Post provided by Chloe Robinson
Whether you refer to them as the ‘briny deep’, the ‘seven seas’ or ‘Davy Jones’ locker’, the world’s oceans play a huge part in all of our lives. Consisting of 70% of the earth’s surface, oceans driving global weather patterns, through regulating a conveyor belt of heat from the equator to the poles. Oceans are also teeming with life, from single-celled organisms to large apex predators, such as the killer whale (Orcinus orca).
As with every other ecosystem on earth, the world’s oceans and the marine life they provide a home to, are under increasing pressure from human-related activities. At the 1992 Earth Summit, Canada proposed the concept of a World Ocean Day as a day to celebrate our oceans and to raise awareness about the crucial role the ocean plays in our lives and the important ways people can help protect it. Since 2002, the Ocean Project has been coordinating and promoting of World Ocean Day.
For 2020, the World Ocean Day theme is “Innovation for a Sustainable Ocean” with the aim of growing the global movement to call on world leaders to protect 30% of our blue planet by 2030. Considering this theme, we asked our Blog Editor, Chloe Robinson, to select her top three favourite Methods in Ecology and Evolution articles to highlight for World Ocean Day.
Resilience Metrics to Inform Coral Reef Ecosystem Management
The first paper that jumped out at me when reading through the ocean-themed articles in Methods in Ecology and Evolution, was an article based on applying a method to quantify engineering resilience for environmental decision making. This article highlighted the difficulty in putting ‘resilience’ metrics into action and identified that there needs to be a method that determines resilience without the restrictions associated with calculating ‘ecological’ and ‘engineering’ resilience. Their technique aimed to tease apart the effects of a globally driven (i.e. unmanageable) stressor such as climate change and ocean acidification from regional- and local-scale (i.e. manageable) stressors on a model coral reef ecosystem.
What I liked most about this article was that it encompassed the concept of ‘ecosystem performance as a metric of engineering resilience’ and clearly demonstrates how these metrics can be linked with management actions for decision-making on large scales. In a world with increasing severity of globally driven stressors, applying a framework for ocean ecosystems, which allows an assessment of current threat management and decision-making for future threat management is important for ocean conservation and marine resource management.
Identifying Plastics Exposure in Live Marine Wildlife
As technology advances, scientists are developing less-invasive techniques for sampling live wildlife. The minimally-invasive nature of the next paper I chose gave me hope for a rapid and effective way of assessing the exposure of ocean life to plastic pollution. Every year 8 million tonnes of plastics end up in our oceans, which makes up 80% of ocean debris. Entanglement and ingestion of plastics by marine life such as seabirds, has detrimental effects on the overall survival of chicks and adults.
The paper I chose by Hardesty et al. (2015), developed a method to detect the exposure of three common plasticizers at both the species and population level. The article ‘A biochemical approach for identifying plastics exposure in live wildlife’, used a gas chromatography–mass spectrometry approach to analyse preen oil samples collected by swabbing the uropygial gland of birds. They found that results collected from live birds were comparable with the levels of plasticizers detected in deceased birds.
An important point which was highlighted in this paper, is the ability to understand exposure of plasticizers in apparently ‘healthy’ individuals, as opposed to exclusively sampling dead birds. This method is also highly applicable to other marine life and could enable a global assessment of ocean plastic exposure. A lot of the long-term impacts of plastics in the marine food chain is largely unknown, but this study provides a fantastic method to start understanding the existing exposure levels.
Environmental DNA for Detecting White Sharks
DNA-based methods are increasingly being used for marine management and conservation strategies. Environmental DNA (eDNA) is a tool that can be used to detect and monitor ocean biodiversity through collecting seawater and/or sediment samples. This tool is particularly useful for detecting megafauna, such as whales, porpoises and sharks.
On this theme, the third paper I have chosen to highlight is a study by Truelove, Andruszkiewicz & Block (2019) ‘A rapid environmental DNA method for detecting white sharks in the open ocean’. This article used eDNA to identify locations where white shark (Carcharodon carcharias) DNA was present in the Pacific Ocean. They managed to confidently identify white sharks and cookie cutter sharks over 1000 nautical miles from shore from just 3L of seawater.
The impressive part of this paper for me, was the use of portable Oxford Nanopore MinIon sequencer to reduce the window of time between sample collection and result generation to ~48 hours. DNA-based monitoring often provides vast quantities of data, however depending on the method, results can sometimes take a while to produce, annotate and interpret. The ‘on-board’ approach in this study provides real-time detection of elusive marine species and has the potential to be applied to boat-based surveys for megafauna.
Overall these three papers detailed a lot of interesting methods and concepts which are important for ocean conservation. From generating robust resilience metrics to using non-invasive techniques and tools to monitor plastic exposure and species presence, innovative methods are increasingly needed to understand more about the health of our oceans. To take action this World Oceans Day, visit the World Oceans Day website to sign the 30×30 petition and find an event near you.
To read more about resilience metrics to inform coral reef ecosystem management featured in this blog, check out the article, ‘Resilience metrics to inform ecosystem management under global change with application to coral reefs’.
To find out more about how camera traps are used to monitor insects, check out ‘Camera transects as a method to monitor high temporal and spatial ephemerality of flying nocturnal insects’.
For more about the use of time-lapse images to estimate penguin reproductive success, see our article, ‘Estimating nest‐level phenology and reproductive success of colonial seabirds using time‐lapse cameras’.