Tag Archives: Marine Conservation

Where the wild things roam: Dispersal, connectivity, marine protected areas, and my PhD project


In my last post I mentioned that I am starting a PhD.  I promised to tell you a little more about what my research will be looking at, so here we go!

The project outline

My research comes very broadly defined already – the work’s raison d’être if you like.  Here it is:

“Movement and dispersal connects marine populations, allowing restoration of depleted local populations by immigrants that renew genetic diversity. Although Canada’s Oceans Act prioritizes ‘linking Canada’s network of marine protected areas (MPA)’, connectivity has not weighed significantly in MPA network design in Canada. This study will optimize regional marine connectivity among protected areas in the Atlantic region by determining optimal locations for new MPAs and evaluating how commercially important species would be representative in the entire MPA network. To model species distribution based on larval dispersal, fishery pressure, and climate change, we will use 3-D ocean circulation models. Then, based on metapopulation theory, we will develop novel spatial network algorithms to optimise the number and spatial connectivity between MPAs under current and future scenarios of climate and fishery pressure that may alter larval supply”.

Sounds complex?  Yep, for me too. Continue reading Where the wild things roam: Dispersal, connectivity, marine protected areas, and my PhD project

On being MIA – and what’s next

Hello my fellow readers

You may have noticed that I have been away for some time.  Some of you have even gotten in contact with me to find out why, and encourage me back – thank you!  Your words of kindness and encouragement were very much appreciated.  I honestly did not mean to disappear for so long, but I did get incredibly busy.  I thought I’d share with you all some of the questions I’ve been asked during my time away – and my responses! Continue reading On being MIA – and what’s next

How special is a ‘Special Area of Conservation?


This week it has been brought to my attention that there is a proposal to dredge for scallops inside a ‘Special Area of Conservation’ located in Cardigan Bay, Wales.  This proposal has divided opinions.  On Twitter this week Professor Callum Roberts, a marine conservation biologist at the University of York (UK) lamented that there was ”No hope for UK marine conservation if this mad proposal to scallop dredge in a protected area goes ahead” .  Dr Magnus Johnson, a Crustacean Fisheries and Ecologist researcher at the University of Hull (UK) quickly countered “It is worth reading the science by first!”, following with a couple of hashtags “#eatmorefish #eatmoreshellfish”.  Two scientists, with two opposing views… what is going on?


What is a Special Area of Conservation anyway?

These are something unique to the European Union.  They arise from the Habitats Directive, first adopted in 1992 in response to a European convention called the Berne Convention.  Special Areas of Conservation (SAC) are designed to protect a number of habitats and species (plants and animals) considered endangered, vulnerable, rare, or endemic.  Once a SAC has been formally designated, the establishment and implementation of management measures are largely left down to the individual Member State.  However, there are certain things that they must do.  Briefly, under Article 6 of the Habitats Directive, these include:

Continue reading How special is a ‘Special Area of Conservation?

Oh Canada – what about your ocean?

This is a big post.  It’s about big things.  Important things too.  It deals with Canada – a big country.  Actually by area, it is the second largest country in the world.  It also has a lot of ocean under its jurisdiction.  Take a look at the website of Fisheries and Oceans Canada, a Federal government body, and you will see statements like this:

“The Government of Canada is working to ensure the future health of Canada’s oceans and ocean resources by increasing understanding and protection of our oceans; supporting sustainable economic opportunities; and demonstrating international leadership in oceans management”

Sounds good doesn’t it.  The Canadian Federal Government (which has just changed as of yesterday – see bottom of the post) have a several Acts in place to govern the bit of the ocean they have claimed as theirs.  Great stuff!  Except maybe, as demonstrated in a recently published paper, authored by 19 Canadian scientists including lead-author Megan Bailey (Dalhousie University), “over the past decade decision-making at the federal level appears to have undermined the government’s own mandates for the sustainable management of Canada’s oceansContinue reading Oh Canada – what about your ocean?

Community-based conservation to rebuild fish stocks

I don’t know about you, but I wouldn’t mind being there right now. This is one of the Fijian islands in the Pacific, and the second largest in the group.  As serene as the picture is, not all is serene for the Islanders.  Fishers in Nagigi, a small community based on the south coast of Vanua Levu Island have been noticing that the number of fish and the size of fish have been decreasing, and habitat degrading – a big problem for a community heavily dependent on its marine resources.  This decline isn’t necessarily down to big foreign boats coming in and taking the critters on which they depend.  Instead, overexploitation and habitat destruction seems to arise from the ever-increasing number of locally based fishers.  The source of this claim?  The villagers of Nagigi.

