Seagrass Decline in Moreton Bay: What Long-Term Research Reveals About Ocean Change

0:00 I want you to imagine you're diving into a shallow bay where your fin stir up a lush green carpet beneath you, a carpet that hides sea turtles, juvenile fish, and secrets of the sea. Now imagine that carpet shrinking, thinning, and changing color vanishing patch by patch. That's what scientists are seeing today in Moreton Bay, Australia, and it's a warning for every coast, including our own. We're gonna be discussing the disappearing Seagrass Meadows over a decadal, or more than a decade study of this area and why we need to protect it as well as other seagrasses around the world. On this episode of the How to Protect the Ocean Podcast, let's start the show.

0:43 Hey everybody. Welcome back to another exciting episode of the How to Protect the Ocean Podcast. I'm your host, Andrew Lewin, and this is the podcast where you find out what's happening with the ocean, how you can speak up for the ocean, and what you can do to live for a better ocean by taking action. And I'm telling you right now, this is a special episode. It's special for a number of reasons. One. I'm discussing a habitat that I really, really enjoy. It's called the Seagrass Meadow. Seagrasses are extremely important. We're gonna get into it, why they're so important today, but today is very special because I have been wanting to do this for a long time. I would like to kick off the project called the Seagrass Effect. It is going to be a Seagrass podcast that's gonna share research, conservation and restoration news from around the world about seagrasses on a podcast.

1:30 Its very own seagrass podcast called The Seagrass Effect. It's going to be part of the Speak Up for Blue Podcast Network, and I am doing a crowdfunding for this podcast, the Seagrass Effect on a crowdfunding site, a new crowdfunding site specific for Ocean Projects called balean.org. You may have seen me interview the founders, Sanders and Bart Oor on this podcast at some point in time over the summer. I did it twice, actually. Talked about collaboration. Now we are capitalizing. They have launched a site, balean.org. They have launched a number of projects including mine, where I'm trying to raise money to launch this podcast, and I'm trying to do it for the new year, and what you can do is you can donate your money to get this podcast going.

2:15 And the reason I'm doing this is because I want this to be your podcast, not just my podcast. I want this to be your podcast. This is a podcast where we're gonna find out what's happening with seagrasses. We're gonna find out what research is going on. We're gonna find out about the restoration efforts that are happening around the world, and of course, the conservation efforts that are happening around the world. It's going to be awesome. We're gonna hear from people all over the world. I can't wait for it. So if you wanna donate and get this thing going, you can go to speak up for blue.com/seagrass. It'll take you right to my Balean page for my project. You can donate right there. You can also donate to Balean to support their work in all the other projects that they're doing. Check it out.

2:56 That's speak up for blue.com/. Sea grass. Now you're wondering, Andrew, why seagrass? Why not coral reefs? Why not the deep sea? There's so many other ways we can do. It's because we don't know a lot about seagrasses and it's not really a thing that we discuss every day. You see on beautiful documentaries of coral reefs, it is wonderful to see. But the sea grasses, they kind of have a bum wrap. They are green, they are lush and they handle a lot of biodiversity, but we just don't really understand how important they are to coastal ecosystems, how important they are to fisheries, how important they are to protecting our coastline. Now I've been talking about it on this podcast for a long time, but when you dive or go snorkeling on a seagrass meadow, you never know what to expect.

3:42 You really don't. It is phenomenal to see. Case in point, I was snorkeling with my brother. We were going out, we were in the Grand Cayman. We were on a family trip. My brother and I decided to go around the corner, around the coast corner, catch a wave. Like catch a current and come back around into this massive bay. So we go, we get a drive, we go to this corner, we hit a bunch of rocks, we go diving in. We have snorkels, we have a mask, we have a buoy just in case we get lost, God forbid. And we don't really know exactly what we're doing or where we're going, but we're told this current will just kind of take us into this bay. So we follow the current and we see, you know, like little sharks. As old, my brother said he saw a massive shark, but it's a little four foot nurse shark. We see a bunch of fish, we see a number of different corals, and we see these rock scapes and sea turtles and everything.

