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Bringing Citizen Science To Lake Pupuke

GUE diver and aquatic eco-toxicologist Ebrahim Hussain applies some serious citizen science to get to the bottom of the trouble in Lake Pupuke, New Zealand. Project Baseline is alive and kicking, thank you very much!

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by Ebrahim Hussain

I have always been passionate about aquatic ecosystems and how they work which inspired me to become an aquatic ecotoxicologist. I have always tried to document observations in an attempt to better understand environmental changes. The biggest challenge I have faced was getting my observations to organizations that are able to use them in a constructive manner. We all constantly see changes in our environments but are often unable to make a positive change.

Citizen science is a greatly underutilized resource by regulatory agencies. There are a myriad of citizen science groups that actively want to participate in the monitoring of their local ecosystems, but they lack the guidance or platform to do so. The Project Baseline Initiative provides an amazing platform for people to display their findings, and in combination with guidance from local authorities, the resulting projects can be an overwhelming success. This article will hopefully take you through my journey to improve a local lake that means a lot to me and the people who use it.

Lake Pupuke is a 186 ft/57m deep volcanic crater lake with a surface area of 110 hectares that drains a 105 hectare urban catchment in Auckland, New Zealand’s North Shore. The influence of this urban catchment on lake water quality is enhanced by the fact that the lake has no direct in and/or out flows and consequently has a high water retention time. Water enters the lake via a variety of diffuse sources (runoff, groundwater & precipitation) and exits through evaporation and intermittent drainage channels.

The lake is used for a variety of recreational purposes and is a venue for national and international events. The lake is also widely used by dive schools and boat clubs from across the region as a training facility.

A Lake Under Threat

I have been diving in Lake Pupuke since 2013, and I quickly came to realize that this lake was under threat. The water clarity had decreased, and according to the local dive schools, this deterioration had been noticed for many years prior. In the summer of 2014 a thick algal bloom developed which had not been recorded previously. The initial concern was the potential human health risk associated with algal blooms, but samples taken by the Auckland Council identified the bloom as Ceratium hirundinella which is a nontoxic species.

It was quite puzzling that even though Ceratium has always been present in the lake it had never formed large scale blooms until 2014. It was thought that this bloom was a once-off event until it occurred the following year and every summer since.


Ebrahim Hussain installing a dissolved oxygen & temperature sensor on the monitoring station. Photo by Andrew Davidson.

In an attempt to understand what had caused this change, I began looking at the Council’s long-term monitoring data, and to my surprise, I could not find anything that pointed to the exact cause of these recurring blooms.

I initially looked at temperature and nutrient loads which are the most common drivers for algal blooms and found that the lake had not been significantly warmer than previous years, and the trophic level index, while elevated, was within the same variance seen over the past ten years. However, there was no associated metadata to support any conclusions. It was clear to me that we could not fully understand what was happening in the lake through seasonal surface-based water quality sampling alone, and that regular subsurface observations were needed.

Enter Project Baseline

That is when I came across the Project Baseline Initiative, and it was the perfect platform for the type of work I wanted to conduct. The primary focus was to collaboratively work with volunteers, local communities, research organizations, and the Auckland Council to collect data that would complement the work already being done by the Council, as well as to specifically address the subsurface knowledge gaps. By doing this we are able to make use of both Council-funded and citizen science-driven data acquisition to support and inform a more holistic management strategy for Lake Pupuke.

We initially started collecting very basic data, such as visibility, temperature, and general meteorological information, but this quickly ramped up once we started noticing what was happening underwater.

Todd Kincaid & Louise Greenshields preparing the sediment coring tubes. Photo by Ebrahim Hussain.

We installed continuous temperature sensors, which log data every 15 minutes, at various depths to get a better understanding of the seasonal thermal stratification in the lake. Our data indicates that the lake usually stratifies from October until June, with an average winter temperature difference of 0.7°C between surface and bottom waters, and a summer difference of 10.2°C.

