The physico-chemical hydrology of a tropical seasonal river-upper Ogun river

Adebisi, A. A.

doi:10.1007/bf00006123

Cited by 88 publications

(84 citation statements)

References 8 publications

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“…The Composition of phytoplankton community of the ponds agreed with reports that blue-green algae and green algae dominate most tropical water bodies (Adebisi, 1981;Ayodele & Ajani, 1999). Increased temperature, sunlight and tropholytic activities as a result of low water level coupled with frequent movement of water from the deep, nutrient-rich sediments into the tropholytic zone, increased the abundance of phytoplankton during dry season.…”

Section: Discussionsupporting

confidence: 86%

“…Changes in the intensity of rainfall affects physico-chemical parameters of water which also affects biomass of aquatic organisms (Adebisi, 1981). The higher turbidity, salinity, TDS and most of the physico-chemical properties in the wet season had been explained to be as a result of flooding during heavy rainfall and run-off from nutrient rich agricultural lands increased (Ayodele & Ajani 1999;Offem, 2008).…”

Section: Discussionmentioning

confidence: 99%

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Plankton Distribution and Diversity in Tropical Earthen Fish Ponds

Ikpi¹,

Offem²,

Okey³

2013

ENRR

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Our knowledge of the consumption of plankton by fish is still fragmentary. Trophic links between fish and plankton are often loose because plankton is a changing assemblage of pelagic organisms of valuable nutritional value. The objectives of the study were to determine the distribution and diversity of planktons in the fish ponds. Water samples for plankton analysis were collected monthly (January-December), along with water samples used for the determination of physico-chemical parameters in 250 ml bottles in Ponds 1, 2 and 5. The freshwater sample was mixed gently and pipetted into 5 ml plankton chamber containing 2 drops of Lugol's solution. The Lugol's solution which served as fixative also enhanced sedimentation of the organisms and was left overnight before analyzing plankton using Zeiss inverted plankton microscope and plankton determination keys. Data was analyzed using Shannon-Weaner diversity index, species richness, means and analysis of varians (ANOVA). The results showed that the highest species richness for dry season phytoplankton value of 27 was recorded in Pond 2, with the highest Shannon-Weaner diversity index value of 0.5401 in pond 5. Merismopaedia elegans with 3,434 in pond 2 was the most abundant phytoplankton species and chlorophyceae the most dominant taxa. The rainy season zooplankton species richness values (5 in pond 2) were higher than that of the dry season (3 in pond 3) with the highest Shannon-Weaner index value of 0.3501 recorded in pond 1. The most abundant zooplankton species Asplanchna species 57 was recorded in pond 2. Significant differences (p < 0.05) was observed for phytoplankton and zooplankton species between the ponds. Physico-chemical parameters had influence on the distribution and diversity of planktons in the fish ponds.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Plankton Distribution and Diversity in Tropical Earthen Fish Ponds

Ikpi¹,

Offem²,

Okey³

2013

ENRR

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“…The phytoplankton composition in this study agreed with reports of Adebisi (1981) and Ayodele and Ajani (1999) that blue-green algae and green algae dominate most tropical African waters. The dominance of Chlorophyceae in respect of species number and population density in this study had also been observed elsewhere (Tressler et al, 1940;Willen, 1959;Vyverman, 1996, Silva, 2005 and the overwhelming presence in the dry season, attributed to the presence of bright sunshine and extensive catchment area, draining calcium rich agriculture land (Pennack, 1949;Kurasawa and Shiraishi, 1954;Lewis, 1996).…”

Section: > Phytoplanktonsupporting

confidence: 92%

Distribution and dynamics of a tropical waterfalls ecosystem

Offem

Ikpi

2012

Knowl. Managt. Aquatic Ecosyst.

