Red Tides – Are We Fertilizing Our Oceans To Death?
In November 2017 more than 300 turtles were found floating dead on the Pacific near the coast of El Salvador.
Such occurrences had been observed in previous years with smaller numbers of 120 between 200 dead animals. Whereas in past cases the cause for this remained unresolved or related to savage fishermen disposing unwanted haul back into the ocean, a monthlong catching moratorium that was active during the time the turtle die-off was discovered turned the attention to the bloom of toxic harmful algae. Algae blooms are a natural component of marine ecosystems. The majority is non-hazardous to living organisms and serves as food source for sea animals. However, certain combinations of nutrients in the water, temperature and oceanic currents can favour the growth of harmful algae blooms (HAB), also considered as red tides, given the colour of the algae turning the water red (Hallegraeff, 1993).
Even though HABs have been reported throughout history at coasts over the globe, researchers see an increase in occurrence and duration of blooms over the past decades, as well as in concentration of toxicity, as HAB in the past did lead to the death of sea animals, but never to such large scale die-offs as discovered on the coast off El Salvador. Research on toxic algae expects this intensification to be anthropogenically rooted in increased levels of urea nitrogen run-off from fertilizers for soil cultivation as well as sewage spills .
As a negative externality from fertilizer application in agriculture and horticulture the increased occurrence of HABs has far reaching consequences to human health as well as marine and coastal-based economies in affected regions. In Florida, a state regularly confronted with the bloom of toxic algae, residents suffer from respiratory, neurologic and gastrointestinal side effects, as not only physical contact, but also exposure to gases arising from HABs is harmful (Kirkpatrick et al, 2006; 2010). From an economic perspective, if sea animals don’t die from the poisonous intake of the algae, their fishing and consumption is impossible given the toxic substances remaining in their bodies (Kirkpatrick et al, 2014). Consequently, HABs result in heavy losses for marine industries and also affect the tourism sector, as polluted areas ought to be abandoned. Residents’ health is not only affected during the time of the bloom but has long-term effects on prolonged diseases in the following months leading to increased public spending on health care.
Market failure occurs as no markets exist for the quality and pollution of water and oceans (Hanley et al, 2013). The disposal of waste water into rivers and oceans is a common practice in the industrial sector and the run-off from fertilizers applied in agricultural production as well as private use accounts for high levels of urea nitrogen in ground water and rivers disemboguing in oceans. Apart from the economic losses, long-term effects of such pollution encounter the reduced services provided by marine ecosystems due to the loss of biodiversity and the enhanced threat to already endangered species being exposed to harmful algae, as seen in El Salvador (Kirkpatrick et al, 2014).
Florida attempted to tackle the occurrence of HAB by an ordinance policy limiting the amount of fertilizer used. During certain times of the year a regulation prohibited the sale and application of urea nitrogen fertilizer in both private and industrial use. However, given a lack of information accompanying the introduction of this measure regarding the connection of using fertilizer favouring the growth of toxic blooms on the coast of Florida, the regulation led to increased use of fertilizer before and after the ban. Kirkpatrick et al (2014) connect the lack of information to an unfavourable fashion of lawn cultivation that is encouraging the private use of fertilizer in order to achieve the desirable ‘perfect lawn’, which is a status symbol in certain neighbourhoods.
In order to reduce the use of fertilizer, a Pigouvian tax would offer a market-based to solution (Hanley et al, 2013). Given that nitrogen fertilizer is generally overused with higher amounts than required, restricting the demand for fertilizer by adding a tax to the final price would decrease the level of nitrogen pollution in the water without having negative effects on the growth of crops or lawn. Reducing the supply of nutrients to toxic algae will help to limit the augmented occurrence of HABs (Suzuki, 2015).
However, in the case of Florida’s high pressure among residents to present well grown lawn, elevated prices could render the use of fertilizer another desirable status symbol. On broader terms, a tax could make fertilizer unaffordable for producers of agricultural goods and would also penalize those having used appropriate amounts in the past.
While in the case of Florida regulating the private use of fertilizer is deemed as the most effective measure to reduce HAB, in other areas industrial misconduct of waste water treatment and drainage from agricultural areas is mainly affecting the concentration of nitrogen in the water (Suzuki, 2015). In such cases, the most effective control measure was the monitoring of water quality and acting accordingly with industrial effluent regulation policies. However, even if the regulation of fertilizer use leads to enhanced water quality favourable to prevent increased HAB in certain regions (Suzuki, 2015), the influencing factors of water temperature as well as streams influencing the spread and growth of blooms require international attention, as over the past decades blooms have occurred on coasts unaffected before (Anderson, 2009).
