Day 6 – Turtle necropsy (Saturday 29 September)
Today’s task was the sobering one of helping Kathy and Zoey undertake necropsies of two dead green sea turtles, one had been rescued and taken into rehabilitation but had to be euthanaised, the other had
been hit by a boat and brought in dead. For each turtle we took detailed measurements of different body parts, and took detailed external observations. Warning – I have included a photo of the dissected turtle below.
Our poor turtle was heavily covered in burrowing barnacles and was in very poor condition – his carapace (shell) was UV damaged and many of the scutes or plates were missing. A sample of a scute was taken for heavy metal sampling. The scutes grow like fingernails so the scientists are able to analyse the heavy metals and see the history of when any metals were absorbed (each scute grows for 3-8 years). Kathy determined the cause of death to be organ failure due to an infestation of a parasite known as blood fluke. All of its major organs were affected. We didn’t find any plastics in its digestive system and Kathy’s research typically finds debris in 35% of dead sea turtles.
Day 5 – Looking down a microscope (Friday 28 September)
Part of the National Marine Debris Survey involves doing debris surveys on beaches every 100km around Australia. Currently they are 3/4 of the way around Australia and Denise told us they are yet to see a beach without debris.
Spent the morning looking down a microscope at debris collected during a tow, it takes a while to remove the organic material. I found 11 small pieces of hard plastic (from half a millimetre to 5mm long) and 3 small pieces of rusty metal (possibly from a small coil as found in a pen).
There were no pieces of soft film-like plastics from bags etc found in this sample but numerous pieces have been found in other trawls. It is astounding how many tiny pieces of plastic are out there floating in the ocean when you can’t detect any with the naked eye.
Next it was back to sorting the debris we collected during the beach survey at the Causeway yesterday.
Each piece collected from the 50m transect during the ‘emu parade’ were recorded in terms of size class, type, colour and description. This is the beach where we found all the polystyrene in the dunes. Having done a lot of beach cleanups before this trip I have been surprised at how much more you find when doing these surveys, the Causeway beach seemed cleaned until we started the transect.
Day 4 – Of jellyfish, polystyrene and stingrays (Thursday 27 September)
A lovely start to the morning with a run, swim and whale-spotting at a nearby beach – very enjoyable until I spotted the plastic and found 27 beverage containers in a couple of minutes. Don’t think you would find that if we had a National Container deposit scheme.
It was Team 2’s turn this morning to go boating with Kathy. We headed out to Amity Point to do trawl samples. This involved deploying a trawl net which was towed behind the boat, along the surface, for half an hour. Any debris on the surface gets funnelled into a small net and the back called a cod end.
By recording the start and finishing location, boat speed and water flow the scientists will be able to calculate the amount of debris collected per volume of water trawled.
We are yet to analyse the samples but a quick look revealed lots of seagrass and at least
a couple of small pieces of blue plastic. In the second trawl we collected 5 big blue jellyfish which we had to clean of debris before returning to the water.
After lunch we headed to the ocean side of the island to do another beach survey. At first glance the beach seemed really clean but we found 112 pieces of polystyrene in a 50m section along the dunes! We also found lots of small pieces of hard plastic and food wrappers.
On our return the lab was a hive of activity – around 50 stingrays had been stranded on a local beach and sadly died. The team was involved in the effort to record, identify, measure, dissect and take organ and tissue samples to help determine the cause of death. This took til about 11pm and lots of new skills were learnt.
Day 3 – Trawling on a sunny afternoon (Wednesday 26 September)
Actually it was in the morning that Team 1 went trawling today – they saw a turtles, dugong and also caught a seahorse in the trawl net which they released. The morning inspired Tim to compose the song “Trawling on a sunny afternoon” which featured in tonights after dinner concert…followed by the line “takes my blues away”. Whilst they enjoyed the trawling we disembarked at Blakesly Beach and Denise taught Susan, Jarrod, Mark and I how to do the beach surveys.
I have been really looking forward to this aspect of the expedition as we hope to do these surveys with school students and Earth Carers volunteers. Surveys can be done by school group, community groups and individuals on a regular basis or as once-off and data is entered into the TeachWild database.
Procedures to do the surveys are well laid out and data sheets can be downloaded. We started off by describing the beach – including position, shape, wind conditions, slope and substrate. Three transect lines were laid out from the water line up the beach until 2m into the vegetation, each line was 50 m apart. Each piece of debris seen 1m either side of the transect line was collected and described. The beach was pretty clean until
we reached the debris line up the beach where we found debris including hard and soft plastic including bags, fishing net and line, aluminium cans, rubber balloons and cigarette butts.
