Thriving reef system discovered in the most unlikely of places: the dirty mouth of the Amazon river

Reef system with 10,000 km2 found at the Amazon River mouth

Researchers mapped a reef system in the most unlikely area of the Brazilian coast; River plume affects sunlight, pH, temperature and salinity; chemosynthesizing microorganisms support the ecosystem — oil and gas companies operate close to the reefs

mouth-of-amazon

From the UNIVERSITY OF SAO PAULO SCIENTIFIC OUTREACH UNIT and the “soon to be complaining we must save the reef” department:

The changes that the Amazon River promotes in the tropical North Atlantic ocean water make an unfavorable environment for reef development. Every second, 175 million liters of water mixed with sediments are brought to the ocean. The result is low sunlight penetration, variability in nutrient concentration, salinity and pH, extensive moody bottoms and significant changes in temperature and oxygenation levels towards the bottom – conditions not associated with reefs. The plume generated by the Amazon River has 1.3 million km2 and flows mostly to the North, reaching areas as far as the Caribbean Sea.

Against all the odds, 39 scientists from nine Brazilian and one North-American universities mobilized two expeditions to the mouth of the river in other to map the bottom of the ocean in the outer shelf. Two previous studies – from the 1970s and 1980s – reported the findings of single samples of carbonatic structures. None suggested the existence of a reef system underneath the river plume. Surprisingly, the researchers found reefs in a complex as extensive as 1,000 km, in depths from 10 to 120 meters, with rhodolith beds, live calcareous algae, sponges, corals and hydrocorals colonies formed from 13,000 years ago till the present. The system is an habitat for 73 species of fishes and six species of lobsters.

The article in which the novelty is described was published in Science Advances, on April 22. (An extensive reef system at the Amazon River mouth). It includes results from geophysical and physical-chemical surveys, radiocarbon dating and petrographic characterization of reef samples, biogeochemical tracers and microbial metagenomics.

OIL DRILLING

The Amazon reefs are already considered at risk despite being a recent discovery. In 2013, auctions defined the oil companies responsible for 80 exploratory blocks at the same area of the study – 20 are in current production. Whether the companies knew about the reefs, they didn’t publish the information broadly, according to the senior author Fabiano L. Thompson, from the Federal University of Rio de Janeiro (UFRJ). He classifies this large-scale industrial activity as a major environmental challenge that can threaten the existence of the reef system. Researchers ask for a more complete social-ecological assessment of the system before “impacts become extensive and conflicts among the stakeholders escalate”.

LOCATION

The reefs are located as a continuity of Manuel Luiz reefs, in the Maranhão state (Northeast Region of Brazil), forming an unique carbonate system that pass in front of Para and Amapa states (North of Brazil), and reach French Guiana. It fills a major gap thought to exist in Western Atlantic reefs, occupying 10,000 km2. Some structures have lengths of up to 300 meters and heights of up to 30 meters.

“It is a paradigm shift in Geology, Ecology and Biology. In Paleogeology, we have to review ancient areas where we assumed there could not be a river mouth because of fossil reefs. These two elements cannot be considered excluding anymore”, Michel Mahiques, geologist and professor at the Oceanographic Institute at University of São Paulo (IO-USP) says. He lead the team responsible for mapping the bottom topography.

The maps were processed from data generated from two side scan sonars. The sonars emit acoustic signals to the left and to the right side towards the bottom. The intensity of the echo and the time it takes to reach the sonar indicate the distance to the bottom, its topography and whether it comes back from hitting a smooth or a hard structure. Eduardo Siegle and Rodolfo J. S. Dias, professor and master student from IO-USP, also participated on mapping and characterization of the bottom.

