Like the ocean’s ‘gut flora’: we sailed from Antarctica to the equator to learn how bacteria affect ocean health


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Eric Jorden Raes, Dalhousie UniversityAboard an Australian research vessel, the RV Investigator, we sailed for 63 days from Antarctica’s ice edge to the warm equator in the South Pacific and collected 387 water samples.

Our goal? To determine how the genetic code of thousands of different micro-organisms can provide insights into the ocean’s functional diversity — the range of tasks performed by bacteria in the ocean.

Our research was published yesterday in Nature Communications. It showed how bacteria can help us measure shifts in energy production at the base of the food web. These results are important, as they highlight an emerging opportunity to use genetic data for large-scale ecosystem assessments in different marine environments.

In light of our rapidly changing climate, this kind of information is critical, as it will allow us to unpack the complexity of nature step by step. Ultimately, it will help us mitigate human pressures to protect and restore our precious marine ecosystems.

Why should we care about marine bacteria?

The oceans cover 71% of our planet and sustain life on Earth. In the upper 100 meters, the sunlit part of the oceans, microscopic life is abundant. In fact, it’s responsible for producing up to 50% of all the oxygen in the world.

A whale breaches the ocean
Marine bacteria provide the energy and food for the entire marine food web, from tiny crustaceans to whales.
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Much like the link recently established between human health and the human microbiome (“gut flora”), ocean health is largely controlled by its bacterial inhabitants.

But the role of bacteria go beyond oxygen production. Bacteria sustain, inject and control the fluxes of energy, nutrients and organic matter in our oceans. They provide the energy and food for the entire marine food web, from tiny crustaceans to fish larvae, whales and the fish we eat.

These micro-organisms also execute key roles in numerous biogeochemical cycles (the carbon, nitrogen, phosphorus, sulphur and iron cycles, to name a few).

So, it’s important to quantify their various tasks and understand how the different bacterial species and their functions respond to environmental changes.

Fundamental questions

Global ocean research initiatives — such as GO-SHIP and GEOTRACES — have been measuring the state of oceans in expeditions like ours for decades. They survey temperature, salinity, nutrients, trace metals (iron, cobalt and more) and other essential ocean variables.

Only recently, however, have these programs begun measuring biological variables, such as bacterial gene data, in their global sampling expeditions.

The author smiles in front of a blue and white ship, with 'Investigator' written on the side.
On board the RV Investigator, we departed Hobart in 2016, beginning our 63-day journey to sample microbes in the South Pacific.
Eric Raes, Author provided

Including bacterial gene data to measure the state of the ocean means we can try to fill critical knowledge gaps about how the diversity of bacteria impacts their various tasks. One hypothesis is whether a greater diversity of bacteria leads to a better resilience in an ecosystem, allowing it to withstand the effects of climate change.

In our paper, we addressed a fundamental question in this global field of marine microbial ecology: what is the relationship between bacterial identity and function? In other words, who is doing what?

What we found

We showed it’s possible to link the genetic code of marine bacteria to the various functions and tasks they execute, and to quantify how these functions changed from Antarctica to the equator.

The functions that changed include taking in carbon dioxide from the atmosphere, bacterial growth, strategies to cope with limited nutrients, and breaking down organic matter.




Read more:
Marine life is fleeing the equator to cooler waters. History tells us this could trigger a mass extinction event


Another key finding is that “oceanographic fronts” can act as boundaries within a seemingly uniform ocean, resulting in unique assemblages of bacteria with specific tasks. Oceanographic fronts are distinct water masses defined by, for instance, sharp changes in temperature and salinity. Where the waters meet and mix, there’s high turbulence.

The change we recorded in energy production across the subtropical front, which separates the colder waters from the Southern Ocean from the warmer waters in the tropics, was a clear example of how oceanographic fronts influenced bacterial functions in the ocean.

Dark blue water meets light blue water under a cloudy sky.
An oceanographic front, where it looks like two oceans meet.
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Tracking changes in our ecosystems

As a result of our research, scientists may start using the functional diversity of bacteria as an indicator to track changes in our ecosystems, like canaries in a coal mine.




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Half of global methane emissions come from aquatic ecosystems – much of this is human-made


So the functional diversity of bacteria can be used to measure how human growth and urbanisation impact coastal areas and estuaries.

For example, we can more accurately and holistically measure the environmental footprint of aquaculture pens, which are known to affect water quality by increasing concentrations of nutrients such as carbon, nitrogen and phosphorus – all favourite elements utilised by bacteria.

Likewise, we can track changes in the environmental services rendered by estuaries, such as their important role in removing excessive nitrogen that enters the waterways due to agriculture run-off and urban waste.

With 44% of the world’s population living along coastlines, the input of nitrogen to marine ecosystems, including estuaries, is predicted to increase, putting a strain on the marine life there.

Ultimately, interrogating the bacterial diversity using gene data, along with the opportunity to predict what this microscopic life is or will be doing in future, will help us better understand nature’s complex interactions that sustain life in our oceans.