Stratification in lakes of this depth is a natural result of the surface water layers being heated by the sun. This heating causes the formation of a thermocline where the warmer water layer sits above the cooler, denser bottom water. This process separates the water column into three distinct layers, the epilimnion which is the warmest layer on the surface, the cooler metalimnion in the middle, and lastly the hypolimnion which is the coldest layer at the bottom of the lake. This separation of layers reduces the mixing of heat, oxygen and nutrients between the surface and bottom waters.

It is important to track these changes in stratification because it is directly related to the potential oxygen cycling and internal nutrient loading within the lake.

We installed continuous dissolved oxygen (DO) sensors within these distinct thermal layers to assess this oxygen cycling, and what we found was surprising. In winter the DO% on the surface ranges from 86% to 98% and gradually drops in even gradations down to about 40% at 55m. In summer the DO% ranges from 80 to 90% on the surface down to less than 3% at 55m. This is expected, but what took us by surprise was the presence of midwater anoxic layers, one near the surface between 7m-9m, and a second layer in the metalimnion between 12m-16m.  

The Results

After seeing this, we began investigating other potential DO dead zones in the lake using multi-parameter water quality meters and have since identified additional areas. There was evidence of anoxia in the macrophyte beds that surround the lake, so we deployed additional sensors, and our finding confirmed our initial assumptions with summer DO% dropping to less than 3%.

This is critical information, as anoxic sediment conditions actively promote the remobilization of nutrients which further contribute to the eutrophication of the lake and drive algal bloom formation. These conditions can also cause the release of ammonium & hydrogen sulphide which are all toxic in high concentrations.

The next question we had was what was causing this anoxia. It is natural for a lake this deep to have anoxic bottom waters during summer, but we did not know what was causing this anoxia midwater and in the macrophyte beds. The dense macrophytes stop water from freely flowing into the shallows, and there is a lot of visible organic material that is decomposing on the bed, which all contributes to the anoxia.

The increased load of organic material, composed of dead macrophytes & phytoplankton, seemed to coincide with the appearance of the algal blooms. To prove this we installed light sensors that continuously measure the photosynthetically active radiation attenuation at various depths. The data shows that at on average there is almost no usable light past 4m after 13:00 and zero light penetration past 10m during the summer blooms. This lack of light caused the macrophytes to die, and coupled with the dead phytoplankton settling down, created an influx of decaying matter on the lake bed. We now regularly conduct macrophyte extent surveys to document seasonal die back and regrowth.

Phytoplankton, Chlorophyll-a & biological oxygen demand sample bottles as well as a photosynthetically active radiation sensor ready for deployment. Photo by Ebrahim Hussain.

We knew where the additional organic material was coming from and what was causing the anoxia in both the macrophyte beds and the hypolimnion. The next question was how many nutrients are being released from these areas and what is causing the midwater anoxia. To answer this, we started a collaborative project with the Auckland Council and the Cawthron Institute.

The first step was to install sediment traps at various depths to understand how much organic material is produced midwater and how much settles down to the bed. The second step was to take a suite of sediment cores from the areas of concern we had previously identified to understand the amount of nutrient remobilization that occurs under various environmental conditions. The third and final step was to take targeted water quality and phytoplankton samples from the midwater anoxic layers to understand how/why they are formed.

Ebrahim Hussain & Tyler Ungureanu purging bottles in preparation for water quality sampling. Photo by Harry Josephson-Rutter.

The majority of the sampling required has been done except one more round of winter sediment traps. Once this has been completed, all the data will be analyzed and will fill a critical knowledge gap regarding internal nutrient cycling. This in turn will help guide the next steps for the wider project as well as inform potential mitigation measures.  

Project Baseline has provided an amazing tool to facilitate the collaboration between citizen science and local government by formalizing community-driven data collection. The Project Baseline Lake Pupuke Initiative is a proven example of how citizen science can be used to satisfy critical knowledge gaps and directly feed into regulatory strategies with the common goal of creating a better, healthier environment.


