~ 123 ~  International Journal of Fisheries and Aquatic Studies 2015; 2(6): 123-127  ISSN: 2347-5129 (ICV-Poland) Impact Value: 5.62  (GIF) Impact Factor: 0.352  IJFAS 2015; 2(6): 123-127 © 2015 IJFAS www.fisheriesjournal.com Received: 27-05-2015 Accepted: 24-06-2015 Job Bassey E. Marine Biology Department, Faculty of Marine Science, University of Calabar, Calabar, Nigeria. Eyo O. Edet Department of Soil Science, Faculty of Agriculture, University of Calabar, Calabar, Nigeria Ekene P. Iwuagwu Physical Oceanography Department, Faculty of Marine Science, University of Calabar, Calabar, Nigeria. Correspondence Bassey E. Job Marine Biology Department, Faculty of Marine Science, University of Calabar, Calabar, Nigeria. Influence of tidal regimes in relation to industrial activities on the hydrodynamics of the Calabar River system in Southern Nigeria Job Bassey E., Eyo O. Edet, Ekene P. Iwuagwu Abstract The Cross River system is formed from numerous tributaries arising from the Western slopes of the Cameroon Mountains which have two spurs into Nigeria as the Oban Hills in the south and the Obudu Hills in the North. A field study was conducted during a single expedition at designated locations to study the influence of tidal regimes in relation to industrial activities on hydrodynamics of Cross River system between 10th and 11th August, 2009 during the high and low tidal regimes using the Institute of Oceanography Research Vessel "Plankton Fisher". The locations used for the studies were CALCEMCO (now UNICEM) jetty, Intels Jetty (left and right Flanks), Calabar/Creek Town entry route, TINAPA Jetty, Adiabo Bridge and Adiabo-Okurikang (control location). River depths and flow velocity were taken in-situ along designated stations using an automated eco-sounding device (for depth), and stop- watch and un-juiced orange fruit as floater (for flow velocity). The choice of stations was based on discharge rate, flow direction, absence of impediment to flow, depth, ab initio. These locations were, however, duly geo-referenced. During high tide, velocity values ranged from 0.01 and 1.42ms -1 . Highest velocity value of 1.42 ms -1 was recorded at Adiabo Bridge with the lowest value at Adiabo-Okurikang (control point). Generally, there were marked variations in velocity of the water current during the survey. Conversely, during low tide, water current velocity ranged between 0.01 and 1.11ms -1 . Least velocity value of 0.01ms -1 was recorded at the left flank of Intel Jetty and Tinapa Jetty, respectively. This was followed by values of 0.03ms -1 , 0.14ms -1 , 0.23ms -1 and 0.35ms -1 at Adiabo-Okurikang, CALCEMCO jetty (UNICEM), Calabar/Creek Town entry route and Intels jetty (right flank), respectively. The study recommends the need for appropriate measures on tidal regime management for enhanced ecosystem functioning of the Cross River System. Keywords: Hydrodynamics, High Tide, Low Tide, Calabar River system, Nigeria. 1. Introduction Cross River is the main river in southeastern Nigeria and gives its name to Cross River State. It flows through swampy rainforest with numerous creeks and forms confluence with the Calabar River Moses, [11] . The Cross River system is formed from numerous tributaries arising from the western slopes of the Cameroon Mountains which have two spurs into Nigeria as the Oban Hills in the south and the Obudu Hills in the north (Enplan Group Consulting Engineers, [7] . The whole Cross River system lies approximately between longitudes 7°30'E and 10°00'E and latitudes 4 o N and 8 o N. The river basin covers an area of 54,000km 2 of which 14,000km 2 lies in the Republic of Cameroon, while the remainder lies in Nigeria which Calabar, Cross River State forms a part Moses, [11] . The climate of the river area is that of tropical rain forest. Temperature variations within the basin are between (27.5 °C – 35 °C maximum and 22 o C - 24.0 °C minimum). The relative humidity is high throughout the year. Practically in the coastal area, 93% has been recorded in the Calabar area of the river during peak rainy period Moses, [11] . During this time, the water leveled rises with the addition of run-offs (Enplan Group Consulting Engineers, [7] . Moses, [11] . Studies of hydrodynamics of aquatic ecosystems provide vital information for river basin management for such studies help to interpret the formation of river morphology and the socio-economic development of the area in addition to the habitual diversity status which invariably are consequential to industrial and anthropogenic activities in the river system (Marmer, [10] ; Zhang et al., [16] . In contemporary river systems history, frequent changes in river systems associated with industrial developments on the coastal areas have been reported