July 02, 2024
What is the first thing that goes through our minds when we think about oxygen production in our planet? For most people, it surely is the color green – trees, forests, the Amazon rainforest, etc. The fact is, it is the wrong color and what should cross our minds is blue. The ocean produces between 50 and 70% of the oxygen that can be found in the atmosphere [1]. Not the ocean itself, of course, but some of the microorganisms that live in it: unicellular algae and cyanobacteria. These creatures, as plants do, are able to photosynthesize.
Fig 1: Distribution map of oceanic chlorophyll. Photo from NOAA National Environmental Satellite on Wikimedia Commons.
These organisms are just a fraction of the whole biodiversity that can be found in Earth’s seawater. Most of the planet is water, it is called the “blue planet” after all. It is estimated that we only know about two-thirds of the whole marine biodiversity, which would be about 250 000 species. Ocean ecosystems and the living beings that inhabit them are incredibly relevant to sustaining Earth’s life balance [2]. This is why it’s vital to protect and conserve them [3].
With this goal, about a year ago on the 19th of July of 2023, the United Nations (UN) signed the informally known High Seas Treaty – whose official name would be Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction –, that as main priority to conserve biodiversity on high seas, spaces that are normally unprotected, as they do not belong to any countries [4].
Among the different objectives in the Kunming-Montreal declaration (COP15 from the Convention on Biological Diversity), one of them is to attain 30% of the protected ocean area by 2030 [5]. There are still 6 years left, but the current situation is quite distant from the objective: only about 8% of the seawater is protected – or “declared as such” –, as some areas do not even have a management plan. One of the main difficulties to deal with is international management, as these areas are unclaimed by countries. The High Seas Treaty, which had been under negotiations for 20 years, proposes certain tools to manage the marine protected areas (MPA) in these “no man’s waters”.
Fig. 2: Map of Marine Protected Areas. Photo from Marine Conservation Institute on Wikimedia Commons.
But what do we have to protect marine biodiversity from? The main threats are overexploitation of fishing resources, water quality decrease, oil spills, habitat fragmentation, invasive species, algal blooms, and climate change [6].
According to the UN Food and Agriculture Organization (FAO), we have gone from 90% of fish populations being in a biologically sustainable status, to 64% by 2015 [7]. This overexploitation is actually the main threat to marine biodiversity. It is urgent to reduce the exploitation of fishing resources, focusing on large-scale fisheries and bottom-trawling. We should work on promoting small-scale traditional fishing which has lower impacts, as well as reducing our consumption.
As well as terrestrial ecosystems, marine ones also experiment with habitat fragmentation. It is easier to observe it in coastal areas, as human intervention is more noticeable. However, in deep waters, the main causes of fragmentation are due to dragnets. These can destroy marine ecosystems, which usually have very complex structures, difficult to recover once perturbated. The designation of marine protected areas in international waters, now sustained by the Treaty, will offer an advantage when protecting key nesting or passing areas for sensitive species.
Marine transport is also responsible for many impacts on seawater ecosystems. Consumption is disproportionate, especially in first-world countries. As an example, in the Mediterranean basin, lies about 1/3 of the global marine transport. Transport not only fragments habitats and has direct impacts on living beings wherever it passes through, it also represents one of the main introduction paths for invasive species. Keeping the actual consumption and production–level means keeping up with this amount of marine transport, and consequently keeping up with its impacts.
Algal blooms do not sound as bad, is it not good for them to grow? More algae means more oxygen, right? Not exactly. Algae produce oxygen through the photosynthetic process, but their excess can destroy a whole ecosystem through a process known as eutrophication. If there is an excess of nutrients algae proliferate in an uncontrolled way. When this happens, they can keep the sunlight from getting to deeper zones, where the organisms will end up dead. Ironically, fertilizers can worsen the ecosystem quality to the point of destruction, as if there would have been an oil spill.
Next year (2025) in Nice (France), a UN summit will be held about oceans, in which we will hear about the treaty, its application, and how many countries will subscribe to it. We can only hope they will take it seriously, and start working on updating the existing MPAs, developing new ones, and ensuring their wellbeing.
References:
Click here to expand the references[1] Rodríguez H. (2023, 3 January). El verdadero pulmón del planeta está en los océanos. Retrieved on 18 June 2024, from https://www.nationalgeographic.com.es/naturaleza/verdadero-pulmon-planeta-esta-oceanos_14776
[2] Pasca Palmer C. La biodiversidad y los ecosistemas marinos mantienen la salud del planeta y sostienen el bienestar social. Retrieved on 19 June 2024, from https://www.un.org/es/chronicle/article/la-biodiversidad-y-los-ecosistemas-marinos-mantienen-la-salud-del-planeta-y-sostienen-el-bienestar#:~:text=Los%20oc%C3%A9anos%20son%20una%20de,especies%20marinas%20del%20mundo1
[3] World Wildlife Foundation (2023, 7 February). Necesitamos triplicar la protección de los océanos hasta 2030. Retrieved on 18 June 2024, from https://www.worldwildlife.org/descubre-wwf/historias/necesitamos-triplicar-la-proteccion-de-los-oceanos-hasta-2030
[4] European Parliament (2024, 19 March). Recommendation on the draft Council decision on the conclusion, on behalf of the European Union, of the Agreement under the United Nations Convention on the Law of the Sea on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction . Retrieved on 18 June 2024, from https://www.europarl.europa.eu/doceo/document/A-9-2024-0177_ES.html#_section1
[5] General Assembly United Nations (2023, 14 April). Proyecto de acuerdo en el marco de la Convención de las Naciones Unidas sobre el Derecho del Mar relativo a la conservación y el uso sostenible de la diversidad biológica marina de las zonas situadas fuera de jurisdicción nacional. Retrieved on 18 June 2024, from https://www.un.org/bbnj/sites/www.un.org.bbnj/files/a_conf232_2023_crp2_rev1_es.pdf
[6] Mancera-Pineda J.E., Gavio B., Lasso-Zapata J. (2013, December). Main threats to marine biodiversity in Actualidades Biológicas. Retrieved on 18 June 2024, from http://www.scielo.org.co/scielo.php?pid=S0304-35842013000200001&script=sci_arttext
[7] FAO. (2022). El estado mundial de la pesca y la acuicultura 2022: Hacia la transformación azul. Retrieved on 18 June 2024, from https://doi.org/10.4060/cc0461
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Cover and preview image: Bleached (dead) coral on the Great Barrier Reaj (2005, January). Photo from J. Roff on Wikimedia Commons.