to examine the trajectory of dialects in a long-lived mammalian species. Dialects were first documented in the temporal patterns of the stereotyped vocal displays produced by breeding males at four sites in the North Pacific in 1968 and 1969, as the population recovered from extreme exploitation. We evaluated the longevity of these geographical differences by comparing these early recordings to calls recently recorded at these same locations. While the presence of vocal dialects in the original recordings was re-confirmed, geographical differences in vocal behaviour were not found at these breeding rookeries nearly 50 years later. Moreover, the calls of contemporary males displayed more structural complexity after approximately four generations, with substantial between-individual variation and call features not present in the historical data. In the absence of measurable genetic variation in this species—owing to an extreme population bottleneck—a combination of migration patterns and cultural mutation are proposed as factors influencing the fall of dialects and the dramatic increase in call diversity.

Subsidence discrepancy in the Valencia Trough revealed from reflection seismic observations and backstripping results

2020 ◽  
Author(s):  
Penggao Fang ◽  
Geoffroy Mohn ◽  
Julie Tugend ◽  
Nick Kusznir
Keyword(s):  
Tectonic Setting ◽  
Temporal Distribution ◽  
Drill Hole ◽  
Western Mediterranean ◽  
Normal Faults ◽  
Seismic Profiles ◽  
Gulf Of Lions ◽  
North West ◽  
The North ◽  
Valencia Trough

<p>    The Valencia Trough is commonly included as part of the set of western Mediterranean Cenozoic extensional basins that formed in relation with the Tethyan oceanic slab rollback during the latest Oligocene to early Miocene. It lies in a complex tectonic setting between the Gulf of Lions to the North-West, the Catalan Coastal Range and the Iberian chain to the West, the Balearic promontory to the East and the Betic orogenic system to the South. This rifting period is coeval with or directly followed by the development of the external Betics fold and thrust belts at the southern tip of the Valencia Trough. Recent investigations suggest that the Valencia Trough is segmented into two main domains exhibiting different geological and geophysical characteristics between its northeastern and southwestern parts. The presence of numerous Cenozoic normal faults and the well-studied subsidence pattern evolution of the NE part of the Valencia Trough suggest that it mainly formed coevally with the rifting of Gulf of Lion. However, if a significant post-Oligocene subsidence is also evidenced in its SW part; fewer Cenozoic rift structures are observed suggesting that the subsidence pattern likely results from the interference of different processes.</p><p>    In this presentation, we quantify the post-Oligocene subsidence history of the SW part of the Valencia Trough with the aim of evaluating the potential mechanisms explaining this apparent subsidence discrepancy. We analyzed the spatial and temporal distribution of the post-Oligocene subsidence using the interpretation of a dense grid of high-quality multi-channel seismic profiles, also integrating drill-hole results and velocity information from expanding spread profiles (ESP). We used the mapping of the main unconformities, especially the so-called Oligocene unconformity, to perform a 3D flexural backstripping, which permits the prediction of the post-Oligocene water-loaded subsidence. Our results confirm that the post-Oligocene subsidence of the SW part of the Valencia Trough cannot be explained by the rifting of the Gulf of Lions. Previous works already showed that the extreme crustal thinning observed to the SW is related to a previous Mesozoic rift event. Here, we further highlight that if few Cenozoic extensional structures are observed, they can be interpreted as gravitational features rooting at the regionally identified Upper Triassic evaporite level. Backstripping results combined with the mapping of the first sediments deposited on top of the Oligocene unconformity show that they are largely controlled by the shape of Betic front with a possible additional effect of preserved Mesozoic structures. At larger scale, we compare the mechanisms accounting for the origin and subsidence at the SW part of the Valencia Trough with those responsible for the subsidence of its NE part and the Gulf of Lions.</p>

scholarly journals Spatial mapping of hepatitis C prevalence in recent injecting drug users in contact with services

