By Jodie L Rummer, Bridie JM Allan, Charitha Pattiaratchi, Ian A Bouyoucos, Irfan Yulianto and Mirjam van der Mheena
Posted Mon 7 Dec 2020 at 6:30am, updated Mon 7 Dec 2020 at 7:33am
By better understanding the threats to the precious Pacific, we can start the long road to protecting it. (Pexels: John Cahil Rom)
The Pacific Ocean is the deepest, largest ocean on Earth, covering about a third of the globe's surface. An ocean that vast may seem invincible.
Yet across its reach — from Antarctica in the south to the Arctic in the north, and from Asia to Australia to the Americas — the Pacific Ocean's delicate ecology is under threat.
And as we pump carbon dioxide into the atmosphere, the Pacific, like other oceans, is becoming more acidic. It means fish are losing their sense of sight and smell, and sea organisms are struggling to build their shells.
Oceans produce most of the oxygen we breathe. They regulate the weather, provide food, and give an income to millions of people. They are places of fun and recreation, solace and spiritual connection. So, a healthy, vibrant Pacific Ocean benefits us all.
By better understanding the threats to the precious Pacific, we can start the long road to protecting it.
The ocean plastic scourge
The problem of ocean plastic was scientifically recognised .. https://link.springer.com/chapter/10.1007/978-3-319-16510-3_1 .. in the 1960s after two scientists saw albatross carcasses littering the beaches of the northwest Hawaiian Islands in the northern Pacific. Almost three in four albatross chicks, who died before they could fledge, had plastic in their stomachs.
Now, plastic debris is found in all major marine habitats around the world, in sizes ranging from nanometres to metres. A small portion of this accumulates into giant floating "garbage patches", and the Pacific Ocean is famously home to the largest of them all.
Discarded fishing nets make up around 45 per cent of the total plastic weight in the Great Pacific Garbage Patch. (Supplied: The Ocean Cleanup Foundation)
Plastic debris in the oceans presents innumerable hazards for marine life. Animals can get tangled in debris such as discarded fishing nets, causing them to be injured or drown.
Some organisms, such as microscopic algae and invertebrates, can also hitch a ride on floating debris .. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100289 , travelling large distances across the oceans. This means they can be dispersed out of their natural range, and can colonise other regions as invasive species.
And of course, wildlife can be badly harmed by ingesting debris, such as microplastics less than five millimetres in size. This plastic can obstruct an animal's mouth or accumulate in its stomach. Often, the animal dies a slow, painful death.
Seabirds, in particular, often mistake floating plastics for food. A 2019 study .. https://www.nature.com/articles/s41598-018-36585-9 .. found there was a 20 per cent chance seabirds would die after ingesting a single item, rising to 100 per cent after consuming 93 items.
Discarded fishing nets, or 'ghost nets' can entangle animals like turtles. (Supplied: Tony Fontes)
And since floating plastics in the open ocean are transported mainly by ocean surface currents and winds, plastic debris accumulates on island coastlines along their path.
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Subtropical garbage patches
Plastic waste can have different fates in the ocean: some sink, some wash up on beaches and some float on the ocean surface, transported by currents, wind and waves.
Around 1 per cent of plastic waste accumulates in five subtropical "garbage patches" in the open ocean. They're formed as a result of ocean circulation, driven by the changing wind fields and the Earth's rotation.
There are two subtropical garbage patches in the Pacific: one in the northern and one in the southern hemisphere.
The northern accumulation region is separated into an eastern patch between California and Hawaii, and a western patch, which extends eastwards from Japan.
50 year simulation Locations of the five subtropical garbage patches.(van der Mheen et al. (2019))
Our ocean garbage shame
First discovered by Captain Charles Moore in the early 2000s, the eastern patch is better known as the Great Pacific Garbage Patch because it's the largest by both size (around 1.6 million square kilometres) and amount of plastic. By weight, this garbage patch can hold more than 100 kilograms per square kilometre.
Discarded fishing nets make up around 45 per cent of the total plastic weight in the Great Pacific Garbage Patch. Waste from the 2011 Japan tsunami is also a major contributor, making up an estimated 20 per cent of the patch.
With time, larger plastic debris degrades into microplastics. Microplasticsform only 8 per cent of the total weight of plastic waste in the Great Pacific Garbage Patch, but make up 94 per cent of the estimated 1.8 trillion pieces of plastic there .. https://www.nationalgeographic.org/article/great-pacific-garbage-patch-isnt-what-you-think/ . In high concentrations, they can make the water "cloudy".
