4. Evidence of impacts in the Western Indian Ocean
4.3 Impacts in Tanzania
17 https://www.preventionweb.net/english/countries/africa/tza/
18 Global Facility for Disaster Risk Reduction country profile for Tanzania https://www.gfdrr.org/en/tanzania
The key national disaster risk policies in Tanzania include the National climate change strategy 2012, the Agriculture climate resilience plan 2014-2019, the Zanzibar Disaster Communication Strategy 2011, and the Zanzibar
Disaster Management Policy, 201117. The 2018 Disaster Risk Profile for Tanzania focuses on the risks from drought and flooding and does not specifically focus on ocean risk (CIMA, 2018).
Extreme weather events - Tanzania
Extreme weather events in Tanzania (flooding, droughts, cyclones, and tropical storms) have always imposed major economic costs on the country18. Individual annual events regularly cost Tanzania more than 1% of its GDP, reducing the country’s capacity for long-term growth and placing millions of people and their livelihoods at risk (Worker and Excell, 2018).
Climate change is forecast to increase average annual temperatures by 1-2.7°C by the 2060s and by 1.5-4.5°C by the 2090s (Irish Aid, 2017). It is also anticipated to increase the intensity, frequency and unpredictably of extreme weather events in Tanzania. According to projections, the economic costs to Tanzania’s main sectors could reach several billion US$ per year by the 2050s, inflicting net economic costs of a further 1-2% decline of GDP per year by 2030 (Global Climate Adaptation Partnership and partners, 2011). The economic costs associated with adapting, building adaptive capacity and enhancing resilience to potential climate-induced threats to coastlines is expected to cost between US$ 100-150 million per year (SEI, 2010).
Coral bleaching - Tanzania
Two-thirds of Tanzania’s 1,000 km coastline is bordered by reefs. A World Resources Institute report on reefs at risk placed Tanzania among the 9 nations most vulnerable to reef
degradation (Burke et al., 2011). According to this report, Tanzania has a low adaptive capacity, high reef dependence and high threat exposure.
For example, the 1998 bleaching event led to the loss of 80-95% of corals in Tanzania (Obura, 2002; Westmacot et al., 2000; Wilkinson et al., 1999). Economic losses to the dive industry in Zanzibar alone were estimated to be US$ 2.2 million in (Brown et al., 2011). A small decline in coral cover has been observed over the past 30 years, but has now stabilised at 35-40% (Obura et al., 2017). Some algae has been observed, which should be monitored in the future (Obura et al., 2017).
As of 2017, over 14 million Tanzanian’s live in coastal regions and many of them earn their livelihood through direct or indirect connections to the reef. Tourism’s economic contribution in Tanzania is relatively small, providing 0.34% of GDP, about US$ 180 million per year
(Spalding et al., 2017). By contrast, one big reef-dependent industry in Tanzania is the seaweed aquaculture industry. Tanzania (Zanzibar specifically) is in the top eight countries for seaweed cultivation contributing 132,000 tonnes (0.7%) to the global production. This industry employs some 25,000 workers, the majority of which are women. Seaweed farming is only possible inside the lagoons created by coral reefs, within a narrow band of the coast, some 380-600m from the shoreline (Hedberg et al., 2018). The loss of coral reefs has the potential to disrupt this profitable industry.
Harmful algal blooms - Tanzania
More than 20 potentially harmful algal species have been identified in the coastal waters of Tanzania (Kyewalyanga and Lugomela, 1999; Lugomela, 2006). Dominant species cover three groups associated with costly HAB events in other countries; cyanobacteria (Trichodesmium sp. and Lyngbya sp) diatoms (Pseudo-nitzschia sp.) and dinoflagellates (Prorocentrum sp. and Gambierdiscus toxicus) (Kyewalyanga and Lugomela, 1999; Lugomela, 2006).
