SPEAKER_00 0:58

Good morning, everyone, and welcome to Word on the Reef. I'm your host, diver and marine conservationist Tanya Murphy. And with me, as always, is Ken's

Marine News Updates

SPEAKER_00 1:06

Aquarium's Marine Educator and Fish Whisperer, Brett Gospel.

SPEAKER_02 1:10

Good morning on this very wet tropical Cairns morning, isn't it?

SPEAKER_00 1:14

Yeah, have you seen any flooding near where you live?

SPEAKER_02 1:17

Yeah, uh not where I am, but yeah, our poor friends up in the Dane Tree. I'm looking at some footage this morning in the Dane Tree River has come right up. Dane Tree Ferry has broken her moorings and is drifting. And the water level is up to the roof of the toilet block on the left before you get onto the Dane Tree Ferry. So please stay safe, everyone up there, North Queensland family. And please make sure that you are ready to go with the cycling kit with those eight beans and toilet paper that apparently everyone needs.

SPEAKER_00 1:59

Yes today. Anyway, uh before we dive into today's interview, a quick wrap of Marine. So you'll have to get the load on the iPhone rate after the authority. Now, obviously, there is a tropical low bringing cloud covering rain, so we're consciously hopeful that might be temperatures without bringing too much flood runoff in its way, which also has an impact. But

Introducing Dr Stephen Lewis

SPEAKER_00 3:25

on to today's topic, we often hear that conditions on the Great Barrier Reef have changed dramatically since pre-industrial times. But how do we actually know that? After all, weather records only stretch back just over a century, and systematic water quality monitoring only began in the 1980s. The answer is written in the coral themselves. By extracting a core sample, much like studying tree rings, scientists can read the chemical signature locked inside the growth layers of coral skeleton revealing what ocean conditions were like hundreds of years ago. Imagine if we could read your skeleton breath, what would it be?

SPEAKER_02 4:07

It might have a few survival tips actually. When I had hair, no one needs to see that either.

SPEAKER_00 4:17

But what stories are these coral cores telling us? To find out, we're joined today by Dr. Stephen Lewis, a senior principal research officer specialising in water quality at James Cook University in Townsville. Good morning, Dr. Lewis. Welcome to Word on the Reef.

SPEAKER_01 4:44

Yeah, we'll send it your way.

SPEAKER_00 4:48

It's great to have you on the show. So to start with, can you tell us about yourself and how you came to be passionate about the marine world?

SPEAKER_01 4:55

Yes, well, I'm a Townsville born and bred local, actually, so which is pretty rare. Wow.

SPEAKER_00 5:00

Have we even ever had a local on this show? No, I don't think so. We won't hold it against you. Yeah, we'll give you a pass.

SPEAKER_01 5:07

Thank you, thank you. My background more is in the earth sciences, geology, sedimentology type field. So I'm interested in looking at long-term changes, which you know we're about to talk about with the coral records, and we also look at uh trying to work out past sea level changes and things like that as well. So I came more from the earth science background and um I did look probably looking at more into getting into mining, and then I realised I don't know if I'm really interested in a fly-in-fly out job and working in the marine environment across well, attachment to reef environment is pretty cool, and you know, you get to go and meet a lot of really interesting people from all walks of life and go to see some amazing places as well. So that's sort of how it all started for me. And then when I got into my PhD, an opportunity came up to work on these fossil corals that were unearthed uh when they were constructing the Nully Bay Harbour here off townswell on on Magnetic Island. We built a new harbour in the early 2000s, and when they were doing that, they unearthed these fossil Parites corals that lived 6,000 years ago, lived for a couple of hundred years, and over that time and the opportunity came to work with them to see well, how has you know climate changed over time? And from there, uh we look wanted to look at a modern record that the Australian Institute of Marine Science had collected in the 1980s. We looked at a long core there to compare, and then we in that core we started to see this big water quality signal in that core related to changes when they first introduced sheep and cattle in the Burdickan River catchment. So from there, you know, it kind of moved I moved across to water quality and and just in general that sort of changes in the Great Barrier Reef understanding, you know, when the coral reef started growing to how water quality's changed. And that sort of has moved me from looking at the catchment to understand the catchment records of land use change and water quality and then how that translates into the marine environment.

SPEAKER_02 7:14

It's like a big time capsule, isn't it? Yeah. Wow, that's cool.

SPEAKER_00 7:18

We're

Coral Cores: The Reef's Time Capsules

SPEAKER_00 7:18

very interested to learn more about these coral core records that allow you to look into the reef's history and see what things were like hundreds of years ago. So can you explain what these coral cores are and how you collect them?