Ebrahim Hussain is an Aquatic Scientist working at the Auckland Council. He began diving when he was 12 years old and has never looked back. Hussain studied aquatic ecotoxicology and zoology at university, and it was clear that he wanted to spend his life studying these subsurface ecosystems and the anthropogenic stressors that impact them. Hussain founded Project Baseline Lake Pupuke with the goal of contributing to preserving and enhancing this natural beauty as well as encouraging others to get involved in actively monitoring their natural surroundings.


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A Journey Into the Unknown

Sailor, diver, and professional software implementation consultant turned adventure blogger Michael Chahley shares his quest to discover the unknowns of our world by stepping out of his comfort zone. Are you ready to take the plunge?

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By Michael Chahley

The engine roars to life, launching me out of a deep slumber and into reality. “That’s not good,” I think out loud. Rocking in my bunk inside the sailboat, I realize the wind is still driving us against the ocean swell. We do not need to be using the engine right now, so why is it on? Bracing myself, I climb into the cockpit as Paul, the captain, swings us over hard to starboard while staring wide-eyed ahead into the darkness. We are on a collision course with an Indonesian fishing boat shrouded in darkness, and it’s close enough to violate the ceiling of a safety stop. Rubbing the sleep out of my eyes, I count a handful of men staring back at us as they also take evasive action. One of them is standing at the railing brushing his teeth while we run parallel alongside one another for a moment. 

Anchored in an isolated atoll in Wakatobi, Indonesia. Photo courtesy of Amanda-Sailing.com.

Luckily for us we didn’t collide. I went back to sleep with another adventure to share. If you were to meet me today, working a full-time job in Canada alongside Lake Ontario as it freezes, it would not be obvious I spent two of the past four years traveling. Balancing a life of adventure with one of responsibility, I feel fortunate to have explored some very remote places in our world–both above and below the water. But before I was able to explore the Pacific Ocean, I first had to navigate a personal path of conflicting identities in order to find the confidence to jump into the unknown. 

Water Baby

For my entire life, I have been more comfortable in the water than on land. My childhood memories consist of watching my parents dive under the water for hours at a time and swim in the currents of the Thousand Islands in the Great Lakes region of North America. I followed the predictable path of our society. I worked hard, achieved an engineering degree, and secured a job. Fortunately, I was able to continue exploring the outdoors with this busy life. Long weekends were spent diving in the Great Lakes or camping in the back-country. I was comfortable enough; however, there was no real satisfaction in my life. As the years ticked by, the gap between my reality and dream world grew. Something had to change, but I did not know where to find the catalyst. 

Going for an afternoon swim in the Marshall Islands.
Photo by Emma Goudout.

Like any other armchair traveler, I idolized the explorers from the Age of Discovery. Adventure books weighed down my bookshelf while travel documentaries glowed on the TV screen in my room at night. I understood what made me happy, but I was unsure of what I stood for and believed in. I was living a life in conflict with the trajectory I wanted to be on, but I had no idea of how to become an ‘explorer’ who lived a life in pursuit of the unknown. While commuting to work each day in a crowded subway, I daydreamed of sailing the oceans and exploring the underwater world. As I grew increasingly more frustrated, one day I unloaded my concerns on a friend. They had the nerve to say I was ‘living in a dream world’ and needed to focus more on my real life. This hurt to hear at first, but then it dawned on me! If dreaming was a part of my life, then why couldn’t I make it a reality, too? This was the catalyst I needed. 

I finally understood that even though others might see my dreams as frivolous, it was okay for me to follow a path that was meaningful for me. Like a weight lifted from my shoulders, I discovered it was okay to be uncomfortable with the status quo. With this in mind, I quit my job, packed a bag, and with no concrete plans, bought a one-way ticket to go halfway around the world.

One-Way Ticket To Ride

Exploring a shipwrecked fishing vessel in the Marshall Islands.
Photo by Michael Chahley.

