Royal Netherlands Institute for Sea Research
Phone number
+31 (0)222 36 9389
Senior Scientist

Dr. Andi Haas

Senior Scientist

‘Coral is deteriorating due to fast food’

Biogeochemist Andreas Haas studies changes in coral reef ecosystems as a consequence of human influence. ‘The infamous bleaching of coral, due to the loss of associated symbiotic algae under warm seawater conditions is well known. That often happens in a relatively short time and yields shocking images that capture our attention. A lesser-known threat for corals comes from other algae. Macroalgae, or filamentous turf algae, can emerge if there is an excess of nutrients in the water - for example from wastewater, or when the ecosystem is disrupted due to overfishing or pollution.’

Quick snack

‘A coral reef system is a complex community comprising a multitude of organisms that coexist in a delicate and co-dependent balance. For instance, when algae increase, then the bacteria seize their chance too. Most algae release sugars that provide a tasty and readily available food source for them. Subsequently, the entire balance shifts and ultimately, algae and other non-calcifying organisms like sponges emerge that can even decompose the calcium carbonate of the corals. We see this effect occurring throughout the world and mainly at locations that are exposed to much human influence. In a comparative study of coral reefs across the pacific, including some exposed to significant human influence, and some of the most pristine reefs on this planet (e.g., Millennium Atoll, 3000 kilometres south of Hawai’i), we could see clear evidence of this fast-food effect.’


‘In my research, I am primarily trying to understand exactly how the balance between algae, corals and bacteria works. Currently we are quantifying tens of thousands of different organic molecules in seawater. That will hopefully provide starting points to tackle the underlying chemical causes of this problem. In addition, we are examining how the negative effects of people on coral can possibly be reduced. For example, it seems the corals experience less damage from harmful algae if the water around a reef is refreshed more often. We can take something like that into account during the design of new waterfronts and harbours. Ultimately we need to understand the biogeochemical mechanisms of coral reefs in detail to save the immense biodiversity and ecosystem services that coral reefs provide.’

Read more +

Linked news

Tuesday 13 February 2024
Warming ocean turns coral environment upside down
Coral that is exposed to higher temperatures, releases more and different organic mater into the seawater. In doing so, the coral feeds unwanted bacteria as well. This is shown by research of marine biologist Milou Arts of NIOZ. Together with…
Monday 26 September 2022
NWO grant for research on the corals across the Caribbean Islands
NIOZ scientist Andi Haas received a NWO-Open Competition Domain Science-M grant for his research on the corals across the Caribbean Islands. In an unprecedented effort over almost half a century Dutch researchers documented the dramatic decline of…
Friday 04 February 2022
“Taste” and “smell” of coral reefs provide insights into dynamic marine ecosystems
Coral reefs are hotspots of biodiversity and are amazingly productive with a vast number of organisms interacting simultaneously. Hundreds of molecules that are made by important members of the coral reef community were recently discovered by a team…
Thursday 07 January 2021
€ 3,5 million awarded for Dutch Caribbean coral reef research
We know that coral reefs worldwide are in decline; remarkably little is known about how exactly this happens. That is why a major multidisciplinary research project will start in the coming years within the NWO's Caribbean Research programme under…
Wednesday 24 June 2020
Microbes decisive in battle between coral and turf algae
Corals worldwide are threatened due to climate change and local stressors. The front line of the battle, however, is microscopic in scale. In the competition between coral and turf algae, microbes can be decisive in the outcome.
Tuesday 03 December 2019
Onderzoekers verkennen diepste en grootste onderwater-zinkgaten ter wereld
Van 5 tot 20 december organiseren het Koninklijk Nederlands Instituut voor Onderzoek der Zee (NIOZ) en Wageningen Marine Research een expeditie naar de Sababank, vlakbij het Nederlandse eiland Saba in het Caribisch gebied. Experts hopen aan boord van…
Friday 23 August 2019
Caribbean coral reefs, between resilience and warmer climates
A group of scientists from NIOZ, MARUM and ZMT are heading to Curacao to gather data on the modern and fossil reefs surrounding the island. Their expedition will last from August 23rd until September 3rd, and they will use state-of-the-art approaches…
Friday 12 April 2019
Pristine coral reefs show remarkable differences in microorganisms depending on the time of day
Nature communication published a study today which captures for the first time the high variability between day and night in microbes living on pristine coral reefs. The here described dramatic changes have never been witnessed before as these reefs…