SPEAKER_01 7:30

Um so what we look at is we look at the Pirietes corals. So uh your viewers might think of them as the big brain or dome corals that you see out there, and these uh parietes, they're in it for the long haul. They can live for several hundreds of years, and they lay annual growth bands like trees do. So effectively they're growing their skeleton from the surrounding seawater, growing their carbonate skeleton, um, and they lay down annual growth bands like trees do. So in the 1970s, they actually x-rayed some of the corals. Someone thought, let's just take an x-ray and see what's in these corals. And it sort of came to I think it was the Bikini Islands where they were conducting nuclear tests, so it was sort of around that, oh, what would you see in the coral? And they discovered these density bands like trees do, where they, you know, they're sort of seasonal bands. So a a high density band and a low density band equals one year of growth. And there's so many other things in the corals too. Like, you know, someone thought of putting one of the coral slices or cores under an ultraviolet light, and you see these bright yellow lines like glowing out of the coral, and they actually coincide with the amount of river discharge that's come out of the adjacent river catchment, and we can measure the intensity of those lines with the volume of water from the adjacent river and reconstruct like river discharge history. So it's like a river cage for us, and we've got a record that extends back uh for the Burdickan River back to 1648.

SPEAKER_02 9:02

Oh my gosh.

SPEAKER_01 9:03

Yeah, that's right, it's a 350-year record. So that coral came from Havana Island, which is in the Palm Island group just north of Townsville, and that was able to tell us, you know, a bit of a climate history of our rainfall history in our local region. So, yeah, the longest records generally extend back the last 300 years, but every now and then these fossil coral records come up, and we've started to look into that as well. Like there's these microetuls on reef flats, which are the Pirite species as well. And they've actually been some of those have been carbon dated or uranium-thorium aged at different, you know, they're some of them are quite a fair few thousand years old, they were living, and they actually provide a record of our past sea level change in our region for the last six to seven thousand years as well. And we're just starting to look take some cores of those sort of fossil corals to reconstruct our river discharge history back in time.

SPEAKER_00 10:02

Wow, so so there's corals alive today that are four hundred years old and so, and so you can get core drillings of corals that are still alive, but then you you can also get cores of fossilized corals that are thousands of years old. And so can you sort of see the same things in the fossilized corals as what you can in the ones that are still living, or do they lose some of their data?

SPEAKER_01 10:22

No, they still retain it, which is so exciting. We had a student look at it a few years ago. We called some, you know, thinking, oh well, we've got these old corals on uh Jeffrey Bay Reef Flat off Magnetic Island, and uh we also have just recently done some new cores at Orpheus Island of some fossil corals, and yeah, we see the luminescent lines well and truly preserved in those corals as well, so we can use them, and that's sort of a work in progress at the moment. But yeah, and we and the big varieties, we look at the you know, the big ones to core, and it's just like quite a concrete core kind of will take, and there's sort of a more intensive setup to go for these longer cores, which can be up to four to five metres in length. They grow about one to two centimetres per year, you know, in this part of the world. But then there's other interests where we might just take a short core that's only about 50 centimetres long. And one of the important things I probably should talk about here too is you know, a lot of the students when I present this work to say, oh, does that actually harm the coral taking a core? Well, the living tissue layer of these corals are only about a few centimetres thick. That's the living part of the coral, and the skeletons underneath it. And the core that we take, we plug it with a concrete plug, and when we go back to the site, we can start to see the tissue layer growing over that concrete plug, and within about a year it's fully grown over that plug, and coral has not, you know, you wouldn't know that was being cored.

SPEAKER_00 11:54

Yeah.

SPEAKER_02 11:55

This is such important work, isn't it? And it it must be so exciting when you get that first core back. It'd be like opening up Pandora's box in history, wouldn't it?

SPEAKER_01 12:02

Yeah. Yeah, and it's well when you start getting your eye in for those luminescent lines, you can put your finger on the big floods, you can see those really bright lines, and you can say, Oh, there's the big 1991 flood, and there's the 1870 flood, and you know, those sort of big events in our history that the corals preserved. And then not only the luminescent lines, but we can do the geochemistry of those corals as well. And it turns out when it gets colder in the winter, the corals take in a bit more strontium relative to calcium, and there's other elements that sort of record this past seawater temperature for us, and there's other elements that are recording like a river discharge, like a sediment load exposure that the coral has recorded over time.

