WorldCat Identities

Abdo, David A.

Overview
Works: 6 works in 7 publications in 1 language and 18 library holdings
Genres: Self-instruction 
Roles: Author
Publication Timeline
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Most widely held works by David A Abdo
Modern written Arabic by David A Abdo( Recording )

2 editions published in 2005 in English and held by 7 WorldCat member libraries worldwide

Modern written Arabic by David A Abdo( Book )

in English and held by 6 WorldCat member libraries worldwide

Modern written Arabic( Book )

1 edition published in 2001 in English and held by 2 WorldCat member libraries worldwide

Modern Written Arabic by David A Abdo( Book )

in English and held by 1 WorldCat member library worldwide

Maintenance and structuring of two temperate Haliclonid sponge populations by David A Abdo( Book )

1 edition published in 2007 in English and held by 1 WorldCat member library worldwide

[Truncated abstract] Sponges have an invaluable ecological importance through the provision of shelter and habitat, consolidation of reefs, bio-erosion, and in benthic-pelagic coupling processes. In addition, sponges are known to be an incredible source of compounds with bio-medicinal and commercial applications. Despite their ecological and economic importance, our understanding of the processes which maintain and structure sponge populations is severely lacking compared to other sessile invertebrates (e.g. Cnidarians). This study examines the processes which help maintain and the factors which structure the populations of two sympatric Haliclona species (Demospongiae; Haplosclerida; Chalinidae) at Hamelin Bay on the south west coast of Australia. In addition, the importance of both species to the broader marine community is examined. The reproductive biology of both species was determined from histological sections taken from each species over two years at Hamelin Bay. No evidence of asexual reproduction was observed in either species. Sexual reproduction occurred from November to April in Haliclona sp. 1 (hereafter green Haliclona) and November to May in Haliclona sp. 2 (hereafter brown Haliclona). The green Haliclona is viviparous with both gonochoric and hermaphroditic individuals observed in the population. The brown Haliclona is also viviparous with separate sexes. The onset and progression of reproduction in both species corresponded to increases in water temperature and photoperiod, but only decreasing wave height showed a significant correlation to gametogenesis. ... A significant (P <0.05) difference in concentration between seasons was also observed, suggesting environmental and physiological factors affect the production of salicylihalamide A in the green Haliclona. The importance of each species to the marine environment was assessed by investigating the endofauna inhabiting each species across their known range ([approx.]1000 km's). A total of 948 and 287 endofaunal individuals were found associated with the green and brown Haliclona, respectively. Twenty four endofaunal taxa were found (from mysid shrimps to teleost fish), and the endofaunal assemblages of each species were significantly different. However, only the endofaunal assemblage associated with the green Haliclona varied among locations. Overall, this study demonstrates that the populations of both species are maintained by limited sexual reproductive output and larval dispersal. Abiotic factors (e.g. water temperature, wave exposure) influence the growth and physiology of both species, which is intimately connected to their abilities to reproduce. This has important consequences for the species populations with regard to their resilience to environmental change, and potential for harvesting of biomass for supply of bioactive compounds. Additionally, both species provide important habitats for many other organisms. The findings highlight the need for a detailed understanding of the ecology of potentially exploitable sponge species, to ensure their conservation and limit the impact on the organisms which rely on the sponges
Modern written arabic : basic course by David A Abdo( Book )

1 edition published in 1960 in English and held by 1 WorldCat member library worldwide

 
Audience Level
0
Audience Level
1
  Kids General Special  
Audience level: 0.60 (from 0.40 for Maintenanc ... to 0.99 for Modern Wri ...)

Modern written Arabic Modern written Arabic Modern written arabic : basic course
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Modern written ArabicModern Written ArabicModern written arabic : basic course
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