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Diel and Tide Variation of Fish Speciesi Kakum River Estuary in the Central Region,Ghana

Abstract

The sequence of day and night has a strong impact on the relative distribution of numerous fish species, causing a change in the richness and the composition of fish assemblages. Changes in fish abundance occur mainly due to the tidal cycle, moon phase, and alternation of night and day. Periodic monitoring of the biodiversity of these estuarine ecosystems requires to be vigorously pursued to assess their status. This study investigated the diel variation related to tidal levels of fish community in Kakum River Estuary in the Central Region of Ghana. On each sampling date, ten castings were done during both day and night capture for a total of twenty casting on each sa mpling date. A total of 1,223 fish belonging to 25 species, 16 families, and a biomass of 10,832.8 grams were recorded during the entire sampling periods from November/2016 to April/2017. The diurnal catches had 24 species, contributing to 52% of the total fish caught and 45% biomass. The nocturnal catches had 19 species, which contributed to 48% of the total catch and 55% biomass. Catch weights of most abundant species in the Kakum River Estuary, the herbivore-phytoplankton Mugil curema, were highest only during the night. Mean fish species were significantly different between tide -time of day and night (F3,20=187.789, p=7.3764) with the highest species values (36) recorded at low tide (Medium salinity) on 10/01/2016 during the day and lowest species of (19 on 12/01/2017 and 21 species on 17/03/2017) were recorded at the peak tide during the nocturnal period. The study provides strong indication that fish inhabiting Kakum River Estuary establish their niches along a temporal scale in Subject to the interaction with the tidal and the diel cycles. The fish community occurred in the estuary at different times during sampling and the abundance of fish changed on an irregular basis. This suggests that temperature may play an important role in determining the behavior of marine migrants. The geomorphological setting of the estuary plays an important role in influencing how fish use the estuary according to the tidal cycles.

Kezia Baidoo*, Seth Mensah Abobi, Noble Asare, Eric Krampah, Christian Ayisis

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