SPEAKER_02 12:47

So the thing that really stands out for me in this is undisputable science, isn't it? This this is the history of the reef, and it's showing us quite clearly the changes that we've had in water quality and the good and the bad. So this is this is it in a nutshell, isn't it? This is so important.

SPEAKER_01 13:03

That's right. So there's certainly research around. There's some other parameters where, you know, a little bit more uncertain what what are they recording? So we went through initially, so the barium-calcium ratio initially came out as more this is a sediment load type change, where some of the subsequent work suggested, oh, maybe it's more freshwater or a combination of the two. So we're still understanding of that. But really, what the barium is telling us in a nutshell is, you know, it's increased terrestrial exposure that that coral is seeing, as you would see the barium increase, whether it's freshwater or sediment or a combination of the two, that coral is seeing more runoff from the land in the last sort of hundred years or so.

SPEAKER_00 13:44

Mm-hmm. So it's as if the corals have written in their diary every year. There you go for hundreds or thousands of years, and and so every day they're like dear diary.

SPEAKER_02 13:55

Hopefully in uh two hundred years some scientists will come out and dig me up and I'll be able to tell my story.

SPEAKER_00 14:00

Dear diary. Today the water was clear. I ate some plankton, it was delicious, and the parrot fish were being noisy as always. That's the sort of thing.

SPEAKER_02 14:12

I saw this gun-shaped object walking down the beach that I'd never seen before, and it turned out to be a human.

SPEAKER_00 14:19

Well, as Dr. Lewis said, we can actually pinpoint the first moment that things like sheep and cattle started to be farmed on the mainland. So it's down to that level of accuracy that we've got.

SPEAKER_02 14:28

That's so cool.

SPEAKER_00 14:29

Yeah, I'm excited to get into more detail about

Written in the Coral: Climate Change and Water Pollution

SPEAKER_00 14:31

it. So, Dr. Lewis, what specifically do the coral cores tell us about how the climate has changed for those corals and how the water quality has changed, especially since European settlement?

SPEAKER_01 14:43

So what the corals are telling us in terms of sort of the climate and the river discharge history, that so that record that we've got that goes back to 1648 AD, is that the last sort of 150 years or so there is bigger uh river discharge events happening. You know, there's a lot more water going out into the Great Barrier Reef Lagoon than there was, you know, in that 150 to 350 year ago period. And particularly in the last sort of fifty years or so, we see those bigger events are becoming more frequent in the record as well, and the flows seem to be getting bigger out of the Burdekan at least. Um and the Burdickan's one of the bigger catchments, it's about 130,000 square kilometres, so it really provides a pretty good representation of those North Queensland weather events. So there's more water going out there, and in terms of water quality, we do see the biggest change in water quality, particularly along our inshore Great Barrier Reefs. So that's the area really from our shoreline to about 20 metres water depth, and so the inshore corals off our inshore continental islands in particular, as well as our seagrass meadows. So most of our seagrass is actually in the inshore Great Barrier Reef zone to support our jugongs and our turtles and things like that. So yeah, that's we do see those changes in the coral records, but also we you know, we take sediment cores offshore as well, and we can see accumulation rates of the sediments increasing in the past sort of hundred years or so as well. That suggests there's you know a little bit more sediment going out there and uh so things like that. So yeah, predominantly in the inshore Great Marriott Reef, where we the record suggests the water quality has changed.

SPEAKER_02 16:29

Gee, so the Burdickan is like a big time capsule in itself, isn't it?

SPEAKER_01 16:32

Yeah, it's a it's a huge river catchment and one I've worked on, you know, most of my career has been monitoring water quality all through the tributaries of the Burdeken and being out on the Burdeken Falls Dam and monitoring off the um Incabin Bridge or the Silver Link uh between Air and Home Hill there. It's and the Burdeken River, it's the biggest river by mean annual discharge in the whole of Australia, actually. So it's a very big system, you know, in terms of Australia.

SPEAKER_00 17:01

And so you mentioned that you could see uh specific bands in the coral cores for known flood events. So it's very accurate. You can really read it there. And it's curious. I know there are some people who still claim that the water quality on the reef hasn't changed and it's doing better than ever. But I I hope that you can show them one of those coral cores.

SPEAKER_03 17:22

Yeah.

SPEAKER_00 17:23

And uh you mentioned that you could pinpoint differences since sheep and cattle were introduced specifically. Uh when was that and what did the corals say about it?

