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Wavelength Reef Cruises Celebrating 40 years of high standard ecotourism and marine biology outreach.
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Some photos from this Friday... The first few are follow-up pictures to the ones we posted in August when we had the low...
18/10/2026

Some photos from this Friday... The first few are follow-up pictures to the ones we posted in August when we had the lowest low tides of the year. Those very shallow corals that were exposed in warm, sunny conditions for a couple of hours each day fared well.

There are some other close-up photos of coral polyps too. It always captivates us how beautiful they are individually never mind amazing it is that they collectively build the vast architecture that all the other reef creatures depend on.

The last pictures are of one of our own pilot coral rehabilitation trials which involves a super-simple method of stabilising rubble without any artificial structures by using specific coral species that are good at binding. We are interested in this technique instead of temporary nursery frames that were then removed. We have done trials with that in the past and it was ok for a few years but didn't last.

After a couple of sunny, calm weeks we are back to unseasonal showers and clouds. The silver lining (pun intended!) is that seawater temperatures are not worrying. We've actually had slightly cooler surface waters in August/ September this year compared to the same periods in the last six years. It can change quickly with local weather... we just had about 1.3 degree jump in the sunny first two weeks of October, but going forward NOAA's Coralwatch three month bleaching forecast for this area does not look alarming. Considering we have El Nino conditions this is great news so far.

text/photos John Edmondson

Great Barrier Reef Marine Park Authority Master Reef Guides Coral Nurture Program

We are very happy to share the latest research article where Wavelength Reef Cruises has been a contributing author. Th...
03/10/2026

We are very happy to share the latest research article where Wavelength Reef Cruises has been a contributing author. This one is “The Coral Nurture Program: a science–practitioner partnership for stewardship-based reef restoration - (Frontiers in Marine Science)”.

This article is open access and easy to find online. It is a large piece of work with Emma Camp as the lead author, summarising many years of collaborative effort. (Wavelength has now been a co-author on 25 peer-reviewed research articles related to the use of restoration techniques to protect and help adaptation at high-value reef sites. This is only made possible by our customers!)

Emma Camp and David Suggett, from University of Technology Sydney, and ourselves started CNP in 2018. The program aims to help people who rely on high value reef sites to play a central role in assisting recovery of live coral cover after impacts, and increase resilience to future bleaching events.

The photos here are from this week. We just finished four days of CNP fieldwork at Opal Reef. This has involved utilising photogrammetry, phenotype testing, and out-planting. The photomosaics help track the real world response of colonies to check how good short-term heat-stress-assays are at predicting real-world response. This is part of our strategy of searching for the more thermally tolerant corals within our sites to stock our coral nurseries. The target colonies have been through the assays either this year or up to three years ago. Later on, these then become donor colonies for frags which will be out-planted in response to impacts that cause a loss of live coral cover. Either the assays are effective, which is great news, or alternatively other environmental factors make them unreliable as predictors of marine heatwave survivorship, which is where temporal changes of specific colonies tracked with photomosaics become a backup plan. (We do this in combination with monitoring natural coral recruitment to prioritise natural recovery and best allocate planting effort.)

Although, ultimately, a combination of larval and asexual propagation techniques has the best prospects, for the time being, locally sourced coral fragments work well for this because of several advantages:

• The fragging methodology is well proven world-wide. We have then developed ways to improve throughput which are suited to the local scale we need and operator logistics.
• Fragging can be done throughout the year, and effort easily scaled up or down annually to suit the need.
• Coral fragments provide about three years head-start in coral cover improvement compared to larval techniques, which is important where a reef site has a high socio-economic value because of aesthetics.
• We can see very quickly if planting technique is successful or needs modifying at a site.
• It takes just a couple of years to grow a sexually reproductive colony, which not only leverages the benefit of the planting, but also helps as bleaching events become more frequent.
• Planting can be targeted to maximise fertility of the population with different genotypes of the same species nearby each other.
• The whole holobiont is passed onto the new colony.
• The cost-per-adult-coral-produced can be very low due to high survivorship (bypassing the early coral life-stages), and planting targeted to ensure corals are in the best micro-habitats for success.
• The methods are simple and well suited to integration into tourism operations, with multiple co-benefits.
• The methods suit our highly protected sites where foundational marine park management does the heavy lifting in reef regeneration. Our targeted planting is aimed at just speeding up natural adaptation and recovery at high value locations (up to a couple of hectares each) to protect their amenity value and the livelihoods that depend on them.

