First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria Nile perch and Nile tilapia

Abstract

Microplastic contamination in the African Great Lakes is currently unreported, and compared to other regions of the world little is known about the occurrence of microplastics in African waters and their fauna. The present study was conducted in the Mwanza region of Tanzania, located on the southern shore of Lake Victoria. The gastrointestinal tracts of locally fished Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) were examined for plastics. Plastics were confirmed in 20% of fish from each species by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. A variety of polymer types were identified with likely sources being urban waste and consumer use. Although further research is required to fully assess the impact of plastic pollution in this region, our study is the first to report the presence of microplastics in Africa's Great Lakes and within the fish species that inhabit them.

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First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria
Nile perch and Nile tilapia
Fares John Biginagwa
a,b,1
, Bahati Sosthenes Mayoma
a,c,1
, Yvonne Shashoua
d
,
Kristian Syberg
a
, Farhan R. Khan
a,
⁎
a
Department of Environmental, Social and Spatial Change (ENSPAC), Roskilde University, Universitetsvej 1, PO. Box 260, DK-4000 Roskilde, Denmark
b
Department of Biological Sciences, Faculty of Science, Sokoine University of Agriculture, P.O. Box 3038, Morogoro, Tanzania
c
Department of Livestock and Fisheries Development, Mtwara District Council, P.O. Box 528, Mtwara, Tanzania
d
Environmental Archaeology and Materials Science, National Museum of Denmark, IC Modewegsvej Brede, DK-2800 Kongens Lyngby, Denmark
abstractarticle info
Article history:
Received 1 August 2015
Accepted 14 October 2015
Available online xxxx
Communicated by Anett Trebitz
Microplastic contamination in the African Great Lakes is currently unreported, and compared to other regions of
the world little is known about the occurrence of microplastics in African waters and their fauna. The present
study was conducted in the Mwanza region of Tanzania, located on the southern shore of Lake Victoria. The
gastrointestinal tracts of locally fished Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) were
examined for plastics. Plastics were confirmed in 20% of fish from each species by Attenuated Total Reflectance
Fourier Transform Infrared (ATR-FTIR) spectroscopy. A variety of polymer types were identified with likely
sources being urban waste and consumer use. Although further research is required to fully assess the impact
of plastic pollution in this region, our study is the first to report the presence of microplastics in Africa's Great
Lakes and within the fish species that inhabit them.
© 2015 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.
Index words:
Plastic ingestion
Lates niloticus
Oreochromis niloticus
Lake Victoria
East Africa
ATR-FTIR analysis
Introduction
The presence of microplastics (b5 mm in size) has been extensively
reported in the marine environment (see reviews by Derraik, 2002 and
Cole et al., 2011), but there is now an increasing focus on documenting
microplastic pollution in freshwaters. Plastic pollution in the Laurentian
Great Lakes of North America has been well studied (Driedger et al.,
2015; Eriksen et al., 2013; Zbyszewski and Corcoran, 2011; Zbyszewski
et al., 2014), and other freshwater habitats have also been the subject
to investigation, e.g. Lake Hovsgol in Mongolia (Free et al., 2014), Lake
Garda in Italy (Imhof et al., 2013) and the River Thames in the United
Kingdom (Morritt et al., 2014). These studies not only show that
microplastics are present in the freshwater environment, but also relate
the type of plastics found to their likely source (urban waste and con-
sumer use). In the absence of environmental sampling, analysis of the
gut contents of resident fish populations has also been used to assess
the extent of plastic pollution. Lusher et al. (2013) found that plastics
are being readily consumed by 10 species, both pelagic and demersal,
in the English Channel, and Sanchez et al. (2014) similarly reported,
for the first time, that freshwater wild gudgeons, Gobio gobio, inhabiting
French rivers are also ingesting microplastic debris. With increased
monitoring in both marine and freshwater environments and fauna,
microplastic pollution can be described as an issue of global concern,
but information regarding the presence of plastics in some regions
remains scarce. Only a handful of studies exist regarding the extent of
plastic pollution in African waters. Both Ryan (1988) and Madzena and
Lasiak (1997) characterized plastic litter along the South African coast-
line, but to date there is no information on plastic pollution in Africa's
Great Lakes and the fish that inhabit them. Here, we present data
showing the presence of microplastics in the gastrointestinal tracts of
Lake Victoria Nile perch (Lates niloticus) and Nile tilapia (Oreochromis
niloticus), that begins to fill this knowledge gap.