SPEAKER_01 17:32

So this was a core off Jeffrey Bay off Magnetic Island that when we were analyzed an element called manganese, we could see the low background levels of this element prior to 1854 was about 0.6 parts per million, and then in the 1854 to 1856 growth of that coral it increased right up to six parts per million, so a tenfold increase. And then it sort of rose up and then started dropping back down by the early 1900s, and that initial increase, there was no Europeans in town at that point. It did townsil came about in about 1865, so it was ten years before any Europeans were in our area, and the only thing that could explain it was the very first sheep run was run in the southern part of the Burdican catchment in 1854. Sheep were first introduced into the Burdickan. And what we would hypothesize is manganese is an element that's enriched in the upper parts of the soil. So with the indigenous burning of our landscape, manganese is actually enriched in ash. So we we think we've had a very we would have had a very enriched manganese layer in that upper soil. And with sheep coming in with their hard hoofs and ripping up the grass from the roots, we would have then mobilized in that next flood this very big amount of manganese enriched sort of topsoil that uh went straight out to our marine environment that our coral recorded very quickly.

SPEAKER_02 19:13

Mm-hmm and conclude that it was the sheep sampling on the ash that sent it out to the reef and it recorded it.

SPEAKER_00 19:18

Mm-hmm. And I mean that would have been much less uh livestock than what we have in reef catchments nowadays. So if the very first earliest sheep could cause that noticeable of an impact, imagine how much impact we uh might be causing nowadays from the removal of vegetation, yeah, industry and everything. And the erosion of the topsoil. Yeah, so that's uh some of the changes in water quality. And and was there anything else that you found out about the climate as well?

SPEAKER_01 19:47

So yeah, the river discharge has increased quite a lot in the last 50 years in particular. So that sort of tells us the rainfall variability has happened, and that's sort of made us interested in going back to look at these fossil corals from thousands of years ago. So one of the we did this work on the fossil coral that lived 6,000 years ago with my supervisor from the Australian Institute of Marine Science, and we're able to show that the um rainfall seasons were quite different 6,000 years ago than what they are today. We're probably less influenced by the El Nino Southern Oscillation back then, and we had probably more consistent rainfall. You know, we didn't have a really strong wet and dry season as we do today. There was more consistent rain um over the year than what we have today with the El Nino Southern Oscillation more influencing our region.

SPEAKER_00 20:38

Yeah, so climate doubters would say, well, clearly the weather has been changing for thousands of years, but do the corals tell you anything about what's different about the climate change that we're seeing now compared to past natural events?

SPEAKER_01 20:53

So when we see that increase from about 1850 in the river discharge records, it's still somewhat debated. The what we think is there was a bit of a natural climate shift around then, actually, because you do see a wetter period coming in around that time up in Indonesia and in some mid parts of the Pacific as well. But there's more of a recent shift since the 1970s or so where we've seen uh much more, you know, bigger flooding events, which we think is part of climate change that we're you know experiencing out in our region now.

SPEAKER_00 21:27

Yeah, so we've had flood events like Cyclone Jasper flood event which caused hundreds of people were flooded in the Cairns uh Maitron's Beach area. Town Townsville's had some pretty big floods over the last few years, and and those flood waters from Cyclone Jasper killed corals and giant clams. There was I can't remember which flood it was that killed more than three thousand giant clams at Orpheus Island. Yeah, that was just last year.

SPEAKER_02 21:51

Wasn't it Jasper that they recorded that some of the reef fish on the coastline inner reefs the solidity level dropped on our coastal beaches? There was that much fresh water heading out there.

SPEAKER_00 22:01

Yeah, and floods are natural, but they're much bigger and they're reaching, you know, hundreds of kilometres out to sea, which is further than they used to reach. And so the impacts are bigger from climate change. Isn't that right, Dr. Lewis?

SPEAKER_01 22:15

Yeah, that's right. The exposure to the discharge is yeah, increasing with that extra water going out. That's correct. And you do see that still predominantly in the inshore Great Barrier Reef area, but you know, stretching wider. A lot of our river plumes tend to follow the coast, you know, up at the coast with the southeasterly winds they push along the coast. Coastline, but we are starting to see some plumes pushing further offshore or even onto that middle and outer shelf in the last few years as well.

Farmers Making a Difference on Water Quality

SPEAKER_00 22:59

How do we measure and how how do you measure and monitor current water quality on the Greatberry Reef? I saw a picture on, I think it was like a JC website, of you leaning out over a muddy, flooded river with a really long pool scoop. Like, is that how you collect water out of the river?

