Tag Archives: ningaloo

The Science of Sousa

Despite all the photos of us smiling and drinking tea on boats, looking at the pretty little dolphins and later playing with baby kangaroos, we are actually here in Exmouth for Scientific Research (note the Important Capitals denoting the Realness of our Science).

Anyways, the research bit is cool too. Out on the boat, we drive transects around the tip of the North West Cape, collecting data on dolphin species, numbers, age classes and groupings, locations, environmental conditions, and the ever-important photographs for identifying individual dolphins from the catalogue Tim’s assembled over the past two years.

We aim for good-quality, zoomed-in, in-focus, and well-lit photographs where the fin is parallel to the plane of focus on the camera and fully out of the water, for maximum potential to identify them. Glare, spray, waves, animal movements, boat lurches, poorly angled light or backlight, focus problems- any of these things and many more can disrupt the camera and leave us with a big pile of crappy photos that we later have to sort through. But occasionally we get a photo like this:

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It’s clear and sharp, all four fins are fully out of the water, the lighting and contrast are good, and the dolphins are nearly exactly at a right angle to the direction of the lens. As a bonus, the two farthest dolphins are surfacing “in position,” meaning that their positioning along with the relative small size of the middle dolphin indicates that they are possibly a mother-juvenile pair (or in boat slang, MJ). From this photo, then, we can identify probably three out of four dolphins in the catalogue, note that the group cohesion is less than 2 meters, observe their traveling behavior, determine likely relationships, and enjoy lovely memories of how blissfully flat the water was that day.

When processing this photo, we first zoom in. Most of our photos (not sure about this one in particular) are shot with the lens fully extended to 400mm. We then have to crop out most of the photo, anything that is just water or unidentifiable parts like flukes or pectoral fins. This photo, since it’s got four good fins in it, will be copied into up to five different files, one for each dolphin and one to demonstrate the MJ pair’s positioning and relationship in the water and in the group.

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The small fin in the middle (a PJ, or potential juvenile) looks fairly unmarked. The edges are smooth, and though there is some spray obscuring a tiny part of the fin, there don’t seem to be any scars that would last from sighting to sighting and allow us to match this dolphin with photos from another time and place. Dolphins heal absurdly fast and absurdly well, sustaining shark attack wounds and other injuries that would seem fatal to a human while continuing to swim around the friggin’ ocean. And their scars often go away really fast, so they can’t regularly be used to tell one fin from another. Therefore, we go mainly on nicks and notches, the unique shapes and textures of a dolphin’s fin. For example:

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In this way-zoomed-in photo, you can see a notch about the middle of the fin, another toward the top, plus two at the tip. By searching the catalogue for a fin with exactly this shape (fairly distinctive, though not nearly the most distinctive fin I’ve seen) we can determine who’s who with relative ease, especially once we get to know the different fins throughout the season. These ones are Tursiops aduncus, Indo-Pacific bottlenose dolphins, not the main study species Sousa sahulensis, and there are more than 250 recognizable individuals in the catalogue, so we probably won’t know all of these really quickly. But there are a few, like “Steps,” that we can recognize immediately.

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Her scarring is even more distinctive from the other side, and we’ve spotted her a fair number of times since I’ve been in Exmouth. That’s part of the benefit of photo-ID though- we recognize her every time we see her and her juvenile, but just because the other dolphins in her ever-changing group aren’t as obvious, they can still be recorded and identified at a later and more leisurely (sort of…) time.

So there it is- the first part of the Science! All the analysis and breakdowns of data will come later, as we get even more sightings and process the backlog of photos from past boat days. As a reward for reading all that and hopefully understanding a bit more about why all that foolin’ around on boats and such is important to this study, for you my dear readers I present a really freaking cute photo of a baby bottlenose:

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Birthday Bommies

 

 

 

Today was Tim’s birthday- we had a gathering last night, a communal meal with some of the best hummus I’ve ever had (thanks Cindy!), beetroot on burgers, happy and then sleepy baby, and a birthday present from the whole of Team Sousa 2014. Kaja emailed every member, present and departed from Exmouth, and added his or her photo to a collage- we took ours on the boat without Tim noticing a thing. Well, okay, he got vaguely suspicious that we were up to something after a while, but forgot soon enough and never saw the signs we’d prepared. Janine, Tim’s wife, and David, his father, took care of printing and laminating, and we surprised him after dinner. Here’s the final collage:

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This morning we baked cupcakes and headed for the Cape Range National Park, driving out across more miles (kilometers, sorry) of shrubs and termite mounds and red soil. It’s still fairly green after the rainy season, but the hills are beginning to brown and animals are on the lookout for water.