The present study was conducted in the Mwanza region of Tanzania,
located on the Southern shore of Lake Victoria (Fig. 1). Lake Victoria is
the world's largest tropical lake (surface area: 68,800 km
2
,average
depth: 40 m, maximum depth: 84 m, Taabu-Munyaho et al., 2013)
and second largest freshwater lake overall (by surface area, the largest
being Lake Superior in North America). Land surrounding the lake is
amongst the most densely populated in the world, and this population
growth is set to continue —by the year 2020 an estimated 53 million
people will inhabit the area around Lake Victoria (Canter and Ndegwa,
2002). The majority of economic activities in the region are associ-
ated with the lake with one of the most important being fishing. The
two species used in the present study, Nile perch and Nile tilapia, are
Journal of Great Lakes Research xxx (2015) xxx–xxx
⁎Corresponding author.
E-mail addresses: frkhan@ruc.dk,farhan.khan@gmx.com (F.R. Khan).
1
Joint first authors.
JGLR-00992; No. of pages: 4; 4C:
http://dx.doi.org/10.1016/j.jglr.2015.10.012
0380-1330/© 2015 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.
Contents lists available at ScienceDirect
Journal of Great Lakes Research
journal homepage: www.elsevier.com/locate/jglr
Please cite this article as: Biginagwa, F.J., et al., First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria Nile perch
and Nile tilapia, J. Great Lakes Res. (2015), http://dx.doi.org/10.1016/j.jglr.2015.10.012

economically and ecologically important. Both species were introduced
to Lake Victoria in the 1950s and 1960s with the aim of supplementing
native fish populations that had declined due, in part, to over fishing
(Ogutu-Ohwayo, 1990; Taabu-Munyaho et al., 2013). However, this
introduction was detrimental to the native species (Kishe-Machumu
et al., 2015), particularly the native tilapiine species such as the
Victoriatilapia (Oreochromis variabilis) andsingidia tilapia (Oreochromis
esculentus), which subsequently disappeared from parts of the Lake
(Njiru et al., 2004; Ogutu-Ohwayo, 1990). Thus Nile perch and Nile tila-
pia are established as dominant commercial and ecological species, and
therefore represent logical choices by which to monitor microplastic
pollution in the area. Moreover, their differing feeding habits may pro-
vide additional information by which to contextualize plastic ingestion.
Nile perch are predatory fish feeding on small fish and macroinverte-
brates, whereas Nile tilapia are omnivorous with a diet ranging from
plankton to small fish.
Methods
In March 2015, 20 Nile perch and 20 Nile tilapia were purchased
from Mwanza harbor market, where fish are caught and sold daily.
The fishing territory for both species extends to Ukerewe Island (the
largest island in Lake Victoria) to the north of Mwanza and across the
Mwanza Gulf to the neighboring district of Sengerema (Fig. 1). Nile
perch and Nile tilapia were 46–50 cm and 25–30 cm in length, and
500–800 g and 500–700 g in weight, respectively. For each fish, the
dissection of the entire gastrointestinal tract (buccal cavity to anus)
was conducted on site. All efforts were made to eliminate sample con-
tamination with separate clean dishes used for each fish and thorough
cleaning of dissection utensils between samples. A preliminary exami-
nation was made of each gastrointestinal tract and in the case of Nile
perch undigested gastropods and cichlids were removed. Gastrointesti-
nal tracts and their contents were then individually preserved in 96%
ethanol and transported to laboratory facilities at the University of Dar
es Salaam (Dar es Salaam, Tanzania). In the laboratory, NaOH digestion
(10 M NaOH at 60 °C for 24 h) was used to isolate plastic litter from the
organic tissue. The NaOH method has been shown to digest organic
matter with an efficacy of N90% (Cole et al., 2014) and our tests of this
protocol prior to its use confirm such high efficiencies (96.6 ± 0.9%,
n = 5, data not shown). Importantly, NaOH digestion has a minimal im-
pact on the chemical and physical states of plastics, especially when
compared to strong acid digestion which, whilst also being an effective
digestant of organic matter, can discolor or degrade plastics. Post-
digestion, plastics and a minimal amount of partially digested tissue
were rinsed from the NaOH through 250 μm mesh stainless steel sieves
under running water and placed on filter paper to dry. Samples were
then brought to the laboratory at Roskilde University (Denmark) and
suspected plastic pieces were separated from other digested residue
under light dissection microscope.