I found myself flying to the Marshall Islands with a one-way ticket to meet someone I had only communicated with over email. The customs officer did not find it amusing, but after some tactful negotiation, I was let into the country and even offered a free ride to the marina. It was 2016, and I was on my way to meet Tom, the captain of a 53-foot, steel-hull ketch named Karaka. Tom invited me to join his crew and help them sail across the Pacific. Even though blue-water sailing was new to me, for him it was a lifestyle. He was nearing the end of a 12-year circumnavigation after saving Karaka from a scrapyard in Hong Kong. Along the way, he would have crew join him as a co-operative, which is how I ended up spending eight months on his boat exploring the Marshall Islands, Micronesia, and Papua New Guinea.

Trying out the local mode of transportation in Papua New Guinea.
Photo by Chelsea Richards
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When not visiting uninhabited atolls, the outer communities we visited were so isolated that we were asked to help out by delivering fuel, cooking oil, and mail. During this trip, our daily routine consisted of free diving on pristine coral reefs, gathering coconuts, and sharing meals with some of the friendliest people in the world. From spearfishing with the local fishermen, exploring the shipwrecks and ruins of World War II, and partaking in long walks on the beach or up a volcano, it was a new adventure every day. As a shipwreck enthusiast, I am incredibly grateful to have had an opportunity to free dive to within sight of the HIJMS Nagato in the lagoon of Bikini Atoll and to dive on Japanese Zeros in waters of Rabaul. Never in my wildest dreams would I have imagined myself exploring these regions of the world; reality had transcended my childhood fantasies.

Visiting a village in Papua New Guinea.
Photo courtesy of Amanda-Sailing.com.

Just like diving is for many of us, once I started traveling, the passion grew and is now a core part of my identity. Flash-forward to earlier this year, and I am back in the capital of Papua New Guinea helping Paul and his partner repair their 34-foot sloop named Amanda-Trabanthea for a journey out of the country and into Indonesia. Adventurers themselves, they had just returned to their boat after sailing through the Northwest Passage. Over three months we managed to visit some of the most hospitable and isolated regions of Papua New Guinea and Eastern Indonesia. I was lucky enough to go diving in Port Moresby, the Banda Islands, Wakatobi, Komodo, Lombok, and Bali. By the time we survived the near-collision with a fishing boat, I had come to expect the unexpected and cherish the exciting moments in life.

Explore The Unknown

Day trip with some friends on Ailuk Atoll.
Photo by Michael Chahley.

Diving and sailing share a lot of similarities. Both are perfect for getting off the well-beaten track to explore places of our world few have ever seen. We must be confident in our abilities and have the appropriate training to safely handle the unexpected. A strong technical understanding of the physics and equipment required to operate safely is very important. Meticulous planning is essential for completing long passages and technical dives. But most importantly, it is the adventure from exploring new places that makes it so fun and gives us reasons to continue doing this. I strongly believe that communities such as GUE play a pivotal role in society by encouraging and promoting exploration within the individual. With time, I will combine my passion for both diving and sailing to help discover some of the most remote and beautiful corners of our world. If you have never sailed before, I highly recommend it.

I am back in Toronto where this journey began. I’m working full-time; however, this time with a much more solid understanding of myself and as well as a greater appreciation of the world we share. Only by stepping outside of my comfort zone to explore our world I was able to overcome the uncertainty that kept me from living an authentic life. Author Dale Dauten put it succinctly, “Success is an act of exploration. That means the first thing you have to find is the unknown. Learning is searching; anything else is just waiting.’’ 

My backyard swimming pool in Micronesia.
Photo by Michael Chahley
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During my travels, I realized that we cannot let others define us. We must reach beyond personal boundaries, take a risk, and venture into the unknown. In doing so, we become explorers in our own reality, which is the only reality that matters. So, rather than daydream about future adventures, we need to believe we can incorporate those dreams into our lives. All we have to do is to dare to take that first step into the unknown. 


Michael Chahley is a professional software implementation consultant and an industrial engineering graduate from the University of Toronto. A finalist for GUE’s 2019 NextGEN Scholarship, he is a passionate diver, photographer, outdoor enthusiast, and an experienced traveller. Founder of the online blog Nothing Unknown.com, Michael is on a quest to discover the unknowns of our world and share them with you. He lives in Toronto, Canada, and can be reached at @NUDiscover on social media or his email mchahley@nothingunknown.com.

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