SPEAKER_01 23:19

Yeah, that all some buckets off bridges and things like that. We've done right in the past. So yeah, we tend to there's a big program under the Reef 2050 plan where there's water quality monitoring pretty much across from a like a paddock scale to river tributary scale to the end of rivers and all out into the Great Barrier Reef through the marine monitoring program. So I've sort of been involved in aspects of that over a number of years now, where you know we're looking at water quality at a more of a tributary scale, which tells us, you know, water quality signals from different land uses and what the challenges are for different crops and different land uses like urban and industrial land uses and things like that. And we also look at the end of river to look at you know how the river loads have changed over time or you know what's a relative bigger years to drier years. And then we, as part of the marine monitoring program, we're taking regular samples along the inshore Great Barrier Reef zone from pretty much Cape York all the way down to the Fitzroy. Part of that program where we're taking regular samples and looking at you know water quality trends over time in that inshore Great Barrier Reef zone.

SPEAKER_00 24:34

What are the water quality issues associated with agriculture? And uh I know you work pretty closely with landholders on that, so I'm interested to hear what you're working on there.

SPEAKER_01 24:44

Yeah, so in in the cropping sort of lands, intensive cropping lands, there's a lot of application of uh nitrogen and phosphorus fertilizers and and certain pesticides and that as well. So we keep an eye on that. That's some of the challenges there. And and in the grazing area, we particularly look at erosional issues. So there's hill slope erosion, gully erosion, and streambank erosion are the three major sources of what we can get sediments exported from the river. And the graziers were managing their ground cover um over the seasons and moving their cattle around to give paddocks a rest and things like that. You keep your cover up so that reduces your hill slope erosion. There's been a lot of government investment from many different programs looking at remediating gullies, and that's been really heartening. We did a lot of work in the Burdeken River where we were able to show that gully erosion was one of the biggest sources of sediment in the Burdeken River, because the Burdekan's not just the biggest river by average annual discharge, but it's also the biggest river in terms of sediment inputs into the Great Barrier Reef Lagoon as well. And we did a bit of a study to show, well, 60% of your sediment loads coming from an area, about 12% of the catchment area below the Burdickan Falls Dam. And most of that is coming from gully erosion. And there's since then there's been a lot of government investment remediating problematic gullies that are probably like legacy issues from either historical grazing practices or even associated with old sort of gull mining practices and things like that back in the day, gold and tin mining. And these are getting it's almost like a mine site rehabilitation process, and some of these giant gullies are being leveled and the soil's being treated, and we can reduce the runoff from that effectively to zero.

SPEAKER_00 26:34

So So do you build something with rocks to stop the soil from eroding away from plant plants there?

SPEAKER_01 26:41

Often so some of the uh big issues are associated with sodic soils, and these soils, when they get exposed and wetted up, they just disperse and just essentially collapse and cause enormous erosion issues. So they do level out the gullies, put in rock chutes to slow the water down, and often in these sodic soil areas they are actually treating the soil with things like gypsum and things like that. Very expensive scenario, but can be very highly affected in these really big localized hot spots.

SPEAKER_00 27:13

So that's where the government funding comes in, because if you've mentioned that it's expensive to fix an eroding gully, I can imagine the barriers to uptake in landholders being able to do that.

SPEAKER_01 27:24

Yeah, there's only so much for the landholders to do. We work very closely with graziers. There's a network in that area downstream of the Burdick and Falls Dam, where we work in the Bowen Broken Bogie catchment, where we have a lot of landholders collecting water quality samples from their local rivers where we go and regularly give them feedback and say, Oh yeah, you can see where these sources are coming from, and they get a little bit more connected with their catchment and a bit more engaged, and you know, they're doing a lot to make some, you know, really important improvements in that area.

SPEAKER_00 27:57

It must be so satisfying if they can get government assistance to fix that stuff and to see the impact that they're making. And then on but on that, is it working? Uh you know, how long have these remediation efforts been going on and has there been an improvement?

SPEAKER_01 28:10

Uh with the gully remediation, probably largely in the last ten years. And yes, there's an issue of scale there because in the Burdick and sediment loads we're talking millions of tons.

unknown 28:21

Wow.

SPEAKER_01 28:22

Often going out in those big flood events, and we're talking probably saving, you know, in the thousands of tons with gully remediation.

SPEAKER_00 28:31

You just gotta take it one at a time, I suppose. And a bit more investment maybe in the city.

SPEAKER_02 28:36

As long as we're stepping forward, but yeah, we need the government to chip in.

