Category Archives: Marine Life

Just keep swimming

This little critter is a limpet.  From the photo they may not look like the most exciting of creatures.  If you’ve ever been down to the coast and taken a look at them yourself… your opinion may not have changed.  They don’t seem to move around a lot, or do a lot.  Of course looks can be deceiving.  Under that shell is the limpet’s squishy body – and their big, muscular foot which, alongside a pretty amazing adhesive secretion, they use to cling onto rocks and other hard surfaces.  Anyone who has ever had a go at trying to get a limpet off a rock knows how good a grip they can have.  This fabulous foot isn’t just used to stop them from drying out when the tide leaves them exposed to the air, or keep pesky predators (or nosy humans) at bay.  Limpets are grazers, feeding on tiny algae on the surface of rocks with their raspy “tongue” (called a radula).  See that empty space behind the limpet in the photo?  That’s where it’s been grazing.  Once they have grazed an area they need to find more food.  That foot gets to work, and along moves the limpet, munching up all the algae in its path.  Some limpet species even appear to have a home – a particular crevice that they return to just before the tide will expose them to the air.

But this isn’t a post about how amazing limpets are.  This is a post about animal movements in the ocean.. Or at least 3 different types of animal movement.  Some of them move a lot further than you think.  Yes, even limpets.

Continue reading Just keep swimming

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

What 415 million year old fossil plankton tells us about heavy metal pollution and extinction

These weird looking things are plankton – from the genus Ancyrochitina to be a little more precise.  They are also fossils – approximately 415 million old, from a period known as the late Silurian.  That’s pretty cool in itself (at least I think so), but what makes this really interesting is that the individual on the left is malformed, whilst the one on the right is ‘normal’.  What is even more interesting than that, is that these malformations coincide with the initial stages of extinction events.

Led by Thijs Vandenbroucke (researcher at the French CNRS and invited professor at Universiteit Gent | Ghent University) and Poul Emsbo (US Geological Survey), an international team of researchers have taken a look at these malformed (known as ‘teratological’) fossil plankton.  They wanted to find out what was causing these malformations. Continue reading What 415 million year old fossil plankton tells us about heavy metal pollution and extinction

A brighter future for the shy albatross

Predicting the future is a tricky business.  As then United States Secretary of Defence Donald Rumsfeld famously said “There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don’t know. But there are also unknown unknowns. There are things we don’t know we don’t know” .  Then there is the interactions between all the variables that determine the outcome of a particular event.  However, few things work in isolation and species decline often results from the accumulation of different stressors.  If we want to put in place conservation management measures that are effective in the long term, then we need to be able to put our known (and measurable) stressors together and figure out what, cumulatively they mean for our potentially at risk species.

The shy albatross (Thalassarche cauta) is an endemic to Australia, breeding on just three Tasmanian islands, including the aptly named Albatross Island.  The albatross of Albatross Island have a long history of human interest.  In the early 19th century adult albatross were extensively hunted for their feathers and egg, taking their numbers down from an estimated 11,100 pairs to just 400.  The population is now recovering, but still faces a number of possible threats.  High on this list are two issues – changing climatic conditions, and the accidental capture of the albatross in longline and trawl fisheries.  To understand just what the combined impact of these stressors could mean for this vulnerable bird, Robin Thomson and colleagues from CSIRO Marine and Atmospheric Research​​​, together with the Tasmanian Government Department of Primary Industries, Parks, Water and the Environment (DPIPWE) put together a model that can hopefully direct management to ensure these birds survive in the long term.

Continue reading A brighter future for the shy albatross

The travelling life of the tiger shark

At 9 foot long, not including the tail, tiger shark (Galeocerdo cuvier) Harry Lindo is not exactly on the small side.  It’s not Harry’s size that is exciting scientists and shark enthusiasts, nor a photograph taken in 2009 by Ian Card showing a shark – suspected to be Harry, trying to eat a 150 lb juvenile tiger shark off the coast of Bermuda.  Between 2009 and 2012 researchers tagged 24 tiger sharks with satellite transmitters in the Challenger Bank, which lies just off Bermuda in the Atlantic Ocean.  In study lead by James Lea (The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Center) and team of international collaborators, those shark movements have been compiled and analysed.  Harry, it turns out, is one heck of an ocean wanderer.  In just over 3 years Harry swam over 44,000 kilometres – that’s more than the circumference of the Earth (just over 40,000 kilometres).  Harry’s track is the longest recorded for a tiger shark, and probably the longest ever published for any shark species.