In this paper,  Abigail Golden from Columbia University and fellow researchers explore the idea of setting up a short-term no take marine protected area within Nagigi’s coastal tenure area (known aqoliqoli ).  This idea hasn’t come from the researchers nor from any top-down government as tends to happen in western countries.  Instead the idea has come from the village leaders themselves.  This sort of bottom-up governance is far from unheard of.  The Pacific Islands are small and numerous, and have a long history of small areas of land and coastal waters managed by local communities.  Some have worked well, some have not, and many have come under strain or been lost through both technological developments, increasing population, increasing demands for resources, and cultural change.  Still, a well-managed community based MPA can work well, particularly in these remoter locations, and especially were more rigorous research and recording is absent.  Regardless of where you are in the world, there are a number of vital steps needed for good management.  One involves getting as much information as possible – about the species that are there now, the fishing methods used, an idea of how conditions have changed, and perceptions towards different management methods.  The other involves bringing the local community into the conservation planning in a meaningful way.  So the team went out and conducted two types of surveys – one looking at the species living on the reef at the time, and one talking to some of the villagers themselves. Continue reading Community-based conservation to rebuild fish stocks

Old fishing line hints at fishing levels inside no-take marine protected areas

Dealing with overfishing and destructive fishing practices are a huge issue for marine conservation and management.  Tackling this problem, and trying to repair some of the damage is no easy task.  We know that if they are done properly, no-take marine protected areas can make an impact, not only reducing habitat degradation by removing damaging fishing techniques, but also increasing the density and even the individual size of species targeted by fisheries.   The benefits these no-take zones provide can spill over to fishers too.  And that’s not just a scientist point of view either – take a look at this short (5 minute video) focusing on lobster potter Geoff Huelin who fishes around Lundy Island – the UK’s first no-take zone.

There are many factors that can make or break a no-take zone.  In the video Geoff touches on just one of those factors – policing the zone to make sure that people are abiding by the regulations.  This is important.  It’s no good having regulations to protect an area from fishing if fishing happens there anyway.  It is the action of people – not the designation itself per se, that makes an appreciable difference to marine biodiversity recovery.  Geoff tells us that for the Lundy Island no-take zone enforcement isn’t a huge challenge because the no-take zone is viewable from the shore.  There is, Geoff tells us, usually somebody watching.  But this can’t be said for all no-take zones.  It’s not just distance from the shoreline that can impact on enforcement capabilities. Lundy’s no-take is small.  Some no-take zones are huge, and very often manager’s budgets and resources are limited.  Take the Great Barrier Reef Marine Park for example, which suffers hundreds of infringements of its regulations each year.  Sure both commercial and recreational fishers who break the regulations inside the Park are successfully caught every year using a host of different surveillance techniques, but many more are likely to go unnoticed.  Getting a handle on the scale of non-compliance is the very issue explored in this recent paper by David Williamson from the ARC Centre of Excellence for Coral Reef Studies and fellow researchers.

The research team focused their efforts on several fringing coral reefs in the Great Barrier Reef Marine Park – those around the Palm Islands, the Whitsundays, and the Keppel Islands. You may have heard of these places.  Beautiful and fairly accessible from the mainland, these areas are popular with tourists and locals alike.  Although all managed by the Park authority, the fringing reefs around these Islands aren’t all no-take, and the Aboriginal people’s of the Palm Island group have fishing and hunting rights across the whole Park – including inside the no-take zones.  The researchers needed a way to estimate fishing effort inside the no-take parts of these reefs, and for this they needed some evidence… evidence in the form of derelict fishing line from hook and line fisheries.  The first thing to do was to calculate the density of derelict fishing line both inside the no-take zones and outside.  So in the water they went and surveyed the derelict line.  Some statistical analysis later, and the team had an estimate of hook and line fishing activity both in and outside no-take zones on the reefs across the three island groups.

