University of Khartoum

Identification of the Giant Clams (Tridacna spp) of Dongonab Bay and the description of their habitats

Identification of the Giant Clams (Tridacna spp) of Dongonab Bay and the description of their habitats

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Title: Identification of the Giant Clams (Tridacna spp) of Dongonab Bay and the description of their habitats
Author: Shackour, Khalid Abd Elrahman
Abstract: The present study is intended to identify the giant clams species of Dongonab Bay, describes their local habitats and establishes their morphometric characteristics. To attain these objectives: • Four transects, each 100 m long, 5 m width, setup in the main bay; were surveyed for Tridacnae abundance. Physicochemical parameters around the transects, including type of substrate, were recorded. • Eighty specimens collected from the transects were identified on the basis of their observable features of the shell and mantle, and the anatomical differences between the posterior pedal retractor and the adductor muscles. • The following measurements were recorded for each of the eighty specimens: Total Length, Height, Width, Total Weight, Total Meat Wet Weight, Right Valve Weight and Left Valve Weight. Dongonab Bay provides the preferable environmental conditions needed for the growth and flourishing of the giant clams. Two species of Giant Clams were found at the Bay: Tridacna maxima and T. squamosa. The anatomical investigations show slight differences between the two species, yet, they have great advantage from the taxonomical point of view. In T. maxima the posterior pedal retractor and the adductor muscles are subequal in 7 circumference. In T. squamosa the posterior pedal retractor muscle is usually about half the size of the posterior adductor muscle, or smaller. The ratio between the populations of Tridacna maxima and T. squamosa in Dongonab Bay is 3.4:1. The former species inhabits the massive corals heads and the rocky floor while adult T. squamosa inhabits mainly the sandy substrates. The following morphomitric equations and their corresponding correlation coefficients were established for the two species: * For Tridacna maxima: 1- Total length (X) Vs Total weight (Y), Y = 0.158X 3.135, r = 0.971 2- Width (X) Vs Total weight (Y), Y = 4.886X 2.454, r = 0.985 3- Height (X) Vs Total weight (Y), Y = 0.867X 2.958, r = 0.976 4- Total length (X) Vs Total meat wet weigh (Y), Y = 0.029X 3.007, r = 0.961 5- Width (X) Vs Total meat wet weight (Y), Y = 1.272X 2.158, r = 0.963 6- Height (X) Vs Total meat wet weight (Y), Y = 0.265X 2.623, r = 0.939 7- Total Length(X) Vs Total valves weight (Y), Y = 0.073X 3.301, r = 0.965 8- Width (X) Vs Total valves weight (Y), Y = 2.670X 2.593, r = 0.981 9- Height (X) Vs Total valves weight (Y), Y = 0.401X 3.157, r = 0.967 * For Tridacna squamosa: 1- Total length (X) Vs Total weight (Y), Y = 0.163X 3.155, r = 0.992 2- Width (X) Vs Total weight (Y), Y = 4.238X 2.501, r = 0.993 3- Height (X) Vs Total weight (Y), Y = 0.802X 3.036, r = 0.988 4- Total length (X) Vs Total meat wet weigh (Y), Y = 0.004X 3.670, r = 0.991 5- Width (X) Vs Total meat wet weight (Y), Y = 0.136X 3.000, r = 0.986 6- Height (X) Vs Total meat wet weight (Y), Y = 0.026X 3.527, r = 0.942 7- Total Length(X) Vs Total valves weight (Y), Y = 0.248X 2.954, r = 0.981 8- Width (X) Vs Total valves weight (Y), Y = 4.433X 2.398, r = 0.982 9- Height (X) Vs Total valves weight (Y), Y = 1.011X 2.873, r = 0.982
URI: http://khartoumspace.uofk.edu/handle/123456789/10739
Date: 2015-05-13


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