NORTHERN, CENTRAL AND SOUTHERN SECTORS

Three sectors were differentiated by the height of the plume layer (higher in the Northern sector); the characteristics of rhodolith beds and carbonate structure (larger rhodolith beds in the Northern sector, rhodoliths more populated by live algae in the Southern sector, carbonate mineralization by rhodoliths in the Central sector, carbonate mineralization by rhodoliths and corals in the Southern sector); the variety of coral species (more species in the Southern sector); the date of the sampled formations (from 13,000 years in the Northern sector to 4,500 years in the Central sector and 150 years in the Southern sector); the reefs’ topography (ridge-like structures in the Southern sector); and the presence of mud (abundant in the Northern sector, almost absent on the benthic casts of the Central and Southern sectors), among other characteristics.

DIFFERENTIAL: CHEMOSYNTHESIS

The Amazon reefs defy the traditional knowledge about the ecological balance of a reef environment. Reefs are usually found in warm see water with constant salinity, high light penetration level and generation of oxygen and biomass by photosynthesizers. The system at the Amazon river mouth lives under a plume layer thanks to chemosynthesizing microorganisms capable of transforming nitrates and other minerals into compounds that can be used as food by the benthic organisms.

The chemosynthesizers support a relatively complex ecosystem in low light levels and anoxic or suboxic conditions in the Northern and Central sectors. Some sponges can also tolerate these conditions for several days and have broader tolerance to acidification and temperature anomalies than corals and coralline algae. Authors indicate that molecular and genetic analysis will likely identify new microorganisms or sponges species in this reef system.

CLIMATE CHANGES

Coral reefs are in rapid decline and register biodiversity losses due to pollution, overfishing, temperature anomalies and ocean acidification. The Amazon system, though, has survived for thousand years now under severe conditions that can be compared to climate change predicted scenarios. It may give important insights on coral reefs’ trajectories in the next decades. The sponge dominance in the Central sector of the Amazon reefs, for example, points towards a phase-shift from coral domination to sponge domination in coral reefs.

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70 thoughts on “Thriving reef system discovered in the most unlikely of places: the dirty mouth of the Amazon river

  1. Quotation mark misplaced ?
    From the UNIVERSITY OF SAO PAULO SCIENTIFIC OUTREACH UNIT and the” soon to be complaining we must save the reef” department:

    • Anybody who writes AN H…abitat, isN goiN toN geN a diN froN meN.
      G
      Never once have I ever heard ANY person say ” Abitat ” , and that means in all of the 57 languages.
      Prertentious snobs !

      • I would have thought that the outflow of a major river like the Amazon, is a very important source of the mineral content of the adjacent ocean. Like maybe IT supplies the iron, that leads to plankton growth.
        G

      • At the risk of being labeled a grammar denier, “an habitat” is actually grammatically correct. An is used for words staring with vowels and “h”.
        If you want to hear it pronounced “abitat” just go to Quebec and ask a local to pronounce it in English.
        Cheers,
        {:}>D

      • A reef is a bar of rock, sand, coral or similar material [and other organisms, i.e. red algae, bryozoans, bivalves], lying beneath the surface of water — wiki
        Scleractinian coral reefs are the major organic reef builders for the past 30 million years and is often what is being colloquially referred to as ‘reefs’ today. The first sentence of their Discussion section sums it up: “Despite the iconic depiction of reefs as megadiverse systems thriving in warm, shallow, and oligotrophic waters, biogenic reefs develop under a much wider range of conditions.”
        It would be surprising to find a scleractinian coral reef in the dirty mouth of a river because they require relatively sediment-free water in high energy conditions, however, two reef complexes they describe were mainly comprised of red algae. The third reef complex (southern most) consisted of corals, but they also mention that there was no mud in the cores at this location. That means that despite being near the mouth of the Amazon, the coral reefs are still in clean, high-energy water, and not surprising at all.

      • English isn’t everyone’s first language, and this item is from Brazil. Let’s stick to what’s important?

      • @Doug in Calgary
        Does that mean you use “an hand” and live in “an house”? As far as I know, “an” is only used with words starting with “h” only when the “h” isn’t pronounced, like “an honor.”