Research on HAB and anthropogenic influences on their formation is ongoing, as well as attempts to design policy measures to control such influences. In order to prevent the loss of environmentally, socially and economically important marine and coastal ecosystem services by the intensified occurrence of toxic algae, multidisciplinary research combined with collaborative efforts between all stakeholders, including governments, policy makers as well as the general public is required to design policies adaptable to the variety of regional needs and specificities (Berdalet et al, 2015).
About the Author:
Natascha Schwarzkopf is a Master's student in Sustainable Development and Environmental Economics.
- Anderson, D.M. (2009) Approaches to monitoring, control and management of harmful algal blooms (HABs). Ocean Coast Management 52(7): 342.
- Berdalet, E., Fleming, L., Gowen R., Davidson K., Hess, P., Backer, L.C., Moore, S.K., Hoagland, P., Enevoldsen, H. (2015) Marine harmful algal blooms, human health and wellbeing: challenges and opportunities in the 21st century. Journal of the Marine Biological Association of the United Kingdom 96 (1): 61-91.
- Florida Department of Environmental Protection (FDEP) (2013) Model ordinance for Florida friendly fertilizer use on urban landscapes/ Estuary-Specific Numeric Interpretations of the Narrative Nutrient Criterion, Available at https://www.flrules.org/gateway/ruleNo.asp?id=62-302.532 [last accessed: 09/04/2018]
- Gibbens, S. (2017) Hundred of Sea turtles found dead, National Geographic. Available at: https://news.nationalgeographic.com/2017/11/sea-turtle-hundreds-die-off-el-salvador-spd/ [last accessed: 09/04/2018]
- Glibert, P.M., Harrison J., Heil, C., Seitzinger, S. (2006) Escalating Worldwide use of Urea – A Global Change Contributing to Coastal Eutrophication. Biogeochemistry 77 (3): 441–463.
- Glibert, P.M., Burkholder, J., Kana, T., Shilling, C. (2009) Grazing by Karenia brevis on Synechococcus enhances its growth rate and may help to sustain blooms. Aquatic Microbial Ecology 55(1):17-30
- Hallegraeff, G. (1993) A Review of Harmful Algal Blooms and Their Apparent Global Increase. Phycologia 32 (2): 79-99.
- Hanley, N., Shogren J., White B. (2013) Introduction to Environmental Economics, 2nd ed. Oxford: Oxford University Press.
- Kirkpatrick, B., Fleming, L.E., Backer, L.C., Bean, J.A., Tamer, R., Kirkpatrick, G., Kane, T., Wanner, A., Dalpra, D., Reich, A., Baden, D.G. (2006) Environmental exposures to Florida red tides: Effects on emergency room respiratory diagnoses admissions. Harmful Algae 5(5):526-533.
- Kirkpatrick, B., Bean, J.A., Fleming, L.E., Kirkpatrick, G., Grief, L., Nierenberg, K., Reich, A., Watkins, S., Naar, J. (2010) A significant 40% increase in the total number of gastrointestinal emergency room admissions for the Florida red tide bloom period was found compared to the non red tide period. Harmful Algae 9(1):82-86.
- Kirkpatrick, B., Kohler, K., Byrne, M., Fleming, L.E., Scheller, K., Reich, A., Hitchcock, G., Kirkpatrick, G., Ullmann, S., Hoagland, P. (2014) Human responses to Florida red tides: Policy awareness and adherence to local fertilizer ordinances. Science of the Total Environment 493: 898–909.
- Marquez, C.M. (2013) No One Can Work Out Why Hundreds Of Dead Sea Turtles Are Washing Up On Central America's Beaches, Business Insider. Available at: http://www.businessinsider.com/no-one-can-work-out-why-hundreds-of-dead-sea-turtles-are-washing-up-on-central-americas-beaches-2013-11?IR=T [Accessed: 09/04/2018]
- Suzuki, C. (2016) Assessing change of environmental dynamics by legislation in Japan, using red tide occurrence in Ise Bay as an indicator. Marine Pollution Bulletin 102: 283–288.