SPEAKER_01 28:39

Yeah, and we've seen you know a lot more investment going on in in the catchbit, which is really encouraging. And I think some of these big gullies, a landholder themselves can't do anything about it other than really fence it off because that's actually dangerous for cattle to be around as well. So, you know, remediating that landscape, you know, is so heartening to sort of see in our local area. Um, into the cropping, you know, on the nutrients and pesticides, the nutrients we've seen a real reduction in the amount of fertilizer being applied, particularly in the last one to two decades, which is also pretty encouraging. There's still a little way to go there, but the news there is really a lot of the farmers are pretty much at the rates that as low as they can go, but then we're starting to look at other options. The agronomists there are looking at things like, you know, more enhanced efficiency fertilizers that are a bit more slow release, that are less prone to runoff, and you know, managing those extra nutrients going on to the paddock. So the sugar cane industry in particular, they might grow a legume crop in the fallow of the sugar cane that puts nitrogen into the soil. There's mill mud going out there from the mills that provide an extra nutrient source, and it's just about working with those growers to account for those nutrient budgets, if you like, that little bit, refine it that little bit more. But yeah, we're we're starting to see some pretty encouraging signs at the in our like bigger river monitoring programs where we're starting to see reductions in sediments and nutrients. So it's been a lot of lot of work there.

SPEAKER_02 30:13

And those farmers, they're all amazing. I mean, they want to help too. Do you know what I mean?

SPEAKER_01 30:17

Yeah, yeah.

SPEAKER_00 30:18

Yes. We have some uh listeners of our program who are farmers who are supporters. We know they love to take their boats out and go visit the reef. They want to see it thrive as well. I think it's important to have standards and rules to make sure that there's not a few people letting everyone down as well, but there's generally a lot of people trying to do the right thing. But we're trying to come back from 200 years of old school practices is the problem. So there is like a lot of work to do.

SPEAKER_02 30:43

I've had a lot of discussions with farmers at work that have come up to me that have had a little chat to me about the reef, etc., etc. And they're all just amazing. I mean, they're incredible people. And and they say to me, look, we can't do it without tourism, and tourism can't do it without farming in North Queensland. So we have to work together. And they they're willing to do whatever they can.

SPEAKER_01 31:00

And and that's right, Brett. You know, yeah, it that's the sort of message that I try to promote in water quality. We're all in this together. There's you know, water quality issues in all different land uses that we have, and we all need to work together on. And and yeah, that that's one of the most rewarding parts of my job, really, is you know, going out onto the landscape, whether I'm working with a grazier or a a farmer in the cropping lands, and you know, doing a bit of a trial to test a new management practice and say, will this reduce the amount of nutrients or pesticides coming off the farm if we shift from this practice to this practice? You know, and that's and that's very rewarding seeing that you know happen almost in real time.

SPEAKER_00 31:40

Yeah, yeah. Well, it's rewarding for the farmers if they've spent all this money on fertilizers and pesticides to not see it washing away down a gully.

SPEAKER_02 31:47

Yeah, that's uh yeah, monetarily that's probably a good option.

SPEAKER_00 31:50

But when it is so expensive to fix gullies, that's why we need a lot of investment in it. And it's an investment in that it'll bring better farming returns in the long term and better uh returns for the Greyberry Reef and its tourism industry. So we are all for supporting

Industrial Water Pollution & Dredging

SPEAKER_00 32:05

these efforts. What about water quality issues associated with industrial land uses, particularly uh dredging is one that I'm interested in.

SPEAKER_01 32:13

So, you know, some of the light industrial lands over around the sort of townswell area, we've done some monitoring of that, and you know, there's challenges there with some of the like phosphorus-based detergents that are used to clean things down, and we see some elevated phosphorus coming from industrial and and urban lands in general, actually, with the higher phosphorus, which we think are anything from you know those kind of phosphorus detergents to people using more phosphorus-based fertilizers on their lawns or even dog poo, really, as well. Like, you know, we've got a lot of dogs in the I've got two dogs myself, so you know, I try and pick up after them and things like that, but you we do see that elevated phosphorus. And then there's in industrial areas, of course, we look at things like oils and greases and things like that as well. You know, PFAS has become sort of a localized issue with our read about that.

SPEAKER_00 33:06

There's sort of there's uh they're forever chemicals that PFAS, what is it used in? Things like uh nonstick pans and stuff. How is that getting into the ocean?