Continue reading The travelling life of the tiger shark

Cool critter of the month: the chambered nautilus (Nautilus pompilius)

Phylum: Mollusca

Family: Nautilidae

Where do they live?
These ocean dwellers can be found throughout the Pacific and Indian Oceans.  As it turns out, there are two sub-species of (Nautilus pompilius).  Nautilus pompilius polpilius is the larger of the two subspecies.  These guys can be found in the Andaman Sea down to Western Australia in the Indian Ocean, and from southern Japan down to Northern Australia in the Pacific.  Nautilus pompilius suluensis has a much more restricted range, staying in the Sulu Sea between Malaysia and the Philippines.

Continue reading Cool critter of the month: the chambered nautilus (Nautilus pompilius)

With ever-warming waters, some European fish are on the move

We all have our favourite types of environment and weather.  Some love those warm, sunny days spent on a beach of golden sands.  Some love those rainy days in the forest, when everything glistens with the raindrops.  Some love nothing more than a cold crisp day in snowy mountains.  We humans are lucky.  We can not only survive but enjoy a wealth of different environmental conditions.  Many other species are not so adaptive.  In the oceans some creatures live in the seabed itself, others on top.  Some may stay in the water column dominated by a particular type of habitat like a kelp forest, whilst others roam into a variety of different locations throughout their lives.  Then there are the varying conditions of the ocean itself.  Some areas are generally calm whilst others may experience a lot of movement.  Salinity levels also vary, as does oxygen, as does temperature.  Actually temperature – as many a fisher will know – is a super important driver of species distribution.  There are a few reasons for this.  First, unlike us, most fish do not have the ability to control their own body temperature.  Their internal body temperature reflects that of the environment they are in.  The second primary reason relates to food.  If the major food of a fish – be it plant (phytoplankton) or animal – changes its abundance (how many) or its distribution (where it is), then the fish may follow. Continue reading With ever-warming waters, some European fish are on the move

Cool critter of the month: Slipper Limpet (Crepidula fornicata)

Cool critter of the month: Slipper Limpet (Crepidula fornicata )

Phylum: Mollusca

Family: Calyptaeidae

Where do they live?
These guys live in the intertidal zone, often attached to any hard substrate…. Literally any.  Although you can find them on the soft substrates as well as clinging onto rocks and pilings, you can find them quite happily living on other creatures such as crabs, oysters – and even other slipper limpets!  These guys can form chains of around 12 limpets long, with the largest ones sitting at the bottom, and the smallest at the top.  The slipper limpet is native to the east coast of America.  It’s pretty widespread too, with its most northerly point starting in Nova Scotia in Canada and most southerly in the Gulf of Mexico.

Continue reading Cool critter of the month: Slipper Limpet (Crepidula fornicata)

Australia’s protected area network fails to adequately protect the world’s most threatened marine fishes

Australia has, compared to some other countries, a fairly extensive network of both marine and terrestrial protected areas.  On the marine side there is of course the Great Barrier Reef Marine Park and more recently the implementation of the Commonwealth Marine Reserve network.  The idea behind any marine protected area is to offer long term “conservation of nature with associated ecosystem services and cultural values”, so one would expect to see some effective protection going on in these areas…right?  Areas chosen, and cared for to ensure they offer conservation value, to do all we can to help keep species going that have suffered population declines because of our actions?  I’m sure many of you won’t be surprised to hear that this isn’t always the case.  Take a look at some of my previous posts over on Google Plushere, here, and here for example.  Unfortunately, as highlighted in a recent study by Karen Devitt, who was based at Charles Darwin University, Australia’s protected areas are inadequate for protecting one of the world’s most threatened marine fishes – the sawfish.

Continue reading Australia’s protected area network fails to adequately protect the world’s most threatened marine fishes

Australia’s protected area network fails to adequately protect the world’s most threatened marine fishes

Australia has, compared to some other countries, a fairly extensive network of both marine and terrestrial protected areas.  On the marine side there is of course the Great Barrier Reef Marine Park and more recently the implementation of the Commonwealth Marine Reserve network.  The idea behind any marine protected area is to offer long-term “conservation of nature with associated ecosystem services and cultural values”, so one would expect to see some effective protection going on in these areas…right?  Areas chosen, and cared for to ensure they offer conservation value, to do all we can to help keep species going that have suffered population declines because of our actions?  I’m sure many of you won’t be surprised to hear that this isn’t always the case.  Take a look at some of my previous posts – here here, and here.  Unfortunately, as highlighted in a recent study by Karen Devitt, who was based at Charles Darwin University at the time of writing, Australia’s protected areas are inadequate for protecting one of the world’s most threatened marine fishes – the sawfish.

