According to the international donor support of Global Environmental Facility,
many small island environments share sustainable development challenges.
Among challenges are rapid growing populations,
a constantly rising number of tourists,
limited freshwater resources, and a fragile marine ecosystem.
An example of how the growing human activities impact
the local ecosystem is a discharge of untreated wastewater into coastal areas.
This also applies to Zanzibar.
So let us listen to how Professor Muhammad Ali Shaikh,
from the State University of Zanzibar,
characterizes Zanzibar marine environment,
and the associated environmental risk.
Zanzibar coastal community largely depends on
marine resources for supporting local livelihoods.
Over 30 percent of country's GDP depends on marine based economy,
including tourism, industry, and fishing.
However, there is unprecedented coastal degradation due to diversified factors,
including increased population density,
with 530 people per square kilometer compared to
Tanzania mainland of 45 people per square kilometer.
Zanzibar is among top three densely populated countries in Africa.
There is mushrooming of beachy resorts along the coast of the island.
Furthermore, there is no treatment facilities for municipal waste,
which are directly disposed to the coastal environment,
synergistically overwhelming the ecosystem health,
and the carrying capacity of the Coastal and marine ecosystem around Zanzibar.
If we look at the data on the extent of human activity in Zanzibar,
we get a picture of the amount of pressure put in the marine ecosystem.
Zanzibar has a population of 1.3 Million,
and despite a decrease in the fertility rate,
the population expected to increase at about three per cent per year.
Similarly, the number of incoming tourists is expected to increase
significantly from the 2016 figure of 378,000 arrivals.
In 1985, only 50 hotel beds were available in the coast.
By 2007, there were close to 8,000,
and by 2017 the number had increased to roughly 15,000 beds.
A study from 2012 found that
almost 60 percent of the more than the 200 hotels on the island,
were built closer to the sea than accepted by national regulation.
No sustainable solutions, such as
large scale sewerage treatment plants have yet been
developed to manage the wastewater generated in Zanzibar.
Figures from 2010 indicate that around nine to 12,000 cubic
meters of waste water is disposed off
untreated or poorly treated directly into the sea per day,
and today that volume will be even greater.
The number of cargo ships entering Malindi port in Stone Town,
has more than double from 2007 to 2014,
carrying bottled water, vegetables and other food items from the mainland Tanzania.
Yet another example of human pressure on the marine ecosystem comes
from the increasing demand for protein and high value fisheries product.
The volume of fish landed by the fisheries industry,
has increased continuously over the past decade as shown here.
Let us ask marine scientist Peter Anson Staerh,
from the University of Aarhus,
who is part of a research team in Zanzibar,
how the increased human pressure,
is impacting on the marine environment around Zanzibar.
Zanzibar is very fortunate from
the nature point of view that it's a system that gets flushed.
Two times every day you have tides coming in and cleaning the area.
So it's basically a very nutrient poor and clean.
And that is basically the reason why things have not gone much worse than they have.
The beaches are beautiful,
the water is clear,
and it's not so evident that you have pollution.
But still, it's quite obvious that many places in the coastal system,
like in the nearest shore,
regions around the island,
that you have sea grass beds which are not doing well.
They are overgrown by fast growing algae,
there are areas where the corals are really not doing well,
you have mangroves which have become partly destroyed by human development,
and some of the waters are obviously not as clear as they should be.
So I've been also fortunate to be with one of your colleagues Mohammed Sheikh,
who took me to a sewage outlet in Stone Town.
I know you've been sampling all along the coast of Zanzibar.
What are the findings in terms of waste water?
Well, we had very interesting findings,
because in some area they have been exceeded some acceptable level of microbial load,
as well as other contaminants, like heavy metals.
Is it close to the coast?
Yes, but we have some cases even to that remote area in
the northern region where there is many tourism activities,
some level of microbial load is higher compared to the acceptable levels.
The research team conducted
a water quality baseline survey around the Nungwi island in 2015.
As expected, the level of nutrients,
chlorophyll concentrations and coliform bacteria,
were high in the waters close to the densely populated city of Stone Town,
resulting most likely from the significant wastewater discharge.
Surprisingly, the levels of
coliform bacteria off the Northern and North-Eastern part of the island,
were even higher than around Stone Town,
suggesting a strong impact from large resorts located along the coastline.
Maybe Pete Stair can explain this phenomena.
Far from the beach,
actually several kilometers into the ocean,
you had quite high levels,
and in other places,
even closer to the shore you had much less.
Any particular reason?
Well, the effluence that provide
the coliform bacteria are very local sources because bacteria,
they get very fast degraded by ultraviolet radiation,
and so there's lots of sources around the island.
So, I think we have around 27 known sewage outlets that are untreated water,
and on top of this you have settlement and lots of hotels that we don't have
any account of how they provide nutrients into the water.
And just to give an example,
there's a small island on the North part out of the mainland,
it's called Mnemba, and we were sailing there,
it's like a paradise island.
Bill Gates went there on holiday, and it's beautiful.
But that was where we actually measured the highest levels of coliform bacteria.
But that's also an area where there's absolutely no management of the sewage.