4:26 It is wonderful. We start to come in closer to the bay. Now, there was a bit of a current that took us in, but it wasn't taking us right into the bay. So we had to kick, kick, kick as much as possible to get into the bay. But once we did, we got into very shallow water. We're probably looking at about maybe four feet, three to four feet, and my brother and I are just kind of going over and we're going over a sea grass meadow. And as we're going over this seagrass meadow, we start to see this movement of all these fish and all these little invertebrates, these little shrimp that are in the seagrass meadow. They're hiding in the blades of these plants, of these specialized aquatic plants. And they're starting to like move away from us as we kind of come across and then we see it. We see this massive stingray just hovering right above the seagrass meadow.

5:09 It was incredible. So incredible that I went, holy cow. Like yelled it out into my snorkel. So more sound like, holy cow. It was awesome. We enjoyed it. We talked about it forever. And once we got to shore, we had a couple beers and we were talking about how cool and how lick the size of that stingray. And my brother, who is not a marine biologist, who doesn't snorkel or doesn't screw. Couldn't believe how much life was in these seagrasses, and this is why they are so important. One of the reasons why they are so important. They provide so much biodiversity and so much protection for juvenile fish. These little larva and growing larvae of invertebrates is just the amount of biodiversity sometimes, and oftentimes outweighs and outperforms and out produces the biodiversity of coral reefs and this is why it's so important.

5:59 We just don't know about it. 'cause we don't talk about it a lot. And there are a lot of researchers out there that are talking about a project seagrass, a numbers, a network of researchers that are doing in Europe and along the coastlines in North America and all over the world. And so we need to talk more about it. But today we're gonna be focusing on Moreton Bay in Australia because there was this long-term study, 19 years I believe was the study and it was absolutely phenomenal in this study. It was a study that was able to document a long-term decline. I know you're like, Andrew, why are you getting so excited about this? A long-term decline in a number of different indicators, I guess is what you'd call it, a number of different indicators of seagrass health.

6:42 And the difference here is that the long-term study shows this long-term decline, but there are a lot of short-term studies that happen. We'll talk about that in a little bit that don't show this long-term decline, and that is where we lose the pieces of how healthy a Seagrass meadow actually is. But first, before we get into that, I wanted to talk a little bit about Moreton Bay. 'cause Moreton Bay is a special area. And I've got some stuff that was written, I did a little research here that I have to remember. there was a lot of stuff to talk about, but essentially it's a large, shallow, semi enclosed coastal embankment in Australia, located in southeastern Queensland, Australia, adjacent to the city of Brisbane. So Brisbane, we know Brisbane.

7:23 It's a coastline town on the east coast of Australia, it's on the Barrier Reef. It's just beautiful. The Moreton Bay stretches roughly about 125 kilometers from Kundra in the north to the Gold Coast in the South, covering an area above 1500 square kilometers. The bay is shielded from the Coral sea by a chain of long sandy barrier islands, Moreton Island, North Strat, broke Island and South Strat, broke Island, which create calm, protected waters inside. This is where the meadows, these sea grass meadows could actually, basically live and thrive in these areas. Now, the base depth average is around 10 meters, making it an ideal environment for seagrass meadows, mangroves, and tidal flats, which together form one of Australia's most productive coastal ecosystems.

8:07 These habitats support an incredible diversity of life. Dugongs, green sea turtles, dolphins, migratory shorebirds, and hundreds of fish species, depending on the bay's rich food webs. Now several rivers, including the Brisbane, Logan and Pine Rivers flow into Moreton Bay carrying sediments and nutrients from the surrounding catchments. The mix of freshwater and seawater creates gradients of salinity and turbidity that influence the distribution of marine vegetation such as sea grass, however. The same river inflows can also bring pollutants and sediments from urban and agricultural areas, threatening the Bay's water quality, which we're gonna get into in just a little bit. Moreton Bay is part of Moreton Bay Park, established in 1993 to protect its ecological, cultural and recreational values.

