Life history of the common blacktip shark, Carcharhinus limbatus, from central eastern Australia and comparative demography of a cryptic shark complex

2019 ◽  
Vol 70 (6) ◽  
pp. 834 ◽  
Author(s):  
Alastair V. Harry ◽  
Paul A. Butcher ◽  
William G. Macbeth ◽  
Jess A. T. Morgan ◽  
Stephen M. Taylor ◽  
...  

Common and Australian blacktip sharks (Carcharhinus limbatus and Carcharhinus tilstoni) occur sympatrically in Australia, where they are reported as a complex because of their morphological similarities. This study provides the first description of the life history of C. limbatus using samples from central eastern Australia, where C. tilstoni is rare. Females (68–267cm total length (TL); n=183) and males (65–255cm TL; n=292) both matured at 8.3 years and 200cm TL, which exceeds the maximum length of C. tilstoni. Vertebral ageing revealed that female and male C. limbatus lived to 22 and 24 years respectively, exceeding known longevity in C. tilstoni. The mean (±s.d.) intrinsic rate of population increase calculated using a Euler–Lotka demographic method was 0.11±0.02year–1 for C. limbatus, compared with 0.17±0.02 and 0.20±0.03year–1 for two C. tilstoni stocks. Despite their similar appearance, these species differed in both their biological productivity and susceptibility to fishing activities. Monitoring of relative abundance should be a priority given they are likely to have divergent responses to fishing.

2004 ◽  
Vol 55 (3) ◽  
pp. 295 ◽  
Author(s):  
A. J. Richardson ◽  
J. E. Growns ◽  
R. A. Cook

Caridean shrimps are an integral component of lowland river ecosystems in south-eastern Australia, but their distributions may be affected by flow alteration. Monthly shrimp samples were collected from slackwaters in three hydrologically distinct sections of the heavily regulated Campaspe River and the less regulated Broken River for three consecutive years. The distributions of Paratya australiensis, Caridina mccullochi and Macrobrachium australiense, along with their life history in river sections with different hydrology are outlined. Paratya australiensis and M. australiense occurred in all sections, but C. mccullochi was absent from sections of the Campaspe River that received irrigation flows during summer/autumn. Shrimp larvae were most abundant in summer (December–February) and juvenile recruitment continued through to mid autumn (April). Breeding and recruitment of P. australiensis occurred for longer than other shrimps. Apart from large adult and berried M. australiense, all life stages of shrimps commonly occurred in slackwaters, particularly the larval and juvenile stages. Irrigation flows in summer/autumn probably adversely affect the size, extent and arrangement of slackwaters, at a time when they may be critical habitats for C. mccullochi larval development and recruitment. Dams and weirs in the Campaspe River may have influenced shrimp abundance and the timing of breeding.


2014 ◽  
Vol 74 (3) ◽  
pp. 691-697 ◽  
Author(s):  
PP Marafeli ◽  
PR Reis ◽  
EC. da Silveira ◽  
GC Souza-Pimentel ◽  
MA. de Toledo

The predatory mite, Neoseiulus californicus(McGregor, 1954) (Acari: Phytoseiidae) is one of the principal natural enemies of tetranychid mites in several countries, promoting efficient control of those mites in several food and ornamental crops. Pest attacks such as that of the spider mite, Tetranychus urticaeKoch, 1836 (Acari: Tetranychidae), is one of the problems faced by farmers, especially in the greenhouse, due to the difficulty of its control with the use of chemicals because of the development of fast resistance making it hard to control it. The objective of this work was to study the life history of the predatory mite N. californicus as a contribution to its mass laboratory rearing, having castor bean plant [Ricinus communis L. (Euphorbiaceae)] pollen as food, for its subsequent use as a natural enemy of T. urticae on a cultivation of greenhouse rosebushes. The studies were carried out in the laboratory, at 25 ± 2°C of temperature, 70 ± 10% RH and a 14 hour photophase. The biological aspects and the fertility life table were appraised. Longevity of 32.9 days was verified for adult females and 40.4 days for males. The intrinsic rate of increase (rm) was 0.2 and the mean generation time (T) was 17.2 days. The population doubled every 4.1 days. The results obtained were similar to those in which the predatory mite N. californicus fed on T. urticae.


1973 ◽  
Vol 71 (1-2) ◽  
pp. 1-8 ◽  
Author(s):  
Sylvio Celso Goncalves da Costa ◽  
Samuel B. Pessoa ◽  
Neize de Moura Pereira ◽  
Tania Colombo

The main object of the present paper is to furnish a brief account to the knowledgement of Protozoa parasitic in common Brazilian frog of the genus Leptodactylus for general students in Zoology and for investigators that use this frog as a laboratory animal. Hepatozoon leptodactyli (Haemogregarina leptodactyli) was found in two species of frogs - Leptodactylus ocellatus and L. pentadactylus - in which develop schizogony whereas sporogony occurs in the leech Haementeria lutzi as was obtainded in experimental conditions. Intracellular forms have been found in peripheral circulation, chiefly in erythrocytes, but we have found them in leukocytes too. Tissue stages were found in frog, liver, lungs, spleen, gut, brain and heart. The occurence of hemogregarine in the Central Nervous System was recorded by Costa & al,(13) and Ball (2). Some cytochemical methods were employed in attempt to differentiate gametocytes from trophozoites in the peripheral blood and to characterize the cystic membrane as well. The speorogonic cycle was developed in only one specie of leech. A brief description of the parasite is given.


1878 ◽  
Vol 27 (185-189) ◽  
pp. 481-485

Notwithstanding the numerous and fruitful researches which have been recently made into the life-history of Bacteria, our knowledge of the common and interesting curved and spiral forms— the Vibrio and Spirillum of Ehrenberg—has made little or no advance since his time, neither embryonic nor reproductive forms having ever been observed; while even the zooglœa phase, so characteristic of Bacterium and Bacillus, has only once been mentioned, and then in a different form. A fresh-water aquarium, which has been stagnating since last summer in the Physiological Laboratory of University College, con­tained in winter vast numbers of ordinary motile Spirillum. On recently re-examining the water, one zooglœa film after another having in the meantime formed on the surface, thickened, broken, and sunk, we found that these motile forms had almost disappeared, while the films consisted almost entirely of resting Spirillum in a gelatinous-looking matrix, similar to that of Bacterium and Bacillus . Among these were two or three apparently distinct kinds of filaments, some resting and colourless, others motile, and filled with highly refracting bright yellowish-brown spheres. Such a field is represented in fig. 1.


1934 ◽  
Vol 66 (1) ◽  
pp. 6-16 ◽  
Author(s):  
Margaret Martin

Very little work has been done on the life history or habits of Mallophaga. Only two papers have heen published since 1913 which give even a general discussion of the life history of these parasites. The number of instars through which the insects pass was not determined in either case. For the experiments reported in this paper, the pigeon louse (Columbicola columbae [Linnaeus]) was chosen because of the ease of obtaining and handling the common host, Columba livia Linn.


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