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Humans are polluting the environment with antibiotic-resistant bacteria, and I’m finding them everywhere


The Conversation


Eric Jorden Raes, Postdoctoral researcher Ocean Frontier Institute, Dalhousie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Climate change is a security threat the government keeps ignoring. We’ll show up empty handed to yet another global summit


Cheryl Durrant, UNSWClimate change is a hot topic in Australian security circles, as it poses an emerging threat to our national resilience and way of life. As a new report from the Australian Strategic Policy Institute (ASPI) last week warned, the federal government is unprepared to meet these challenges.

The report, authored by Dr Robert Glasser, said the government has largely overlooked the security threat posed by rising seas, climate-induced famine, extreme weather events, mass migrations and other climate change damage in Southeast Asia. Australia is sitting on the frontline of this vulnerable region.

Glasser’s report focuses on Southeast Asia, but in the bigger picture, climate security is an existential global risk which the Australian government is yet to fully grasp. It is this global aspect of climate and security which will be on the agenda in two weeks time at the Biden Leaders Summit in the US.

Why should we be worried?

The global risk is broader than traditional security threats, such as the rise of China, terrorism and separatist movements. As the ASPI report emphasises, there is a relationship between climate security and other sectors such as food, health and environmental security.

Unlike traditional national security threats, climate threats have no respect for national or sector borders and cannot be solved with missiles.

The threat is urgent. With the end of the Donald Trump presidency, climate change is back on regional and international security action agendas. The penny has dropped on how little time is left to take action to prepare for the worst of consequences.

This is especially the case when there are long lead times to implement action, such as infrastructure development and military capability development.




Read more:
Climate change poses a ‘direct threat’ to Australia’s national security. It must be a political priority


ASPI’s key recommendations to the government include:

  • improving understanding of climate change risks through a broad whole-of-government process
  • building capacity in government agencies to assess ongoing risks
  • identifying opportunities for regional aid and investments.

These make sense, as the first step of preparedness is understanding the risk.

Security risks go beyond natural disasters

The ASPI report notes Southeast Asia “has the world’s highest sea-level rise per kilometre of coastline and the largest coastal population affected by it”. The region is a hot spot for cyclones, with some nations vulnerable to catastrophic heat or fires.

The ASPI report notes:

Those hazards will not only exacerbate the traditional regional security threats […] but also lead to new threats and the prospect of multiple, simultaneous crises, including food insecurity, population displacement and humanitarian disasters that will greatly test our national capacities, commitments and resilience.

The report focuses on Southeast Asia and natural disasters, but the risks and the affected regions are bigger than that.

The Indo-Pacific region may see the displacement of millions of people due to climate change-related extreme weather events, heatwaves, droughts, rising seas and floods. We’re already seeing this occur in Bangladesh and small island developing states.

We could also see conflict arise as climate change affects global food or water resources. A particular concern is the potential geopolitical tensions between India and China over dwindling Tibetan water resources.

Australia is getting left behind

Urgency and risk are central to an executive order from President Joe Biden in January. The order requires a US national security estimate on the economic and national security impacts of climate change by June. The US Department of Defence must also complete an analysis of the security implications of climate change in the same timeframe.




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Most tellingly, the US is taking an integrated approach to climate security. Foreign policy, defence and economic risk analysis are being conducted in a joined-up, systemic way.

In contrast, the Australian Defence Strategic Update 2020 was conducted in isolation from foreign policy and economic reviews. Taking a narrow military perspective, it does mention climate change, but only once, as a subset of human security threats.

Australia risks being left behind as other countries follow the US lead. Across the Tasman, our Kiwi friends are already well advanced in turning risk awareness into action. The New Zealand government completed its first national climate risk assessment last year, with a national adaptation plan to be completed by August 2022.

What are the consequences?

Being left behind has consequences for Australia’s international standing, national resilience and economic position.

From a diplomatic perspective, Australia’s influence in the Indo-Pacific region is diminished, relative to other actors, especially in states where climate change risk is a top priority, such as Vanuatu or Kiribati.

Risks offer opportunities as well. For example, Australia has an abundance of critical minerals and rare earths needed for modern communications, space technologies, and renewable energy generation and transmission. These are key for business, as well as critical for defence forces.




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However, processing and manufacturing is largely conducted offshore — in countries vulnerable to climate risks such as Malaysia — before returning to Australia as finished products.

This puts Australian defence and space and energy sectors at risk of disruption, and Australian businesses at risks of economic loss.

What needs to happen next?

ASPI’s report echoes the earlier recommendation from a 2018 Senate inquiry into the implications of climate change for Australia’s national security. The inquiry also called for a coordinated whole-of-government response to climate change risks.

Three years later, the federal government has yet to act on its recommendations.

The Australian government now needs to have a greater sense of urgency to act on the growing national and international calls to act on climate risk. But first, our leaders need a changed mindset. They must accept that climate change is an immediate threat to Australia.




Read more:
Senate report: climate change is a clear and present danger to Australia’s security


The Conversation


Cheryl Durrant, Adjunct Associate Professor, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.