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International Journal of Marine Science 2014, Vol.4, No.42, 1-11
http://ijms.biopublisher.ca
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Research Article Open Access
Does Primary Productivity Affect Benthic Macroinvertebrate Abundance and
Diversity in Estuarine Ecosystem? ACase Study in Lagos Lagoon, Nigeria
.
R.E. Uwadiae , A.A. Ajose
Benthic Ecology Unit, Department of Marine Sciences, University of Lagos, Akoka, Lagos, Nigeria
Corresponding author email
International Journal of Marine Science, 2014, Vol.4, No.42 doi: 10.5376/ijms.2014.04.0042
Received: 31 Mar., 2014
Accepted: 15 May, 2014
Published: 11 Jul, 2014
Copyright
©
2014 Uwadiae and Ajose, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Uwadiae, R.E. and Ajose, A.A. 2014, Does Primary Productivity Affect Benthic Macroinvertebrate Abundance and Diversity in Estuarine Ecosystem? A Case
Study in Lagos Lagoon, Nigeria. International Journal of Marine Science, Vol.4, No.42 1
-
11 (doi: 10.5376/ijms.2014.04.0042)
Abstract
Whether the level of primary productivity as expressed in the concentration of chlorophyll a (chl-a) in water and sediment
affect the abundance and diversity of benthic macroinvertebrates in an estuarine ecosystem was investigated using data generated
from a six month study in the Lagos Lagoon, Nigeria. Overall trends in physical variables were relatively inconsistent for study sites.
Water transparency varied between 3 and 32 cm. Turbidity values varied inversely as transparency and directly with depth. Two
major macroinvertebrate groups (Annelida and Mollusca) made up of eight species were identified from a total density of 7820
ind/m
2
. Mollusca were the most abundant group with a density of 7800 ind/m
2
and accounted for 99.7 % of the total
macroinvertebrate density. Significant difference (ANOVA,
F
= 8.282,
p
> 0.05) was observed in the density of benthic
macroinvertebrate recorded in study stations. Generally, values of chl-a were higher in water samples than in sediment. The
concentrations of chl-a in sediment and water samples were significantly different (ANOVA,
F
=1.927,
p >
0.05; ANOVA,
F
= 8.883,
p <
0.05) during the study months. There was significant and positive correlation between macroinvertebrate density (
r
s
= 1;
p
< 0.01),
diversity (
r
s
= 1;
p
< 0.01) and chl-a in water, while a negative correlation was observed between macroinvertebrate density (
r
s
= 0.43;
p
> 0.01), diversity (
r
s
= 0.45;
p
> 0.01) and chl-a in sediment. Transparency of water correlated positively and significantly with
chl-a in sediment (
r
s
= 1;
p
< 0.01) and water (
r
s
= 0.8;
p
< 0.01). Turbidity and depth of water related negatively but significantly
with chl-a in water and sediment. Results obtained in this study suggest that primary production may influence benthic
macroinvertebrate abundance and diversity in estuarine ecosystems.
Keywords
Chl-a; Benthic macroinvertebrate; Abundance and diversity; Estuarine ecosystem
Introduction
Primary producers form the basis of ecosystems by
transferring the energy in sunlight or inorganic
compounds into the chemical energy stored in sugars.
Net primary productivity results in biomass. In every
aquatic ecosystem, the chemical energy in primary
producers eventually moves to one of two types of
organisms; primary consumers or decomposers.
Primary consumers are a key link to the grazing food
web. Not all plant tissues are consumed by herbivores,
however. Tissues that are not consumed eventually die.
When they do, they enter the decomposer food web,
which is composed of species that eat the dead
remains of organisms (Scot, 2005).
Productivity in coastal water bodies such as estuaries
is higher than those of the deep open ocean. This
stems from the fact the neritic and intertitidal zones
along coasts receive nutrients from two major sources
(Scot, 2005): 1) Rivers that carry and deposit nutrients
from terrestrial ecosystem and 2) Near-shore ocean
currents that bring nutrients that have rained down
into the cold, deep water of the oceanic zone back up
the surface. Both of these sources are absent in the
surface waters of the open ocean. In addition, nutrients
found in organisms near the surface of the open ocean
where light is abundant constantly rain down to dark,
deeper waters in the form of dead cells and are lost.
Microalgae play an important role as primary
producers. Primary production of organic compounds
is the main food source for benthic fauna and
contributes in no small measure to the abundance and
diversity of macroinvertebrates (Guillard, 1975;
Pinckney and Sandulli, 1990; Kang et al. 2003;
Pinckney et al
.
2003). Primary production contributes
to a substantial proportion of the energy flow in
estuarine systems. Benthic microalgae for instance,