Thesis (M.Sc. (Physiology)) --University of Limpopo, 2015 / Water is an essential and yet scarce resource, which has a vital role for human use
and also serve as a habitat for numerous organisms in aquatic environments. Despite
its scarcity there have been many reports indicating that it is continually polluted by
domestic, agricultural, mining and other anthropogenic activities; subsequently
affecting the health of organisms residing in such water bodies. Fish have been
selected as the bio-monitoring species due to its direct interaction with the
environment; thereby making it an appropriate model to monitor and evaluate the
health status of the environment. The feral population of the alien species,
Hypopthalmichtys molitrix (Valenciennes, 1844) commonly known as the silver carp in
Flag Boshielo Dam has been considered a healthy population. However, this
perception changed considerably after reports of lethargic, dying fish were first noted
in 2011. Currently the sporadic deaths amongst mature specimens (>0.7m) persist;
and the reason(s) for their demise remains unclear. Therefore, the aim was to employ
a seasonal study design to investigate the health status of selected fish species such
as H. molitrix in Flag Boshielo Dam by evaluating haematological parameters,
oxidative stress biomarkers and bio-accumulation levels of particular transition metals.
Seasonal surveys were carried out from February 2012 to January 2013 at Flag
Boshielo Dam, Olifants River System, Limpopo Province. The locality surrounding the
dam is known to be in an agriculture and mining catchment. Hypopthalmichtys molitrix
and Labeo rosae (Steindachner, 1894) commonly known as the rednose labeo were
collected with the use of scoop nets, conventional angling gear and gill nets.
Following collection, morphometric measurements were taken and blood was
collected. The blood samples required for further analysis at the Medical Science
Department, University of Limpopo were kept on ice (4˚C). After the collection of all
blood samples the specific fish was sacrificed and muscle samples were collected for
bio-accumulation analysis and gills and liver samples were collected for the
measurement of oxidative stress biomarkers. These tissue samples were rapidly
frozen and kept frozen (-85˚C) until further analysis.
Haematological parameters from the study reflected a variation amongst
comparison of the inter- and intra-species. It was observed that mature H. molitrix
suffered from anaemia. The response of glutathione-S-transferase (GST) and
thiobarbituric acid reactive substances (TBARS) was relatively constant throughout all
seasons when the young (<0.5m) and mature H. molitrix (0.6 – 0.90m) specimens
were compared. However, the catalase (CAT) response of mature H. molitrix was
dramatically impaired. This would increase their vulnerability to oxidative stress. Bioaccumulation
levels of the eleven selected transition elements exhibited various
trends. Metals such as Molybdenum (Mo), Vanadium (V), (Chromium) Cr, Cobalt (Co),
Zinc (Zn), Cadmium (Cd) and Mercury (Hg) exhibited seasonal bio-accumulation
levels that were in support of the various feeding behaviours of the fish species in this
study. On the other hand, metals such as Manganese (Mn), Iron (Fe), Copper (Cu),
Zinc (Zn), Cadmium (Cd) and Mercury (Hg) also illustrated the potential to be
contributing factors in the death of the mature specimens.
In conclusion, the findings from this study illustrate the complex nature of
metabolic disturbances resulting in the death of mature H. molitrix specimens. It is
clear that no single aspect investigated in this study could be solely implicated as the
major cause of death. This multifactorial presentation necessitates further
haematological assessment focussing on blood cell morphology and pathology, as
well as investigations into other oxidative stress biomarkers in liver and gill tissue. In
addition, identifying the most appropriate tissue type for future bio-accumulation
measurements of transition metals in this feral population is necessitated. It is further
suggested that neuro-muscular assessments, focussing on neurotransmitters such as
γ-aminobutyric acid (GABA) and acetylcholine (Ach), form part of the investigation into
the lethargic behaviour of the mature fish.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ul/oai:ulspace.ul.ac.za:10386/1188 |
| Date | January 2015 |
| Creators | Mogashoa, M. E. |
| Contributors | Erasmus, L. J. C, Luus-Powel, W. J., Botha-Oberholster, A. |
| Publisher | University of Limpopo |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | xv, 106 leaves |
| Relation |
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