When good animals like bad habitats: ecological traps in the marine environment

By Dr Michael Sievers and Guest Author Professor Stephen Swearer,

Read Time: 608 words, about 5 minutes

By altering the environment, are humans tricking animals into making poor life choices?

African Penguin. Photo: Pixabay.

You’re a young penguin about to forage for the very first time. You jump in the water to search for food. Your instincts kick in, and you swim to cold water with lots of chlorophyll; it’s these areas, you innately know, where fish thrive.

Time to dine, bon appétit!

But, there’s no fish! It turns out that human-induced climate change and industrial fishing have depleted the fish stocks here. The cues that used to be accurate predictors of food availability (cold water high in chlorophyll) are no longer reliable. As a result, you have a poor chance at surviving. You’ve been caught in what’s scientifically known as an ‘ecological trap’.

This sad story is precisely what happened to a population of African penguins.

We are living in the (not so) fabulous Anthropocene epoch; the most recent period in Earth’s history when human activity started to have a significant impact on the planet’s climate and ecosystems. Photo: Unknown.

Ecological traps are a potentially devastating phenomenon. The accelerating rate of human impacts in the ocean means it is likely that traps will be more prevalent in the future.

Humans are effecting the natural environment in ways that are causing animals to make poor decisions, such as preferring to feed in areas devoid of food. Photo: Sherly et al. 2017 Current Biology.

Ecological traps form when animals are attracted into poor-quality habitats where survival, reproduction or growth is compromised. They’re more common than you might think. Stormwater wetlands are traps for frogs; adult frogs readily live and breed in these polluted habitats despite their offspring suffering low survival. Building windows are traps too. Insects like mayflies confuse the polarised light reflecting off them, and lay their eggs on the glass thinking it’s a body of water.

These (incorrect) decisions matter. Traps can lead to population declines and increase extinction risk.

Interestingly, the penguin story is one of a mere handful of traps we know exist in the ocean. Is this because the phenomenon has so far received little attention from marine scientists? Or because they are indeed uncommon in marine environments?

We answer this question in a recent paper. We show that the data needed to identify ecological traps are not being collected when researchers evaluate the effects of human impacts to animals in the ocean.

Ecological trap data collection. Photo: Dr Michael Sievers and Professor Stephen Swearer.

Traps are potentially common, but under-researched, in marine ecosystems. They could be there, but we really don’t know because we are not measuring the right things.

But, measuring the right things isn’t easy. To assist, we devised a list of species traits – such as dispersal potential and mobility – that influence a species’ susceptibility to ecological traps and also the ease at which they can be studied. This information can guide future research into the existence and impact of marine traps.

Species and life-history traits that influence the likelihood of selecting traps or experiencing fitness-related consequences. Photo: Swearer et al. 2021 Frontiers in Ecology and the Environment.

Ecological traps are a potentially devastating phenomenon. The accelerating rate of human impacts in the ocean means it is likely that traps will be more prevalent in the future. But, we cannot effectively manage and mitigate traps unless we know they’re there. Our research hopes to shine a light on ecological traps, and the potential for human-induced environmental change in our oceans to make good animals make bad decisions.

Article Notes:

Authors and Paper details:

Our study appeared in the journal Frontiers in Ecology and the Environment. Dr Michael Sievers is a Research Fellow in The Global Wetlands Project (GLOW), Australian Rivers Institute, Coastal and Marine Research Centre, Griffith University. Dr Stephen Swearer is a professor of marine biology at the University of Melbourne and Director of the National Centre for Coasts and Climate (NCCC).


You can follow Dr Michael Sievers at @SieversSci.

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