      • I don’t speak Quebequistani, so If I went there (why) , I wouldn’t even be able to ask where the Loo is, so they would think I was nutz if suddenly out of the blue, I blurted out in Dr. Richard Lederer’s standard as she is spoke common English: “WANhy tANhe ANhell do you say “ANhabitat” instead of saying ” a livable place?? ”
        I think I said prertentious snobs up tANhere.
        I meant pretentious snobs up tANhere.
        I still mean pretentious snobs.
        G
        ” A haitch, a hay, a couple of hars, a hi a hess a ho and a nen; ANharrison; tANhat’s me ! “

      • Waytogo KatANerine !
        ANowcum, you use common sense ??
        As for ….. Ze French wood ‘ave an ‘abitat. ….. I think it should be ….. Ye French wood ‘ave an abitat. …..
        At least in Geneva, their typewriter keyboards are QWERTZ keyboards, instead of QWERTY. So it’s Ye FrencAN wANo ANave tANeir EnglisAN all screwed up !
        G

    • Refer them to ENCORE. http://www.whoi.edu/cms/files/Koop_2001_Marine-Pollution-Bulletin_42485.pdf
      A well buried study where nutrients were fed into coral communities at a rate way in excess of run-offs from farming or communities. They had to go ballistic to even recorded an effect. Despite this study they are still hammering farmers in Australia. Guess who was part of the study, Bolt’s old mate and Attenborough’s new found friend Professor Ove Hoegh-Guldberg.
      Funny how a google search tends to find interpretations of the data, not the actual experimental results.

  2. It may give important insights on coral reefs’ trajectories in the next decades. The sponge dominance in the Central sector of the Amazon reefs, for example, points towards a phase-shift from coral domination to sponge domination in coral reefs.

    So, they didn’t expect to find a reef system because of the sediments, low sunlight, and differing salinity and pH. Then they find one and conclude that this anomalous reef may be indicative of the trajectory of all reefs? Ridiculous.
    Perhaps sponges simply do better in those conditions than corals.

    • So what about the corals that grow at such great depths that there isn’t much sunlight even though the water is clear.
      Corals ain’t exactly as active as a Cheetah family might be. I doubt that they are energy hogs.
      G

  3. Progress is being held back, not by what we don’t know, but what we know that just ain’t so.
    The findings in the Bikini atoll and the long existence of coral should have been clues that they are resilient and can tolerate a wide range of environmental variability.

  4. there’s so much wrong with this…they found living things, filter feeders, growing on rocks and in mud, and claim they are the first to discover a reef….where people in the area have been collecting tropical fish, from that exact same reef, for over a hundred years

  5. ” pollution, overfishing, temperature anomalies and ocean acidification”
    Would that be the ocean acidification that everyone talks about, but nobody can find?

    • ..I think they are having “Acid Flashbacks” from their 1960’s experimentations ! LOL

    • The very same ocean acidiification that pushes real action to be taken on the invasion of aggressive dragon fish. Dragon fish have destroyed all other fish populations including those that eat starfish.
      With no predators, starfish multiply and eat corals.
      Some Climate change hacks now claim starfish boom is from agricultural run-off and still ignore dragon fish invasions.
      This equates with those who claimed the neural tube defects on US/Mexico border were from industrial waste …while ignoring CDC proof they were from lack of folic acid….so nobody did anything about real cause until much later. It does not fit the propaganda agenda and the destruction does not matter to them.

  6. Sorry for the corrections but I hate to give Toneb, Simon, Wagen and the others any kind of reason to complain.. Just ask and I won’t bother…
    “The Amazon system, though, has survived for thousand years now” = “thousandS OF years now” ?

    • I’m not a grammar snob either, but it should probably be “muddy” bottoms, not “moody” and “in order to map” not “in OTHER to map”. Is “an habitat” better than “a habitat”? And did the professor say the two elements are “excluding” or “exclusive”?
      I loathe autocorrect too Anthony!

