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Keeping pace with climate change

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Harmful algal blooms and climate change

  • An ongoing, Mote-led study supported by a competitive grant from NOAA’s ECOHAB program is shedding new light on how Karenia brevis (Florida red tide) blooms change over time, respond to extreme events like storms that wash nutrients into the water and climate change, which may increase storm severity, and ultimately terminate (die and/or break apart)—the least understood bloom stage. Mote and partners at Bigelow Laboratory for Ocean Sciences, the Florida Fish and Wildlife Conservation Commission (FWC), New York University-Abu Dhabi, University of Maryland, and the University of South Florida are learning that:

    • Karenia brevis red tide blooms in the eastern Gulf of Mexico have four major patterns of termination, which project scientists identified by analyzing bloom data from 1998-2021. The researchers are describing these patterns in detail for an upcoming scientific publication. Understanding what drives these patterns could improve bloom prediction and monitoring.

    • The K. brevis bloom that started in December 2020 might have been strengthened later by nutrient-polluted waters from the spring 2021 Piney Point spill as well as nutrients from extensive fish kills.  Mote scientists and their University of Maryland collaborators conducted lab experiments comparing and combining water samples from the spill area in Tampa Bay with samples of the ongoing red tide bloom. Overall, the spill area has been monitored over time by FWC, Tampa Bay Estuary Program and others, while Mote scientists collected a limited set of samples in April 2021 for experimental studies. Those spill-affected water samples contained abundant micro-organisms called picocyanobacteria. When those samples were combined with the K. brevis bloom samples in various concentrations in the lab study, picocyanobacteria disappeared—one hint that the red tide bloom was able to consume picocyanobacterial cells as a nutrient source and may have strengthened in the Piney Point water.

    • K. brevis may be able to handle hotter water temperatures than scientists previously realized. While peer-reviewed scientific papers suggested Florida red tide would fare best in water temperatures of 20-28 degrees Celsius (68-82.4 degrees Fahrenheit), and some lab studies concluded the algae became stressed at 30 Celsius (86 Fahrenheit), project partners point out that some of the most severe recent blooms (2005-2006 and 2017-2019) and this year’s bad bloom lasted through summer months with temperatures exceeding those limits and reaching up to 34 Celsius (93.2 Fahrenheit). Establishing the temperature range of red tide is important for predicting the impacts of climate change on red tide.

    • Together, project partners are building improved mathematical models to help explain and predict the behavior of Florida red tide blooms and conditions that affect them, such as extreme weather events expected to increase with climate change. This means gathering better data on bloom dynamics that are little understood—for instance, when do K. brevis algae feed on other microscopic organisms, rather than just making their own food through photosynthesis powered by the sun?

 

  • Mote scientists authored a scientific review paper about red tide risks amid climate change.  Read the paper: https://www.frontiersin.org/articles/10.3389/fevo.2021.646080/full
    This paper “Florida’s Harmful Algal Bloom Problem: Escalating Risks to Human, Environmental and Economic Health With Climate Change” was published this year in the scientific journal Frontiers in Ecology and Evolution. It shares critical discoveries from Mote scientists and many others in their field, raising awareness of growing risks that multiple species of harmful algae in Florida could pose to our growing population. Mote is dedicated to informing societal decisions with sound science—including decisions about the response to harmful algal blooms that can greatly impact public health, economies, ecosystems and our quality of life.
     

  • A new report on harmful algal blooms and ocean acidification (OA) is now available, based on a national workshop with invited participants from Mote. Read the report: https://hab.whoi.edu/wp-content/uploads/2021/08/HABs_OA_2021_noaa_30908_DS1.pdf
    The report focuses on defining the research agenda for this important topic—one that Mote scientists are investigating actively already. As leaders in this field, Mote scientists were invited by NOAA to prepare a future peer-reviewed research paper on harmful algal blooms and OA, providing perspective from the U.S. southeast and helping provide perspective on the Gulf of Mexico. 

  • Mote and FWC scientists work together in the longstanding Cooperative Red Tide Program—a year-round source of reliable data on Florida red tide presence, absence, concentrations and related environmental conditions—part of a massive monitoring partnership along the Gulf of Mexico Coast that informs the public and societal leaders. The Mote-FWC Cooperative Red Tide Program is the only group regularly gathering data on K. brevis and carbonate chemistry together in the natural environment on the west coast of Florida. Carbonate chemistry is important for studying climate change—increased temperature and ocean acidification from excess carbon dioxide in the atmosphere—impacts on marine species, including harmful algae. Their efforts include regular Cooperative surveys and NOAA’s Atlantic Oceanographic and Meteorological Laboratory cruises with funding from Mote-FWC Cooperative and the Southeast Coastal Ocean Observing Regional Association. 

