Tasmania’s other threatened forest

Giovanna Fasanelli | VOLUME 22, ISSUE 6

A diving exploration reveals the towering kelp forests of Tasmania.

I’m not sure when it was that I developed an interest in exploring the towering kelp forests of Tasmania. But I knew that it would mean diving in eerie and jaw-clenching cold water far, far away from the northern reaches of sun-kissed Queensland. Blame David Attenborough and his intrepid film crew. It was through their nature documentaries that I got my first glimpse of Tasmania’s underwater sea forests. I just knew I wanted to see them for myself; they promised to be spectacular and adventure-packed.

Before I dive, literally, into the giant kelp forests of Tasmania, a word about the miraculous nature of kelp, particularly giant kelp. It may be obvious to point out that kelp is really just oversized seaweed (of the brown type), which is more broadly referred to as algae. From a biophysiological point of view, algae, in its various collective forms, is a ‘primary producer’. Stationed as it is at the base of the food chain, it contributes up to 60 per cent of our planet’s primary production levels (the energy captured and transferred for direct use in fuelling the food chains of the world). Not only is kelp part of the reason we’re able to enjoy a lazy Sunday lunch of fish ‘n chips, it’s actually the foundation of the world’s ecology and economy.

Kelp is harvested on a major scale to extract algin, which is used as an emulsifier in various products such as cosmetics, paints and pharmaceuticals. Alginates, which are sticky gums found in the cell walls of brown algae, are sought-after compounds used in the production of asphalt, ice-cream, cheese and paper.

Kelp is also a major ecological keystone species, capable of influencing coastal oceanographic patterns. And then there is the provision of key habitats and nurseries for the recruitment of countless other marine species. Kelp is important to fisheries of various shellfish species such as abalone and rock lobster, which rely on the kelp forests for habitat and food, as well as shelter for larvae. Kelp brings in temperate water diving tourism dollars and, of course, kelp forests are beautiful.

So … kelp is amazing, worthy of all of our respect and protection. Time for an up-close and personal entangling experience in the kelp forests of Fortescue Bay.

ALARMING DECLINE

The dive masters from Eaglehawk Neck Dive Centre, Gary Myors and Mick Baron, are surely two of Tassie’s greatest divers. Their knowledge and hospitality was only surpassed by their passion for diving and protecting the kelp forests of Tasmania. Regretfully, despite their passion, the kelp forests continue to decline at an alarming rate.

After a superb sight-seeing boat journey past the weather-beaten cliffs of Cape Hauy and the Tasman Peninsula and countless visits from cheeky local Australian fur seals, it was soon time to get wet. Well, cold and wet. The water was an inhospitable 17 degrees. Simply put, I was not adequately prepared.

Not more than a minute into the dive, my eyes fixed upon a golden, glowing mass in the watery distance – an extensive bed of Macrocystis pyrifera, the giant bladder kelp. Sorry to sound clichéd, but my first sight of Tasmania’s kelp forest was a dream come true.

Giant bladder kelp often grows to lengths over 30m and at rates of up to half a metre a day. I was filled with a quiet sense of awe as I floated around the swaying amber life forms, marvelling at their brilliant evolutionary strength as well as their seeming frailty.

Kelp is not technically a true plant; it’s quite simple in its morphological ‘ultra-structure’. Kelp is made up of three distinct parts – a holdfast, (which looks like a plant’s root system), a stipe (like a plant stalk) and fronds (the plant leaves).

The ‘bladders’ (or pneumatocysts) of the giant bladder kelp are gas-filled bubbles found at the base of the fronds. The bladder kelp has cleverly evolved these bladders to keep its fronds upright, ever-reaching toward the sunlight and fulfilling its primary function to photosynthesize. It is this evolutionary trait which allows this kelp species to turn light energy into usable chemical energy – and provide a broad base for the global food chain.

CRAZY CREATURES

As the dive progressed and my air bubbled and wobbled its way to the surface, we discovered all kinds of crazy creatures hiding in the mysterious, dense carpet of decaying fronds. We came across the strange and stocky draughtboard shark (aka Australian swellshark), a native species which lacks the cutting-edge, threatening look of its larger, more formidable cousins. This particular draughtboard shark struck me as the dopiest fish imaginable. I was genuinely amused as it accidentally and repeatedly bumped into us.

When Mick pointed out a pair of weedy sea dragons, I was filled with delight. If ever there was a creature that God had decided to hand-paint with the utmost care, it is this pipe fish. As I poked around the forest, I was surrounded by a multitude of other stealthy fish species: wrasse, cowfish, leather jackets and butterfly perch.

Aside from all the tiny juvenile fish and crustaceans hiding in the fronds, I was particularly interested in the sea urchins. Sea urchins are well known algae eaters, and their abundance in this area may be a sign of large-scale changes.

Some say that over-fishing has removed the urchins’ natural predator, the lobster, and caused a shift in predatory-pressure. Others speculate that the global rise of sea water temperatures (approximately 1.5 to 2°C since 1940) is the true cause of the urchin baby boom.

Now I didn’t particularly observe a large number of urchins in this area, but it made me think about the longevity of these incredible forests, knowing that urchins have been attacking beds further up the east coast. Over the last 30 years, there has been an alarming decline in kelp along the east and south-east coasts of Tasmania. The area is now less than five per cent of the original territory colonised by Macrocystis pyrifera.

Gary and Mick spoke about the visual evidence of the loss that they have personally witnessed over the many years they’d been diving the forests. Truth is, Tasmania is not immune to the harsh handling of our environment. The very particular niche requirements of kelp (cold, clean, nutrient-rich waters below 20°C at the right depth and light levels) have been severely affected by the rising sea temperatures, commercial harvesting, marine pollution, coastal run-off and introduced species. At risk of local extinction, the declining kelp beds are now a major national environmental issue. Protection programs are, thankfully, underway; we can only hope that it’s not too late.

After witnessing the mysterious, mystical beauty of the kelp forest, and seeing, first-hand, the profound role kelp plays in supporting marine biodiversity, I can safely say that I was right: this experience was spectacular and action-packed. Our exploration of the kelp forest has given me a new sense of wonder about the circle of life.

Visit www.geog.utas.edu.au/kelpwatch to find out more about how you can assist with conservation projects and raise awareness about the desperate need for the preservation of our kelp forests.

Giovanna Fasanelli has completed a Bachelor of Science, majoring in Marine Biology at James Cook University, Townsville and is also a presenter with Channel 10’s Escape with ET show.


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