Our next survey was interestingly title the “emu parade”! This entailed our group walking in a line up and down between the first 2 transect lines and collecting every piece of debris. This bag we then took back to the lab for sorting, classification and spectrophotometry. It was a busy afternoon processing the samples and starting to enter data.
Was great to hear of the Year 11 Biology Class at PLC today whowatched the Catalyst program Plastic Oceans and read my blog. I appreciated all of your wishes of support and was glad to hear of your reactions to this issue of marine debris and your concern and resolve to be part of the change. My head is full of ideas on how we can work together on this – I am really looking forward to talking to you soon.
Day 2 – Tuesday 25 September, 2012
My group spent a day in the lab today whilst the others braved blustery winds carrying out beach surveys. We spent the morning learning the technique of spectrophotometry on marine debris with Zoey. The debris we sampled was collected from a beach survey done on a previous expedition. The idea was to get a lot of measurements on a lot of different objects. The collection was laid out on a table and with closed eyes (no peaking allowed) we each selected 10 random items so we had a total of 50. We then also selected 15 ‘range’ samples (unusual or outliers).
Spectrophotometry is the measurement of the reflective properties of a material. The debris we measured was from beach samples and the research project has also measured the plastics and other debris ingested by sea turtles. The scientists are looking at what colours in the spectrum are visible to sea turtles. They are interested in comparing the properties of the plastics washed up on the beach with the plastics collected from the turtles from the near-shore environments. This can hopefully to be used to see whether the turtles are selecting particular types of plastics in terms of colour and texture. We will be doing more of these measurements in the coming days.
This afternoon it was time to look at material collected from trawl surveys along the coast. The nets are towed behind a boat and collect any debris or other material floating in the ocean. The samples we looked at had been dried so we needed to rehydrate them for at least half an hour in a bucket of seawater. Then the detective work began as we extracted small pieces of plastic and other debris from the material floating on the surface and put into petri dishes. Most plastic floats so, in theory, this should have been easy but there was seaweed, small pieces of driftwood, krill, seagrass and other organic material all combined and it was pretty tricky to figure out what was (as the scientists say) anthropogenic debris.
If in doubt we added the item to the petri dish as well and then looked at our samples under the microscope. This next stage did make it easier though it was still difficult to tell the difference between small pieces of plastic and parts of brightly coloured marine organisms. Once identified we recorded each item into category, type (ie hard or soft plastic), colour, buoyancy and size. Just about all of the items we found today were were less than 1cm, some less than 1mm and we needed to record length, width and depth. In our final sample we found a number of segments of blue and white fishing line, 0.7mm in diameter.
Our day finished with delicious stir fries prepared by one of the other groups and hearing stories of the inspiring projects some of the teachers are doing with their students. Off on the boat tomorrow, I’m looking forward to my first beach survey.
Day 1 – Monday 24 September, 2012
This afternoon I met up with participants of the TeachWild expedition for the ferry journey to North Stradbroke Island. Our group consists of 3 teachers, 5 Shell employees and myself. Geraldine from EarthWatch drove the minivan to Moreton Bay Research Station, our home for the next seven days.
As a storm brewed over the Bay we were introduced to the global issue of marine debris and the Marine Debris Research Project. Marine debris has been identified by the federal government as a key threatening process. Dr Denise Hardesty spoke of being exposed to the issue from seeing albatross at Midway Atoll, where 5 tonnes of plastic is brought to the island each year by the seabirds. Dr Kathy Townsend studies the impact of marine debris on sea turtles – in this area marine debris accounts for about 30% of sea turtle deaths.
It is a commonly held belief in Australia that marine debris comes from ‘somewhere else’ but studies have found the opposite, it is our problem. To respond to this problem there is a need for information. This is the most extensive national study in the world, and has been going for 13 months. The surveys taught in the TeachWild program can then be used by teachers and their students to input into the national database.
Just a few of some other interesting things I learnt today about marine debris;-
- top 10 debris items worldwide by count are: cigarettes & filters, caps, cups/plates/utensils, bags, food wrappers, beverage bottles glass/cans/plastic, straws and rope.
- fishing gear not in top 10 but 6,400,000 tonnes per year in ocean (2002)
- 250 marine species affected by marine debris (ingestion & entanglement)
- one 10cm by 10cm piece of net on a seal means they have to spend 5 times more energy to do the same thing
- turtles eat plastic bags and balloons in concentrations higher than one would expect. Released balloons shred when they hit the stratosphere, are shredded and come back down looking like squid.
Tomorrow looks like being another big day so I’m off for a well earned rest.