      • …Geeze Aphan, I was trying to be gentle !! LOL
        p.s. I don’t use Auto-correct, I use spellcheck, so I have a choice….

      • There was also the “Reefs are usually found in warm see water with constant salinity, high light penetration level and generation of oxygen and biomass by photosynthesizers.”

  7. The obligatory funding justification:
    The Amazon system, though, has survived for thousand years now under severe conditions that can be compared to climate change predicted scenarios
    Why didn’t they say: “Wow. Amazing! Coral reefs are really resilient”.

    • “Why didn’t they say: “Wow. Amazing! Coral reefs are really resilient”.
      Perhaps because these aren’t coral reefs. They are sponge and algal reefs. There are lots of non-coral biogenic reefs, there are even cyanobacterial reefs.
      There have been great variations in what type of reef has been most common at different times. At the moment scleractinian coral reefs are dominant. Interestingly this may be a very recent phenomenon. Almost no coral reef anywhere seems to be older than c. 700,000 years. It seems that the current “long” (100,000 years) ice-ages suit corals much better than the previous short (41,000 year) ones did.

  8. .. “In 2013, auctions defined the oil companies responsible for 80 exploratory blocks at the same area of the study – 20 are in current production. Whether the companies knew about the reefs, they didn’t publish the information broadly,” ???
    If these scientists just found them with high tech sonar, why would they think an oil company would find them by simply drilling ? What is auction ?

    • In the US, the govt auctions off the right to explore/develop various sections in the Gulf for oil.
      Perhaps it is something similar.

    • Those of us in the evil oil biz have long known there are reefs in front of the Mahakam Delta in Indonesia. Just like global warming, we covered it up.

  9. Re “ocean acidification” I came across this post, here repeated in its entirety from an article in “Scientific” American (sic) that attempted to scaremonger ocean “acidification” as “the other CO2 problem”. I would also note the to me fraudulent description of “acidification” when “less alkaline” or less basic is the actual situation even if the pH decline is correct – the oceans are in no danger of becoming “acidic”.
    Many articles on the internet can be found about “ocean acidification” and how it seems to be just another scam. Here is one:
    https://arizonadailyindependent.com/2014/12/26/noaa-caught-committing-fraud-in-congressional-testimony-about-ocean-acidification/
    This post after the SA article seems to me to be right on the money and expounds pretty much basic science:
    2. insideps January 19, 2010
    This has to be about the most “unscientific” drivel I have read in years.
    FACT 1: The solubility of a gas – any gas – in a liquid – any liquid, is inversely proportional to the temperature of the liquid, (assuming more or less constant atmospheric pressure). This is one of the so-called “Gas Laws”.
    Therefore the “amount” of CO2 (regardless of source) dissolved in the ocean is DIRECTLY dependent on the TEMPERATURE of the water, and on NO other factor .
    FACT 2: If indeed the global temperatures are rising (including the oceans) – as some would have us believe, then the total amount of dissolved CO2 will – MUST – DECREASE, not INCREASE, and atmospheric levels of CO2 WILL increase.
    Conversely, if global temperatures are decreasing, as some argue, the levels of dissolved CO2 WILL increase, and levels of atmospheric CO2 WILL decrease.
    Since there would have been a vastly higher level of dissolved CO2 in the oceans during the last Ice Age than now, and since every species alive now in the oceans survived that, preposterous arguments about “man-made ocean acidification” causing damage can be seen for what they are – asinine, entirely non-scientific attempts by the clueless to jump on the AGW gravy train.

    • The concentration of a gas in a fluid depends on both the temperature of the fluid and the it’s concentration levels in the air above the fluid.

