Tag: daniela schmidt

Tiny oceanic plankton adapted to warming during the last ice age, but probably won’t survive future climate change – new study

Posted on by amanda.woodman-hardy

Phytoplankton

Global temperature records are expected to exceed the 1.5 °C threshold for the first time this year. This has happened much sooner than predicted. So can life on the planet adapt quickly enough?

In our new research, published today in Nature, we explored the ability of tiny marine organisms called plankton to adapt to global warming. Our conclusion: some plankton are less able to adapt now than they were in the past.

Plankton live in the top few metres of ocean. These algae (phytoplankton) and animals (zooplankton) are transported by ocean currents as they do not actively swim.

Climate change is increasing the frequency of heatwaves in the sea. But predicting the future effects of climate change is difficult because some projections depend on ocean physics and chemistry, while others consider the effects on ecosystems and their services.

Some data suggest that current climate change have already altered the marine plankton dramatically. Models project a shift of plankton towards both poles (where ocean temperatures are cooler), and losses to zooplankton in the tropics but might not predict the patterns we see in data. Satellite data for plankton biomass are still too short term to determine trends through time.

To overcome these problems, we have compared how plankton responded to past environmental change and modelled how they could respond to future climate changes. As the scientist Charles Lyell said, “the past is the key to the present”.

We explored one of the best fossil records from a group of marine plankton with hard shells called Foraminifera. This comprehensive database of current and past distributions, compiled by researchers at the University of Bremen, has been collected by hundreds of scientists from the seafloor across the globe since the 1960s. We compared data from the last ice age, around 21,000 years ago, and modern records to see what happened when the world has previously warmed.

We used computational models, which combine climate trends with traits of marine plankton and their effect on marine plankton, to simulate the oceanic ecosystems from the last ice age to the pre-industrial age. Comparing the model with the data from the fossil record is giving us support that the model simulated the rules determining plankton growth and distribution.

We found that some subtropical and tropical species’ optimum temperature for peak growth and reproduction could deal with seawater warming in the past, supported by both fossil data and model. Colder water species of plankton managed to drift to flourish under more favourable water temperatures.

Our analysis shows that Foraminifera could handle the natural climate change, even without the need to adapt via evolution. But could they deal with the current warming and future changes in ocean conditions, such as temperature?

Future of the food chain

We used this model to predict the future under four different degrees of warming from 1.5 to 4 °C. Unfortunately, this type of plankton’s ability to deal with climate change is much more limited than it was during past warming. Our study highlights the difference between faster human-induced and slower-paced geological warming for marine plankton. Current climate change is too rapid and is reducing food supply due to ocean stratification, both making plankton difficult to adapt to this time.

Phytoplankton produce around 50% of the world’s oxygen. So every second breath we take comes from marine algae, while the rest comes from plants on land. Some plankton eat other plankton. That in turn gets eaten by fish and then marine mammals, so energy transfers further up the food chain. As it photosynthesises, phytoplankton is also a natural carbon fixation machine, storing 45 times more carbon than the atmosphere.

Around the world, many people depend heavily on food from the ocean as their primary protein sources. When climate change threatens marine plankton, this has huge knock-on effects throughout the rest of the marine food web. Plankton-eating marine mammals like whales won’t have enough food to prey on and there’ll be fewer fish to eat for predators (and people). Reducing warming magnitude and slowing down the warming rate are necessary to protect ocean health.

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This blog is written by Rui Ying, Postdoctoral Researcher, Marine Ecology, and Daniela Schmidt, Professor in Palaebiology, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Rui Ying
Rui Ying
Daniela Schmidt
Daniela Schmidt

Putting algae and seaweed on the menu could help save our seafood

Posted on by janet.crompton
File 20171213 27593 sfv3nk.jpg?ixlib=rb 1.1
Shutterstock
This article was written by Pallavi Anand, The Open University and Daniela Schmidt, University of Bristol Cabot Institute. 


If we have to feed 9.8 billion people by 2050, food from the ocean will have to play a major role. Ending hunger and malnutrition while meeting the demand for more meat and fish as the world grows richer will require 60% more food by the middle of the century.But around 90% of the world’s fish stocks are already seriously depleted. Pollution and increasing levels of carbon dioxide (CO₂) in the atmosphere, which is making the oceans warmer and more acidic, are also a significant threat to marine life.There is potential to increase ocean food production but, under these conditions, eating more of the species at the top of the food chain, such as tuna and salmon, is just not sustainable. As a recent EU report highlighted, we should instead be looking at how we can harvest more smaller fish and shellfish, but also species that aren’t as widely eaten such as seaweed and other algae.The oceans have absorbed around one third of the CO₂ emitted into the atmosphere since the Industrial Revolution. The absorbed CO₂ goes through a series of chemical reactions that form carbonic acid and lower the pH of the water. These reactions also reduce the concentration of carbonate ions, which are vital for those creatures that grow external skeletons such as corals and shellfish.

The acid and the lack of carbonate mean these organisms form weaker skeletons and have to use more energy to do so, leaving less energy for growth and reproduction. Consequently, they up smaller in size. Aside from the impact this has on shellfish, several of the species affected, such as corals in the tropics or coralline algae in the waters around the UK, also play a key role in providing food and nursing grounds for fish. And less fish food leads to fewer fish for us to catch.

Climate change is affecting food production

The impact of ocean acidification varies widely across the globe. But it is already affecting marine food production, particularly of shellfish. For example, CO₂-rich water along the west coast of the US means more oysters in local hatcheries are dying when they are still larvae.
Warmer seas due to climate change are also affecting food supplies. Some species are moving towards the poles in search of cooler water, forcing fishermen into more northerly waters or leaving them without stocks altogether. Some fishing fleets in northern locations will find more fish available but many will see the amount of fish available to catch fall by between 6% and 30% depending on the region. The biggest impact will be on areas that are already the most dependent on fishing, such as Southeast Asia and West Africa.

One possible solution is to eat more smaller fish and shellfish such as mussels. Large fish need to eat smaller fish to grow. If we eat smaller fish instead then we remove a step from the food chain and reduce the amount of energy lost in the process. What’s more, it might become easier to farm these smaller fish because the algae, cyanobacteria and other plankton they eat could actually benefit from warmer waters and higher levels of CO₂ in the atmosphere. This is because they get their energy from photosynthesis and so use CO₂ like fuel.

Spirulina, the new seafood cocktail.
Shutterstock

It might also be possible to take this a step further and add some of these organisms directly to our diet, giving us an abundant new source of food. Seaweed, for example, is a type of algae that has been eaten for centuries, but only 35 countries commercially harvest it today. Spirulina cyanobacteria is already eaten as a food supplement and several companies are trying to turn other forms of algae into a human food source.

Farming these organisms in the right way could even help counter some of the effects of climate change on the rest of the food chain. For example, growing more seaweed lowers the amount of CO2 in the surrounding water, reduces acidification, and improves the environment for oysters and other shellfish. Managing seaweed harvest correctly will also maintain the dissolved oxygen and nutrient levels in the water, contributing to the overall health of the ocean.

The ConversationMaking algae a common part of more people’s diets won’t be easy. We need to ensure that any new algae food products on our dinner plates have the needed nutritional value but are also attractive and safe to eat. But sticking with our traditional salmon and tuna diet isn’t sustainable. Expanding our seafood menus could be a vital way of keeping the ocean healthy while it supplies the food we need.
Pallavi Anand, Lecturer in Ocean Biogeochemistry, The Open University and Daniela Schmidt, Professor in Palaebiology, University of Bristol

This article was originally published on The Conversation. Read the original article.

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