In the Whitsundays and the Palm Island, the no-take zones that had been around for over 20 years had the lowest density of fishing line within them compared to zones established 5 years before the surveying, and ‘normal’ sites.  Interestingly no-take zones that had been established for only 5 years didn’t show any significant difference in line density when compared to ‘normal’ sites.  But fishing line is typically made from hardy stuff, and doesn’t easily break down.  The researchers note that 99% of the fishing line found had accumulated algae and sessile organisms on them, and/or become partially embedded in the reef matrix itself.  This indicates that most of the line had been there for months or even years, but ascertaining just how long is difficult.  Some of the line likely was there prior to establishment of the no-take zones but just how much… well that is a difficult question to answer.

The team did not stop with simply working out the density of fishing line though.  Around the Palm Islands the researchers used the assistance of Reef Check Australia – a citizen science organization that is heavily involved in marine monitoring – to remove derelict fishing line from both no-take zones and monitored the sites to see just how quickly fishing line accumulated in the no-take zones and in the areas outside them for some 3 years.  Here the rates of line accumulation between the no-take zones and the other cleaned ‘normal’ sites were, statistically speaking, “marginally non-significant”.  In arguably more real terms, the researchers note that the rate of fishing line that accumulated inside the cleaned no-take zones was 32.4% of that accumulated inside the ‘normal’ cleaned sites. And 32.4%, say they researchers, is worrying for a zone that is supposed to be a no-fishing area.  But what about those Aboriginal fishers that have a right to fish inside the no-take zones – couldn’t some of the line be from them?  Well yes, though the authors note that at least from personal observations not all of the no-take zones they cleaned and monitored were regularly used by Aboriginal fishers.  What all this points to, the researchers argue, is that non-compliance with no-take zones isn’t just an issue in the more remote parts of the Great Barrier Marine Park.  They also note that when assessing how effective a no-take zone is in restoring marine biodiversity, it is worth taking into account the level of non-compliance with regulations as best one can.

This paper (including an open access link to their data) was published in the open access journal PLOS ONE.  You can read it here http://dx.doi.org/10.1371/journal.pone.0114395

Image:  The Whitsundays.  Credit Richard Rydge/Flickr (CC BY-NC-ND 2.0)

How not to hit a whale:  Move the shipping lane

Coming in at around 170 tonnes The blue whale (Balaenoptera musculus) is the heaviest animal known to have existed on Earth.  This huge critter feeds on some of the smallest, filtering zooplankton through its baleen plates that hang from its upper jaw.  The blue whale as a group (there are several sub-species) is unfortunately listed as Endangered on the IUCN Red List.  Commercial whaling certainly took its toll on the global population and was, without a doubt, the most threatening of human activities to these large enigmatic creatures.  With commercial whaling now largely ended, the human threat to their persistence has declined greatly.  But there are still incidents between humans and the blues, like entanglement in fishing gear and marine litter, noise pollution that can hamper their communication, and ship strikes.  Certainly the recovery of the blues in the eastern North Pacific isn’t as good as we would expect, but the reasons for this somewhat lacklustre comeback are much harder to pin down.  Many avenues need to be explored – including seemingly infrequent events like ship strikes.

Ladd Irvine of Oregon State University and a team of researchers wanted to take a closer look at blue whale movements off California, an area which also contains a great deal of shipping activity.  When looking at movement of any population, it’s really important to get as much historical data as possible because animals can vary their movements year on year.  The team used 15 years’ worth of data collected from 171 tagged whales.  These satellite monitored radio tags are pretty nifty pieces of kit, collecting the time and location of the whales at the surface and transmitting to satellites.  With this wealth of data, the team set to work figuring out which areas of the Californian coast are particularly important to blue whales.  Sure enough, some rather interesting patterns emerged.