There are 5 species of sawfish (Pristidae) in the world.  In a previous study focusing on sawfish, Nick Dulvy and fellow researchers reported that the group, which can occupy marine, brackish, and fresh water habitats at different stages in their life cycle, are probably “the world’s most imperilled marine fishes”.  Three of the five species – smalltooth sawfish (Pristis pectinata), largetooth sawfish (Pristis pristis), and green sawfish (Pristis zijsron) are classified on the IUCN Red List as critically endangered.  The remaining two species – narrow sawfish (Anoxypristis cuspidate), and dwarf sawfish (Pristis clavata) are classified as endangered.   Out of the five species of sawfish, only the smalltooth is not found in Australian waters.  More so, northern Australia is home to “some of the few remaining viable sawfish populations” in the world.  Looking after these guys isn’t just important for the Australian population of sawfish, but for the global population of sawfish.  Northern Australia’s waters is in fact, globally significant.  If northern Australia’s populations decline, then the outlook is extremely bleak for these rather unusual looking fish.

One of the key steps Karen and fellow collaborators undertook was to accurately map the range of each of the sawfish species in Australia.  They had to do this themselves because only very coarse range maps had been produced from limited data.  Sounds silly doesn’t it – a seriously threatened species, and we don’t even really know where it lives.  Understanding ranges is (rather obviously) crucial for implementing effective protected areas for these guys.  After all, a protected area situated over very little or even none of their habitats is rather pointless.  The team managed to obtain a number of records of each species that they could confidently use in their analysis.  They also used the known habitat preference of each of the 4 species and maps of Australia’s land (for the freshwater habitats they use) and sea-scapes to figure out what the most likely ranges of these endangered critters are.  Of the 2,908 records of narrow sawfish, 741 records of green sawfish, 247 records of dwarf sawfish, and 470 of large sawfish, a total of 524 records were taken within a protected area.  The percentage of range protected was also low.  For their inland (freshwater) range, between ~9 and 17% had some protection designation attached.  Their marine ranges fared a little better – around 22 – 44% some protection.

But there is something else to consider.  Not all protected areas afford equal protection.  The IUCN has a range of different categories for both terrestrial and marine protected areas.  In a marine context, at the upper end you have strong protection like areas you can’t extract things from – fishing and mining is banned.  At the lower ends you have sustainable use zones, which allow (hopefully) carefully managed activities to take place.  This can include things like fishing or mining.  When you are dealing with a species – or indeed a group of species like the sawfishes that are living in a very precarious position, ideally you want the protected areas to offer them the strongest protection possible.  Alas this is not so.  Karen and colleagues maps showed that most of the protected areas (terrestrial and marine) that covered the sawfishes ranges were sustainable use zones – zones in which activities known to be a direct threat to sawfish still take place.  What’s more, the team also note that the Commonwealth Marine Reserve network may not be all it is cracked up to be, with the current Australian Government, elected in 2013, suspending the management plans for the network.  In reality, the little protection the sawfish were supposed to be afforded by the network may be significantly eroded.

There was one final issue that the team raised in their paper – that of connectivity.  It is becoming well understood by scientists (if not politicians) that marine protected areas cannot function as single isolated islands.  Many species undertake dispersal at some time or another – the larvae of sessile organisms can travel on currents to new settlement sites, for example.  Some species – like sawfishes – can travel large distances, utilizing different habitats.  An effective marine protected area may very well need to be included inside a network, and that network needs to consider how critters move around, and how in reality seemingly disconnected sites are in fact connected.  Female largetooth and dwarf sawfish for example both pup in estuaries.  Their juveniles live in freshwater and riverine habitats.  It is only when they are older that they head out into the ocean.  These seemingly disparate but essential habitats for the sawfish (and indeed many other species) has not been considered in network design.  The urgency to consider connectivity is heightened by proposals to develop hydroelectric dams in northern Australia, something that has the potential to block migrations of these critters.

In terms of size, Australia’s terrestrial and marine protected areas may be making advances in achieving targets set by the international community, but they are far from achieving any meaningful contribution towards species like sawfishes which so desperately need help.

The paper which was published in Global Ecology and Conservation has been made open access.  You can have a read of it here http://dx.doi.org/10.1016/j.gecco.2015.01.007

 

Image: Sawfish (species unknown).  Credit Simon Fraser University – University Communications/Flickr (CC BY 2.0)