you're reading...


Marine heat waves leave seabeds ice cold

Marine heat waves, climate change, and failed spawning by coastal invertebrates. 2020. Shanks, A.L., Rasmuson, L.K., Valley, J.R., Jarvis, M.A., Salant, C., Sutherland, D.A., Lamont, E.I., Hainey, M.A.H., and R.B. Emlet. Limnol. Oceanogr. 65: 627-636

Doi: 10.1002/lno.11331

Marine Heat Waves

Human caused climate change is increasing temperatures not only on land, but in the oceans as well. Heat waves are becoming more frequent, longer, and more extreme. Scientific models also suggest that the frequency of these Marine Heat Waves (MHWs) will only continue to increase. These heat waves can have dramatic effects on marine animals, for example bleaching marine corals and disrupting food webs. We still don’t know whether (or how) these MHWs affect the early life stages of marine invertebrates like bivalves, crustaceans, and sea urchins, crucial members of marine ecosystems.

A sea urchin spawning, or releasing a cloud of gametes into the water. Picture from BiologyWise: https://biologywise.com/sea-urchin-reproduction

Marine Heat Waves

Most marine invertebrates reproduce by broadcast spawning, a process where animals release eggs and sperm into the water. These eggs and sperm, or gametes, must come into contact with each other for spawning to be successful and lead to embryo development. Most invertebrates live near coasts, but juveniles migrate out towards the open ocean to develop away from coastal predators and turbulence. Researchers from the Oregon Institute of Marine Biology recently investigated spawning success across years with a high frequency of MHWs, which dramatically affected the success of invertebrate spawning.

The Experiment

In order to look at spawning success the researchers collected daily water samples at high tide from the end of a dock at their institute from January to March of 2014, 2015, and 2016. This dock was near the end of an estuary and received water from the coastal ocean consistently. Water was pumped through several filters to get rid of both big and small debris, and to get embryos in the middle size range (between 125 micrometers and 1 centimeter). The number of embryos and juvenile animals were used to determine spawning success. Larvae and embryos from these water samples were counted, photographed, and identified as closely as possible, before being frozen for later genetic analysis. They also took temperature and salinity measurements of the water. The researchers then compared the daily average and annual abundance of embryos across the three years and looked at how the temperature and salinity of the water also changed from 2014-2016.

Map of the “blob”, a marine heat wave seen in 2015-2016. Warmer colors show higher temperatures and cooler colors show lower temperatures. By NOAA/ESRL Physical Sciences Division – http://www.climate.washington.edu/newsletter/2014Jun.pdf Office of Washington State Climatologist (University of Washington), Public Domain, https://commons.wikimedia.org/w/index.php?curid=39837693

During the winter 2015 sampling, the researchers saw an anomalously warm “blob” of water, very characteristic of a MHW, move to the Oregon shore. Temperatures in 2015 and 2016 were much higher than in 2014, and salinities were significantly lower in those years as well, all indications of a marine heat wave. When they compared the average number of embryos across years, they found that spawning success in 2015 and 2016 (the warm years) was much lower than in 2014.

Climate change, marine heat waves, and spawning success

So why does warmer, less salty water decrease spawning success? It’s possible that high temperatures cause adult animals to die off, and no adult population means there’s no one left to spawn. Warmer temperatures could also have slowed down the development of gametes or stopped the production of sperm and eggs altogether. Or the ocean conditions that trigger spawning in many species may not have happened during these marine heat waves.

Climate change is caused by the burning of fossil fuels. CCO https://www.pexels.com/photo/air-air-pollution-climate-change-dawn-221012/

Whatever causes these spawning failures, it’s definitely related to the warming of ocean waters and human caused climate change. Even a small decrease in spawning success could have far reaching effects on invertebrate populations, and the science is clear: marine heat waves are becoming more common, larger, and hotter because of climate change.

It’s sometimes hard to feel hopeful about the future when the science is so dire. However, there’s good news on the horizon. The United States has rejoined the Paris Climate Accord, signaling a recommitment to climate policy. The new Presidential administration has also made a pledge to make the United States carbon neutral by 2050. Individual people can also take steps to reduce their own carbon footprint and help the country reach this goal.


-eating less red meat, or buying local

-buying energy efficient appliances

-taking public transportation instead of driving

-keep the climate conversations going with family and friends

-advocate and vote for green policies


No comments yet.

Post a Comment


  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 4 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 5 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 7 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 8 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 9 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 9 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 9 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 10 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 11 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 11 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com