Posts Tagged human impacts

Australian media on a mission to make scientists look dodgy Rebecca McLeod Dec 21

7 Comments

Yesterday 895,000 Australians (and this one Kiwi) woke up to the headline “HOPES FADE IN COPENHAGEN, RISE ON THE REEF” in a national newspaper. As one who is always up for a bit of optimism I began reading… but by the second line my hopes were somewhat dashed: “Scientists ‘crying wolf’ over coral”.

This front page story reported the views of one (I repeat ONE) scientist, Peter Ridd, a physicist from James Cook University, who believes that ecologists and biologists studying the Great Barrier Reef are guilty of exaggerating threats to the reef, such as increased sedimentation, crown of thorns starfish, pollution, and temperature-induced damage called bleaching. Ridd argues that the reef is still in ‘good health’ despite public attention being drawn to these individual threats over recent years, thus affecting the credibility of marine scientists, particularly with respect to current concerns about the susceptibility of coral reefs to climate change.

It seems to me that The Australian has gone out of its way to turn this scientific debate, which is essentially one marine scientist disagreeing with a score of others, into another example of how ‘dodgy scientists’ are conspiring to delude the public into thinking that climate change is a real phenomenon.

A more in depth article further inside the newspaper “How the reef became blue again” does quite a good job of describing recent research findings by scientists at the Australian Institute of Marine Science, regarding the ability of corals to recover from bleaching events caused by increases in water temperature. However, you have to dig really deep to get to what I think is the part that is deserving of the headline:

“Ocean acidification is another matter, however. This lesser-known product of climate change is a greater danger to the reef by Ridd’s assessment. It happens as the ocean absorbs CO2 from the atmosphere, altering its pH value. Although surface sea temperatures are rising fastest in tropical regions, the threat of acidification comes from the higher latitudes, where the colder water takes in CO2 more easily.

The theory is that when atmospheric CO2 reaches between 480ppm and 500ppm, the warmer water lapping coral reefs will cease to be a barrier to acidification: even a small change is thought to spell trouble for calcifying organisms such as corals, making it more difficult for them to make the skeleton structures that in turn build reefs.”

If you would like to find out more about this incredibly scary phenomenon, I posted a rather thought-provoking film on it a couple of months ago. Even Peter Ridd thinks that ocean acidification is the single greatest threat to the Great Barrier Reef – but only those few of the 895,000 that got close to the end of the 2 page article would be aware of this!

Are the public so supersaturated with climate change stories that the media are having to infer scientific controversy to get the attention of the public? Quite possibly. How sad.

A+ for Australian Marine Scientists Rebecca McLeod Dec 04

No Comments

The Marine Climate Change Impacts and Adaptation Report Card Australia 2009 has just been released. Hiding behind the long-winded name is an excellent resource – a website-based state-of-knowledge of how climate change is likely to affect Australia’s marine life, with expert opinions from more than 70 marine scientists across the country.

Whilst the majority of the information presented on the website is available in various scientific papers, having it all combined on a common site, and in plain English is a real leap forward in making marine issues accessible to the public. Through many many many many (you get the drift) hours of careful research, scientists from a large range of disciplines have come to conclude that climate change has, is and will continue to affect marine life.

And these implications seem to reach every kind of marine environment there is – from the open ocean to coastal reefs to estuaries. Particularly concerning are stresses upon species that provide a home for marine animals – for example, kelp forests, among which a multitude of fish and invertebrate species live, are very sensitive to changes in seawater temperature, and so are predicted to disappear from southern Australia if seawater temperatures continue to rise.

Kelp forests are predicted to disappear from Tasmania should the sea temperature continue to rise

Kelp forests are predicted to disappear from Tasmania should the sea temperature continue to rise

Meanwhile in more tropical regions, such as the Great Barrier Reef, corals are suffering from multiple climate change related issues. Increased water temperature can stress corals, causing death of the individual anemone-like creatures that come together to form a coral colony. This occurrence is known as “bleaching”, and is becoming increasingly common and severe. A more recently-discovered phenomenon – ocean acidification – has the potential to devastate corals and other organisms that have skeletons made of calcium carbonate. It isn’t pleasant to think about, but if the corals disappear, so too will all of those who live on and amongst them.

Of course, with environmental science, and science in general, it is difficult to “prove” things beyond all doubt. To reflect such uncertainty, the observations, predictions and forecasts are rated with high, medium or low confidence, and I think that this is a really worthwhile addition to the site. Also included are sections on things that aren’t yet known, and require further research.