8:53 The park encompasses both protected zones and areas open to sustainable fishing, boating, and tourism. This looks like a multi management system, just like the Great Barrier Reef. Obviously not in the same size. In addition to its ecological importance, the Bay holds deep cultural significance to the Quandamooka people, the traditional custodians of the region who have maintained connections to these waters for thousands of years through fishing ceremony and stewardship. Today, Moreton Bay is a living laboratory where scientists study coastal change, habitat restoration and the effects of climate and human activity on marine ecosystems. It represents both a biodiversity hotspot and a warning system showing how quickly coastal environments can change when pressures like development, pollution, and extreme weather converge.

9:38 So in this study, decal monitoring shows seagrass decline and community shifts following environmental disturbance in Moreton Bay, Southeastern Queensland. Australia is such a long, long, long title. The Decadal range covered between 2004 and 2023. So there's a long range. Now, what's nice about this is no matter what disturbances happen, so we talked about earlier I mentioned how there's like storm events or flood events. These things have short term effects on a seagrass meadows. So if you're looking at short term, you can see that the seagrass meadows is probably ruined or uprooted in some areas. May shrink in size after a flood or after some sort of major storm event. But it quickly, in about one or two years, come back to a normal size, but not all the time.

10:19 Sometimes bigger, sometimes smaller, depending on what's happening after that. However, when you look at a long-term study 19 years between 2004 and 2023, you start to see how the patches are getting smaller. And what's happening. So some of the disturbance events that happened with major flood cyclones and water quality fluctuations allowed scientists to evaluate how their seagrass Meadows responded and recovered or even failed to recover over time. So I thought it was really cool. They looked at seagrass extent. species of actual seagrasses and resilience to environmental disturbances in Moreton Bay, Queensland. So that's what they're looking for. So what they noticed was that the total seagrass cover declined. The overall area of Seagrass Meadows in Eastern Banks of Moreton Bay shrunk compared to the early two thousands Baseline.

11:05 The loss was most pronounced after major disturbance events, such as extreme rainfall, flooding and resulting turbidity which reduce light penetration and smothered sea grass. Species diversity and dominance changed. There was a decline in species richness. So the number of species which sensitive species like Halophila ovalis and Halodule uninervis, sorry for my mispronounced of the species names losing ground in some areas. They lost ground in some areas. These were often replaced or out competed by more tolerant, opportunistic species that can handle the turbidity and the unstable conditions indicating that a shift in community structure happen. Now, this is really interesting because when you start to see these shifts from like more sensitive to disturbance a species to a more tolerant species, this is very similar to what we're seeing happen in a lot of coral reef areas.

11:55 A lot of the corals, like the branching corals are a little bit more sensitive to temperature change or pH change. We're starting to see them functionally extinct in certain areas like Key West, which is very disturbing, and to even see that. It's not something we wanna see. It's the precursor to like actual extinction in specific areas, but we're seeing a more tolerant species stay around like the softer corals that can handle these different types of species, which was predicted a long, long time ago when we start to look at how climate change was gonna affect coral reefs. It is kind of interesting to see that it's the same thing happening with a lot of different species, especially in these important, important habitats. Now, we also saw change in habitat quality and density that decrease. So seagrass biomass and chute density.

12:37 So the chutes are like underneath, fell in several monitoring zones, meaning less habitat, complexity for marine life such as turtles, dugongs, and fish nurseries. And then of course, these declines reduce the bay's blue carbon capacity. Now these seagrass meadows have the ability to sequester carbon. That means they can keep carbon inside, not only their aquatic plants, but also in the root system, which is really interesting. So the fact that they lose that the ability, it's the ability to score carbon and the ecosystem resilience of having a diverse and more complex system of Seagrass Meadows. It'll actually lead to further environmental change down the road. So, in short, the study documented decrease in seagrass area species diversity and structural health with long-term implications for biodiversity, carbon storage, and coastal ecosystem stability.