SPEAKER_01 33:15

And yeah, firefighting foams and things like that of them in some areas, you know, it's leached into some of the ground waters and yeah, there's issues there. Um on the dredging, you know, I could talk from experience in towns we'll let we've had a look. You know, the dredging will do like what they call a maintenance dredge each year where they'll sort of remove the sediment that's been most recently deposited in that previous year. And then there's um capital dredging, which where they're digging out a new channel, and that's quite different sort of practices. So the maintenance dredging, some of the monitoring I've done associated with that, we see quite little impact of you know on the corals around Magnetic Island where we've had the instruments deployed. I know that's a bit of a area of contention for the local residents in Magnetic Island, though, as well as say, oh, you're not monitoring in maybe the right places. And one of the areas they're concerned about is where the dredge spoil is placed, where the port's quite constrained where they can put the dredge spoil. They can't like ideally it would be probably good to put it in deeper water where you're sort of below the area of wavery suspension where that sediment can be reworked and moved, whereas where it's being put at the moment it can get sort of reworked and potentially go back into the the channel that they've dug out as well, that they've got a maintenance dredge. So there's sort of challenges there. And the capital dredging where they're dredging a new area that we could potentially get higher values there, but Townsville just underwent that and some of the monitoring suggested that that had quite low impact as well. But the historical dredging I think has had an influence in Cleveland Bay, and I imagine it's probably up in Cairns as well, where the dredge spoil back in the early 1900s was dumped very close to shore in Cleveland Bay, that we're still seeing those legacy influences from that earlier dumping. Yeah.

SPEAKER_00 35:11

Do you know anything about Gladstone Harbor? Because I know there was a lot of stuff going on like new gas developments and dredging for that back in uh the early 2010s.

SPEAKER_01 35:21

Yeah, they did have some issues there in Gladstone with fish and things like that. So one of the other potential issues is, you know, like metals when they're dredging up, particularly anoxic sediments that then become oxidized, and then you might have quite acid sulfate soils being released. Um, and that can have some big impacts. That's probably the extent of my knowledge of Gladstone. But I know there's you know a lot of active report cards and monitoring work that's gone on there since. So hopefully we're yeah, we're in a much better position now than what we were sort of 10-15 years ago or so when those issues started really emerging.

SPEAKER_00 36:01

Okay, so uh just uh jumping ahead a

How Are We Tracking on Addressing Water Pollution?

SPEAKER_00 36:03

bit because we've only got ten minutes left, the UNESCO World Heritage Committee has for a number of years been pressuring the Australian government to take stronger action on meeting water quality targets or risk the reef being placed on the World Heritage in Danger list. They're going to make a decision about that in just a few months. How are we progressing to meeting water quality targets at the moment?

SPEAKER_01 36:26

So with the latest reef plan report cards work, it shows it's probably a bit of a mixed bag, really. Like there's some areas where we're getting quite close to the targets, and there's actually some river basins that seem to be almost achieving the water quality targets.

SPEAKER_00 36:42

Oh, that's good. Where which one? What's an example?

SPEAKER_01 36:45

Calan Basin in the Burnett Mary, there's a few areas like that, and other areas we're probably getting pretty close to. But then there's other areas where you know there's still a little way to go. So that's what the report card shows. In truth, it's probably quite complicated because for the Burdeken River we've got a big target on suspended sediment, and we've actually seen the loads come down in the Burdeken River in the last fifteen years or so, but that is also influenced by the drought and wet cycles as well. So the Burdickan's been in a wetter climate cycle in the last fifteen years, and we saw some really big sediment loads coming out of the Burdeken in the late 2000s, for example, which were associated with those drought-breaking flood events where the catchment hasn't been in such great condition in terms of ground cover. Recently, we haven't really been in those drought conditions. So in some ways, when you take that into account, we're probably pretty close to meeting those targets if we look at that climate factor, but we've got to err on the side of caution. If we have the next drought, it's about, you know, working with the landholders to manage those drought conditions and the ground cover during those drier periods, so we reduce that extra erosion that happens following those drought breaking floods.

SPEAKER_00 38:02

Yeah, it sounds like a lot of progress is being made. We had a guest talk to us late last year about water quality science who said we're still about 90 years away from meeting the nitrogen targets, i.e. fertilizer targets, and then that's 85 years behind when we're supposed to meet that. So it's uh obvious that everything's going in a good direction, but uh more government investment is basically what he was uh adjusting that's needed so that uh things can move along faster and uh whilst remediating gullies stopping uh land from being cleared in other areas is uh hopefully something that's happening since the reform of the EPBC Act last year. So uh hopefully that will go a bit of a way to stop new land being cleared and eroded. Uh we've only got uh six minutes left.