This site does make for some scary reading, and I wonder whether a section along the lines of “what you can do”, or “alternative pathways” section might lessen the blow. But then, it could be argued that individual efforts from the public would not be enough to stop the processes that are already in motion – what is needed are global-scale changes introduced by world leaders.

In the meantime, marine scientists will keep working to document our rapidly changing marine environments…

Solved: the problem of the cross-dressing frogs Rebecca McLeod Nov 03

4 Comments

The global plight of amphibians received a lot of attention last year – the official Year of the Frog. Just in case you missed it, amphibians are currently undergoing a worldwide extinction crisis, with 32% of all species threatened with extinction. The reasons for this sorry state of affairs are believed to be many – loss of habitat, increased incidence of disease, competitive exclusion from introduced species, climate change, increased UV radiation, pollution, predation, and overexploitation.

But I don’t want this to be yet another story documenting the alarming state of our global ecosystem. Recently I attended a very inspiring seminar given by Jen Germano – and it gave me hope that innovative approaches to conservation might just lead to some species recovering to healthy levels. Germano is a doctoral student at Otago University who is about to submit her PhD thesis under the supervision of Drs Phil Bishop and Alison Cree, and in collaboration with Landcare Research scientist Dr Frank Molinia.

A Maud Island frog (Leiopelma pakeka)

A Maud Island frog (Leiopelma pakeka)

Germano has spent the past 5 years focusing on ways to improve the success of conservation efforts for New Zealand native frogs (genus Leiopelma). New Zealand currently has 4 species of native frog – all classified as endangered – and 3 species that are believed to be extinct. Our frogs are from an archaic lineage and have a few traits that set them apart from those inhabiting other parts of the globe. Most notably, New Zealand native frogs do not have external eardrums, and therefore do not croak, instead communicating with chemical signals. There is also no easy way to tell males and females apart – there are no colour, size, or other morphological differences between sexes (hence the crass but attention-grabbing headline!), and this has posed problems for those trying to save them.

Jen Germano with some Maud Island froglets (babies)

Jen Germano with some Maud Island froglets (babies)

A proactive approach is being taken to frog conservation in this country, and many organizations are involved with efforts to breed and translocate frogs, to encourage sustainable populations. With other endangered species captive breeding populations have provided a form of “insurance”, but one major problem has arisen for NZ frogs – whilst our zoos have put a great deal of effort into starting captive frog colonies, they haven’t been able to successful breed any of the native frogs. This setback led Germano to develop a method for telling apart males and females based on hormone levels in their urine. The method is relatively non-invasive, and has allowed Germano and her colleagues to sex Maud Island frogs with 94% certainty. The ability to identify the sex of our native frogs is a big leap forward for captive breeding and translocation programs, as now they will be able to provide even sex ratios, which will hopefully lead to higher breeding success. Germano has been passing on her skills to staff at Auckland Zoo and Orana Park, where captive breeding programs are underway.

Germano explains that until recently, very little was known about the basic life history of our native frog species. “While I was working on frog translocations for my Masters project, I saw many of the problems that other scientists were facing when working with these frogs and it was obvious that there were huge gaps in the knowledge that we had for the basic biology of our endemic species and in the information that managers and scientists needed to conserve them.” A large part of Germano’s thesis involved determining the breeding season of Maud Island frogs – and surprisingly she found it is likely to occur in mid winter. Germano has also discovered that Maud Island frogs have incredibly low sperm counts, which may also help to explain why their numbers are so low.

With her PhD thesis soon to be submitted, Germano will be heading to Memphis Zoo in the USA to begin a position as a postdoctoral researcher in amphibian reproductive biology. But she can leave with the satisfaction of knowing that the Maud Island frogs and those working to save them in a much better position than when she began her studies.

The largest remaining population of native frogs in NZ exists on Maud Island, a predator-free island in the Marlborough Sounds.

The largest remaining population of native frogs in NZ exists on Maud Island, a predator-free island in the Marlborough Sounds.

Dissolving marine life Rebecca McLeod Sep 26

2 Comments

Four years ago I went to a Marine Science Conference where a few scientists were talking about the idea of acidification of the oceans. That is how recently we have become aware of this issue that is going to lead to massive changes in the marine ecosystem, should atmospheric carbon dioxide levels continue to rise. The absorption of carbon dioxide into seawater, has the the effect of making seawater more acidic. And that has serious consequences for marine life that has carbonate skeletons (think corals, zooplankton, molluscs, bony fishes…), and also for animals that need these species to survive (like animals that live amongst corals, or feed upon those with carbonate skeletons). Seawater chemistry is changing rapidly, and scientists are predicting massive consequences to marine life within the next 20 years. This film has just been released by the US Natural Resources Defense Council, and I think EVERYBODY should see it. It has the credibility of some leading marine scientists, some amazing footage, and some incredibly sobering truths about how human activity is impacting marine life. A must see.