We want to say a big thankyou to Emma and Dave for this collaboration. A big part of the program's success is their listening to what exactly are the challenges that a reef tour operator faces, and then translating this into a great collaboration that is balanced so that both sides benefit from the other to create highly viable reef protection and climate change adaptation options.

Photos and text by John Edmondson

Great Barrier Reef Marine Park Authority Master Reef Guides Master Reef Guides Visit Queensland, Australia

September is biodiversity month in Australia with a purpose to promote awareness about the importance of biodiversity.Th...
11/09/2026

September is biodiversity month in Australia with a purpose to promote awareness about the importance of biodiversity.

The photos here are all recent ones of Acropora corals at our sites at Opal Reef. This genus is hugely diverse. Identification to genus level is easy, but to species level can be very challenging! All Acropora species share the same characteristic of having an axial polyp at the tip of branches or branchlets and radial polyps lower down. Our shallow reefs are often dominated by Acropora corals. They make a major contribution to the fish habitat but also tend to be fast growing and fragile. This makes them vulnerable to bleaching and storms but also quick to recover. Very fortunately, we still see lots of new recruits on suitable substrate.

We also want to mention cryptic (‘hidden”) diversity, which is a big thing with corals.

The general definition of a species is a group of organisms that interbreed and produce fertile offspring. It's easy to think of physical appearance as the only thing that defines species, but imagine the situation for non-visual animals like corals. Sometimes these have blurred species boundaries, species complexes, and distinct genetic groups.

So, it is quite possible to get groups of individuals within a named species that may have unknown boundaries to interbreeding, or have separate species that look the same. They may have close ancestry but have evolved into different genetic groups, for example having adapted to different depths. Recent studies have also found surprisingly large genetic distinctions between corals considered the same species but from different geographic regions, to the same extent as would be found between different species.

This does have important implications….
1. It is possible that when an environment changes or degrades some genetic groups can be lost but this goes unnoticed, hiding a reduction in community resilience.
2. Along with many reef researchers, we are very interested in the variation in how corals of the same species at the same location respond to marine heatwaves (phenotypic characteristics). One reason is that a potential way to help sites adapt to warmer seas is to boost the more thermally tolerant individuals by selecting them for nursery propagation and out-planting. Cryptic diversity can distort estimates for this phenotypic variation.
3. There is strong potential for genetic constraints on interbreeding between introduced and local corals even if they are thought to be the same species.

In practice, with our partnership with University of Technology Sydney and the Coral Nurture Program (which we co-founded with UTS in 2018), this means cryptic diversity has to be taken into consideration in experimental design and, as much as possible, in monitoring how corals respond to bleaching conditions. The way coral reefs support this biodiversity is one of the mesmerising things about them.

photos and text by John Edmondson

Great Barrier Reef Marine Park Authority Master Reef Guides Coral Nurture Program

These photos from this week show some of the lowest tides this year. It is easy to take the tides for granted but they a...
14/08/2026

These photos from this week show some of the lowest tides this year. It is easy to take the tides for granted but they are fascinating….

Our tidal range is up to about 3m. We almost always have two high tides a day and two low tides. The exception is during very neap tides (half-moon), when sometimes only one high and one low happens in a day.

For each day one of the low tides is lower than the other. During spring tides (full and new moon) the difference can be around 50cm between the two. At this time of year our lowest low tides are in the early afternoon. In January/February they are at night. This is has big implications….

Very low tides are super-stressful for the reef flat corals. They produce lots of mucous to try to avoid dehydration but are vulnerable to UV and dry conditions at this time of year (with daytime exposure), and in the wet-season the night-time extreme lows can coincide with high rainfall. These stresses can cause emersion mortality which has a huge influence on the way shallow reefs grow.

El Nino conditions can also lower the low tides in the Western Pacific by over 20cm and increase them by a similar amount in the Eastern Pacific.