So, local sources have huge impact,
and if they're not managed properly,
then they can provide substantial problems.
The problems referred to by Pete Stair not only impact the marine environment,
but also carries a risk to human health.
Contamination of the coastal marine environment by sewage,
increase the risk of infectious diseases,
including diarrhea and cholera.
These can be obtained by activities such as swimming, or consuming seafood.
Pathogenic bacteria in wastewater can survive in the sea from one day to several weeks.
And viruses can survive in water,
fish, or shellfish for even month.
The high levels of nutrients in the water may also increase
human exposure to toxins connected with algae blooms.
Depending on its source,
sewage may also contain a range of chemicals,
heavy metals, medical waste, and oil products.
This results in additional risk to human health,
although the impacts are very difficult to assess.
In 2006, the government of Zanzibar required hotels to manage their own sewage properly,
but this rule seems to be widely ignored.
And since there's no official sewage treatment planned on Zanzibar,
the vast majority of hotels use septic tanks,
or discharge it's sewage directly into the sea.
So, water quality is an issue
and you have told us about some of these diffuse unknown sources also,
known and unknown sources of effluent waste,
or the human feces entering into the sea.
What are some of the other main risk to the health of the ecosystem around Zanzibar?
Marine litter, that is really a huge issue.
You cannot go anywhere along the beaches where you do not see plastic debris,
wood debris, any kind of construction debris.
And we did a survey along some 100 meters stretches
of beaches using international standards for this,
and sorted out all the different types of litter and there is a lot of plastic.
A study conducted by
Professor Mohammed Sheikh and team at the State University of Zanzibar,
to estimate the amount and composition of litter on the beaches,
found out that about half of the garbage consisted of plastic,
and around a third from textile.
We are particularly concerned about the plastic litter.
Instead of being biologically degraded through metabolism,
plastic is simply divided into
smaller and smaller polymer chains by the effect of UV sunlight.
Even though there is no historical data to
compare and evaluate changes over time in Zanzibar,
let us ask Pete Stair about the current status of plastic accumulating in Zanzibar.
Yes. So, we investigated along beach stretches,
and also in sediments in the water.
Took samples to measure in very detail the size structure,
and the composition of the different types of litter.
And you do see the very small fragments that is not really visible to the human eye,
like less than a millimeter or so.
They are quite abundant also along the shores and in the sediments around the island.
And this is something that is of concern.
And the numbers that we are getting are suggesting that they are at least at
the same levels as other areas around the West Indian Ocean, if not higher.
Would they accumulate in the food chain?
To some extent they will.
They actually become inert in the tissue of some of these filtrating organisms,
like molluscs, but even in some fish.
And they can, because of some of these plastics,
they have these hormone like effects so,
they can affect even the fecundity like
the number of offsprings that these individuals can produce.
So, that's another more or less indirect effect
that you can have off of pollution that accumulates,
and over longer time periods sort
of diminishes the productivity and the health of these systems.
Let me also ask Mohammed Sheikh specifically,
what he thinks hotels should do to improve the situation.
Well, the first choice I think is treatment,
they have to treat their wastewaters.
They have to recycle,
and they can use for gardening and other activities.
But if they are going to use septic tank,
they make sure that they have concrete septic tanks in order to
avoid some intrusion of sewage to the marine environment.
Untreated sewage that enter the sea and marine litter,
seemed to be some of the main reasons for
the degradation of the marine environment in Zanzibar.
By acknowledging that coastal tourism is the dominating sector of the economy,
accounting for 27 percent of GDP,
one would think it's high interest to conserve the attractive beaches,
and clear blue sea.
So, why has degradation gone so far,
and why is the pressure on coastal areas not managed and regulated?
According to a study,
part of the answer lies in the distribution of economic benefits from tourism.
Much of the tourism industry has excluded local communities,
and left the population with
limited economic incentives to protect the marine environment.
Overall, it sounds a bit depressing,
but there might still be hope for sustainable solutions for tourism in Zanzibar.
There's a growing understanding among common people,
among fishermen, among hotel owners,
and also along local scientists that we really need to do something.
Do you have examples of successes and things that improve the situation at the moment?
Yes, we actually do have some very encouraging news from collaboration,
we have especially from the Chumbe Reef Sanctuary,
where they have, since the 1990s,
protected areas from over-fishing,
they have removed threats by invasive species,
and they have made sure not to pollute the waters around the island.
And it occurs that recovery can be very fast,
and it gives me hope that with proper management that we will actually be able to see
a fast recover of many of these beautiful, high diverse habitats.
An example of how sustainable tourism is being promoted in Zanzibar
is the upgrading of the old Mtoni Marine Hotel,
two kilometers outside Stone Town.
Here the chairman of the Bakhresa Group states,
"We are serious about being the leaders of the Green Economy sector,
and therefore we approached the development of Africa's Greenest Hotel,
Verde Hotels to ensure that Hotel Verde Zanzibar
will be the Greenest hotel in East Africa."
He describes the grey water recycling,
and waste management systems they're planning to implement.
However, you can also read that the project is claiming
30 hectares of sea to construct a waterpark.
In other words, the pressure on the coastal environment continues but in different ways.