Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.
Two weeks ago, I found myself hitting the water on Norfolk Island, complete with a survey reel, slate and camera.
Norfolk Island is a small volcanic outcrop located between New Caledonia and New Zealand, 1,400 kilometres east of Australia’s Gold Coast. It’s surrounded by coral reefs, with a shallow lagoon on the south side that looks out on two smaller islands: Nepean and Phillip.
The island is picturesque, but like marine environments the world over, Norfolk Marine Park is subject to pressures from climate change, fishing pressure, habitat change and pollution.
I was diving in the marine park as a volunteer for Reef Life Survey, a citizen science program where trained SCUBA divers survey marine biodiversity in rocky and coral reefs around the world. We first surveyed Norfolk Island in 2009, then again in 2013, with an eight year hiatus before our return this month.
While the scientific analysis of our data is yet to be done, we can make anecdotal observations to compare this year’s findings with prior records and photographs. This time, our surveys turned up several new sightings and observations.
Diving under the waves in Norfolk Marine Park takes you into a world of crackling, popping reef sounds through clear blue water, with darting tropical fish, a tapestry of algae and hard and soft corals in pink, green, brown and red.
In these surveys we record fish species including their size and abundance, invertebrates such as urchins and sea stars, and habitat such as coral cover. This allows us to track changes in marine life using standardised scientific methods.
Given recent major marine heatwaves and bleaching events in Australia, we were pleased to see healthy corals on many of our survey sites on Norfolk. We even felt there had been increases in coral cover at some sites.
This may be due to Norfolk’s location. The island is further south than most Australian coral reefs, which means it has cooler seas, and it’s surrounded by deeper water. I’m a marine ecologist involved in soft coral monitoring at the University of NSW, so I particularly noticed the wonderful diversity and size of soft corals.
I noticed generally low numbers of large fish such as morwong and sharks on our survey sites. Some classes of invertebrate were also rare on this year’s surveys, particularly sea shell animals like tritons and whelks.
Urchins, on the other hand, were common, particularly the red urchin. Some sites also had numerous black long-spined urchins and large sea lamingtons.
These invertebrate observations follow patterns we see in eastern and southern Australia, where there are declines in the numbers of many invertebrate species, and increases in urchin barrens — regions where urchin populations grow unchecked.
The expansion of urchin barrens can threaten biodiversity in a region, as large numbers of a single species of urchin can out-compete multiple species of other invertebrates, over-graze algae and reduce habitat suitable for fish.
A highlight of any survey dive is when you find an animal you suspect may not have been recorded at a location before, and I had several of those on this trip.
I recorded first sightings for Reef Life Survey of blue mao mao, convict surgeonfish, the blue band glidergoby, sergeant major (a damselfish), chestnut blenny, Susan’s flatworm, red-ringed nudibranch, fine-net peristernia and an undescribed weedfish.
While some of these sightings are yet to be confirmed by specialists, they gave a buzz of excitement each night as we searched the records to confirm our suspicions of a new find.
Other highlights for me included the warm welcome we received from the local community on Norfolk and the great turnout we had at our community seminar. Everyone I spoke to was supportive and encouraging when they heard we were on the island as volunteers doing surveys, and several people expressed interest in getting involved.
This is great news, as the best outcome is for local people to be trained to conduct their own local surveys.
Ideally we will return for comprehensive surveys of our 17 sites every two years or so, allowing us to plot trends over time. Only then can we hope to understand what is really happening in our marine environment, and make evidence-based conservation decisions. Having a skilled local team would make this easier and more likely to happen.
In any case, our 2021 surveys in Norfolk Marine Park, conducted by our team of five dedicated volunteers and supported by many others, give us one more essential point in time in the Norfolk series, and gave me some great memories to boot.
You can view my full photo album from the Norfolk Island survey here.
Have you ever clapped your hands to get someone’s attention? The resulting “crack!” sound is hard to ignore, rising above and penetrating through any background noise.
Now imagine trying to do it underwater – you would be unlikely to achieve quite the same impact.
Amazingly, new footage released this week in the journal Marine Mammal Science shows breeding grey seals doing just that: they clap at each other to warn off competitors and attract potential mates.
Like their land-living relatives, marine mammals primarily communicate vocally – think of dolphin whistles or the famous song of humpback whales. Grey seals are no exception, and in fact can be surprisingly versatile.
Besides the bizarre “rup” and “rupe” calls these seals normally make in the wild (see the video below), some captive animals have even been trained to perform the Star Wars theme tune!
But vocals are only half the story. Many marine mammals also produce percussive sounds, such as by slapping the water with their flippers or tails. Normally this happens at the surface, and only involves one flipper at a time.
What makes grey seals different is that – like humans – they literally clap their forelimbs together, and they do it entirely underwater.
Recording the claps was far from easy, and took no less than 17 years of scuba diving by “seal diver” and marine biologist Ben Burville.
Ben was no stranger to the clapping sound itself. For years, he had heard it when diving with grey seals during their breeding season. Similar noises had also been detected by researchers using underwater microphones, but had been mistaken for a vocal signal.
It wasn’t until he actually saw a big male clapping together its paw-like flippers that Ben finally identified the true source of the sound. Yet the claps were quick and difficult to film; by the time he pointed his camera, things had usually moved on.
Years passed until finally, in October 2017, Ben caught the behaviour on film while diving near the Farne Islands, UK. A male grey seal performed seven claps right in front of him while his camera was rolling.
At first, the discovery might not seem that surprising. After all, seals are famous for performing this behaviour in zoos and aquaria. However, there is a crucial difference: whereas captive animals (usually fur seals or sea lions) have been trained to clap for our entertainment, grey seals do so in the wild and of their own accord.
So why do they do it?
Imagine being in a noisy room, with everyone around you chatting away. Getting attention can be difficult, unless you make a statement. That’s exactly what a clap is: a sharp, loud noise that rises above the background chatter.
Usually it’s males that do the clapping – sometimes by themselves, and sometimes at each other. Depending on the context, the claps may help ward off competitors and/or attract potential mates.
Similar functions underlie display behaviour in many other species. Think of a chest-beating male gorilla, for example. Like seal claps, those chest beats carry two messages: “I am strong, stay away”, and “I am strong, my genes are good.”
The short answer seems to be no, or at least not as far as we know. Clapping seems to be a genuinely novel behaviour that evolved in seals only once. Perhaps larger species such as sea lions are prevented from doing it by increased water resistance.
Of course, it is also possible that some other species also clap, but haven’t done so in front of a camera.
Even if clapping were unique to grey seals, it seems the sharp signal it generates is important for many marine mammals. Several dolphins, whales and seals produce similar sounds via tail or flipper slaps, or even gunshot-like vocalisations. The oceans are a noisy place, after all, and it can be important to stand out in a crowd.
Clapping seals show us just how much we still don’t know about the remarkable mammals in our oceans. Clapping seems to be an important social behaviour, hence anything that disturbs it may impact breeding success and survival.
Human noise pollution is known to interfere with other forms of marine mammal communication, including whale song. Loud industrial noises could conceivably disturb grey seals (and other species that rely on acoustic signals) in similar ways.
But if we do not know a behaviour exists, we cannot easily act to protect it.
Understanding the animals around us better can therefore help us to protect them and their way of life.