We don’t know of any real-time publicly available tide gauge data on the GBR so can’t say if this week’s low tides were normal lows fitting with tide predictions or influenced by El Nino, but we would love to find out.

For more detail read on ...

El Nino strength is measured by the Southern Ocean Oscillation Index and the July numbers are the lowest since records began in 1876 (the index normally peaks around December to January so is expected to become more negative in the coming months).

Another fascinating thing about the low tides is related to clouds … Marine microalgae, including the symbiotic algae in corals (as well as other parts of the coral holobiont), produce a chemical called DMSP (Dimethylsulfoniopropionate) as an antioxidant to control reactive oxygen molecules created during photosynthesis. DMSP breaks down to DMS which enters the air and becomes the major source of sulphur nuclei which help clouds form (and also make the ocean-air smell). Heaps more atmospheric DMS is produced by exposed corals, so in theory it should help make more clouds over the reef.

Another fascinating thing about these reef flat corals is adaptation to the reef flat conditions. The necessary adaptation to such low tides that happen a few times a year is to short term stress and DMS-rich mucous is a feature. For us, with our coral propagation and planting research interest, we try to select thermally tolerant corals from the local population. Other than blindly trying to pick survivor-corals after bleaching events (which can be unreliable), the only current way to test for these is short term heat-stress assays (MTP and CBASS) but these tests only last a short time whereas real-world marine-heatwave bleaching events last weeks. This illustrates some of the complexity of testing for individual genotype thermal adaption, and the current gaps in knowledge of verifying that short term tests accurately reflect a coral’s real world marine heat-wave fate.

pics and text by John Edmondson

Great Barrier Reef Marine Park Authority Master Reef Guides Visit Queensland, Australia Coral Nurture Program

These are some photos from this week at Opal Reef on Wavelength trips. We have had strong winds but clear water and lots...
02/08/2026

These are some photos from this week at Opal Reef on Wavelength trips. We have had strong winds but clear water and lots of whale sightings.

Group 1 shows the great visibility we have at the moment at the outer reef and some of the cool critters.

Group 2 shows some examples of our coral outplants. We invented Coralclips in 2017. These simple spring clips with a small masonry nail hold coral fragments or larval seeding devices in place until they self-attach. They can work with diverse coral morphologies but work best on clean, consolidated reef substrate. We have planted over 80,000 corals ourselves at our sites as part of research projects as well as co-founding the Coral Nurture Program for work on the GBR. Wavelength have been supplying Coralclips on a not-for-profit basis to projects in over 26 countries.

Group 3 shows some examples of the many natural coral recruits we continue to see despite recent bleaching and cyclone events. We monitor natural recruitment at our sites because it is vital to understand alongside any coral planting that aims to boost local-scale live coral cover. These are the main source of hope for the reef's future!

It is still too early to say what will happen next summer but El Nino conditions are worrying. Since 2017 we have had a consistent and simple strategy in preparation for the likelihood of future coral bleaching, that is ... research the optimisation of coral propagation and planting to boost coral cover and thermal resilience at individual high-value sites and rely on foundational marine park management to protect the wider areas that interconnect to help supply new coral, invertebrate and fish recruits.

photos and text by John Edmondson

Great Barrier Reef Marine Park Authority Coral Nurture Program Master Reef Guides Visit Queensland, Australia

27/06/2026

Really fantastic today to have our first humpback whale sightings of the season with two different whales a few kms apart about half way out to the outer reef. On the GBR we have regulations not to get too close to whales but these were both quite curious with Wavelength 4 when we stopped and waited. Thanks to Zoe Hiscock for the video clip.

These pictures from Opal Reef are intended to help visualise what lower levels of coral bleaching looks like. We have ex...
17/06/2026

These pictures from Opal Reef are intended to help visualise what lower levels of coral bleaching looks like. We have experienced coral bleaching like this in the summers of 2020, 2022, 2024, 2025 and 2026. This has matched with ocean temperatures that have been elevated but not extreme. Our very severe coral bleaching was in 2016/17, so El Nino conditions are concerning.

The individual encrusting/foliose coral picture shows paling at the height of the summer followed by recovery (this coral was planted by us as a cluster of finger-sized frags on a bare rock in 2019 and has grown really well since, including providing frags for other planting).