We must act urgently to stem the flow. This includes developing plans .. https://theoceancleanup.com/ .. to collect and remove the plastics and, vitally, stop producing so much in the first place.
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Fisheries on the verge of collapse
As the largest and deepest sea on Earth, the Pacific supports some of the world's biggest fisheries. For thousands of years, people have relied on these fisheries for their food and livelihoods.
But, around the world, including in the Pacific, fishing operations are depleting fish populations faster than they can recover. This overfishing is considered one of the most serious threats to the world's oceans.
The decline in fish populations is not just a problem for humans. Fish play an important role in marine ecosystems and are a crucial link in the ocean's complex food webs. Not plenty of fish in the sea
Let's take Indonesia as an example. Indonesia lies between the Pacific and Indian oceans and is the world's third-biggest producer .. http://www.fao.org/3/ca9229en/CA9229EN.pdf .. of wild-capture ?sh after China and Peru. Some 60 per cent of the catch is made by small-scale ?shers. Many hail from poor coastal communities.
Stocks of fish used to make sushi have declined in number. (Pexels: Valeria Boltneva)
Indonesia's experience shows how there is no easy fix to the overfishing problem.
In 2017, the Indonesian government issued a decree .. http://jdih.kkp.go.id/peraturan/50%20KEPMEN-KP%202017.pdf .. that was supposed to keep fishing to a sustainable level — 12.5 million tonnes per year. Yet, in may places, the practice continued — largely because the rules were not clear and local enforcement was inadequate.
Implementation was complicated by the fact that almost all Indonesia's smaller fishing boats come under the control of provincial governments .. http://sidatik.kkp.go.id/files/src/023dfaa957829d846cfb59164b6c5774.pdf . This reveals the need for better cooperation between levels of government in cracking down on overfishing.
What else can we do?
To prevent overfishing, governments should address the issue of poverty and poor education in small fishing communities. This may involve finding them a new source of income.
Tackling overfishing in the Pacific will also require cooperation among nations to monitor fishing practices and enforce the rules.
And the world's network of marine protected areas should be expanded and strengthened to conserve marine life. Currently, less than 3 per cent of the world's oceans are highly protected "no take" zones. In Australia, many marine reserves are small and located in areas of little value .. https://theconversation.com/australian-commercial-fish-populations-drop-by-a-third-over-ten-years-97689 .. to commercial fishers.
The collapse of fisheries .. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC39409/ .. around the world shows just how vulnerable our marine life is. It's clear that humans are exploiting the oceans beyond sustainable levels. Billions of people rely on seafood for protein and for their livelihoods. But by allowing overfishing to continue, we harm not just the oceans, but ourselves.
Providing fishers with an alternative income can help prevent overfishing. (Kim Honan)
Reefs provide jobs — such as in tourism and fishing – and places for recreation. Globally, coral reefs represent an industry worth US$11.9 trillion per year .. http://coralreefs.org/wp-content/uploads/2020/02/modified-consensus-statement-ICRS-2018.pdf . And importantly, they're a place of deep cultural and spiritual connection for Indigenous people around the world.
Ocean acidification is not the only threat to coral reefs. Under climate change, the rate of ocean warming has doubled since the 1990s .. https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/ . The Great Barrier Reef, for example, has warmed by 0.8? since the Industrial Revolution.
Cutting greenhouse gas emissions must become a global mission. COVID-19 has slowed our movements across the planet, showing it's possible to radically slash our production of CO2. If the world meets the most ambitious goals of the Paris Agreement .. https://climateactiontracker.org/methodology/paris-temperature-goal/ .. and keeps global temperature increases below 1.5?, the Pacific will experience far less severe decreases in oceanic pH.
We will, however, have to curb emissions by a lot more — 45 per cent over the next decade .. https://doi.org/10.1038/d41586-019-02737-8 — to keep global warming below 1.5?. This would give some hope that coral reefs in the Pacific, and worldwide, are not completely lost.
Clearly, the decisions we make today will affect what our oceans look like tomorrow.
Jodie L Rummer is an Associate Professor & Principal Research Fellow at James Cook University. Bridie JM Allan is a Lecturer/researcher at the University of Otago. Charitha Pattiaratchi is a Professor of Coastal Oceanography at the University of Western Australia. Ian A Bouyoucos is a Postdoctoral fellow at James Cook University. Irfan Yulianto is from IPB University. Mirjam van der Mheena is a fellow at the University of Western Australia. This article originally appeared on The Conversation .. https://theconversation.com/it-might-be-the-worlds-biggest-ocean-but-the-mighty-pacific-is-in-peril-150745 .