    • Key questions in this effort include: How will acidification affect Karenia itself, and how might Karenia blooms affect regional or local carbonate chemistry?
      In general, the Cooperative Program’s data collected so far drive home that acidification isn’t just global—it can vary locally with coastal conditions. The team has observed seasonal differences in carbonate chemistry in surveyed areas, and differences between surveyed estuaries along Florida’s Gulf Coast.

Corals and climate change

This year, Mote research revealed that:

  • Some staghorn corals are genetically hardwired to tolerate climate change impacts (increased temperature and ocean acidification) better than others, and they can likely pass this advantage to their babies, according to a Mote-led study published this year in Proceedings of the Royal Society B. These climate-resilient, native coral genotypes (genetic varieties) are being grown in Mote’s coral nurseries and are valuable for helping reef restoration succeed in our changing climate. Mote scientists exposed the corals to increased temperatures, increased carbon dioxide (the driver of ocean acidification), both stressors together, or seawater with neither stressor, and they collected data to check for changes in 12 traits of coral physiology. As a group, the corals experienced the worst impacts to their physiology when both temperature and carbon dioxide were elevated—a finding that portends trouble for wild staghorn corals that will bear the brunt of climate change. However, many traits varied among the coral genets suggesting the population hosts diverse levels of resistance to stressors and several traits showed high levels of heritability. Excitingly, the corals in this study didn’t suffer any significant tradeoffs (having climate resilience but losing other beneficial traits), which indicates corals could be robust to multiple stressors without hosting physiological disadvantages. 
     
  • Ocean acidification, a component of climate change, could boost the growth of sponges that can compete with corals, reported a Mote-led laboratory study published this year in the peer-reviewed Journal of Marine Science and Engineering. The study, titled “Ocean Acidification and Direct Interactions Affect Coral, Macroalga, and Sponge Growth in the Florida Keys,” tested how corals, algae and sponges grew when paired with each other or alone, under forecast levels of increased carbon dioxide—a driver of ocean acidification—vs. present day carbon dioxide. The sponges (a species called Pione lampa) grew significantly more amid the increased carbon dioxide. The algae (brown algae species Dictyota) declined slightly when grown alone or with coral, but it grew when paired with sponges. This might indicate that the water had limited nutrients, which the sponges supplied to the algae. In this 28-day experiment, the acidified water didn’t significantly change the growth of corals (lesser starlet corals, Siderastrea radians)—however, a growing body of research does suggest that many coral species will decline over time with ocean acidification, which can impede the formation of coral skeletons. By showing that sponges benefited from increased carbon dioxide, and algae may benefit from the sponges, this project supports a growing notion in the scientific community: that future reefs could be dominated by sponges and algae as corals decline. This study is one of relatively few to explore how ocean acidification could affect not just individual species, but also, the complex interactions between species that shape coral reefs.

Other highlights from our scientists studying corals and climate change impacts:

  • 20 groups of scientists from across the nation did research in Mote’s Climate and Acidification Ocean Simulator (CAOS) system this year. Project scientists hailed from Mote, Smithsonian Institution, Oregon State University, University of Southern California, Appalachian State University, College of Charleston, Goshen College, Florida Atlantic University, Old Dominion University, Pennsylvania State University, Louisiana State University, University of Mississippi, and University of Florida. Several peer-reviewed scientific publications came out this year from previous experiments in CAOS, demonstrating the versatility and importance of this system that can house fish, sponges, urchins, macroalgae, and corals under unique temperature and pH levels for short- or long-term studies.
     
  • Strengthening our climate change data: Mote scientists were selected for a competitive grant from SECOORA/IOOS to place a continuous pH monitoring station at Looe Key, Florida, to fill an important monitoring gap in ocean sensing networks for detecting ocean acidification impacts. Ocean acidification, a climate-change impact caused by excess carbon dioxide in the atmosphere entering the ocean, and coastal acidification due to multiple processes, are accelerating challenges affecting multiple marine species in ways that scientists are striving to predict and detect.