Habitat Preferences of PokeA (Batissa violacea var. celebensis von Martens, 1897) Basic on Substrat Characterisation in Pohara River Southeast Sulawesi

Abstract

This research is motivated by the lack of information about the habitat preferences of pokea clams in Pohara River, Southeast Sulawesi. This study aims to determine the density, distribution pattern and habitat preferences of pokea clams in the Pohara River, Southeast Sulawesi. This research was conducted for 6 months (April-September 2011). Sampling of pokea, water quality, and sediment texture was carried out in the Pohara River and analyzed at the FPIK UHO Laboratory. The density and distribution of pokea were calculated using a standard formula and analyzed using Mann Whitney and Chi Square respectively, while the habitat preferences based on different substrate textures were analyzed using Principal Component Analysis (PCA) and Cluster Analysis (CA) in the Multivariate Statistical Package (MVSP). The results showed that the density of pokea clams ranged from 117±96.78-816±594.84 ind/m2 which was distributed in cluster over the entire cross-section of the river. Pokea clams were found in all substrate textures from gravel to clay. The habitat preference of pokea clams indicated by the highest density was found in the clay texture. Pokea clams relatively do not like the habitat of coarse sand and gravel texture which is characterized by pokea population with the lowest density

Temporal variations in growth and condition index of kalandue clams (Polymesoda erosa, Solander 1786) in Kendari Bay, Southeast Sulawesi

“…This was followed by isometric b values in the following months (June-September) and increase in October towards positive allometry [2]. The same pattern was shown in clams of the same family, namely Batissa violacea [1] and Donax trunculus [35], which showed increase in b values at early maturity, gonadal growth and peak maturity [36].…”

“…However, the values differ from that of the same species but different areas, such as in Butuan Bay, Philippines with 3.12 [9], as well as areas with b value less than 3.0 are Polymesoda erosa in North Australia at 2.91 [13] , and Marudu Bay, Malaysia by 2.27 [26], and other shellfish, namely: Batissa violacea var. celebensis in the Pohara River with a value range of 1.87-2.83 [1], Pisidium amnicum of 2.7 [32], and Donax semestriatus [11].The different b values in each of these species can be caused by: 1) the width-weight relationship of the species that may reach a constant at a point below 3.0, 2) the low quality of the aquatic environment, that may be reflected in aspects such as low availability of food [12] and the high turbidity that interferes with feeding of the clams. In such case, the number of clams with high condition index, thus considered fat, is low, such as the Batissa violacea clams in the Pohara River [1], 3) latitude conditions [3], and 4) clam exploitation [21].…”