2011 ◽  
Vol 140 (6) ◽  
pp. 1054-1063 ◽  
Author(s):  
R. J. HARRIS ◽  
V. D. HOPE ◽  
A. MORONGIU ◽  
M. HICKMAN ◽  
F. NCUBE ◽  
...  
Keyword(s):  
Hepatitis C ◽  
Drug Users ◽  
Injecting Drug Users ◽  
Developed Countries ◽  
Geographical Differences ◽  
Random Effects Models ◽  
North West ◽  
Spatially Correlated ◽  
The North ◽  
Hcv Prevalence

SUMMARYIn developed countries the majority of hepatitis C virus (HCV) infections occur in injecting drug users (IDUs) with prevalence in IDUs often high, but with wide geographical differences within countries. Estimates of local prevalence are needed for planning services for IDUs, but it is not practical to conduct HCV seroprevalence surveys in all areas. In this study survey data from IDUs attending specialist services were collected in 52/149 sites in England between 2006 and 2008. Spatially correlated random-effects models were used to estimate HCV prevalence for all sites, using auxiliary data to aid prediction. Estimates ranged from 14% to 82%, with larger cities, London and the North West having the highest HCV prevalence. The methods used generated robust estimates for each area, with a well-identified spatial pattern that improved predictions. Such models may be of use in other areas of study where surveillance data are sparse.

scholarly journals Estimating the impact of Tiny Targets in reducing the incidence of Gambian sleeping sickness in the North-west Uganda focus

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Paul R. Bessell ◽  
Johan Esterhuizen ◽  
Michael J. Lehane ◽  
Joshua Longbottom ◽  
Albert Mugenyi ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Temporal Distribution ◽  
Public Health Problem ◽  
Sensitivity Analyses ◽  
Tsetse Control ◽  
North West ◽  
The North ◽  
Intervention Area ◽  
Western Uganda ◽  
The Impact

Abstract Background Riverine species of tsetse (Glossina) transmit Trypanosoma brucei gambiense, which causes Gambian human African trypanosomiasis (gHAT), a neglected tropical disease. Uganda aims to eliminate gHAT as a public health problem through detection and treatment of human cases and vector control. The latter is being achieved through the deployment of ‘Tiny Targets’, insecticide-impregnated panels of material which attract and kill tsetse. We analysed the spatial and temporal distribution of cases of gHAT in Uganda during the period 2010–2019 to assess whether Tiny Targets have had an impact on disease incidence. Methods To quantify the deployment of Tiny Targets, we mapped the rivers and their associated watersheds in the intervention area. We then categorised each of these on a scale of 0–3 according to whether Tiny Targets were absent (0), present only in neighbouring watersheds (1), present in the watersheds but not all neighbours (2), or present in the watershed and all neighbours (3). We overlaid all cases that were diagnosed between 2000 and 2020 and assessed whether the probability of finding cases in a watershed changed following the deployment of targets. We also estimated the number of cases averted through tsetse control. Results We found that following the deployment of Tiny Targets in a watershed, there were fewer cases of HAT, with a sampled error probability of 0.007. We estimate that during the intervention period 2012–2019 we should have expected 48 cases (95% confidence intervals = 40–57) compared to the 36 cases observed. The results are robust to a range of sensitivity analyses. Conclusions Tiny Targets have reduced the incidence of gHAT by 25% in north-western Uganda. Graphical abstract

Reproductive Cycle of Nassarius Reticulatus in the Ria De Aveiro, Portugal: Implications for Imposex Studies

1998 ◽  
Vol 78 (4) ◽  
pp. 1233-1246 ◽  
Author(s):  
C.M. Barroso ◽  
M.H. Moreira
Keyword(s):  
Water Temperature ◽  
Reproductive Cycle ◽  
Seasonal Pattern ◽  
Shell Height ◽  
Ria De Aveiro ◽  
North West ◽  
The North ◽  
Nassarius Reticulatus ◽  
Clear Seasonal Pattern ◽  
Penis Length