YouTube Preview Image

Is it wise to ‘mow’ our kelp forests??? Rebecca McLeod Sep 24

2 Comments

Submissions closed on Monday the 21st for a proposal by the Ministry of Fisheries to enter giant kelp (Macrocystis pyrifera) into the Quota Management System. There is demand for giant kelp on the international market, and at least one Canterbury-based business is keen to develop a harvest of live kelp in the near future. On first thoughts, this might seem like a great idea – the kelp can be used for so many things: pharmaceuticals, food products, fertilizers, feed for aquaculture and farm animals… the possible applications appear to be limited only by the imagination.

However, as the story unfolded on Campbell Live on Monday night , it became clear that there are two sides that are clashing over the potential for kelp to be commercially harvested. One side comprises fishermen, scientists and environmentalists who are concerned that harvesting could lead to a loss of kelp forests and the multitude of species that live amongst them. The other side seems to be made up of a small group of entrepreneurs, who can see only benefits when it comes to kelp harvesting. Financial benefits. This is an unusual situation: it isn’t often that environmentalists and fishermen are united in their views. I feel that it is time to inject some science to the debate, to gauge whether the concerns of the objectors are legitimate.

There are currently two MFish proposals that are undergoing public consultation. In the North Island, it has been proposed that drift kelp (that which is floating unattached, or stranded on beaches) be allowed to be collected from all beaches by commercial operators under permit. Whilst such collection certainly has the potential for ecological impact, it is the other proposal that is attracting the most attention from marine scientists – the entry of live growing giant kelp into the Quota Management System, effectively opening the door to commercial harvesting of kelp forests.

Macrocystis kelp growing up through murky water towards the light

Macrocystis kelp growing up through murky water towards the light

In other countries, kelp forests are cut to one metre below the surface either by hand, or using ships equipped with cutting blades. It might seem appropriate then for the practise to be likened to mowing the lawns. Supporters of kelp harvesting here say that giant kelp grows one metre a day, therefore harvesting it will be totally sustainable. But Dr. Chris Hepburn, a marine botanist at Otago University, believes that growth at that rate, in New Zealand at least, is a myth. Despite many years researching Macrocystis growth around the South Island, and publishing on the topic1, he has never come across the original source of that figure, nor measured growth rates anything like it. It is quite likely that the one metre per day figure is an exaggerated value from research in California, where expansive forests are harvested. “Frond elongation rates of 2-10 cm per day are typical for Macrocystis, while maximal growth rates of 40 cm a day may be possible when a kelp frond first grows up through the water column under perfect conditions. Frond rates really have little relevance to how Macrocystis will respond to harvesting – if you chop the top of a frond it stops growing. It’s the rate that a kelp individual can produce new fronds that matters from a harvest recovery perspective.”

Throughout the MFish proposal, references are made to the operation in California, with a suggestion that it provides a model upon which to base any future harvesting here. But is it wise to make comparisons between New Zealand and Californian kelp forests in this way? Dr Nick Shears is a marine ecologist who has recently returned to work in New Zealand from California. Having expertise in kelp forest ecology2, he is in an ideal position to make comparisons between the two. “The giant kelp forests off California are world renowned for their size and productivity – forests span for miles along the coast, grow to depths of 30 m, and individual plants grow up to 60 m in length. In comparison, New Zealand kelp forests are a fraction of the size, the plants grow slower, are smaller and are less dense”. Dr Shears believes that given the differing sizes of kelp forests in California and New Zealand it is difficult to envisage a viable and ecologically sustainable fishery for kelp in New Zealand.

Kelp forests are highly productive, in that they provide a food source and a habitat for a diverse range of marine species, including many fish and invertebrates that form the basis of large commercial, recreational and cultural fisheries. For example, it is thought that crayfish are closely associated with kelp both as adults, and as juveniles, as larvae recruit into the canopy of the forest, and then make their way down the fronds to the seafloor. Blue cod, moki, trumpeter, paua, kina, and greenbone also inhabit kelp forests. Dr Hepburn says that this provision of habitat for other species is a key difference between giant kelp and every other marine species managed under the Quota Management System. “To harvest a habitat is very shortsighted. Imagine a fishery is supported by a coral reef – does it make sense to allow someone to come in and remove the coral for commercial use and risk the fishery? Harvesting Macrocystis risks high value fisheries and ecosystem services provided by the kelp for an unproven product. At this stage it’s a no-brainer – Macrocystis is worth more in the water than spread over paddocks as fertilser, and we simply don’t know enough about how kelp forests will respond to harvesting.”