At Oyster Stacks, a well-known snorkel spot, we suited up and jumped in. I’ve never seen plate corals and healthy staghorn and elkhorn formations like those, nor such a diversity of fishes. The Caribbean, or more specifically the Cayman Islands, which were my last dive destination, has lost nearly all of its staghorn corals and much of its coral health due to human activity and development in the area. In Hawaii, where I’ve done most of my diving, the coral and fish populations are impoverished due to the extreme distance between the islands and any other major coral reef masses. The corals that made it out across the Pacific to those newly-formed volcanoes in the sea were rare and mostly boulder-type structures, growing in bulbous mounds across the seafloor and creating nooks and crannies for the fish that made the crossing too. The number of species in the Hawaiian Islands is therefore much lower than those supported by the Great Barrier Reef and the chains of islands and barrier reefs connecting the whole of the South Pacific. That’s not to say it isn’t a lovely place, plenty of color and interesting fauna, and I’ve loved every minute of every dive there, but the reef architecture of Ningaloo is fascinating.

Purple boulder corals mixed with giant orange plates, surrounded by interlocking horns of bright green polyps, all filled with darting crowds of blue and yellow and red fishes. Big coral heads, nearing the surface of the water or even breaking through it, are referred to here as “bommies,” etymology still unclear. It’s a useful term, though, as we’re often sampling around or in shallow coral communities and need to be watching out lest our propeller should take issue and start a fight with one of the more prominent examples of the phenomenon.

Giant clams nestle in on the reef, showing striped colored mantles. They flinch away from shadows but seem so impenetrably large. I don’t know why they don’t live in the Hawaiian chain- possibly temperature, nutrients, or similar reef structural issues, though distance is likely not the issue. Small clams and other bivalves (two-shelled mollusks like scallops, mussels, and oysters) float as plankton on ocean currents until they grow large enough to settle onto the substrate and develop fully, so a giant clam larva could probably span the ocean to the islands if no other factors impeded its spread.

Anyways, I’ve never seen them before and they’re gorgeous. Their thick-walled shells are impressive on their own, and the exposed inner surfaces ripple with blues and greens created by symbiotic communities of algae that provide the clams with solar energy in the form of sugars while taking shelter in its skin.

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Kaja, talented marine photographer of all of this post’s photos, nearly backed into this black-tip reef shark when it rounded a bommie at her back. About 5 feet long and intriguingly deep-chested (possibly pregnant? Later in the season I hope to visit the blacktip nursery out by the mangroves), it is easily identifiable by a layer of black over a mostly-white fin on a gray body. It didn’t seem at all perturbed to see us, nor did it have to work hard at all to outdistance us over the reef when it decided it had had a good enough look.

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I’m so glad to have finally made it into the water. We stayed out until we got cold and tired of getting tossed around in the shallow surf, but I’m confident that we’ll have plenty more opportunity to explore. There’s so much to see, and so many questions to ask and answer out on the reef! #SCIENCE

Playing Catch-Up

Marine life can be slow- nudibranchs, jellyfish, sunfish, algae- but can also move at unbelievable speeds. Turtles may seem to take their time, but they whizz by under the boat daily and (I know from personal experience) don’t even have to exert themselves to outpace an intrusive camera-wielding diver. Even motivated dugongs, with their blubbery bulk, can pick up enough speed to evade good photography from a boat. But for the most part if left undisturbed and not on the hunt, marine mammals like dolphins and whales move at a fairly leisurely pace, taking a few shallow dives between breaths and then a longer dive below the surface.

That wasn’t the case at all when we met Pseudorca crassidens, the false killer whale. Somewhere upwards of thirty of them were spotted charging north along the outside reef, slicing through deep water and breaking the scattered whitecaps with seafoam of their own. Coming in relatively close to the boat and staying shallow, they didn’t seem to be disturbed by our presence (they have a reputation for enjoying boat races and wakes) but rather headed somewhere unknown on an urgent errand. At their speed and with spray over their short rostrums at every surfacing, they were near impossible to photograph, but fun to watch as the whole group flew by us. When we were surrounded, they were spread nearly as far as we could see through the swells, and we could turn any direction still expecting to see sleek black bodies in the waves.

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In the wake of these odontocetes (toothed whales), we spotted two different sailfishes. Although they are sometimes said to be traveling with the false killer whales, the orca research boat that pulled up alongside us for a chat informed us that they were more likely scared out of the way by the oncoming pod and are seen at the surface somewhat dazed, tired from avoiding the whales. These didn’t seem at their peak- sailfishes are supposed to be among the fastest in the ocean, but one allowed us to pull the boat (and GoPro) up alongside:

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I was worried I had the little camera (on the end of a long pole, which was catching an alarming amount of drag as we drove through the water) pointed in entirely the wrong direction to catch the big fish, but after looking at the photos, there it was. When the boat got close it dove, but only a little, and hovered around below the water for nearly a minute before disappearing deeper into the blue.

All of this is a big stupid metaphor for the fact that I haven’t blogged as much in the past few days and have a backlog of photos from this fast-paced trip that I just haven’t been able to keep up with. I haven’t even written yet about dingoes (70% on the West Coast here are pure dingo; only 5% on the East Coast can claim that level of genetic isolation from dogs; we almost certainly saw a crystalline example of Canis lupus dingo the other day on the road) or baby emus or sea snakes, and tomorrow we’ll be snorkeling and I’ll have even more to talk about. Life moves fast and even the biggest and most impressive things slip away, but I’m just going to keep moving anyways.

This is Agent Red Squirrel, sprinting off for the next adventure!