International Journal of Marine Science 2016, Vol.6, No.27, 1-22
15
The species
Sphyraena sphyraena
related well with Revelle factor and total alkalinity but showed a negative
relation with pH and nitrates (Figure 7). The other dominant species identified in this fishery did not seem to be
influenced by any of the variables. For the rare fish species (species with relative abundance lesser than 1%)
identified in this fishery during the lean season,
Ephippion guttiffer
was identified to relate well with pH (Figure
8).
Figure 8: CCA biplot showing relationship between rare fish species identified in the lean season of the artisanal fishery
For the peak season of the artisanal fishery, the first two axes cumulatively explained 100% of the variation found
in species abundance as a result of the selected environmental variables. The first ordination axis reflected species
with a gradient related to Revelle factor, nitrates and phosphates on the positive end of the axis and pH, total
alkalinity and carbonate ion concentration on the negative end. The second axis had pH, total alkalinity, carbonate
ion concentration and nitrates on the positive end and phosphates and Revelle factor on the negative end (Figure
9). The species
Chloroscombrus chrysusrus
related well with pH and carbonate ion concentration but showed a
negative relation with nitrates, Revelle factor and phosphates (Figure 9).
Drepane africana
however related well
with Revelle factor and phosphates but showed negative relation with pH and carbonate ion concentration. For the
rare fish species (species with relative abundance lesser than 1%) identified in this fishery during the lean season,
Sepia officinalis was identified to relate well with pH (Figure 10).
Figure 9: CCA biplot showing relationship between dominant fish species identified in the peak season of the artisanal fishery
-1.5
1.5
-1.0
1.0
T.teraia
S.japoni
S.fiatol
D.margar
P.senega
S.offici
S.m dere P.pel
P.brachy P typus
E.fimbr
E.guttif
M c ph l
D.rhoncu
C senega . pidu
TOTAL AL
REVELLE
PH
CARBONAT
Nitrates
Phosphat
-0.8
1.0
-1.5
1.5
B.auritu
S.dorsal
P.peli
I.africa
C.chrysu
C. pidu
P.notial
G.decada
S.sphyra
T.ovatus
P.senega
D.africa
TOTAL AL
REVELLE
PH
CARBONAT
Nitrates
Phosphat