The chemical composition of all suspected plastics were identified
non-destructively by Attenuated Total Reflectance Fourier Transform
Infrared (ATR-FTIR) spectroscopy (conducted at the National Museum
of Denmark), a standard analytical technique for identifying the chem-
ical composition of samples larger than 0.5 mm. Scans were run at a
resolution of 2 cm
−1
between 4000 and 650 cm
−1
on a Bruker Alpha
FT-IR instrument (Bruker, Billirica, MA, USA) fitted with a diamond
internal reflectanceelement. Spectra were compared with standard ref-
erences on the same instrument and processed using Opus software
supplied by Bruker.
Results
Suspected plastics were recovered from the gastrointestinal tracts of
11 perch (55%) and 7 tilapia (35%). However, some plastics were too
small (i.e. b0.5 mm) to have their chemical structure confirmed by
ATR-FTIR. In addition, spectroscopy of some suspected plastic samples
showed that their compositions most closely resembled cellulose, sug-
gesting these samples were likely plant material or paper originating
from perhaps newspaper, tissues or cigarette filters. Thus 20% of each
fish species (i.e. 4 individuals) contained confirmed microplastics within
their gastrointestinal tracts. The polymers recovered from th e fish were:
polyethylene, polyurethane, polyester, polyethylene/polypropylene co-
polymer and silicone rubber (Fig. 2). The common use of such materials
includes packaging, clothing, food and drink containers, insulation and
industrial applications (Table 1).
Discussion
This work provides the first evidence that microplastics are present
in the African Great Lakes and that they are ingested by economically
important fish species. In addition to confirming the ingestion of
microplastics by freshwater fish species (Sanchez et al., 2014), we iden-
tify the chemical composition of microplastics found in Lake Victoria
fish. However, ours is a preliminary study and only limited conclusions
can be drawn. Plastics were confirmed in only 20% of both species, but
due to the constraints of ATR-FTIR analysis and the inability to confirm
the identity of the smaller-sized suspected ‘microplastics’, we likely un-
derestimate the true extent of plastic ingestion by Nile perch and Nile
tilapia. Similarly, it is not possible to determine whether the feeding
preferences of the two species effected their ingestion of plastics.
Thus, whilst our study reports the presence of plastics in these species,
further research needs to be undertaken to fully characterize theextent
of microplastic pollution in Lake Victoria.
Fig. 1. The map of study area showing the Mwanza region (A). The localfishing area extendsacross the Mwanza Gulfand to Ukerewe Island. Inset LakeVictoria (LV) bordered by Uganda,
Kenya and Tanzania. The Mwanza region located on the southern shore of Lake Victoria is highlighted. (B) Urban waste in Mwanza, including plastic debris, collects in drainage ditches
which are a potential source of plastic pollution in Lake Victoria. (C) Nile tilapia (photographed prior to dissection) and Nile perch used in this study were purchased from the market
at Mwanza.
2F.J. Biginagwa et al. / Journal of Great Lakes Research xxx (2015) xxx–xxx
Please cite this article as: Biginagwa, F.J., et al., First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria Nile perch
and Nile tilapia, J. Great Lakes Res. (2015), http://dx.doi.org/10.1016/j.jglr.2015.10.012

Microplastics ingested by the fish (Fig. 2) may be secondary
microplastics which have resulted from the degradation and break-
down of larger plastic pieces (Derraik, 2002). The identification of
different polymers allows speculation regarding points of entry of plas-
tics into the study area and a likely source of the input of such materials
into the Mwanza Gulf area is from the drainage ditches that are filled
with urbanwaste, includingplastic products(Fig. 1B).This may be a par-
ticular problem during heavy rain when input into the lake is increased.
In common with other studies conducted at freshwater sites (Eriksen
et al., 2013; Free et al., 2014), it appears that the nature of the plastic
pollution may be related to the usage and waste by the local human
population. The characterization of plastic litter found in Mongolia's
Lake Hovsgol has led to calls for better waste management (Free et al.,
2014), a call we echo for the Mwanza region.
The ingestion of plastics by Nile perch and Nile tilapia may poten-
tially lead to disturbances in their digestive physiology or deleterious
effects arising from the possible consumption of chemical pollutants
adsorbed to plastic surfaces (i.e. ‘vector-effect’,Cole et al., 2011; Syberg
et al., 2015). Although both organic pollutants (Fries and Zarfl, 2012;
Koelmans et al., 2013) and trace metals (Ashton et al., 2010; Holmes
et al., 2012) have been shown to adsorb to a variety of plastic surfaces,
the vector effect has yet to be unambiguously demonstrated. However,
in some studies, and particularly when the adsorption of pollutants
to plastic surfaces is promoted, microplastics have been shown to alter
pollutant–organism interactions (Chua et al., 2014; Khan et al., 2015).
