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Title:	A study on the biology and sound-producing mechanisms of the sea catfish, hexanematichthys sagor
Authors:	Ho Grace Hui Xuan (P39428 )
Supervisor:	Mazlan Abd Ghaffar, Prof. Dr.
Keywords:	Sea catfishes. Sea Catfish - Research
Issue Date:	27-Oct-2011
Description:	The present study was conducted to identify and describe the sound-producing mechanisms of the sea catfish, Hexanematichthys sagor, to characterise its sound signals, and to investigate the relationships between the basic acoustic parameters. Fish samples were obtained from the estuaries of Matang Mangrove Reserve in Perak, Malaysia, with sizes ranging between 285 - 505 mm TL. The relative growth condition of the fish population was allometrically negative with “b” value < 3.0 (W = 0.000026SL 2.9267 ). Presence of eggs and developing hatchlings in possession of large yolks in the males' buccal cavity has given proof that the fish takes up paternal oral incubation. Stomach content analysis demonstrated that the H. sagor is essentially an avid benthic feeder with an estimated trophic level of 3.3 ± 0.51 and a diet composition dominated by benthic crustaceans, zoobenthos, and fish. Anatomical studies have shown that H. sagor possesses two types of sound-producing mechanisms, i.e. (i) drumming of swimbladder extrinsic sonic muscles and (ii) pectoral fin spine stridulation. The elastic spring apparatus, Springfederapparat, formed by the modified, flexible transverse process of the fourth vertebra i.e. Müllerian ramus, to which the anterior surface of the swimbladder is attached to, is essential to the swimbladder drumming mechanism. The associated protractor muscles originate from the occipital region of the neurocranium and insert themselves onto the anterior surfaces of the enlarged ramus. Incidentally, contractions of the adductor profundus and superficial adductor muscles allows adduction and abduction movements of the pectoral spine respectively; simultaneously, contraction of the arrector ventralis of the pectoral spine allows the pulling and pressing the microscopic bony ridges located on the distal end of pectoral fin spine against the rough lateral face of the spinal fossa wall, ensuing in the stridulatory mechanism. Passive acoustic surveys were conducted both in the field and at the hatchery under controlled conditions and sound samples were collected using a single hydrophone (HP-A1, Burns Electronic Hydrophone System) connected to a digital recorder (Edirol R1, Roland). Subsequent sound analysis was done using the acoustical analysis software SoundRuler ver. 0.9.6.0 written by Marcos Gridi Papp. Based on the results acquired from the sound signal processing and spectrograms, the frequency range of the H. sagor lies within 190 to 1077 Hz. The mean sound duration for drumming sounds is 31.8 ± 20.18 ms with a dominant frequency of 658 ± 86 Hz. On the other hand, stridulation sounds have a mean sound duration of 75.2 ± 17.43 ms and a dominant frequency of 1012 ± 65 Hz. Results from studies between the relationships of various acoustic parameters have shown that the H. sagor has the ability to manipulate the number of pulses and the inter-pulse interval; the number of pulses has little influence on the pulse duration whereas its pulse repetition rate shows significant influences towards time-related parameters including inter-pulse interval and pulse duration. A series of cluster analyses using frequency-related and time-related parameters have been conducted and the results serve to verify the two types of sound-producing mechanisms applied by the H. sagor and that the sound samples collected were produced by two distinct size groups.,Master
Pages:	206
Call Number:	QL638.A755 H634 2011
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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