Royal Netherlands Institute for Sea Research
Phone number
+31 (0)222 36 9482
Research Leader
  • Microbial community assembly and function
  • Microbes as sentinels of environmental change
  • Biodiversity and biogeography across domains of life
  • Microbiomes and emerging environmental HABS and pathogens
  • Algal DNA and lipid biomarkers in aquatic environments

Current project(s)


Prof. Dr. Linda Amaral - Zettler

Research Leader

Living on a plastic planet

Marine microbiologist professor Linda Amaral-Zettler is fascinated by plastic, or rather: by the life that attaches to plastic. ‘Plastic probably has a far larger influence on our life than we think. An increasing amount of plastic waste is floating in the seas and ocean. You can see that when you walk along the high-water mark. If you examine such a piece of plastic from the beach carefully, then you can sometimes see that it is entirely covered by a layer of bacteria, algae and other living organisms. They have mainly seen an opportunity in that plastic; a surface to attach to. Just like the thin layer of life on the outside of the earth, which is called the biosphere, I see the layer of life on a piece of plastic as the plastisphere.’

Deserts in the ocean

‘The waste in the ocean is sometimes referred to as the “plastic soup”. It collects in large rotating swirls that are hundreds of kilometres in diameter. That soup is certainly not a thick, substantial soup, let alone a carpet of waste. However, our oceans definitely contain an awful lot of plastic! The ocean water at those locations is very poor in nutrients, and not much life is found there either. These locations are effectively deserts in the oceans. And so it is even more interesting that bacteria and algae inhabit the plastic. What attracts them to settle there? Together with my colleagues and students, I am trying to discover what the interaction is between plastic and microorganisms.’

Plastic transport

‘It could also be the case that the bacteria use plastic as a sort of raw material, although I do not believe they actually eat the intact polymer very efficiently. Microbes are not a solution for the plastic problem either. At the same time, those plastic objects might be a means of transport for microorganisms. There are indications that harmful algae, such as dinoflagellates or cyanobacteria, can be transported over thousands of kilometres on pieces of plastic. They could then reach locations that they would otherwise not have reached that easily. Also, bacteria that cause illnesses in aquaculture or on coral reefs, such as various vibrios, seem to be able to move via plastic. If this is true, then the plastisphere could have a far greater influence on marine life than we currently think.’

Read more +

 Diatoms are important colonizers of plastic in aquatic systems.

Microbial community assembly and function

Basic ecological questions that drive this research include: (1) How do diversity and function vary between natural and human impacted environments? (2) How are the bacterial, archaeal and eukaryotic communities linked to each other and to what extent do they interact at the gene level? (3) What role does history (order of species arrival) play in community assembly? This is a cross-cutting theme of my research that I have been pursuing in a variety of projects and site-based science locations including pH/heavy-metal extreme environments, the rapidly-warming waters off the western Antarctic Peninsula, microbial communities on plastic marine debris from around the world (what I have termed the "Plastisphere"), fish microbiomes, and anaerobic phototrophic microcosms derived from freshwater and marine environments. While much of this work has targeted "sun-lit" waters due to accessibility, much of my work in Spain's Rio Tinto and elsewhere has been with heterotrophs and chemoautotrophs, and I am equally fascinated with the dark ocean and applying some of these questions to this under-sampled marine biome.

Automated phytoplankton samplers allow for sampling during bloom events.

Microbes as sentinels of environmental change

This theme explores natural and anthropogenic changes and their impact on microbial biodiversity. Projects include the impact of flooding and sewage overflow due to storms, as well as other factors such as thermal pollution and temperature increases on microbial communities in rivers, lakes, and coastal waters. Another project is examining the connection between harmful algal bloom dynamics and bacterial diversity and succession patterns in coastal waters. Very fine scale sampling at different points along the bloom period using automated samplers, in combination with machine-learning algorithms is helping us determine whether microbial community diversity and structure pre-bloom can be modeled to help predict bloom onset or termination. Harmful algal blooms are an increasing problem worldwide and threaten marine food resources. In addition to the automated plankton samplers used in this study, I have also worked with instrument manufacturers to develop technology to allow fine scale in situ measurements within microbial biofilms.Holopelagic Sargassum is now a common feature of Caribbean coastlines including those of the Netherlands Antilles.

Biodiversity and biogeography across the three domains of microbial life

This research has been on-going in my laboratory since my postdoctoral studies of pH extreme environments and has continued in a variety of site-based locations including coral reefs on the tropical island of Moorea in French Polynesia, local estuaries, globally-distributed open ocean sites, and the biotic and abiotic surfaces of macroalgae and microplastics in the sea. I employ both marker gene surveys and metagenomic assessments of microbial diversity using next-generation sequencing methodologies with an eye towards understanding larger scale biogeographic patterns and the mechanisms behind them. A recent addition to my biodiversity studies has been holopelagic species of the brown alga Sargassum and its associated communities. My lab is developing population genomic markers with which to study recent strandings of these floating ecosystems in the Caribbean and most recently Brazil.

Fish microbiomes are powerful tools for studying emerging pathogens.

Microbiomes and emerging environmental HABs and pathogens

The fish model system is a promising one because fish depend heavily on their microbial-influenced innate immune system and readily lend themselves to experimental microcosms involving pathogens. My lab is studying how pathogens emerge in nature using Vibrio and Legionella as a model systems. We are employing genomics in combination with transcriptomics of Vibrio that colonize plastic and other substrates in the marine environment. Vibrio's ability to rapidly colonize the surface of plastic and be transported large distance in the ocean make it a good model for understanding its role as an emerging pathogen in aquaculture.

