Decline of Amphibians

I want to talk to you about the Green and Golden Bell frog (Litoria aurea) today.  This is an amphibian which is native to New South Wales (NSW) Australia and an invasive species in both New Zealand and New Caledonia. It’s also the species which I spent almost a year focusing on during my time in Australia for my professional training year, so a species I know quite a bit about. Now although many of you will have no idea what a Bell frog is and are unlikely ever to see one in the wild, the contents of this post is extremely relevant. This is because all amphibians across the world have all been struggling. In fact 34% of amphibians are endangered while 22.5% are data deficient (there is not enough information on them to deduce their conservation status), Bell frogs are in the same boat as they too are endangered in NSW.

The decline of amphibians has been down to a number of different selection pressures some of which a specific to particular species and while others cover a broad range of species, such as habitat destruction, the spread of disease and also the introduction of invasive or ‘alien’ species.

The Bell frog is under pressure for all these categories, habitat destruction is a key factor along NSW, as agriculture and development has been expanding along the central coast as the population expands. This expansion means that the remaining Bell frog populations are fragmented into several isolated populations, in some cases they are refined to just a single pond such as in the case of Avoca Lagoon. This fragmentation is a problem as it stops migration and immigration of individuals between populations; this means areas are unable to be repopulated after a disaster. However the development in the area is not always a bad thing as in the case of the redevelopment of Sydney Olympic Park has meant that two new self-sustaining populations have been created whilst maintaining a third successful population. Although the recent planning permission of a 4^th coal terminal on Kooragang Island in Newcastle means the populations found there will be under even more pressure in future years.

Invasive species are also an issue for the Bell frog as the introduction of a mosquito fish in 1920s (Gambusia holbrooki) has dramatically increased tadpole mortality. This is not direct predation however as the fish aren’t big enough to directly predate on the tadpoles but they do conduct a process called fin nipping. This reduces the area of a tadpole tail and so reduces their ability to escape from larger predators and search for food. These fish are an extreme problem in Australia and have successfully spread across the whole of Australia except from the Northern territories.

The third main reason the Bell frog populations are in decline like many amphibians around the world is due to the spread of the Chytrid Fungus, Batrachochytrium Dendrobatidis. This fungus is thought to have originated from Africa, due to the movement of people and produce across the world it has been found on nearly every continent. Although some frogs are capable of surviving being infected by this fungus such as the African Long Clawed frog, while to many other frog species contracting this is fatal. The Fungus can be contracted at any life stage from spores which are suspended in the water. The fungus basically affects the epidermis of the frog, which is vital for the survival of an amphibian as they absorb water and oxygen through their skin. There are currently many people looking into a method to control and treat the spread of this fungus, and research is looking into the effects of salinity and heat on the survival of Chytrid.

So like I said at the beginning this post mainly focuses on the Green and Golden Bell frog but the selection pressures being put on this species are either the same or similar to many amphibians which are under pressure throughout the world.

Thanks for reading

Check out these videos

 Not a Bell Frog but pretty cool piece of footage

Ghost Fishing - The never ending catch

It’s been quite I while since I’ve posted on here so sorry about that, but things have been mad for me for the last month or so.

Right I’m going to get straight into the topic this week which is something many of you might not have been thinking about, ghost catching. Ghost catching is a process which has been going on for many years all since the development of non-biodegradable nets and happens across our oceans and inland waterways and has a massive ecological effect on the environment.

So starting at the beginning ghost catching is a secondary process of fishing whether it is commercial or recreational fishing. Now as many people will know millions of tonnes of fish are removed from our oceans and waterways every single year with around 4.1 billion people in the world relying on fish as their primary source of protein throughout the world. Just to give you

a few numbers 90 million tonnes of wild fish were removed from oceans in 2012 and this number does not take into account those fish which are farmed such as salmon. It’s important to remember that fisheries do not only have to feed more people, they are also needed to provide more fish per person. The average consumption of fish per person growing from 9kg to 16kg per year from 1960s-1997 and this is a trend which is continuing to grow. The number does not just stop there however as these numbers are only the fish
which are landed in the ports, many more millions of tonnes of fish are also caught and then returned to the sea either dead or dying. This is known as bycatch and can take the form of either over catch for a fishing quota or non-target species which in some cases takes the form of dolphins and turtles.

Bycatch is not what I want to write this post about however as I’ve said before I want to talk about ghost fishing. So finally a description, ghost fishing is fishing which is done via gear such as nets and hooks which have been lost or dumped in the sea or rivers. Unlike human fishing the organisms which this lost gear catch are not used for anything and simply rot.

So the main point to remember is ghost fishing equipment is catching fish 24 hours a day 7 days a week, or nearly. This equipment will fish and trap organisms and these death fish will attract large predators and scavengers which it will also trap. This continues till the nest gets weighed down by the number of bodies and is pull to the ocean floor, and then it stops fishing. However this does not mark the end though, as once the bodies have rotted away the net will rise again and then the whole process starts over. This ghost fishing is an endless cycle and is set to continue for hundreds of year until the nets break up.

This is a terrible thing and it is important to remember to those nets do not just catch fish, sea birds, mammals and crustaceans are affected from this equipment. The process of ghost fishing also takes place in inland waterways and in some cases animals such as swans and otters can be caught up in recreational fishing lines and hooks.

So what can you do about this? Well unless you are a heavily experienced diver I suggest you do not going hunting for nets to remove. There are certain steps open to everyone however which will help the situation for instance, if you are a keen fisherman always attempt to retrieve all your gear is you get it stuck. Also is you visit the coast and see netting on the beach please remove as much as possible and dispose of it responsibly, so they are not washed back out to sea to continue ghost fishing.

Thanks for reading

Check out these links!

This link relates to general farming but make sure you keep an eye on the number of marine creatures at the top!

http://www.adaptt.org/killcounter.html

Just a bit more information about ghost fishing

http://www.fao.org/fishery/topic/14798/en

Check out these videos