Blue whales are attracted to the west coast of the US during the summer months to feast on the large numbers of krill found in the California Current System.  The krill are super-abundant during this time as a result of upwellings that increase productivity in the region, and by currents and the bathymetry (equivalent to topography – how the sea floor looks) of the area that concentrate the krill into certain areas.  As you might expect, the blue whales concentrated in areas where krill was most abundant.  Early in the summer the whales tended to stay in the more southerly sections, where upwelling intensity (and thus productivity) is fairly moderate.  During October and November the northern section of California experiences much stronger upwellings, and sure enough that’s exactly where the whales tended to hang out.  The whales don’t just head up north around the same time every year though.  Because the tracking data spanned 15 years, the researchers were able to compare movements over multiple years.  The timing of the more intense northerly upwelling varies year on year, and it was quite apparent that the whales tailored their northerly migration in line with this variation.  With variation in krill availability, you might expect that the whales would stay in California waters as long as krill abundance was high enough to give a decent meal.  Interestingly, the whales didn’t really alter when they continued on their migration out of California in line with productivity timings.  There was only one notable time when they did leave significantly later – in 2004.  What’s so special about 2004?  Well not much.  There was a weak  El Niño, but the researchers note that it didn’t really have an impact in the California Current System.  1999 was a super-productive year in the California Current System and no doubt prey was super-abundant.  Did the whales hang out there for longer than usual?  Nope!

So far so good, but the tracking data also revealed some potential issues.  The blues tended to be most concentrated alongside areas where human population is high, and where there are busy ports.  Busy ports means busy shipping lanes, which run straight through the places where the whales can be found.  Now remember that ship strikes are thought to be relatively infrequent, but the question is how do we know if there has been a ship strike?  Well first of all we have to know we have hit a whale.  Sounds daft, but if you’re in a huge freight vessel you might not notice.  You might also hit a whale and injure it (with unknown survival), or you might fatally hit a whale, and just not report it.  We do have evidence that on the whole ship strikes are on the increase, and this paper makes a seemingly simple suggestion to reduce the likelihood of a strike on a blue whale: move the shipping lane during the months when the whales are migrating through.  Of course such a move is an economic, political, and social minefield, but it’s not impossible – and there is a prescient.  Twelve years ago shipping lanes in the Bay of Fundy, Canada were moved just 6 km away from a key North Atlantic right whale feeding ground.  Since then, the right whale population has shown a small increase.  Of course correlation doesn’t imply causation, but it is food for thought.

This paper is published in the open access journal PLoS ONE.  Have a read of it here http://dx.doi.org/10.1371/journal.pone.0102959

Image:  Blue whales aren’t the only whale species to be susceptible to ship strikes.  This image shows an North Atlantic right whale (Eubalaena glacialis) who died after colliding with a vessel and suffering significant propeller cuts.  Credit: NOAA National Marine Sanctuaries/Center for Coastal Studies (Public Domain Licence)

Marine conservation and the human equation

People are as much a part of this planet as any other species.  We are ecosystem engineers, modifying and creating new environments to suit our needs.  We are incredibly adaptable, and our ability to make tools – both simple and technologically complex – has allowed us to prosper and rise above many of the restrictions that limit other species.  This doesn’t mean we can now act completely in isolation from the rest of the world.  Many of our activities have altered ecosystems in ways that mean they are less likely to meet our current and future needs.  Conservation efforts are attempting to remedy many of the problems we have created, but conservation isn’t just about nature – it’s about people too.

Nathan Bennett has been actively researching the links between the environment and human societies for many years.  His work takes a perspective that historically has often been forgotten in conservation management; what about humans.  This isn’t about developing opportunities of industry – it’s about conservation initiatives that look to sustain environment and communities together.  This week he has shared three of his papers on his blog – one from 2013 and two from this year.  Thanks to Nathan, all three are now open access…all three very much worth a read.  Here’s a brief overview of each paper to whet your appetite.

The trouble with marine protected areas
So here’s the deal.  We can find an area of the ocean that is becoming heavily degraded because of human activities.  To try to reduce the damage and allow recovery we can place a boundary around that area and place restrictions on the sorts of activities that take place inside.  But what of those people whose activities have been displaced?  We aren’t just talking about recreational fishers here.  In some circumstances, communities which are heavily dependent on the marine environment can be affected.  In this paper, Nathan and his colleague Phil Dearden surveyed coastal resource dependent communities living on the Andaman Coast of Thailand – an area which boasts 17 National Marine Parks.  The perspective of these people makes for grim reading.  They saw little benefit in the parks for their community, they felt that fishing and harvesting was negatively impacted by the parks, and they felt little incentive to support let alone participate in conservation efforts.  What needs to happen, writes Nathan and Phil, is for managers to start including socio-economic development considerations within protected area management planning.  This won’t just be better for the communities, but better for marine conservation.