Thus when assessing the effects of microplastics to field populations it
may be necessary to consider the other chemical pollutants present in
that environment.
Our study is the first to describe the presence of microplasticsin fish
inhabiting Africa's Great Lakes. Within Lake Victoria, Nile perchand Nile
tilapia are both economically and ecologically important, especially
since they are heavily consumed by local human residents. Future inves-
tigations should consider the trophic transfer of microplastics through
the freshwater food chain, particularly in the case of Nile perch which
are known to feed on smaller fish (including haplochromine cichlids)
and macroinvertebrates, as well as any potential ‘vector effect’that
facilitates the movement of adhered contaminants through the food
chain. Given the density of the human population in the region and its
estimated growth, the prevalence of microplastics in Lake Victoria
would be expected to increase. The reliance on the lake as a resource
means that any potential impacts of microplastics on the ecosystem
and biota need to be researched, assessed and, if possible, mitigated.
Author information
F.J.B and B.S.M are joint first authors of this study and contributed
equally to design, sample collection and analysis.
Fig. 2. Variety of plastic debris recovered fromNile perch and Nile tilapia.Images A–E are examples of therange of polymers isolated after NaOHdigestion of the gastrointestinaltissue. In
each casethe identity of thepolymer was confirmedby ATR-FTIR spectroscopy. Spectra attributedto silicone rubber(D) and polyethylene/polypropylene co-polymer (E) debrisare shown
next to their respective plastic samples.
Table 1
Polymers recovered from the gastrointestinal tracts of sampled fish, and their common
uses and potential source of plastic pollution in Lake Victoria.
Polymer Common uses and potential sources
Polyethylene/polypropylene
co-polymer
Packaging, carrier bags
Polyethylene Carrier bags, food wrappers, beverage bottles
Polyester Beverage bottles, textile (clothing, carpets, curtains)
Polyurethane Insulation, sealants, packaging
Silicone rubber Industrial sealants. O-rings, molds, food storage
3F.J. Biginagwa et al. / Journal of Great Lakes Research xxx (2015) xxx–xxx
Please cite this article as: Biginagwa, F.J., et al., First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria Nile perch
and Nile tilapia, J. Great Lakes Res. (2015), http://dx.doi.org/10.1016/j.jglr.2015.10.012

Acknowledgments
F.J.B and B.S.M were supported by grants from Danida Fellowship
Centre through the Building Stronger Universities program (Grants
MEC13-1M1 and MEC12-1B1). F.R.K and K.S are supported by The
Environmental Risk Strategic Research Initiative at Roskilde University.
We acknowledge the assistance of the University of Dar es Salaam for
providing laboratory facilities.
References
Ashton, K., Holmes, L., Turner, A., 2010. Association of metals with plastic production
pellets in the marine environment. Mar. Pollut. Bull. 60, 2050–2055.
Canter, M.J.,Ndegwa, S.N., 2002. Environmental scarcityand conflict: a contrary casefrom
Lake Victoria. Glob. Environ. Polit. 2, 40–62.
Chua, E.M., Shimeta, J., Nugegoda, D., Morrison, P.D., Clarke, B.O., 2014. Assimilation of
polybrominated diphenyl ethers from microplastics by the marine amphipod,
Allorchestes compressa. Environ. Sci. Technol. 48, 8127–8134.
Cole, M., Lindeque, P., Halsband, C., Galloway, T.S., 2011. Microplastics as contaminants in
the marine environment: a review. Mar. Pollut. Bull. 62, 2588–2597.
Cole, M., Webb, H., Lindeque, P.K., Fileman, E.S., Halsband, C., Galloway, T.S., 2014. Isola-
tion of microplastics in biota-rich seawater samp les and marine organisms. Sci.
Rep. 4 (4528).
Derraik, J.G.B., 2002. The pollution of the marine environment by plastic debris: a review.
Mar. Pollut. Bull. 44, 842–852.
Driedger, A.G., Dürr, H.H., Mitchell, K., Van Cappellen, P., 2015. Plastic debris in th e
Laurentian Great Lakes: a review. J. Great Lakes Res. 41, 9–19.
Eriksen, M., Mason, M., Wilson, S., Box, C., Zellers, A., Edwards, W., Farley, H., Amato, S.,
2013. Microplastic pollution in the surface waters of the Laurentian Great Lakes.
Mar. Pollut. Bull. 77, 177–182.
Free, C.M., Jensen, O.P., Mason, S.A., Eriksen, M., Williamson, N.J., Boldgiv, B., 2014. High
levels of microplastic pollution in a large, remote, mountain lake. Mar. Pollut. Bull.