The reproductive cycle of Nassarius (Hinia) reticulatus was investigated in the Ria de Aveiro on the north-west Portuguese coast during 1992 and 1993. A clear seasonal pattern was observed with the beginning of gametogenesis in August followed by ripening of the gonads in January and February and spawning from February to July. The increase of water temperature above 11°C in February 1993 was associated presumably with the release of gametes. Recruitment inside the Ria of juveniles with 6·5 mm mean shell height was detected in February 1993 and these individuals were spawned in the previous year. Males of N. reticulatus exhibited a considerable variation in length of the penis throughout the reproductive cycle. The accuracy of the use of relative penis length (RPL) index for intersite comparisons of imposex is discussed and the magnitude of the error that might be involved when comparisons are made using populations in different phases of the reproductive cycle is evaluated.

The influence of urban built environment on residential burglary in China: Testing the encounter and enclosure hypotheses

2019 ◽  
pp. 174889581987486 ◽  
Author(s):  
Han Yue ◽  
Xinyan Zhu
Keyword(s):  
Built Environment ◽  
Spatial Regression ◽  
Housing Prices ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Time Of Day ◽  
Residential Burglary ◽  
North West ◽  
The North ◽  
Residential Burglaries

It is widely recognized that crimes are clustered in space. Features of the built environment are among various factors associated with crime clustering patterns. There are two competing perspectives on this association: the “encounter” and “enclosure” hypotheses. This study examines the effect of the built environment on the spatial distribution of residential burglary in Wuhan, China, aiming to test these two competing perspectives. First, we review existing studies analyzing the influence of the built environment on residential burglary, especially those based on the two hypotheses. We then conduct an exploratory data analysis to observe the spatial and temporal distribution patterns of residential burglaries. Next, we use a multivariate spatial regression model to evaluate the influence of various built environment characteristics on residential burglaries, after controlling for socio-demographic variables, guardianship, and the time-of-day effect. The results suggest a double peak in the hourly distribution of burglaries: 6:00 a.m.–8:59 a.m. and 5:00 p.m.–7:59 p.m. Burglaries are positively and significantly autocorrelated in space and mainly concentrated in the north-west and central areas of Wuhan. Two transport facilities features (intersection density and the presence of subway stations), three building features (multiple stories, high housing prices, and older houses), and land-use mix are each positively correlated with burglary. However, the burglary count is negatively correlated with the ratio of the residential land. Overall, neighborhoods with high permeability are vulnerable to residential burglaries. Thus, the principle of access control promoted by the enclosure hypothesis appears effective in preventing residential crime. The results’ implications for crime prevention and urban design practice are also discussed.

Geographical variation in growth and maturation of the squid illex coindeth (Oegopsida, Ommastrephidae) off the north-west African coast

1996 ◽  
Vol 76 (4) ◽  
pp. 1091-1106 ◽  
Author(s):  
Alexander Arkhipkin
Keyword(s):  
Life Span ◽  
Sierra Leone ◽  
Growth Rates ◽  
West African ◽  
Age And Growth ◽  
Geographical Differences ◽  
Western Sahara ◽  
North West ◽  
The North ◽  
Growth Increments

Statolith microstructure was studied in 162 specimens of Illex coindetii (mantle length ranging from 48 to 300 mm) captured on the shelves of Sierra Leone and Western Sahara between May and November 1987. Growth increments were revealed in all statoliths studied, but they were not well-resolved as in other congeneric species Illex illecebrosus and Illex argentinus. Age and growth rates were estimated assuming that growth increments within statoliths were produced. In both regions, differences in growth rates between sexes (females become larger than males) occurred first in length and then in weight. Geographical differences in sex-specific growth (Western Sahara squid grow faster and attain larger sizes than Sierra Leone squid) was apparent after 150 d in females and 120 d in males. Illex coindetii in Sierra Leone started maturing at smaller sizes but at approximately the same age as the Western Sahara squid. Small sized early maturing groups of I. coindetii with a life span of ~0.5 y occurred in both regions. However, large sized late maturing squid with a life span of ~1 y were encountered only in the Western Sahara. In waters of the west African shelf, I. coindetii spawn throughout the year.

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