13:23 That is essentially what the study covered . This is something that is not good when we look at how we monitor and manage these areas. Now, the monitoring is important. Having this long-term study where short-term studies can see quick recovery after storms or flooding doesn't necessarily mean that it's going better. What they notice is that the patches kept getting smaller and smaller over the years, but when you see like a patch get really, really small and then grow back, you're like, oh, it actually did really well. Within a year or two, it started to come back. That means it must be coming back. But when you look at the 19 year data set and you start to see these patches over time getting smaller and smaller, even though the fluctuation kind of goes, it shrinks and then grows and shrinks and grows. It's growing smaller and smaller.

14:04 It doesn't have the time to recover. I assume what would happen if it's in a healthy state and these storms come in, they break down maybe a specific habitat, shrink it in its size and maybe even species diversity or even just size. Having that species diversity still there can allow it to grow back to its original size if it's given the time. But the frequency of those storms, the frequency of those flood events, the frequency of those disturbances with other cumulative effects like increased nutrients or sediment that can actually smother these plants is not going to help when we're looking at long-term data sets or long-term health of the seagrasses. So that's something that needs to improve. So here's what the study authors kind of said between the two things.

14:47 Obviously we need more decadal study, we need more long-term data sets and continued monitoring. That's something that's really big. So that's something that really needs to help. So we need to improve water quality. The study identified turbidity and nutrient runoff, especially from catchments that are key drivers to sea grass decline. Looking at sediments and nutrient loads entering Moreton Bay by improving catchment manages, especially around the Brisbane and Logan Rivers. So those are two rivers that cause the most damage. Actions include strengthening the erosion control or on agricultural and construction lands. That'll be really important. Upgrading stormwater and wastewater treatment infrastructure. Restoring riparian vegetation and filter runoff before it enters the coastal waters. All three of these things can be done.

15:27 That's the good news. All three of these things can be done if the political will and the money is there to help these seagrass meadows. That can be done. That's not difficult to do. That's been done before, and it can be done again. So don't let people tell you that it can't be done, that this restoration or protection, long-term protection can be done. You can also maintain and expand long-term monitoring. That's something that's gonna be really good. Monitoring costs money. Now you can use like remote sensing. You can use drone footage. You can use just regular monitoring, quadrat studies and so forth, quadrat monitoring. And that can be done by students and by academic institutions and by nonprofit organizations. These things are not quite expensive, although the resources are expensive.

16:07 Obviously drones are expensive. Satellite imagery can be costly if it's not freely available. But you can actually tell a lot from this. But it costs money. It costs resources like people and, materials and stuff to actually do this kind of monitoring. And it can get expensive at time. I've seen this before with long-term monitoring studies is that you'll see like gaps during those certain years where funding was either taken away or at reallocated to something else. But as long as you have that long-term data set and you keep coming back and allowing it to kind of grow and grow and grow. You can get back into a better state with these long-term monitoring data sets. You can manage the disturbance impact. So Seagrass lost in Moreton Bay was strongly linked to extreme weather events. So obviously you can't stop the weather events, floods and storms.

16:49 And of course there are turbidity pulses. However, the authors suggest proactive measures to mitigate and manage disturbances, such as protecting refuge meadows, so areas that are less impacted by runoff or turbidity to allow them to serve as a seed and propag resources for the recovery. So allow them to be like they're in good shape even during these storm areas. So allow them to, you know, like they'll have their seeds and allow them to restore the rest of the reef. Use that as a source. You can implement rapid response plans after major disturbances to assess and assist recovery, for instance, by reducing local stressors like boat damage or dredging after runoff. So let's not put more impact on them after these big stressors.