Linked blogs

Wednesday 04 December 2019
NIOZ@SEA | Sinkhole expedition to the Sababank
From 5 to 18 December, NIOZ and Wageningen Marine Research (WMR) are organizing an expedition to the Saba Bank, near the Dutch island of Saba in the Caribbean. Experts on board the research vessel Pelagia hope to gain more knowledge about the…
Friday 23 August 2019
NIOZ@SEA | Curacao mapping
A group of scientists from NIOZ, MARUM and ZMT are heading to Curacao to gather data on the modern and fossil reefs surrounding the island. Their expedition will last from August 23rd until September 3rd, and they will use state-of-the-art approaches…

NIOZ publications

  • 2023
    Baer, J.L.; Carilli, J.; Chadwick, B.; Hatay, M.; van der Geer, A.; Scholten, Y.; Barnes, W.; Aquino, J.; Ballard, A.; Little, M.; Brzenski, J.; Liu, X.; Rosen, G.; Wang, P.-F.; Castillo, J.; Haas, A.F.; Hartmann, A.C.; Rohwer, F. (2023). Coral reef arks: An In Situ mesocosm and toolkit for assembling reef communities. Jove-Journal of Visualized Experiments 191: e64778.
    Candy, A.S.; Taylor Parkins, S.K.; van Duyl, F.C.; Mueller, B.; Arts, M.G.I.; Barnes, W.; Carstensen, M.; Scholten, Y.; El-Khaled, Y.C.; Wild, C.; Wegley Kelly, L.; Nelson, C.E.; Sandin, S.A.; Vermeij, M.J.A.; Rohwer, F.; Picioreanu, C.; Stocchi, P.; Haas, A.F. (2023). Small-scale oxygen distribution patterns in a coral reef. Front. Mar. Sci. 10.
    Quinlan, Z.A.; Bennett, M.-J.; Arts, M.G.I.; Levenstein, M.A.; Flores, D.; Tholen, H.M.; Tichy, L.; Juarez, G.; Haas, A.F.; Chamberland, V.F.; Latijnhouwers, K.R.W.; Vermeij, M.J.A.; Johnson, A.W.; Marhaver, K.L.; Kelly, L.W. (2023). Coral larval settlement induction using tissue-associated and exuded coralline algae metabolites and the identification of putative chemical cues. Proc. - Royal Soc., Biol. Sci. 290(2009).
  • 2022
    Humphreys, M.P.; Meesters, E.H.; de Haas, H.; Karancz, S.; Delaigue, L.; Bakker, K.; Duineveld, G.; de Goeyse, S.; Haas, A.F.; Mienis, F.; Ossebaar, S.; van Duyl, F.C. (2022). Dissolution of a submarine carbonate platform by a submerged lake of acidic seawater. Biogeosciences 19(2): 347-358.
    Leliaert, F.; Kelly, E.L.A.; Janouskovec, J.; Fox, M.D.; Johnson, M.D.; Redfern, F.M.; Eria, T.; Haas, A.F.; Sala, E.; Sandin, S.A.; Smith, J.E. (2022). Brilliantia kiribatiensis, a new genus and species of Cladophorales (Chlorophyta) from the remote coral reefs of the Southern Line Islands, Pacific Ocean. J. Phycol. 58(2): 183-197.
    Nelson, C.E.; Wegley Kelly, L.; Haas, A.F. (2023). Microbial interactions with dissolved organic matter are central to coral reef ecosystem function and resilience. Ann. Rev. Mar. Sci. 15: 431-460.
    Wegley Kelly, L.; Nelson, C.E.; Petras, D.; Koester, I.; Quinlan, Z.A.; Arts, M.G.I.; Nothias, L.-F.; Comstock, J.; White, B.M.; Hopmans, E.C.; van Duyl, F.C.; Carlson, C.A.; Aluwihare, L.I.; Dorrestein, P.C.; Haas, A.F. (2022). Distinguishing the molecular diversity, nutrient content, and energetic potential of exometabolomes produced by macroalgae and reef-building corals  . Proc. Natl. Acad. Sci. U.S.A. 119(5): e2110283119.
  • 2021
    Bale, N.J.; Ding, S.; Hopmans, E.C.; Arts, M.G.I.; Villanueva, L.; Boschman, C.; Haas, A.F.; Schouten, S.; Sinninghe Damsté, J.S (2021). Lipidomics of environmental microbial communities. I: visualization of component distributions using untargeted analysis of high-resolution mass spectrometry data. Front. Microbiol. 12.