It’s not just about how vulnerable you are, it’s what you can do to adapt
We’re back to the Andaman Coast of Thailand again, this time to consider their vulnerability and ability to adapt to climate change.  There are a whole host of different factors that can affect a community’s ability to adapt to climate change – and indeed any other sort of stressor.  Some of these are biophysical – climate change related impacts such as coral bleaching, or increasing number of storms, as well as environmental impacts such as marine pollution and overfishing.  Some of the factors are economic – like increasing costs of fuel, social – like increasing immigration, and some are related to governance, like corruption, policies, or illegal fishing.  Nathan and the team wanted to find out how communities felt about stressors.  They surveyed 237 households across 7 coastal communities to ascertain which of the 36 stressors identified in the region were considered having highest impact on the communities.  The results were a bit of a mixed bag, and despite the communities being just 10 km apart, differed between each community.  There were a few common factors though.  Many of the stressors were heavily intertwined.  Climate change impacts like more extreme storms and changes to rainfall were rated highly in the stress-rankings.  Economic factors – particularly rising costs – also came out as a major concern among all the communities.  Interestingly somewhat in contrast to the study above, marine protected areas were not really felt to be causing too much trouble.  What about overfishing?  Not a concern either… but then again the fish populations declined long ago, so overfishing isn’t really an immediate concern any more.  The thing about these sorts of stressors is that they aren’t really something that the community can deal with themselves.  They are part of wider regional and global problems.  From an adaptation perspective, this raises a number of issues.  There is not a ‘one adaptation plan to fit all’, but there are common factors that need to be looked at beyond the communities themselves.  Equally important, if we want to help communities to adapt, we cannot treat one stressor as separate from another.  A more integrated approach is vital for the success of any adaptation plan.

The eco-social economy:  How conservation can aid social and economic development
In this final paper the focus is turned to the Northwest Territories Canada and the Lutsel K’e Dene First Nation.  There have been plans afoot for their traditional territory…plans for a national park/protected area.  This is an old idea, and one that back in 1969 when the Government of Canada (Federal Government) tried to implement met with the opposition of the local people, who were successful in preventing the creation of a park.  In 2006, the First Nation and the Government of Canada signed a Memorandum of Understanding to look at implementing a park on those very same territories.  So what happened?  This new proposal has come from the local people themselves – a bottom up rather than top-down approach to conservation.  Through this collaborative process the park is taking an eco-social perspective to conservation.  Here, people aren’t just seen as the cause of degradation, but are seen as part of the ecosystem, impacted by the degradation.  The national park is not yet set up but is moving forward.  When it is, it is hoped that the park won’t just protect nature and the Lutsel K’e Dene First Nation culture, but work to meet social and economic development goals.

If you want to follow more of Nathan’s work head over to his blog http://nathanbennett.ca.  There is a follow option which will automatically update you of any new posts.  Now there’s some emails worth getting.

Image:  The Lutsel K’e Dene on  Great Slave Lake, Northwest Territories, Canada.  Credit:  Leslie Philipp/Flickr (CC BY 2.0)

Are marine protected areas protecting the places that need protecting?

Marine protected areas (MPAs).  They sound like a pretty good thing for biodiversity conservation…right?  As always the devil is in the detail.  It first starts with what a MPA actually is.  Well we have already stumbled into slightly tricky ground here, because there is not one single globally recognised definition of MPAs.  For arguments sake we’ll go with the International Union for Conservation of Nature definition:

“A protected area is a clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values”

Ok… seems pretty straightforward, but look carefully – it’s a little vague isn’t it.  What are these ‘other effective means’ that you can manage the area?  What about the phrase ‘long-term’ – what scale are we talking here?  What do we do if there is conflict between ‘ecosystem services and cultural values’?  The IUCN have categorised MPAs into seven different types, based on the primary management objective of the area.  These range from fully protected areas where no extraction of any kind is allowed, right down to “sustainable use” zones.  If you want full details including the sorts of activities that are allowed in each MPA type, I’d recommend reading the ‘Guidelines for Applying the IUCN Protected Area Management Categories to Marine Protected Areas’.

