AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: 2151-7517, ISSN Online: 2151-7525, doi:10.5251/abjna.2011.2.6.897.901 © 2011, ScienceHuβ, http://www.scihub.org/ABJNA Food and feeding ecology of the MUDSKIPPER Periopthalmus koelreuteri (PALLAS) Gobiidae at Rumuolumeni Creek, Niger Delta, Nigeria F.G. Bob-Manuel Rivers State University of Education, Rumuolumeni, P. M. B. 5047, Port Harcourt, Nigeria ABSTRACT The food habits of the mudskipper Periophthalmus keolreuteri (Pallas) from the mudflats at Rumuolumeni Creek, Niger Delta, Nigeria were studied. The frequency of occurrence and ‘point’ methods was used for the gut content analysis. The results indicate that the juveniles were herbivorous feeding more on aquatic macrophytes, diatoms and algal filaments while the adults had a dietary shift towards crustaceans, aquatic and terrestrial insects and polychaetes. The amphibious lifestyle of the mudskipper confers on it the trophic position of a zoobenthivore and a predator. Keywords: diet composition, mudskippers, food web, trophic relations, Niger Delta. INTRODUCTION The mudskippers Periophthalmus koelreuteri (Gobiidae: Oxudercinae) live in the intertidal habitat of the mudflats and in mangrove ecosystem (Murdy, 1989). These fishes are uniquely adapted to a completely amphibious lifestyle (Graham, 1997). They are quite active when out of water, feeding and interacting with one another and defending their territories. The mudskippers, Periophthalmus koelreuteri (Pallas) have a range of peculiar behavioural and physiological adaptations to an amphibious lifestyle. These include anatomical and behavioural adaptations that allow them to move effectively on land as well as in the water (Harris, 1960) the ability to breathe through their skin and the lining of their mouth (the mucosa) and throat (the pharynx) by means of cutaneous air breathing (Graham, 1997), digging of deeps burrows in soft sediments that allow the fish to thermo-regulate (Tytler and Vaughan, 1983); avoid marine predators during high tide when the fish and burrow are submerged (Sasekumar et al 1994) The mudskipper, P. Koelreuteri in widely fascinating of all tropical fish. They can be seen jumping, climbing, and skipping about with great agility in the mangrove creeks of the Niger Delta region of Nigeria. These fish have no legs but move with their arm-like pectoral fins. The mudskippers are widely distributed in the brackish water rivers, creeks, and lagoons in the Niger-Delta area of Nigeria. This fish is economically important and actively fished by the local inhabitants of this area to whom it serves as a special delicacy. The fish is also used as bait to catch bigger fishes. The rich food supplies in the mangrove mud flat have been the impetus which led the goby-like ancestors of modern mudskippers to leave the water from time to time. (Evans et al., 1999) The mudskippers can move rapidly on the mud, which is inaccessible to people. The mudskipper, P. koelreuteri is a residential fish inhabiting the mudflats of the Niger Delta estuaries, the waterways, and the mangrove forests in Nigeria. The objective of this work is to investigate the food and feeding ecology of the mudskipper P. koelreuteri in the mudflat of the Rumuolumeni creek in the Niger Delta, Nigeria. MATERIALS AND METHODS Study Site: The study site was the mangrove swamp and mudflat at the Western end of the Rivers State University of Education Rumuolumeni, Port Harcourt. The vegetation of the Rumuolumeni Mangrove Creek consist of the red mangrove Rhizophora racemosa and the white mangrove Avicennia Africana with heights ranging from 2.50 to 5.60m. The main river bifurcates into two smaller tributaries. The water is brackish. At low tide stilt-like prop roots of the mangrove were visible; the intertidal mudflats were exposed and served as feeding ground for the mudskippers. Burrows and small holes between 3.5- 6cm in diameter abound around the prop-roots of the Rhizophora trees. These areas served as Periophthalmus. species hide out. Traps were set around these areas. The substrate consisted of hydromorphic soil of the marine alluvium type heavily impregnated with products of decayed organic