85, 156–163.
Fries, E., Zarfl, C., 2012. Sorption of polycyclic aromatic hydrocarbons (PAHs) to low and
high density polyethylene (PE). Environ. Sci. Pollut. Res. 19, 1296–1304.
Holmes, L.A., Turner, A., Thompson, R.C., 2012. Adsorption of trace metals to plastic resin
pellets in the marine environment. Environ. Pollut. 160, 42–48.
Imhof, H.K., Ivleva, N.P., Schmid, J., Niessner, R., Laforsch, C., 2013. Conta mination of
beach sediments of a subalpine lake with microplastic particles . Curr. Biol. 23,
R867–R868.
Khan, F.R.,Syberg, K., Shashoua, Y., Bury, N.R., 2015. Influenceof polyethylene microplastic
beads on the uptake and localization of silver in zebrafish (Danio rerio). Environ.
Pollut. 206, 73–79.
Kishe-Machumu, M.A., van Rijssel, J.C., Wanink, J.H., Witte, F., 2015. Differential recovery
and spatialdistribution pattern of haplochromine cichlidsin the Mwanza Gulf of Lake
Victoria. J. Great Lakes Res. 41, 454–462.
Koelmans, A.A., Besseling, E., Wegner, A., Foekema, E.M., 2013. Plastic as a carrier of POPs
to aquatic organisms: a model analysis. Environ. Sci. Technol. 47, 7812–7820.
Lusher, A.L., McHugh, M., Thompson, R.C.,2013. Occurrence of microplasticsin the gastro-
intestinal tract of pelagic and demersal fish from the English Channel. Mar. Pollut.
Bull. 67, 94–99.
Madzena, A., Lasiak, T., 1997. Spatial and tempora l variations in beach litter on the
Transkei coast of South Africa. Mar. Pollut. Bull. 34, 900–907.
Morritt, D., Stefanoudis, P.V., Pearce, D., Crimmen, O.A., Clark, P.F., 2014. Plastic in the
Thames: a river runs through it. Mar. Pollut. Bull. 78, 196–200.
Njiru, M., Okeyo‐Owuor, J.B., Muchiri, M., Cowx, I.G., 2004.Shifts in the food of Nile tilapia,
Oreochromis niloticus (L.) in Lake Victoria, Kenya. Afr. J. Ecol. 42, 163–170.
Ogutu-Ohwayo, R., 1990.The decline of the native fishes of lakes Victoria andKyoga (East
Africa) and theimpact of introduced species, especially the Nile perch, Lates niloticus,
and the Nile ti lapia, Oreochromis niloticus. Environ. Biol. Fish 27, 81–96.
Ryan, P.G., 1988. The characteristics and distribution of plastic particles at the sea-
surface off the southwestern Cape Province, South Africa. Mar. Environ. Res. 25,
249–273.
Sanchez, W., Bender, C., Porcher, J.M., 2014. Wild gudgeons (Gobio gobio) from French
rivers are conta minated by microplastics: preliminary study and first evidence.
Environ. Res. 128, 98–100.
Syberg, K., Khan, F.R., Selck, H., Palmqvist, A., Banta, G.T., Daley, J., Sano, L., Duhaime,M.B.,
2015. Microplastics: addr essing ecological risk through lessons learned. Enviro n.
Toxicol. Chem. 34, 945–953.
Taabu-Munyaho, A., Kayanda, R.J., Everson, I., Grabowski, T.B., Marteinsdóttir, G., 2013.
Distribution and exploitation of Nile perch Lates niloticus in relation to stratification
in Lake Victoria, East Africa. J. Great Lakes Res. 39, 466–475.
Zbyszewski, M., Corcoran, P.L., 2011. Distribution and degradation of fresh water plastic
particles along th e beaches of Lake Huron, Canada. Water Air So il Pollut. 220,
365–372.
Zbyszewski, M., Corcoran, P.L., Hockin, A., 2014. Comparison of the distribution and deg-
radation of plastic debris along shorelines of the Great Lakes, North America. J. Great
Lakes Res. 40, 288–299.
4F.J. Biginagwa et al. / Journal of Great Lakes Research xxx (2015) xxx–xxx
Please cite this article as: Biginagwa, F.J., et al., First evidence of microplastics in the African Great Lakes: Recovery from Lake Victoria Nile perch
and Nile tilapia, J. Great Lakes Res. (2015), http://dx.doi.org/10.1016/j.jglr.2015.10.012