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Waterfalls gives the impression of a lifeless zone because researchers have historically focused on the hydrology, ecotourism and geological features. Effective management will require an understanding of changes in species composition and distribution of macro-biota. Monthly samples were taken in wet and dry seasons, over two year period in three regions along the 6817.7 m length of the Agbokum waterfalls. Macro-biota exhibited distinct pattern in respect of seasonal and spatial changes. Trachelomonas volzii, the most abundant phytoplankton species reduced from 686 in the dry season to 143 in the wet, and from 455 downstream to 91, midstream (waterfalls region). Zooplankton species Calanus finmarchicus decreased from 511 during dry season to 36 in the wet and from 334 downstream to 7, midstream. 71.7 percent of the total macro-invertebrates were recorded from downstream reaches while only 6.3 percent were contributed by midstream. Percentage cover of marginal vegetation by Bambusasp, Symphonia and Elaeis guineesis displayed progressive increase from upstream reaching a maximum of 38.5 mean percent cover in the relatively undisturbed downstream. In contrast, Raphia vinifera, Havea brasiliensis, Grewia sp. and Cocos nucifera shrank in size from 34% to 8% at the midstream stretches of the river while only nymphia-rich vegetation becomes more frequent in the middle reaches. The disturbance regimes of the midstream reaches of Agbokum waterfalls combined with its very low faunal and floral diversity has made the environment unstable therefore susceptible to the invasion of disturbance tolerant biota. RÉSUMÉ Distribution et dynamique d'un écosystème tropical de cascadesLes cascades donnent l'impression d'une zone morte parce que les chercheurs ont toujours mis l'accent sur l'hydrologie, l'écotourisme et les caractéristiques géologiques. Une gestion efficace nécessite la compréhension des changements dans la composition des espèces et la distribution des macro-organismes. Des échantillons mensuels ont été pris au cours des saisons humides et sèches, pendant plus de deux ans dans trois régions le long des 6817,7 m des cascades Agbokum. Les macrobiotes présentent des patterns différents selon les changements saisonniers et spatiaux. Calanus finmarchicus passe de 511 pendant la saison sèche à 36 en saison humide et de 334 en aval à 7, en zone médiane. 71,7 % du total des macroinvertébrés ont été rencontrés dans les tronçons situés en aval, tandis que seulement 6,3 % sont trouvés dans les tronçons médians.

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“…In other places, the intensity of waterfalls andpressure generated from it due to gravity has given the im-pression of a lifeless zone [1]. Knowledge of waterfalls systems in Africa are therefore limited to hydrology and geological features [2,3], as natural monuments for revenue generation, because of their ecotourism potentials [4] and as source for drinking, irrigation and other domestic purposes. Studies on the fisheries and aquaculture tuarine and open water body systems.…”

Section: Introductionmentioning

confidence: 99%

Distribution and Dynamics of a Tropical Waterfalls Ecosystem

Offem¹,

Ikpi²

2012

IJE

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Waterfalls gives the impression of a lifeless zone because researchers have historically focused on the hydrology, ecotourism and geological features. Effective management will require an understanding of changes in species composition and distribution of macro-biota. Monthly samples were taken in wet and dry seasons, over two year period in three regions along the 6817.7m length of the Agbokum waterfalls. Macro-biota exhibited distinct pattern in respect of seasonal and spatial changes. Trachelomonas volzii, the most abundant phytoplankton species reduced from 686 in the dry season to 143 in the wet, and from 455 downstream to 91, midstream (waterfalls region). Zooplankton species Calanus finmarchicus decreased from 511 during dry season to 36 in the wet and from 334 downstream to7, midstream. 71.7 percent of the total macro-invertebrates were recorded from downstream reaches while only 6.3 percent were contributed by midstream. Among the three dominant fish species Tilapia zillii, Clarias gariepinus and Labeo coubie, constituting 45.5% of total catch, two benthic fishes (L. coubie and C. gariepinus) showed inverse distributional patterns. Clariid fish (C. gariepinus) was most abundant downstream and least represented upstream. Cyprinid (L.coubie), on the other hand, dominated the upstream reaches and scarce downstream. Percentage cover of marginal vegetation by Bambusasp, Symphonia and Elaeis guineesis displayed progressive increase from upstream reaching a maximum of 38.5 mean percent cover in the relatively undisturbed downstream. In contrast, Raphia vinifera, Havea brasiliensis, Grewia sp and Cocos nucifera shrank in size from 34% to 8% at the midstream stretches of the river while only nymphia-rich vegetation becomes more frequent in the middle reaches. Nymphia has become a biological invader and has exhibited a full range of impact and abundance in this disturbed midstream reaches. The disturbance regimes of the midstream reaches of Agbokum waterfalls combined with its very low faunal and floral diversity has made the environment unstable therefore susceptible to the invasion of disturbance tolerant biota.

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The physico-chemical hydrology of a tropical seasonal river-upper Ogun river

Cited by 88 publications

References 8 publications

Plankton Distribution and Diversity in Tropical Earthen Fish Ponds

Plankton Distribution and Diversity in Tropical Earthen Fish Ponds

Distribution and dynamics of a tropical waterfalls ecosystem

Distribution and Dynamics of a Tropical Waterfalls Ecosystem

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