The reef photos show how brighter colours are often seen with low-level bleaching because corals that are heat-stressed are making colourful photoprotective pigments. If temperatures drop within time, the corals generally recover and have more golden-brown colours. These are due to the natural colour of the internal symbiotic algae with much less photoprotective pigmentation.

So when you hear about coral bleaching, bear in mind the language is oversimplistic and covers a range of severity. Coral bleaching is sometimes limited to being a warning sign that things are stressed, without a major ecological impact. But severe bleaching with high mortality is a huge concern for reefs worldwide and El Nino years carry a higher risk.

pics by John Edmondson

Great Barrier Reef Marine Park Authority Master Reef Guides Coral Nurture Program Tourism Tropical North Queensland

Some photos from a couple of days ago showing how June has started with perfect weather conditions....The underwater pho...
08/06/2026

Some photos from a couple of days ago showing how June has started with perfect weather conditions....

The underwater photos are picked to show the healthy shallowest coral at one of our sites, normally the most vulnerable to wet-season impacts from tropical lows and cyclones, and/or from thermal stress with too-warm water. Nearly all signs of bleaching we had earlier this year have now gone as water temperatures have dropped. Some spots got a bashing from Cyclone Narelle but most places, like the site where these photos were taken, escaped major damage from swell caused when the cyclone passed further north in March.

Some great recent news has been the continuation of the Reef Authority's Tourism Reef Protection Initiative which was vital this past few months for enabling monitoring and responding to the major weather impacts. We are one of over 20 reef operators who are part of this initiative.

Big thanks to Agostino Arrigo for the drone shots.

Great Barrier Reef Marine Park Authority Master Reef Guides Tourism Tropical North Queensland Visit Queensland, Australia

Here are some shrimp, crab, mantis shrimp, and squat-lobster photos to brighten up your morning....We get many of these ...
13/05/2026

Here are some shrimp, crab, mantis shrimp, and squat-lobster photos to brighten up your morning....

We get many of these here, but this group of photos are from our trip to Bali earlier this month (Tulamben) like the last post. They are small and cryptic so are difficult to spot by snorkelling, and maybe easier to photograph over there being used to close-up cameras!

We want to share them as the critters are so fascinating, and beautiful, but also to illustrate that when people talk about protecting coral reefs that includes the many 1000's of amazing species of small creatures that are dependent on them.

Crustaceans often have very specific relationships with other animals like corals, nudibranchs, gobies or seastars. This just makes you marvel at nature and how strange these creatures are..

photos by John Edmondson

We spent last week in Bali checking out some reef restoration installations.... but the pictures here are just of frogfi...
09/05/2026

We spent last week in Bali checking out some reef restoration installations.... but the pictures here are just of frogfish we photographed there ... too cute not to share!

Since 2016, at Wavelength we have made a conscious effort to keep learning from the experiences in other countries with a longer history of reef interventions, including first hand visits to find out more about mistakes and long term outcomes, that might otherwise be unreported.

This is approached with the understanding that vast numbers of people are all doing their best to protect and help places they love, But, the methods are still mostly experimental and not every intervention turns out the way people hope, The best we can do is keep learning, including knowing what not to do, and improving methods we do use .... we are convinced the need is there.

Our own focus at Wavelength is coral planting in response to coral loss caused by bleaching and cyclone damage. This is at a local scale of high value tourism sites, such that planting is not noticeable ... really just in a similar way that high-use areas of terrestrial national park areas are protected and maintained. The goal of planting is to boost live coral cover and resilience of the site to ongoing ocean warming. This in turn contributes to sustainability of nature-based reef ecotourism and helps economically justify marine protected areas due to the jobs and revenue from ecotourism, It is then the marine protected areas that do they heavy lifting in ecosystem protection, not the coral planting by itself, We do this primarily through the Coral Nurture Program which we co-founded with Assoc Pro Emma Camp and Prof Dave Suggest at the University of Technology Sydney,

Back to the frogfish!

photos by John Edmondson

CoCoral Nurture ProgramrGreat Barrier Reef Marine Park AuthorityaMaster Reef Guides

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