17:31 Let's put less impact by doing that right after. And maybe just short term responses. You can protect high quality habitats. So we kind of mentioned it earlier before. They emphasize protecting remaining healthy seagrass meadows from physical disturbances such as anchoring, dredging, and coastal development. I've had the project Seagrasses guys, and, team on this podcast a number of times. The biggest thing that they said is anchoring. So having a buoy system where you can actually, the boats can like link up to a buoy system so they don't put their anchors down. They can stay in one spot to do whatever they need to do. That will be really helpful. Let's limit dredging and then of coastal development. Of course. And then expanding and strengthening marine park zoning in Moreton Bay was highlighted as a way to ensure these meadowss remain functional and can recolonize degradated areas.

18:13 And then, support active restoration and research. That's gonna be very important. Restoration is very expensive, so you can support that. That would be great. So active restoration, such as transplanting sea grass shoots, reseeding, and improving substrate stability is always helpful. They encourage further research in restoration techniques, light thresholds for recovery and the resilience traits of local species to inform large scale restoration planning. And then finally address climate and cumulative stressors. We know what we need to do to do that. Let's limit our emissions, include protecting deeper, cooler water meadows, and identifying potential migration zones for seagrass as conditions shift. So the big thing is reduce local stressors. So pollution, turbidity, dredging, sustaining long-term monitoring to track trends like we're already doing, protecting and restoring key habitats, and integrating climate resilience into coastal management.

19:02 That's what we need to do. So we have the problem, we have the area, we have the problem that it's facing, and we have the solutions now we need to implement it. And what's interesting about this. You know, like I said, I love seagrasses. I almost did a PhD on Seagrasses. but the one thing that's interesting to me about this, and the project that I'm putting on for the Seagrass effect is that people who donate to the Seagrass effect, we're gonna be taking a portion of that money and we're gonna be helping restore a site of seagrasses somewhere in the world. And we're gonna just keep going. As long as the Seagrass effect is going, we're gonna continue to support Seagrass restoration by your donation. So, par of the Seagrass donation is not only gonna go to the Seagrass effect, the podcast to produce podcasts, to share resources, to share research, to share conservation efforts, and to share tactics among scientists who also listen to this.

19:52 'cause one thing that I learned about doing podcasting is that researchers will listen to it. Early career scientists will listen to it. Scientists will listen to the podcast 'cause they wanna find out what their colleagues are doing or they wanna find out what somebody in their particular area are doing that's different from them or where they can collaborate or they can learn from. And so just by having this podcast, we are actually into integrating, sharing of knowledge for people around the world on a regular basis, once a week basis. That's the goal. Once a week we release an interview episode. That's the goal for this, and I can't wait to bring it to you. On top of that, we're gonna help an active seagrass restoration site. We're gonna help do that. We're gonna come in on the project and we're gonna talk about the increase of what we were able to accomplish and what that site is able to do.

20:34 You're gonna be a part of that restoration process. It's gonna be a lot of fun. I can't wait for you to do it. So if you go to speak up for blue.com/. Seagrass, so speak up for blue.com/seagrass. All one word. You can donate to the project that's right now on Balean for the Seagrass Effect podcast. I can't wait for you to see it. I can't wait to do it, to be honest, but I need. That initial money to start this project. It's expensive, it's time consuming, and I wanna make sure that I do this right. So, the Seagrass Effect, speak up for blue.com/seagrass is where you can go to donate. And of course, if you wanna find out any of the resources, just check in the show notes. And if you have a question, a comment, love to hear it. Let me know in the comments below. If you're watching this on YouTube. If you're listening to this on your favorite podcast app, you can contact me in two ways.

21:17 Instagram dm me at how to protect the Ocean, that's at How to Protect the Ocean. Or you can go to speak up for blue.com/contact, fill out the form and go right to my email. I'll answer you back as soon as possible. I wanna thank you so much for not only those of you who are considering donating to this project and getting it to start up and supporting conservation research for sea grass and restoration, but also for listening to this podcast here at How to Protect The Ocean Podcast. Thank you so much for listening. I'm your host, Andrew Lewin from the True North Strong and Free. Have a great day. We'll talk to you next time and happy conservation.