SOME ABSTRACTS FROM DR. OYEWO’S PAPERS

 Acute toxicity and induced weight changes in laboratory tests with Mn and Cu against Tilapia guineenses (Dumeril) and Typanotonus fuscatus (Linne)

E.O. Oyewo¹  and K.N. Don-Pedro²

¹Nigerian Institute for oceanography and Marine Research, P.M.B. 12729, Lagos, Nigeria

²Toxicology Laboratory, Zoology Unit, Department of Zoology,

Marine Biology and Fisheries, University of Lagos, Lagos, Nigeria

(Received 29 July, 204; Accepted 21 December, 2005)

Abstract:   The acute toxicity of Mn and Cu  against Tilapia guineensis and Tympanotonus fuscatus and the sub-lethal effects of the metals on weight changes were investigated in laboratory experiments employing standard bioassay techniques.  Based on 96 hr LC₅₀ values, Copper was more toxic than Manganese to either test animal by several orders of magnitude. Against either test metal, T. guineensis was remarkably more susceptible than T. fuscatus. At sub-lethal concentrations, particularly the two highest concentrations tested (0.016 and 0.03 mg Cu L^-1, 23.0 and 46.0mg Mn L^-1), both metals adversely affected the test species by bringing about reduced weight gains or weight loss in exposed animals compared to untreated controls at the end the test periods.  The implications of these findings for ecosystem viability and management are discussed.

Key words: Acute toxicity, Sub-lethal toxicity, Tilapia guineensis, Tympanotonus fuscatus

Journal of Environmental Biology

27 (2), 327-334 (2006)

http: //www.geocities.com/-environ-biol/     

Variability  in Some Oceanographic and Meteorological Conditions

Around the Lagos Harbour Entrance, Nigeria (1987)

E. O. Oyewo, E.A Ajao, A.C Ibe, T.Orekoya, B.E Jarikre

Nigerian Institute for Oceanography and Marine Research

P.M.B. 12729 Lagos – Nigeria

and

A.M. Asante-Nimako

Department of Meteorological Service

Federal Ministry of Civil Aviation, Lagos - Nigeria

ABSTRACT 

Surface water temperatures and sediments at two stations around the Lagos Harbour entrance were measured from January 1978 to December 1987.  Surface water dissolved oxygen (D.O) was also measured at one of the stations from January 1982 to December 1987.  This paper presents the findings for the period and the inter-relationship of the measured parameters with the prevailing hydrological and meteorological regimes.  The pattern of surface water temperatures at both stations in the study period showed a clearly defined mean maximum of 29.5⁰C around April  and an equal clearly defined mean minimum  of 25.8 ⁰C around August.  Occasionally, there were also less clearly defined mean maximum and minimum temperatures in October /November and January respectively. The salinity amplitude at both stations is influenced by rainfall especially at the Harbour station and also possibly by local upwelling which couples both stations through tidal flushing.  The mean minimum salinity at the Harbour station (12.29+6 psu) was recorded in October while the highest mean maximum (13.23 +1.7) at this station was in April. At the Beach station, mean maximum (32.3 1 1.3) and minimum (27.53 1 3.1) salinities were recorded in May and September respectively.  It was observed that in most of the years of study, the rainfall pattern showed no break in the month of August . Surface D.O values were generally greater than 4.50mg L^-1 .  There was a peak D.O period in July/August.  The inter-and intra-annual variability in the D.O pattern is explicable in terms of the non-conservative nature of the gas, its involvement in the bio-geochemical cycle the influence of physical processes on its temporal and spatial concentration.

                       Journal Sci. Res. Dev. 2001.Vol.6. 115-126

Variability  in Some Oceanographic and Meteorological Conditions

Around the Lagos Harbour Entrance, Nigeria (1987)

E. O. Oyewo, E.A Ajao, A.C Ibe, T.Orekoya, B.E Jarikre

Nigerian Institute for Oceanography and Marine Research

P.M.B. 12729 Lagos – Nigeria

and

A.M. Asante-Nimako

Department of Meteorological Service

Federal Ministry of Civil Aviation, Lagos - Nigeria

ABSTRACT

Surface water temperatures and sediments at two stations around the Lagos Harbour entrance were measured from January 1978 to December 1987.  Surface water dissolved oxygen (D.O) was also measured at one of the stations from January 1982 to December 1987.  This paper presents the findings for the period and the inter-relationship of the measured parameters with the prevailing hydrological and meteorological regimes.  The pattern of surface water temperatures at both stations in the study period showed a clearly defined mean maximum of 29.5⁰C around April  and an equal clearly defined mean minimum  of 25.8 ⁰C around August.  Occasionally, there were also less clearly defined mean maximum and minimum temperatures in October /November and January respectively. The salinity amplitude at both stations is influenced by rainfall especially at the Harbour station and also possibly by local upwelling which couples both stations through tidal flushing.  The mean minimum salinity at the Harbour station (12.29+6 psu) was recorded in October while the highest mean maximum (13.23 +1.7) at this station was in April. At the Beach station, mean maximum (32.3 1 1.3) and minimum (27.53 1 3.1) salinities were recorded in May and September respectively.  It was observed that in most of the years of study, the rainfall pattern showed no break in the month of August . Surface D.O values were generally greater than 4.50mg L^-1 .  There was a peak D.O period in July/August.  The inter-and intra-annual variability in the D.O pattern is explicable in terms of the non-conservative nature of the gas, its involvement in the bio-geochemical cycle the influence of physical processes on its temporal and spatial concentration.

                       Journal Sci. Res. Dev. 2001.Vol.6. 115-126

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