What happens when an entomologist-turned-marine biologist skims the latest articles in Coral Reefs: I read this as "the impact of NEONICOTINOIDS on the geomorphology of the northern Great Barrier Reef" and thought surely there can be no connection 😅

There's much more in the paper, including modelling to estimate the amount of bias one can expect under different irradiance levels and with different shading methods. We hope this serves as a reminder to the coral reef research community to think carefully about how you deploy loggers!

Fortunately, there is a cheap and easy way to improve data accuracy: shade your loggers! We recommend putting them inside a PVC pipe, which shades them enough from the sun but allows water to flow freely around them. With proper calibration, even cheap logger models can give reliable data.

Another way to visualize this is to plot the offset from the "true" temperature against irradiance on the x-axis. Here you can see the relationship is linear - as irradiance increases, the offset does too. But luckily, when you shade all models, this relationship disappears!

Below you can see that most loggers suffer solar bias - but some are much worse than others! In general, the brighter it is, the higher the error (that is, the logger overestimates the true temperature more when it's sunny).

We then performed field trials to see how much solar bias affects loggers. First, we determined that one model (SBE-56, pictured below) is unaffected by sunlight. We compared unshaded loggers to a SBE-56 on a shallow reef flat. We also measured irradiance to relate light levels with solar bias.

Our next task was to compare the "out of the box" accuracy of newly-purchsed loggers in a high-accuracy calibration bath. Accuracy varied among models, as well as a function of response time - some are spot on and others are off by 0.2-0.5ºC. Lesson 1 is calibrate your loggers before deployment!

Out of 329 coral reef studies we surveyed since 2013, we were surprised to see that less than 5% of papers mentioned shading loggers. This is despite >40% deploying loggers in less than 5 meters of water, where the potential for solar bias is high!

We revisited the problem of "solar bias" and surveyed recent literature to see how often researchers mentioned shading or calibrating loggers. We then assessed 10 logger models for accuracy and whether different models are affected differently by direct sunlight in shading trials.

Temperature loggers deployed directly on reefs can reveal subtle changes in thermal dynamics that can't be captured by satellites. This information is crucial, as corals are threatened by warming oceans - in most places, an increase of just 1ºC above the usual max temperature can cause bleaching.

I started surveying the shallow reef flats in front of KAUST for my PhD in 2020. I was impressed that corals could live in such extreme conditions - the water hits 38ºC in the summer! However, heatwaves in '23 and '24 were too much even for these corals. Today's survey had nearly 100% mortality 😞 🌊🦑

Last week we spent a few days in the northern Red Sea to deploy more temperature logger arrays. It was cold (for those of us used to southern Red Sea temperatures 😅) but the reefs are beautiful! We'll swap out the loggers periodically to see how temperatures change across depths over the year 🦑🌊

All of this was down by a great team of marine scientists from KAUST and Bangor University. Can't wait to revisit these sites next year and continue this project for years to come! 🦑

We also did benthic surveys and collected coral samples to characterize the reef communities at each site. We've generated hundreds of gigabytes of phototransect data and tons of frozen samples... plenty to keep us busy well after the expedition has finished!

Our loggers are distributed across 160km of the south central Red Sea and are deployed at several depths to capture temperature fluctuations at different scales. Hopefully, the data will help us understand why some reefs fare better than others during marine heatwaves.

Despite the temperature reprieve, many of these reefs are not in great shape. Most of them experienced massive mortality in the 2015/16 global bleaching event and have not recovered to pre-bleaching levels. This is especially true of the shallows where there are few live branching corals left.

Our temperature data show that these sites didn't get as warm as the central Red Sea, which may have spared the corals from the unprecedented heat stress that occured elsewhere in the region. Our loggers collect data every 15 seconds - that's over 800,000 measurements since we deployed them in June!

We're back! We visited 6 reefs to swap out temperature loggers, collect biological samples, and get some basic oceanographic data following our June expedition. Surprisingly, despite major coral bleaching in the central Red Sea this summer, the southern reefs seemed to fare better 🦑

Home for the next week! We're off to the Farasan Banks of the south-central Red Sea to repeat some coral reef surveys. We visited in early June to gather benthic data and deploy temperature loggers. This data will shed light on how the unique oceanography of this region influences reef communities 🌊