A multitude of animals live on and among the forest habitat that giant kelp provides

A multitude of animals live on and among the forest habitat that giant kelp provides

Despite the Californian kelp forests having a century-long history of harvesting, questions are now being raised as to the sustainability of the practise. The annual takes reported by the California Department of Fish and Game have regularly exceeded 150,000 tonnes, but have dropped to less than 5,000 tonnes per year since 2006. This sudden decline reflects the major harvester ceasing operation due to a lack of economic viability, which is caused by competition from exporters in Mexico and China. The exit of this harvester from the market will probably be of much relief to environmentalists in the region, who have observed a dramatic reduction in the extent of kelp forests over the last 35 years3. Scientists from the Scripps Institution of Oceanography have identified many environmental pressures that could be causing this decline, including changes in currents linked to the El Niño – Southern Oscillation, increased abundances of sea urchins due to overfishing of their predators, sedimentation, pollution and kelp harvesting. When it comes to kelp forest health, teasing apart the importance of these different factors is proving to be an incredibly difficult task3. One thing is for sure, kelp forests are under pressure, and they are threatened in many places around the globe. In Tasmania, a more than 50% decline in extent of giant kelp over the past 60 years has prompted the State Government to consider listing Macrocystis kelp forests as an endangered habitat type. They are already listed alongside the Great Barrier Reef as a Special Marine Area. Whether kelp has suffered similar declines in New Zealand has not been monitored by scientists, although there is anecdotal evidence of kelp forest loss in the Otago region.

Back in New Zealand, Dr Hepburn has many concerns about what might happen if you harvest kelp. Unlike California, the East Coast of the South Island has a lot of sediment in the water, which acts to limit the amount of sunlight reaching kelp, and frequent storms act to resuspend the sediment into the water column. The growth of Macrocystis kelp is limited by the amount of sunlight1, meaning that in times when there is a lot of sediment in the water, such as following rainfall or a storm, kelp growth rates slow. “My concern is that were a harvesting event to coincide with a period of high sediment load in the water, the kelp would not receive enough light to promote regeneration and the forest would therefore be at risk of dying off.” There is also the issue of the invasive kelp Undaria. This highly opportunistic species may take advantage of a temporary reduction in giant kelp, and out-compete the species. Such a shift in kelp assemblages, would not necessarily correct itself over time. There are a lot of uncertainties about how kelp, and the species associated with the forest habitat it creates, will respond to harvesting, yet surprisingly little research that could help to address these concerns. The only relevant study was conducted in Akaroa Harbour – a wave sheltered environment that is very different from the exposed coastlines along the extent of the proposed harvesting areas. To progress with harvesting along the East Coast of the South Island appears to be incredibly risky, particularly when the size of associated fisheries are considered. Is it wise to risk the multi-million dollar blue cod and crayfish fisheries, for a market that is yet to be tested?

Many prominent marine scientists have voiced their concerns with the Ministry of Fisheries about the current proposal, along with fishermen, environmental groups and iwi. This large, diverse group of objectors is at odds with one small group of supporters, whom stand to benefit financially from a positive outcome. It will certainly be interesting to see the outcome of this process of public consultation – will the Ministry listen to the voices and experience of the opposition and consider the lack of scientific testing of the sustainability of kelp harvesting when they make their decision? Furthermore will the Ministry adhere to their own management objectives – to protect and maintain habitats that are significant for fisheries? It certainly seems to me that there is a lot at stake.

References

1. Hepburn CD, Holborow JD, Wing SR, Frew RD, Hurd CL (2007) Exposure to waves enhances the growth rate and nitrogen status of the giant kelp Macrocystis pyrifera. Marine Ecology Progress Series 339:99-108

2. Salomon AK, Shears NT, Langlois TJ, Babcock RC (2008) Cascading effects of fishing can alter carbon flow through a temperate coastal ecosystem. Ecological Applications 18(8): 1874-1887

3. Dayton PK, Tegner MJ, Edwards PB, Riser KL (1998) Sliding baselines, ghosts, and reduced expectations in kelp forest communities