Doug Bonderud

Aug 12th 2020

Genetics in Microscopic Marine Life: The Plankton Potential


Plankton don’t get the credit they deserve. Despite weighing at just 1% of the world’s photosynthetic biomass, these predominantly unicellular protists account for almost 50% of photosynthetic production, making them a very big deal that comes in a very small package. Researchers tackling genetics in microscopic marine life recently unlocked a new gene editing tool that could help us better understand plankton biology and leverage their promising potential to keep oceans clean.

Photo Finish

Also called phytoplankton, from the Greek phylo (plant) and plankton (to drift or wander), these sort-of-fauna floaters play an incredibly important role in Earth’s ecosystem at large thanks to their unparalleled diversity. As noted by the NASA Earth Observatory, it’s hard to nail down a single plankton definition — some are bacteria, some are protists and many are single-celled plants. And that’s not all. Zooplankton are tiny animals that feed on phytoplankton and become food for fish and other species, while even smaller subsets — bacterioplankton and virioplankton — are also making oceanic rounds.

Mass-wise they’re not a big deal, but their sheer volume makes them valuable thanks to massive photosynthetic output; they’re one of the world’s most important producers of oxygen, according to National Geographic. They’re also critical in the carbon cycle: Plankton remove approximately 10 gigatonnes of carbon dioxide from the atmosphere each year and then transfer that carbon to sea life, lakes and deeper ocean layers.

Given their role as food for larger marine life, photosynthesis front-runners and carbon collectors, there’s no doubt that plankton play a critical role in environmental regulation — but their genetic makeup remains largely mysterious.

The Plankton Problem

Climate change is now driving zooplankton adrift, pushing them toward the poles as marine temperatures increase. According to Dr. Lukas Jonkers, however, “We think that these findings are indicative of what is happening in marine ecosystems. If you take that assumption, it means that most species have moved their distribution.” If that’s the case, it means plankton of all types are now on the move, but there’s no guarantee that they can handle the differing season lengths and light conditions that come with more northerly or southerly latitudes. Best case? Similar shifts in sea life distributions, which could have knock-on effects for the fishing industry at scale. Worst case? Shrinking species population as once-abundant plankton becomes perilously difficult to find.

The genetics of microscopic marine life also pose potential problems. As the NASA piece notes, some plankton species are biotoxic and create so-called “red blooms,” which are massive plankton growths that can kill both marine life and humans who ingest contaminated seafood. Even non-toxic blooms can cause critical conundrums when substantial amounts of plankton die simultaneously. The resulting deadfall sinks toward ocean or lake floors and is set upon by bacteria, which use available oxygen to power their process of decomposition. The issue? This depletes all available water-borne oxygen to create a “dead zone” that kills marine life.

As noted by Science Daily, new algorithms make it possible to observe and assess the impact of phytoplankton blooms across the globe using satellites to provide evolving data on water quality and potentially toxic hot spots.

Scientific Sea Change

While satellite imaging lets researchers observe the outer life of plankton populations, the complex genetics in microscopic marine life have made looking inward more challenging. According to a new study published in Nature Methods, researchers from the University of East Anglia were able to deliver and express foreign DNA in 13 species that have never before transformed. They were also able to evaluate the potential cause of non-transformation in 17 other species; in turn, laying the foundation for an expanded understanding of genomes discovered in plankton.

The sheer variety of plankton potential — from antibacterial compounds to antiviral and antifungal solutions — makes this a worthwhile endeavor. If scientists can create reliable methods to modify phytoplankton, it should be possible to reduce their toxic impact, better control their bloom cycle and even increase the photosynthetic output — all critical in the fight to keep our oceans blue and our terra firma green.

As noted by Science Magainze, the international research team used a variety of methods to modify plankton DNA. For some species, shooting tiny gold or tungsten particles covered with DNA through cell walls produced the best result. For others, jolts of electricity made cell walls “leaky” and allowed new DNA to seep through. Specific protist successes included modification of a fish-killing toxic plankton species, and one that infects both mollusks and amphibians. While these discoveries don’t present a complete understanding of the genetics in microscopic marine life, they provide a key testing protocol: By modifying genetic structure and then observing how plankton react, teams could uncover ways to boost antibiotic resistance or lower infectious impact. According to lead UK study author Thomas Mock, “These insights will improve our understanding about their role in the oceans, and they are invaluable for biotechnological applications such as building factories for biofuel or the production of bioactive compounds.”

Blue Genes, Green Benefits

Genomes discovered in plankton play a critical role in the management of marine life, the consistency of carbon and the output of oxygen worldwide. But these small-scale big hitters remain most mysterious thanks to the sheer volume and variety of species worldwide. New gene-editing efforts, however, may help unlock promising plankton potential to deliver positive environmental and economic outcomes.