    • Chicken little. I’m tired of correcting this. Your points are just wrong.
      C(water)=H*P(air)*C(air)
      Look up “Henry’s Law”. You can do the math yourself in five minutes.
      There are two mechanisms at work, the changing Henry’s constant due to temperature and the CO2 increase due to increased concentration. The increase in concentration dominates this balance by an order of magnitude. This far from the boiling point, there just isn’t much change in solubility due to a degree’s change in temperature. However, C(air) in the equation above has doubled.
      Your reasoning is just nonsensical and at this point, willfully ignorant of basic chemistry.

      • Please explain why carbonated beverage manufacturers both lower the temperature of the liquid and increase the gas pressure as well as the concentration, to get CO2 to go into the liquid – per your explanation just an increase in CO2 concentration, which has a force an order of magnitude greater according to you, should be enough, shouldn’t it?
        Did you look at the link I provided about “ocean acidification” which shows that it really isn’t taking place now if you include the 80 years of data that was left out, and that CO2 concentration has been much higher in the past and yet marine life took it in stride?

      • Because there is a huge difference between the Henry’s constant at 40F and 70F and a miniscule difference between 70F and 71F. Also, lower temperature allows them to lower the pressure. High pressure is both expensive and likely to burst the can. Besides, low temperature preserves it.
        http://henrys-law.org/henry-3.0.pdfz
        at 25C, CO2 has a solubility of 0.34 M/atm
        at 0C, it has a solubility of 0.71 M/atm
        at 26C, it has a solubility of 0.33 M/atm
        Seriously, it ain’t hard to do math. If you’re going to argue something’s not happening, that’s perfectly fine, but arguing that it’s not possible with less than a high school level understanding of the physics involved is absurd.

  10. In New Zealand, (being next door ) describing an Austrain ( Australian) ” he is and or a conman ” With the “Great Barrier ” Reef he once again is out of his depth.

  11. As the mathematician from Jurassic Park said, life finds a way.
    On similar lines, researchers studying wildlife in the Chernobyl exclusion zone have discovered a number of animal species that have evolved to survive in the high radiation environment.
    Fish are not only surviving, but thriving in the Chernobyl cooling pond which was directly contaminated with both uranium and plutonium during the accident. An entire ecosystem of fish from small bait fist up to 5 foot Wells Catfish have evolved ways to protect themselves from radiation damage in an area so hot it could kill a human in hours.
    At least one bird species has been discovered that has likewise evolved the means to live in the exclusion zone without suffering radiation damage.
    The ecosystem is not so fragile as the eco-nuts would have us believe. Life finds a way.

    • The loonies cant figure out that corals that are either in slightly cooler waters or experience regular upwelling suffer badly during El ninos.
      3 mass bleachings since 98, how many warm El Ninos since 98?

  12. Consistent poor conditions are better for marine life than great then bad then great then band conditions.
    Life will adapt, as long as the change is slower than their ability to adapt, even corals.

    • Mark
      “Life will adapt, as long as the change is slower than their ability to adapt, even corals.”
      And that is the whole issue with AGW in a nutshell. Will life be able to adapt with the rate of warming we are experiencing? Only a fool (or fools) would dismiss the possibility that the sharp spike we are experiencing will stress a number of organisms on the planet and some will not make it.

      • Forrest Gardener
        Simon, the line that anybody who disagrees must be a fool is the basis of the fable of the Emporer’s new clothes.
        I said only a fool would dismiss the possibility. Are you saying there is no possibility?

      • Simon,
        Sure, there is a possibility, but the odds of it happening are lower than your odds of winning the lottery or getting struck by lightning.

      • Matts
        I would say the odds of some species becoming extinct because of climate change are very high. Guess we will have to wait and see.

      • “the sharp spike we are experiencing will stress a number of organisms on the planet and some will not make it.”
        They all did make it through about 50 ice-ages and nobody knows how many D-O events in the last 3 million years. And those spikes were pretty sharp too. As a matter of fact so sharp that we can’t resolve them except perhaps for the most recent ones, like Dryas 3 when temperatures rose 5 degrees in 50 years (or less).

