The Covid-19 pandemic has impacted everything from the largest societies on earth to the smallest microalgae in the sea.

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The oceans directly influence life on Earth, regulating the global climate, stimulating rainfall, and providing 50 to 80 percent of the Earth’s oxygen. Any change on the surface of the ocean has a direct effect on life on this planet. They also constitute the Earth’s largest source of food, with more than 40 percent of the world’s population relying on the oceans as their primary food source. As the pandemic caused by the novel coronavirus has shown a pronounced effect on the environment in general, recognizing its effect on the oceans is paramount.

Dr. Maryam R. Al Shehhi, Assistant Professor in the Khalifa University Department of Civil Infrastructure and Environmental Engineering, investigated the effects of the Covid-19 pandemic on the oceans with Dr. Yarjan Abdul Samad from the University of Cambridge. They published their findings recently in the journal .

“The global Covid-19 lockdowns resulted in the closure of the largest industries in the world for a period of two months,” explained Dr. Al Shehhi. “This was enough to cause a seven percent drop in anthropogenic carbon dioxide in the atmosphere. While there have already been investigations into the effect of the pandemic on the atmosphere, the question remains: what happened to the oceans?”

One way of determining the state of the oceans is to consider their productivity. Ocean productivity represents the health of the marine ecosystem and the carbon cycle and largely refers to the production of organic matter by phytoplankton suspended in the ocean. Phytoplankton harvest light to convert inorganic carbon to organic carbon and then supply this organic carbon to organisms that obtain their energy from the respiration of organic matter, such as zooplankton, fish, and marine mammals.

“Productivity is commonly estimated as the plant biomass in the ocean, and chlorophyll-a is one of the key metric indicators,” explained Dr. Al Shehhi. “Associated with ocean productivity are the sea temperature and the carbon cycle.

“Big industries, such as the automobile factories, textile and clothing factories, and maritime fishing and shipping operations, were on hold for a period of two months, with many fishing vehicles unable to leave port and a substantially reduced demand for many seafood products,” explained Dr. Al Shehhi. “These human stressors have been seriously affecting the ocean for several decades, causing a high sea surface temperature, ocean acidification, and increasing ultraviolet radiation. If these industries continue to operate as they have, the sea surface temperature is projected to rise by 2.8°C by 2100, which would have devastating effects on the planet.”

However, during the pandemic lockdowns, there was a seven percent reduction in global carbon dioxide emissions from cumulative human activity. The researchers considered how this reduction could have affected the oceans by examining the levels of chlorophyll-a (chl-a) before and during the pandemic using satellite images. Their results show a reduction in chl-a concentrations in the global oceans, particularly in the coastal regions.

Satellite images can be used to measure the concentration of chl-a, the pigment used by phytoplankton to photosynthesize. The levels of chl-a in the surface water are an indication of how much primary production is occurring in the surface of the ocean. Since phytoplankton need nutrients for photosynthesis and growth, chlorophyll concentrations are highest where nutrient concentrations are highest. Currents in the ocean can bring nutrient rich water from the deep up to the surface, which means there is a correlation between water temperature and chlorophyll concentration. Cold water generally has higher chl-a concentrations than warm water because it contains nutrients that have recently been carried up from the deep ocean. The cold, nutrient-rich waters of the North Atlantic are more productive than the warmer, tropical waters found around the equator.

Dr. Al Shehhi and Dr. Samad investigated the chl-a concentrations in eleven regions, selected for the presence of either high industrial activity or large population: Alaska, Northeast United States, Southeast USA, Pacific Ocean, Southeast America, China and South Korea, Middle East, North Europe, Northwest Africa, Southwest Africa, and Southeast Australia.

“We saw a prominent decrease off Alaska, Northern Europe, South China and the Southeast USA,” said Dr. Al Shehhi. “CO₂ emissions from South China dropped by 123 tonnes during the pandemic, and this resulted in a five percent drop in chl-a in the surrounding ocean. This drop in chl-a could be caused by the reduction of the CO2 emissions during the pandemic period because phytoplankton biomass takes up the atmospheric CO2 during photosynthesis.”

The reduction in atmospheric CO2 emissions has also affected the carbon cycle in the ocean. The ratio of inorganic carbon to organic carbon has decreased, indicating a reduction in CO2 uptake. In Europe, the reported reduction of atmospheric CO2 emissions by 24 percent may have caused a direct 75 percent decrease in the carbon ratio of the seas in northern Europe. The coastal areas off Alaska and in the North Indian Ocean and Eastern Pacific also saw a cooling response of 0.5°C following the reduction in CO2 emissions. As the water there had previously been warmed by global climate change, this cooling can be attributed to a reduction in emissions.

“A lower surface temperature can improve the uptake of atmospheric CO2 by the ocean and can enhance the productivity process,” explained Dr. Al Shehhi. “Therefore, the reduction in CO2 emissions doesn’t have a direct effect on chl-a and surface temperature, rather, it is related to both of them.”

The researchers explained that while carbon dioxide in the atmosphere is needed by phytoplankton to photosynthesize, during this process, the water in the oceans becomes warmer, more acidic, and less oxygenated.

“If anthropogenic pressures return to normal, CO2 emissions will return to normal,” said Dr. Al Shehhi. “This will continue to contribute to global warming and affect the oceans by causing acidification, stratification, increasing sea temperature and increasing productivity. Instead, maintaining global activities at the levels observed during the pandemic period could help to recover the oceans.”