Haptophytes are rich in lipids used as paleotemperature proxies.

Algal DNA and lipid biomarkers in aquatic environments

This research theme connects my research interests and those of my organic geochemistry colleagues at NIOZ-Texel and Brown University in the US. We have been comparing laboratory paleotemperature proxies with in situ measurements and are developing new proxies for application to lacustrine and estuarine paleothermometry for quantifying climate history. As part of this research focus, my laboratory has contributed to documenting the diversity of alkenone-producing haptophytes at lacustrine sites across the world, performing laboratory manipulations to identify the environmental controls for production of certain classes of alkenones, and most recently, exploring biosynthetic pathways of alkenone production. The study of alkenone metabolic pathways is an area of on-going interest in my laboratory.

Linked news

Tuesday 09 April 2024
Prestigious European grant for research into biodegradable plastics
Professor dr. Linda Amaral-Zettler, Research Leader at NIOZ Royal Netherlands Institute of Sea Research and the Chair in Marine Microbiology at the University of Amsterdam has been awarded a prestigious Advanced ERC-grant by the European Commission…
Monday 12 June 2023
'Perfect storm'; Sargassum blooms and marine plastic bring potentially unhealthy bacteria to the beach
A huge mass of seaweed filled with plastic and bacteria could have unhealthy effects on the coasts of Florida and the Caribbean. This is what research in Linda Amaral-Zettler's group recently published alongside colleagues in the United States. Some…
Monday 28 November 2022
NWO grant for research project to understand Sargassum inundations in the Caribbean
Climate change or Natural Range Expansion? As of 2011, the Caribbean Sea regularly suffers from washed-up masses of seaweed, called Sargassum, that rot if left to accumulate on beaches and in harbors. As part of an international call, a Dutch-led…
Tuesday 07 June 2022
World Ocean Day 8th June 2022 | Thank you sea, and five challenges
June 8th is World Oceans Day: declared 30 years ago by the United Nations to draw attention to the importance of healthy oceans for a habitable planet Earth. In this short video from the Royal Netherlands Institute for Sea Research (NIOZ), we present…
Tuesday 08 February 2022
‘Missing’ plastics uncovered deep in the ocean
About 51 trillion microplastics are floating in the surface waters of oceans around the world. Many more particles are missing as they were not to be found at the surface or at the bottom of the ocean. New research has found that some of these…
Monday 04 October 2021
The colonization of the Azores began 700 years prior to Portuguese arrival
The human occupation of the Azores Islands in the Atlantic Ocean began 700 years earlier than the onset of Portuguese settlement of the island, which as historical documents indicate, was in the 14th century. This is the main conclusion of new…
Monday 02 March 2020
UU-NIOZ-Leiden consortium receives Nanoplastics NWO ENW Groot award
A multidisciplinary research team will investigate the origin, structure and fate of nanoplastics in aquatic environments. Prof. dr. Linda Amaral-Zettler from NIOZ/UvA will lead one of the five workpackages for this NWO ENW Groot project with Prof.…
Tuesday 26 November 2019
Trouble on the High Seas: From Microplastics to Macroalgae
On 29 November 2019 at 16.00, Prof. dr. Linda A. Amaral Zettler, Special Chair Marine Microbiology at the Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam will hold her inaugural speech "Trouble on the High Seas: From…
Tuesday 13 August 2019
NIOZ Pelagia cruise: In search of Sargassum
A multidisciplinary team of scientists aboard NIOZ flagship RV Pelagia sailed from July 11th till August 11th the Northern Atlantic Ocean to study Sargassum; an open-ocean brown macroalga that started forming unprecendented accumulations and…
Monday 25 February 2019
Linda Amaral-Zettler benoemd tot bijzonder hoogleraar Marine Microbiology aan de UvA
Mw. dr L.A. Amaral-Zettler is benoemd tot bijzonder hoogleraar Marine Microbiology aan de Faculteit der Natuurwetenschappen, Wiskunde en Informatica van de Universiteit van Amsterdam (UvA). De leerstoel is ingesteld door NIOZ Koninklijk Nederlands…

Linked blogs

Monday 17 June 2024
NIOZ@Sea: The Weeds of Change expedition
The brown macroalgal genus Sargassum, the namesake of the Sargasso Sea, is an essential habitat and refuge for many organisms including endemic species. Historically, this so-called 'golden rainforest of the Atlantic Ocean' was constrained to the…
Tuesday 13 August 2019
NIOZ@SEA | RV Pelagia Sargassum Cruise PE-455
The holopelagic species of Sargassum (i.e. S. natans and S. fluitans), which are normally associated with the Sargasso Sea, have begun forming unprecedented accumulations and subsequent strandings on the western coast of Africa, northern Brazil, and…
Thursday 24 January 2019
NIOZ@SEA | South Atlantic Subtropical Gyre Plastics Cruise
Microplastics (MP) are an emerging threat to the global environment. The Southern Ocean around Antarctica is considered an exception because it is thought to be less impacted by anthropogenic activities due to currents acting as effective barriers…
Monday 06 August 2018
Blog NIOZ@Sea | Microplastics Transit Cruise
RV Pelagia cruise 64PE442 takes advantage of a transit leg from Praia de Vitória, Terceira Island in the Azores to Catania on the Island of Sicily to collect samples of plastic marine debris, phytoplankton, and other particles and to compare…

NIOZ publications