So to sum up, MPAs differ if how much protection they offer, and some may in reality not offer much more protection than you get in the rest of the ocean anyway.  This might seem a little daft – after all, why bother setting up a MPA if it really isn’t adding any substantial conservation value – to biodiversity of cultural values?  The answer, as it often does, may lie in politics.  There is a wealth of transnational and international agreements set in place through which nation states have agreed to implement MPAs – and with good reason.  MPAs are one of several excellent tools we have through which we can manage our interactions with the ocean, reducing our footprint on it.  The problem comes when nations set MPAs that are meaningless in terms of conservation purely to meet targets.  This includes placing MPAs in areas where even under strict protection, the conservation benefit is minimal.

Rodolphe Devillers of Memorial University of Newfoundland and colleagues in the USA and Australia have recently analysed the motivation behind the placement of MPAs.  The areas of the ocean under the greatest threat are by virtue the areas of the ocean that are most highly utilised – and not just by fishers.  There are a number of human activities that take place in and around the ocean that harm the ocean environment including oil and mineral extraction, and dumping.  Understandably, these are the areas where MPA placement will receive the most resistance.  Conversely, placing MPAs in areas that aren’t really used – and thus not necessarily as threatened as other places – would likely meet less resistance.  Such areas are ‘residual’ to commercial purposes.  The placement of the MPA has little to no impact of stakeholders.  In other words, it’s business as usual.  So which is it?  Are managers going for the path of least resistance, or are they battling to protect the areas which need the most protection?

The researchers assessed this question from a decidedly Australian perspective.  First, the looked at MPAs located across the globe.  They then took a much more regional approach, looking at MPAs within Australian waters.  Finally for a more local look, they assessed the Great Barrier Reef Marine Park.  What they uncovered was (perhaps unsurprisingly) a little damning for managers.  At both a global and regional scale, MPA placement was largely done following the path of least resistance, placed in the areas where human activities were not so prevalent.  This includes all of these very large MPAs that we see being set up across the world.  Whilst large in scale, different parts of the protected areas allow different activities (known as multiple use).  The areas that are the most restrictive tend to be located in the places where we aren’t busy extracting resources.  But all is not lost.  The Great Barrier Reef Marine Park – a multiple use zone – was called ‘exemplary’ by the researchers for its planning and zonation.  Although there were some discrepancies between bioregions (large-scale areas defined by features and processes ) covered by the Park, overall protection was placed at a scale for the area it covered.  It might be worth noting here that the research for this paper and it’s acceptance by the journal for publication occurred before the recent ‘dumping fiasco’ within the park boundaries.

An argument can be made that protecting areas not currently heavily exploited, and thus not as threatened as areas heavily exploited is a form of pro-active management.  Pro-active management is a good thing – and should be encouraged.  Pro-active management means that we aren’t sitting around waiting for an ecosystem to be so severely damaged (sometimes with no chance of recovery) before trying to do something about it.  It may very well be that some of the ‘residual’ MPAs are placed under the goal of pro-active management, but this is not the case for the majority.  Balancing social, political, economic, and ecological needs and concerns is a difficult business.  Invariably in any decision-making process some aspects will come out as ‘more important’ than others, but to consistently ignore the ecological side is, in the long-term, pure folly.  And it is wrong to claim that we as a species are effectively conserving the very resources on which we depend when we are in fact merely paying lip-service.

This open access paper was published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems.  This is a very well written paper and unlike some science papers, not overly verbose.  It explains the complexities of ocean management well – very much worth a read.  http://doi.wiley.com/10.1002/aqc.2445

Image:  Gray’s Reef National Marine Sanctuary, located off the coast of Georgia.  Credit: NOAA

Restoration ecology – bringing back lost undersea worlds

Indulge me a little… lets travel through time and (depending on where you are) space.  First stop – it’s the 1960s and we’re in Sydney, Australia.  We head out to some shallow, subtidal rocky reefs and we see an abundance of seaweed – specifically crayweed (Phyllospora comosa).  This crayweed is quite substantial in size, typically reaching 1-2 meters long.  Living for around two years, these guys produce all year round, providing not just a high level of canopy cover but also extensive cover.  The expanse of crayweed isn’t just limited to Sydney, stretching for some 2,500 km along Australia’s east coast.  Crayweed provides an underwater forest, and just like forests the habitat is important for a whole host of other organisms – invertebrates, fish, molluscs.  Come down to these waters and you see a fantastic show of marine biodiversity.