Jade Sterling
Science Writer
18 May 2021

The post Effects of the COVID-19 Pandemic on the Oceans appeared first on Khalifa University.

Postdoctoral fellow Dr. Maryam Al Shehhi working with MIT Faculty to Adapt Ocean Model to Arabian Gulf’s Unique Inputs

Increasing our understanding of the ebbs, flows, and impacts on the Arabian Gulf – the body of water that provides the UAE water for desalination, seafood for local consumption, a transit route for shipping, and a tourism attraction through its coastal areas – is crucial to improving its sustainable management and conservation.

That is why Dr. Maryam Al Shehhi, KU postdoctoral fellow and alumnus of the Masdar Institute, is currently collaborating with researchers at the Massachusetts Institute of Technology (MIT) to develop advanced models of the Arabian Gulf using numerical and theoretical frameworks supported by field and satellite data.

“The Arabian Gulf is central to many functions of the UAE – our desalination plants, local fisheries, transport of oil, etc. For all these reasons and more, there is a need to build a physical-biogeochemical marine model calibrated for the Gulf that includes the influence of transportation, mixing and diffusion processes driven by tides, winds, and density grades,” Dr. Al Shehhi explained.

The UAE is heavily reliant on the Arabian Gulf for the desalinated water that makes up for its shortfall in natural freshwater – with natural gas-powered thermal desalination estimated to produce around 80% of the country’s domestic water. The Arabian Gulf is also the source of the UAE’s many beaches, which are a huge draw in the country’s travel and leisure sector, which accounted for 11.3 percent of the UAE’s gross domestic product in 2017, according to data released by the World Travel and Tourism Council. The UAE and all other countries bordering the Arabian Gulf also trawl its waters for seafood, with the United Nations Environment Program estimating that some 298,490 tons of seafood were harvested from the Arabian Gulf in 2011-2012.

Additionally, with the UAE, Saudi Arabia and other major oil and gas producing countries bordering the Arabian Gulf, an estimated 30% of the world’s crude oil is shipped through the Strait of Hormuz alone, which is the small gap between the Arabian Gulf and the Gulf of Oman. Over 90% of the global trade flows by weight passes through the Strait of Hormuz according to the International Maritime Organization.

“Given the many inputs and influences on the Arabian Gulf, including more than 100 desalination plants that discharge hot and salty effluent that can significantly change the physical and biochemical properties of the waters and the cargo ships that release ballast water that often contains oil and invasive species. Therefore, it is of great importance to understand the risks Arabian Gulf faces, and how they can play out,” Dr. Al Shehhi explained.

She has been working with KU Professor and Director of the Research Center for Renewable Energy Mapping and Assessment Dr. Hosni Ghedira, and MIT Cecil and Ida Green Professor of Oceanography Dr. John Marshall to develop a marine model that takes all of the many complex factors that impact and influence the Arabian Gulf into consideration, which Dr. Al Shehhi graduated from the Masdar Institute in 2016 as the first UAE National to gain a PhD in earth observation and ocean color remote sensing, and later joined Masdar Institute as a faculty member.

“Such models could be used to predict what can happen around offshore drilling sites, the trajectories and landing points of accidental marine pollution events (e.g. tracking oil spills and harmful algae bloom events), nutrient cycles, contaminant dispersion, eutrophication and aquaculture-ecosystem interactions. Moreover, the models can be set up to operate in real time and forecasting schemes developed depending on the application,” Dr. Al Shehhi explained.

Harmful algae bloom events – or HABS – are potentially harmful to marine life, water quality, human health, and desalination plants, and have been reportedly increasing in the Arabian Gulf due to rising human activity and its resultant pollution.

The team is working with an existing MIT atmosphere, ocean, and climate model – the MIT General Circulation Model (MITgcm) – which they are adapting and tailoring to address the specific characteristics of, and applications to, the Gulf region. The model has never been used in regional oceanography, and one of the challenges Dr. Al Shehhi and the team face is adapting it to new mixing parameterizations and the biogeochemical modeling that reflect the unique parameters of the Arabian Gulf. A biogeochemical model, also developed at MIT, will then be overlaid on the physical model to study the bio-chemical properties of the Gulf region. This ocean component will then be coupled to an existing regional atmospheric/chemical model which is already operational at Khalifa University. The model is currently being integrated with the atmospheric data generated by Khalifa University’s Research Center for Renewable Energy Mapping and Assessment, which uses satellites to gather atmospheric data.

“This modelling work can lay the ground for coupling of ocean circulation with high resolution atmospheric models already under development at Khalifa University, thus leading to a coupled atmosphere-ocean system that could have a wide range of applications to monitor marine environmental conditions and changes in the Gulf region,” Dr. Al Shehhi shared.

Improving available monitoring models for the Arabian Gulf can provide robust systems for many types of users in the UAE and wider region. For instance, the UAE Ministry of Climate Change and Environment could benefit from enhanced monitoring and forecasting of water quality to alert desalination plants of pollution incidents that can damage their systems. The models can be set up for real time operation or forecasting depending on the desired application.

“I am returning to the UAE in March, and where I will work with my colleagues at Khalifa University to continue to advance this project. I am confident the Arabian Gulf model we develop will enhance the current marine monitoring system, to work in real-time to improve the UAE’s preparedness for potential risks of marine pollution, mainly from harmful algae blooms and oil spills,” Dr. Al Shehhi concluded.

Zarina Khan

Senior Editor

27 January 2019

The post Modeling Gulf Waters for Enhanced Management appeared first on Khalifa University.