Medications, Laundry Liquid and Dog Poo: How our Household Actions Impact the Ocean

SPEAKER_00 38:53

So maybe we do have time to talk about urban runoff because I'm interested about how our actions at home, like gardening, car washing, and I was interested to hear that when we take medications like gout medications or contraceptions or even party drugs, and when it passes through our body, it goes into the toilet, and then eventually ends up somehow in the ocean. And so they're doing blood tests on turtles and finding all of our party drugs and gout medications and contraceptives that are ending up in fish and turtles and things like that. How big of an impact is coming from our household pollution? I guess it's it's I I already know it's not as big as the other like industrial and agricultural level things, but it must have some impact, right?

SPEAKER_01 39:35

Yeah, so yeah, Tanya, one of the less exciting parts of our job that I had quite a few years ago was actually doing some monitoring of sewage treatment plant facilities.

SPEAKER_02 39:45

Oh, gee.

SPEAKER_01 39:46

That actually came up your way and did some samples from a couple of the sewage treatment plants up there, and we looked at the primary sewage and the um treated sewage and how that changes, and we could actually still detect you know pesticides within those sewage and different pharmaceuticals. I know the lab that we went through also did look at illicit drugs as well, but they didn't report that to us, so I can't comment on on cans, but in that part.

SPEAKER_02 40:15

I've seen it I I've seen a few questionable fish out there, so blowing their whistles with their glow sticks. I'm not quite sure what was going on.

SPEAKER_00 40:23

I mean Cairns is a party town, so that kind of stuff, don't we?

SPEAKER_01 40:28

But we do see some of the you know, the sewage treatment plants up and down the coast have upgraded to the tertiary treatment, which is the best treatment we can do, and that is effective on removing a lot of different pesticides and some pharmaceuticals as well as nutrient treatments as well that they do as part of that process. So where they discharge that etulin into streams, it gets diluted quite quickly, we think. So it is probably less of an issue. You know, it is quite a big issue around the world though, you know, in in some of those uh bigger countries like America where the sewage treatment plant might discharge into a river that's got to go several hundreds of kilometers that the next town is relying on for their drinking water while then the pharmaceuticals are moving down through the system.

SPEAKER_00 41:15

But you know, free gap medication, just drink the water.

SPEAKER_02 41:18

No no one in the next town has ever had stomach acid but is feeling really good.

SPEAKER_01 41:23

Yes, yes. So for for us, yeah, we've did some of those tests to assess, you know, the risk of that and and I guess our conclusion was it's probably as you said, tenure at the lower end. But you know, something that we need to keep an eye on, you know, these emerging contaminants, there's also studies my colleagues at the University of Queensland look at is like tyre rubber, you know, there's chemicals associated with rubber on tyre so it can be quite toxic that runoff that they're looking into at the moment as well. What we sort of think it's probably, you know, by the time it moves through our rivers and gets diluted by the bigger catchment, it is probably of lower concern, but it's definitely something we need to keep an eye on and to ensure that that's the case and and then what we can do potentially if there are issues that emerge from these different contaminants.

SPEAKER_00 42:16

Okay, so uh Revheads, sorry, no burnouts if you love the rev heads.

SPEAKER_02 42:21

Yeah, no no burnouts. But this has been a really big eye opener for everyone who who's listened to this show this morning. It just shows you how sensitive our water systems are, that it can pick up uh you know stomach acid medication and and etc, etc.

SPEAKER_00 42:33

Yeah, well we're not telling anyone to stop taking your medication, but the phosphorus-free um laundry detergent, eco-friendly hair shampoo, it all ends up. I don't know. The only way is down for liquids and down into the ocean there. Uh we're very low on time, sadly. So Dr. Stephen Lewis, senior principal research officer specialising in water quality at James Cook University in Townsville. Thanks for all your amazing work. Do you want to leave us on we will get cut off in about 30 seconds by the 11 o'clock news, but do you want to leave us on some final thoughts, maybe what listeners at home can do to minimize their impact on marine water quality?

SPEAKER_01 43:09

Sure. The other probably one is yeah, pick up after your dogs and when you're applying a pesticide, like follow the label, and that's not just for the environment, that's for your health and safety. You know, like if it says to wear gloves or a mask or something, please do that for your own safety. Um yeah, it's been a pleasure to talk to you both today, and and I hope everybody up around the Cairns region stays safe with this weather event.

SPEAKER_00 43:34

And thanks to you all for joining us on the website.