A study on the biology of Osangularia cf. venusta (Brady): an epiphytic foraminifera on the intertidal seagrass Halodule uninervis in Shelly Bay, Townsville, North Queensland

Ludvianto, Bayu (1992) A study on the biology of Osangularia cf. venusta (Brady): an epiphytic foraminifera on the intertidal seagrass Halodule uninervis in Shelly Bay, Townsville, North Queensland. PhD thesis, James Cook University of North Queensland.

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A study on the biology of an epiphytic foraminifera (Osangularia cf. venusta) has been conducted in the intertidal zone at Shelly Bay near Townsville, Australia, during the period of 1988 to 1990.

The aims of the study were 1) to understand the general biology of O. cf. venusta, 2) to investigate the temporal patterns of O. cf. venusta distribution and its relationship with the substratum (seagrass blades), 3) to obtain information on the population' dynamics of O. cf. venusta including growth rate, recolonization, and migration.

Sampling was carried out during low tide (< 0.5 metres), over three different time intervals : 1) monthly, 2) fortnightly, and 3) daily. Samples were fixed by using 70% ethanol as soon as the field works were completed. O. cf. venusta specimens were collected by detaching them from the seagrass blades under a stereo microscope. Detailed observations of the specimen was made by means of a stereo microscope and a scanning electron microscope. Locomotion was observed by video recording the movements of O. cf. venusta individuals on the Halodule uninervis blades. The study shows that individuals dislodging by physical and biological forces, may influence the population dynamics of O. cf. venusta especially the "age" distribution. These factors were also suspected to affect the temporal abundance, density and the proportion of microspheric and megalospheric individuals in the population. Other factors such as the condition of the seagrass, its abundance and blade area are also strongly believed to affect the temporal abundance of O. cf. venusta. Generally, left coiled individuals dominated the population during the study period. This coiling direction preference, however, could not be correlated to the temperature variations of the surrounding environment. "Twinned" specimens were observed in the O. cf. venusta population during the study period.

The study shows that the "twinned" phenomenon in O. cf. venusta was probably initiated by the creation of a second aperture whilst the juvenile had only one chamber. The juvenile, then developed two rows of later chambers based on the two apertures. The present study also reveals that O. cf. venusta maintained its existence in the harsh intertidal environment by 1) reinforcing the test, 2) producing a large number of juveniles, 3) clinging on the blades of the intertidal seagrass Halodule uninervis, and 4) rapidly colonizing and recolonizing the "empty" seagrass blades.

Item ID: 33779
Item Type: Thesis (PhD)
Keywords: biology; distribution; epiphytes; Foraminifera; growth; Halodule uninervis; migration; Osangularia cf. venusta; population; Shelly Bay; Townsville
Date Deposited: 21 Jul 2015 04:36
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 30%
06 BIOLOGICAL SCIENCES > 0605 Microbiology > 060504 Microbial Ecology @ 70%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50%
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