Microplastics in marine organisms in KZN:A new conservation threat?

A representation of studies conducted on microplastics in various countries worldwide showing the number of publications per country/region.

• UK is the most active country in microplastics research• Africa has no published studies focusing solely on microplastics to date .

So what does this mean?

80 % of microplastics in Durban are from domestic sources!

“… medical studies on both

rodents and humans have

also shown that particles of

polyvinylchloride and

polystyrene <150 µm can

translocate from the gut

cavity to the lymph and

circulatory systems.”

Microplastics get consumed by

fish which affect their endocrine

and reproductive systems thus

impacting overall conservation of

aquatic organisms

R.P. Mofokeng, G. Gerber, M.W. Coote, S.K. Mkhize, T. Mkhize, D. Robertson-Andersson, and G.K. Moodley.University of KwaZulu-Natal (Westville Campus), School of Life Sciences.

What are microplastics?

• Small plastic particles, <5 mm in

size.

• There are two forms of

microplastics (MP) namely; primary

(A1) and secondary (B) MP.

• Primary MP (A1) are found mostly

in cosmetics, plastic beads and

industrial effluent (A2).

• Secondary MP (B) result from

degradation of large plastic debris

which break down over a period of

time.

p <0.0001

F value = 31.98

Stomopneutes Tripneustes

3 X

Conclusion• All investigated organisms ingested microplastics.

• Microplastics are not only abrasive causing physical harm to organisms, they also tend to accumulate heavy metals and Persistent Organic

Pollutants.

• Microplastics may therefore cause accelerated bioaccumulation of toxins up the food chain thus impacting conservation of aquatic

biodiversity as well as human health.

The solution , however, is in our homes!!!• 80% of microplastics in Durban's marine waters are beads and fibres, which are present in daily household products such as toothpaste,

facial cleansers, make-up and synthetic fibres.

• Simple behavioural changes such as using alternative products that do not contain microplastics and installing filters in washing machines to

trap fibres from entering aquatic systems are some of the measures that can be taken to reduce the amount of microplastics entering marine

systems.

• This will enhance conservation of aquatic systems, ensuring a healthier and sustainable marine environment.

2 X

X

Microbeads (< 1 mm & 1 – 2 mm) - similar to natural gut retention time

Microbeads (> 5 mm) - 3 x Natural gut retention time (39.6 + 5.8 h)

Microfibres (> 1 mm) - 2 x Natural gut retention (23.8 + 10.4h)

Mussels ingest more plastics with increasing

concentration of microplastics in the water column.

• Sea urchins can take up microplastics through the

madreporite as well as ingesting them.

• The larger the madreporite pore size, the potentially

higher the intake of microplastics.

Globally more than 240million tonnes of

plastic is used each year.

The number of plastics produced now is

around 250 million t.y-1 with a 10 %

annual increase

Mussel: Perna perna

Sea urchins:Stomopneustes variolaris & Tripneustes gratillaMullet: Mugil cephalus

EFFECTS OF MICROPLASTICS ON AQUATIC ORGANISMS IN THE KZN BIGHT

• Of 187 fish dissected, 34 % had plastics in them• ALL 16 species caught contained microplastics

• Fish caught in the Durban eddy contained significantly higher microplastic concentrations than fish caught in Richards Bay or Durban.

• 141 plastic pieces were recovered from fish digestive tracts.

A1

A2

B

Microplastics transport to aquatic

systems?

• Directly introduced into aquatic systems

(freshwater & marine):

• Through drains, sewage, factories, etc.

• Or they are a result of UV degradation

of plastics over time.

Cocktails of toxicants scorb onto MP particles

PCB

PAH

PBDE’s