It’s now the early 1980s and we are back in Sydney.  Again we head out to those shallow, subtidal rocky reefs but this time something is amiss.  The crayweed is gone.  We hear about near-shore sewage outfall in Sydney and how the volume of outfall peaked in the 70s and 80s.  Is there a connection?  Well possibly.  It’s quite tricky to point to a single, definitive cause for such thing, but it turns out that pollutants found in sewage are detrimental to the crayweed’s embryos.  No embryo’s means no offspring and with a two-year life-span…well you can see where that ends up.

Moving forward to the 1990s.  Sydney has improved its sewage infrastructure.  Sewage is now being pumped into the deep ocean; near-shore outfalls are being taken out.  Water quality is on the up, and there is hope for the crayweed.

It’s now the mid-2000’s.  The crayweed has not returned to Sydney’s shallow subtidal rocky reefs.  In that 2,500 km band of crayweed that stretches from Port Macquarie (New South Wales) to Robe (South Australia), the 70 km gap along Sydney is about as conspicuous as it gets.

Moving forward now to 2011 and there is still no signs of recovery.  Time for Alexandra Campbell from the Sydney Institute of Marine Sciences and colleagues to step in.  They plan to try something bold, something controversial – restoration of the crayweed.

The first thing the researchers needed to do was determine if the crayweed could survive in the Sydney area.  For this, they transplanted some adult plants from two habitats near the edge of Sydney and placed them in one of three treatment locations.  The first group went to Sydney itself (two locations), one to an area where crayweed currently resides (two locations) and finally, one group returned back to the area they were removed from.  That final step might sound a little strange, but if transplanted crayweed can’t survive and reproduce where it originally came from there is a problem.  It also gives the researchers another benchmark to work from in determining just how well crayweed does in the new areas around Sydney.  The transplantation was repeated twice.  The first time (between February and May 2011), the researchers visited each of the transplantation sites every -4 weeks and recorded some important survival information.  At the end of this stage of the experiment, the transplanted individuals were collected up and their length measured.  Some had their ecopyhsiological condition assessed by testing their photosynthetic capabilities.  In the second stage of the experiment (August 2011 to January 2012), the transplant sites were visited every 5-10 weeks and again important survival information collected.  In addition between February 2012 and August 2012 the researchers also calculated the density of crayweed recruits, and their distance from the transplanted patches.  And just to see how they well they were growing, the length of the recruits was also measured.

The results are a bit of a mixed bag, but overall positive.  At one of the sites in Sydney transplanted individuals did well – not just surviving but reproducing at a greater rate than their counterparts in their original area.  18 months after transplant around half of the recruits had grown four times their length than they were at just 6 months old.  Good stuff.  The same can’t be said for the second transplant site in Sydney though.  After 6 months, both survival and reproduction was low, with all the crayweed seeming to have suffered from herbivory (they were being eaten by fish).  So, some parts of Sydney’s subtidal reefs may be more suitable for transplantation than others.  The researchers note that this is not an insurmountable problem though.  Excessive herbivory isn’t an issue unique to this study.  With a reduction in their predators largely due to overfishing, herbivores can run rampant in many areas.  Adding the crayweed provided them with a new, delicious, and compact source of food that was all too quickly gobbled up.  One simple answer might be to increase the size of the transplant so that some plants survive becoming dinner.  Another problem might be a lack of adult plants that can offer canopy cover to recruits.  Even in the area where recruitment was good, most were found on or in the edges of the canopy provided by the adults.  If we want the restoration to be even more successful, the authors suggest, more research into reproduction and recruitment needs to be done.

One of the controversies around restoration is the cost.  How much should we spend of restoring ecosystems lost or in decline?  Well the researchers believe that transplantation of crayweed is a cost-effective measure.  They calculated that all in, their method cost AUD 38,000 per hectare – and believe this will likely reduce as methods develop and improve their efficiency.  The most direct pay-off for people?  These habitats are important for commercial and recreationally caught species.  If successful, this sort of restoration could help boost these industries – and the provision of food – for Australia.

This paper is published in the open access journal PLoS ONE.  If you fancy having a read of it, you can find it here: http://dx.doi.org/10.1371/journal.pone.0084106


Image: Transplanted seaweed is attached to a reef by a team member.  Credit: UNSW, made available with the media release on this paper.  Photographer unknown.