      • “Simon May 3, 2016 at 3:04 pm
        1 Degree and rising fast”
        Strange that life seems to manage well with temperature swings between night and day of 10’s of degrees seems to manage well. But please Simon, “1 Degree and rising fast”, can you provide evidence of that?

      • Simon, 0.7C or 1F.
        As to rising fast, with the exception of the recent and now ending El Nino, there has been no increase for almost 20 years. As soon as the El Nino is over, the current spike will end as well, just as it did in 1998.
        Are you really this desperate?

      • Simon, if a few tenths of a degree is enough to drive a species into extinction, it had bigger problems to begin with.

  13. Two things in the article caught my eye: 1) the southern reef is 150 years old. What changed then? 2) the plume of the Amazon goes north into the Carribbean. Is this part of the energy causing the GS?

  14. On rare occasions where vis allows it, existence of substrate dwelling invertebrate animals in of all places muddy SF Bay is revealed. Sponges are probably no surprise however what may surprise some are the corals. SF Bay waters are significantly warmer than the open Pacific due to combination of shallow depths, very low slope and high degree of incident sunshine.

  15. Next they will tell us of their greatest discovery, all edited about tidal estuaries and the life these habitats encourage.
    Is there a prerequisite in Climatology that one must be born yesterday to “understand” the message?

  16. The Amazon system, though, has survived for thousand years now under severe conditions that can be compared to climate change predicted scenarios. It may give important insights on coral reefs’ trajectories in the next decades.

    Wow. I never recognized fully climate disruption was projected to be consistent with ocean mudification, perhaps.
    (Should you put this stuff on your hair, it may grow up to 47.83% thicker)

      • A “mud reef” isn’t a reef strictly speaking. A reef has a biogenic carbonate framework, i e it has a core of limestone that has been created, directly or indirectly, by living organisms

        • Actually, I couldn’t find any core limestone here, just organisms built on top of each other, with mud infill, able to walk amongst the invertebrates and other sea life at low tide in barefoot, on a fairly solid silty mud base, very unique. Off the Amazon mouth I would expect the same. The water at low tide is very muddy compared to other reef systems, which makes Cable Beach water colour a pale turquoise.

  17. First para, “moody bottoms” Should be muddy bottoms, though moody bottoms would probably be more fun.

      • Muddy bottoms can be moody. One mood is huge flocs floating by, another is mass vis wipe out. Worst thing is bad surge – almost nothing to hold onto and you’re just sliding along the slimy muck, with the muck getting into you reg and other places.

  18. NORTHERN, CENTRAL AND SOUTHERN SECTORS
    Three sectors were differentiated by the height of the plume layer (higher in the Northern sector); the characteristics of rhodolith beds and carbonate structure (larger rhodolith beds in the Northern sector, rhodoliths more populated by live algae in the Southern sector, carbonate mineralization by rhodoliths in the Central sector, carbonate mineralization by rhodoliths and corals in the Southern sector); the variety of coral species (more species in the Southern sector); the date of the sampled formations (from 13,000 years in the Northern sector to 4,500 years in the Central sector and 150 years in the Southern sector)
    ___________________________________________
    Yes, that dirty kitchen sink. Givit another 13.000 ys and that planet is a biological pested mess.
    Time for reglaciation.

  19. Collette, B. B. and K.Rutzler. 1977. Reef fishes over sponges off the mouth of the Amazon River. Proceedings Third International Coral Reef Symposium. Rosenstiel School of Marine and Atmospheric Sciences. From collections of the Pascagoula Based Oregon II, Cruise 58, with earlier literature cited about reef invertebrates off northern Brazil and French Guiana. A list of fish and sponge species included, bottom salinities around 36. Never underestimate the productivity of a delta.

  20. Thriving and reef are two words that are not allowed together over at the Ministry of Truth and its affiliates.

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