HABs harm both seaweed production and farmers in Zanzibar. In February and March 2012, a cyanobacterial bloom of algae belonging to the genus Lyngbya stopped work in the seaweed farms in two villages in Zanzibar (IOC-UNESCO, 2016). Lyngbya produces several cyanotoxins, which have irritant, dermatoxic, inflammatory and neurotoxic effects and is also associated with the seafood poisoning syndrome clupeotoxism (Bláha et al., 2009; Said et al., 2018;
Zanchett and Oliveira-Filho, 2013). A survey found that more than half of the seaweed farmers in Zanzibar and mainland Tanzania had suffered health problems. Fifty per cent experienced skin irritation (>120 cases), 30% (>72 cases) eye-related problems, and 20% (48 cases) had respiratory disorders (Said et al., 2018). The highest occurrence of skin irritation cases was prevalent during the warmer seasons, which resulted in lost income and productivity for these farmers. The economic burden of illnesses has not been calculated, but is likely to contribute to a decrease in seaweed productivity, harvest and income (Said et al., 2018). Farmer’s children have also shown signs of health problems, which may stem from exposure during seaweed drying and preparation at home (Said et al., 2018).
Women seaweed farmers in Zanzibar face health problems arising from growing numbers of cyanobacterial blooms in seaweed farms.
Source: Imke.stahlmann / Flickr (CC BY-SA 2.0)
Food security via fisheries and aquaculture - Tanzania
Tanzania may be one of the poorest countries in the world, but it has one of the richest marine and inland fisheries, mainly because of its 1,424 km long coastline and productive inland lakes (Yusuf et al., 2015). The fishing sector plays an important role in the coastal economy of Tanzania, as well as enhancing the country’s food security and local livelihoods.
Small-scale fisheries in Tanzania account for 98% of total fish production and 1.3% of GDP, or US$ 12.4 million19. Although the contribution of small-scale fisheries to the GDP appears somewhat marginal, this sector is a vital source of food, employment and income for coastal communities (ASCLME, 2012b), supporting more than 4,000,000 Tanzanians (Sigalla, 2014). Since 1998, there has been a steady decline in the contribution of the fisheries sector to Tanzania’s national GDP. This could be related to climate change and environmental degradation, decreases in fish catches, over-participation in fishing related activities, changes in species distribution and/or increases in population (Sobo, 2012).
Limited information is available on the economic costs and losses of the entire fisheries sector for Tanzania, but some information does exist on the costs and losses endured by discreet sectors such as the country’s seaweed farming industry. Seaweed production for example, has fallen dramatically from 423.9 tonnes worth US$ 82,000 in 2003, to just 28 tonnes worth US$
4,300 in 2012 due to a combination of factors linked to increasing sea temperature, epiphytic growth, including of HABs, caused by increasing sea temperature and eutrophication and disease (Msuya and Porter, 2014).
Human health and diseases - Tanzania
Several infectious and diarrheal diseases are prevalent in Tanzania, including those caused by Campylobacter, Salmonella, Shigella, Vibrio cholerae, Rotovirus, Escherichia coli, Giardia, Hepatitis A and intoxication biotoxins produced by HABs (ReliefWeb, 2018).
Regarding cholera, the WHO (2018) reported that 47% out of 7,000 specimens that were tested for cholera stemmed from the marine-borne Vibrio bacteria. Most cases that occur are reported on the coast, with five coastal regions in Tanzania among the top-eight regions by the number of cases per capita (Taylor et al., 2009 cited in Mboera et al., 2011). In 2018 alone, 66 deaths from cholera were reported (Reliefweb, 2018).
The magnitude of costs and losses resulting from cholera (attributed to climate change) is significant and considerably higher than many of the budgets currently allocated for diarrhoeal diseases in developing countries (Trærup et al., 2011). An increase in temperature of 1-2 °C is estimated to increase the risks of catching cholera in Tanzania by 29%. This would mean there would be an additional 7,809 deaths. The total cost of climate change-induced changes in cholera is expected to range from 0.32 to 1.4 percent of GDP in Tanzania by 2030 (including costs of treating the sick, productivity losses and the value of lost lives (Trærup et al., 2011). With marine-borne bacteria accounting for just under half of the cases of cholera, further monitoring is required to evaluate the incidence and prevalence of cholera cases from the marine environment and study the effects of a changed ocean environment on these figures.
19 https://iwlearn.net/resolveuid/aa54393d9cd045d7b692d629263840fa