    George, E.; Mullinix, J.A.; Meng, F.; Bailey, B.A.; Edwards, C.; Felts, B.; Haas, A.F.; Hartmann, A.C.; Mueller, B.; Roach, T.N.F.; Salamon, P.; Silveira, C.B.; Vermeij, M.J.A.; Rohwer, F.; Luque, A. (2021). Space-filling and benthic competition on coral reefs. PeerJ 9: e11213.
    Little, M.; George, E.E.; Arts, M.G. I.; Shivak, J.; Benler, S.; Huckeba, J.; Quinlan, Z.A.; Boscaro, V.; Mueller, B.; Güemes, A.G.C.; Rojas, M.I.; White, B.; Petras, D.; Silveira, C. B.; Haas, A.F.; Kelly, L.W.; Vermeij, M.J.A.; Quinn, R.A.; Keeling, P.J.; Dorrestein, P.C.; Rohwer, F.; Roach, T.N.F. (2021). Three-dimensional molecular cartography of the Caribbean reef-building coral Orbicella faveolata. Front. Mar. Sci. 8: 627724.
    Wegley Kelly, L.; Nelson, C.E.; Aluwihare, L.I.; Arts, M.G.I.; Dorrestein, P.C.; Koester, I.; Matsuda, S.B.; Petras, D.; Quinlan, Z.A.; Haas, A.F. (2021). Molecular commerce on coral reefs: using metabolomics to reveal biochemical exchanges underlying holobiont biology and the ecology of coastal ecosystems. Front. Mar. Sci. 8: 630799.
  • 2020
    Roach, T.N.F.; Little, M.; Arts; Huckeba; Haas, A.F.; George; Quinn, R.A.; Cobián-Güemes; Naliboff, D.S.; Silveira, C.B.; Vermeij, M.J.A.; Kelly; Dorrestein, P.C.; Rohwer, F. (2020). A multiomic analysis of in situ coral-turf algal interactions. Proc. Natl. Acad. Sci. U.S.A. 117(24): 13588-13595.
  • 2019
    Silveira, C.B.; Luque; Roach, T.N.F.; Villela; Barno; Green; Reyes; Rubio-Portillo; Le; Mead; Hatay, M.; Vermeij, M.J.A.; Takeshita, Y.; Haas, A.; Bailey; Rohwer, F. (2019). Biophysical and physiological processes causing oxygen loss from coral reefs. eLIFE 8: e49114.
    Wegley Kelly, L.; Nelson, C.E.; Haas, A.F.; Naliboff, D.S.; Calhoun, S.; Carlson, C.A.; Edwards; Fox, M.G.; Hatay, M.; Johnson, M.D.; Kelly, E.L.A.; Lim, Y.W.; Macherla, S.; Quinlan, Z.A.; Silva, G.G.Z.; Vermeij, M.J.A.; Zgliczynski, B.; Sandin, S.A.; Smith; Rohwer (2019). Diel population and functional synchrony of microbial communities on coral reefs. Nature Comm. 10(1): 1691.
  • 2018
    Freeman, S.E.; Freeman, L.A.; Giorli, G.; Haas, A.F. (2018). Photosynthesis by marine algae produces sound, contributing to the daytime soundscape on coral reefs. PLoS One 13(10): e0201766.
    Nakajima, R.; Haas, A.F.; Silveira, C.B.; Kelly, E.L.A.; Smith, J.E.; Sandin, S.; Kelly, L.W.; Rohwer, F.; Nakatomi, N.; Kurihara, H. (2018). Release of dissolved and particulate organic matter by the soft coral Lobophytum and subsequent microbial degradation. J. Exp. Mar. Biol. Ecol. 504: 53-60.
    Roach, T.N.F.; Salamon, P.; Nulton, J.; Andresen, B.; Felts, B.; Haas, A.; Calhoun, S.; Robinett, N.; Rohwer, F. (2018). Application of finite-time and control thermodynamics to biological processes at multiple scales. Journal of Non-Equilibrium Thermodynamics 43(3): 193-210.
    Wegley Kelly, L.; Haas, A.F.; Nelson, C.E. (2018). Ecosystem microbiology of coral reefs: linking genomic, metabolomic, and biogeochemical dynamics from animal symbioses to reefscape processes. mSystems 3(2): e00162-17.
  • 2017
    Petras, D.; Koester, I.; Da Silva, R.; Stephens, B.M.; Haas, A.F.; Nelson, C.E.; Kelly, L.W.; Aluwihare, L.I.; Dorrestein, P.C. (2017). High-Resolution Liquid Chromatography Tandem Mass Spectrometry Enables Large Scale Molecular Characterization of Dissolved Organic Matter. Front. Mar. Sci. 4: 405.

Linked projects

Andi Haas
Project duration
1 Jun 2010 - 31 Dec 2030
UUNIOZ_Turning the tide
Andi Haas
Utrecht University
Project duration
1 Jan 2021 - 31 Dec 2025