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International Journal of Marine Science 2013, Vol.3, No.41, 333-343
http://ijms.sophiapublisher.com
333
Research Article Open Access
Tracking the Response of Phytoplankton following Gyttja Disturbance: a
Mesocosm Field Study in Myall Lakes, New South Wales, Australia
Nita Rukminasari
Faculty of Marine Science and Fisheries Hasanuddin University, Jl. Perintis Kemerdekaan Km. 10, Makassar – 90245, South Sulawesi - Indonesia
Corresponding author email: nita_r@unhas.ac.id
International Journal of Marine Science, 2013, Vol.3, No.41 doi: 10.5376/ijms.2013.03.0041
Received: 13 May, 2013
Accepted: 16 Jun., 2013
Published: 02 Sep., 2013
Copyright
©
2013 Rukminasari, 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:
Rukminasari, 2013, Tracking the Response of Phytoplankton following Gyttja Disturbance: a Mesocosm Field Study in Myall Lakes, New South Wales,
Australia, International Journal of Marine Science, Vol.3, No.41 333
-
343 (doi: 10.5376/ijms.2013.03.0041)
Abstract
This study determined whether artificially mixing gyttja, an organic sediment that contains high levels of NH4, with its overlying
waters, affected phytoplankton abundance and species composition in Myall Lake (NSW, Australia). A series of mesocosms was employed,
with three mesocosms being designated as controls, i.e. no gyttja mixing, and three others termed impact mesocosms, i.e. in which gyttja was
mixed with the overlying waters. Sampling was undertaken during a 5 day period in sediment disturbance, and phytoplankton community
variables were recorded at seven intervals, i.e. just prior to disturbance and 30 minutes, 3 hours, 1, 2, 3, 4 and 5 days after gyttja disturbance.
Comparisons of these community variables among treatments and over time convincingly demonstrated that overall phytoplankton
abundance rose from 20,000 cells/mL just prior to disturbance to between 30,000 cells/mL and 55,000 cells/mL 2 to 4 days after gyttja
mixing. This rise in abundance was attributable to a substantial increase in the cyanophycea over the same period. In contrast to the
cyanophyceae, the abundance of bacillariophyceae increased sharply following disturbance from 150 to >1000 cell/mL and did not exceed
1000 cell/mL for the duration of the experiment. This supported the hypothesis that gyttja mixing does introduce benthic microalgae into the
water column. Sediment disturbance caused differences in species composition in time, with cyanobacteria being mostly influenced taxa.
Each period of disturbance between mesocosm have different assemblages of species.
Keywords
Phytoplankton; Sediment disturbance; Mesocosm; Community structure
1 Introduction
In shallow coastal lakes, such as the Myall Lake in
Australia, wind, tidal action and anthropogenic
activities, such as boating or jetskiing, can cause water
turbulence which results in mixing of the water
column and occasionally resuspension of the bottom
sediments into overlying waters. Such mixing will
therefore act to increase the water turbidity, which in
turn decreases the attenuation of light. Mixing of the
water column with bottom sediments can also increase
nutrient availability as a result of nutrient release from
the substrates. Changes in light attenuation and
nutrient availability have been recorded to have a
significant effect on the abundance, biomass and
species composition of phytoplankton in such coastal
lakes (Carrick et al., 1993; Huisman et al
.
, 1999;
Kiorboe, 1993, Olrik and Nauwerek, 1993). For
example, Carrick et al
.,
1993) showed that intermittent
turbulence in a small lake influences phytoplankton
biomass and species composition by directly
resuspending phytoplankton cells in particular silicate
cell type from the lake sediments.
The processes that occur during sediment resuspension
have also been shown to be related to the presence of
blooms of phytoplankton in certain environments
(Hansson et al
.
, 1994; Huisman et al
.
, 1999; Garstecki
et al
.
, 2002). For example, phytoplankton blooms
occur mainly during the low mixing periods in neap
tides of South San Francisco Bay, a large marine
embayment (Cloern, 1991).
Although there is some understanding of the effect of
mixing of the water column on phytoplankton biomass
in estuaries and lakes (Huismann et al, 1999; Olrik et
al, 1993; Lauria et al 1999), the changes in
phytoplankton composition and abundance with water
column mixing in coastal lakes are not well
understood. Such information would be essential
information for managers who are developing plans
for management of such coastal lakes.
Myall Lake, in central New South Wales, is a shallow
coastal lake that is subject to considerable water