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Life at Lizard: Light trapping

By: Nicola Fraser, Dr Anne Hoggett, Category: Science, Date: 19 Feb 2014

“I’m going to work” takes on a whole new meaning when you’re a marine scientist on a tropical island.

Life at Lizard: Light trapping #1

Nicola Fraser  © Australian Museum

Life at Lizard is a blog series containing stories about life at the Australian Museum’s Lizard Island Research Station (LIRS).

Instead of a fleet of cars, Lizard Island Research Station has a fleet of small boats and kayaks. These are available for teams of scientists who use them to undertake marine research activities such as diving, collecting specimens (under permit) and snorkelling.

The first task is bringing the boat to shore so appropriate equipment can be loaded, ready for the day’s work.

One of the things I’ve been doing this past week is deploying and collecting light traps with Christoph Braun, from the University of Queensland. A light trap is basically a Perspex box with a fluorescent light inside and a mesh ‘box’ below.

Some marine species such as small fish are attracted to the light and become trapped in the mesh box. We put the traps out at dusk, attaching each one to a mooring, and retrieve them early the next morning.

We do an initial sorting of fish on the boat on our morning trip, returning unwanted individuals to their watery home, and bring the rest back to shore for more specific sorting. Ashore, the traps are washed and the batteries removed for charging.

Species caught vary with the season, ocean conditions, and moon phases. So far we haven’t collected many of the particular fishes that Christoph needs for his research (such as the damselfish Pomacentrus amboinensis and Pomacentrus moluccensis), but we have come across some interesting polychaete worms (these were very bristly and looked dangerous), a juvenile barracuda, and a couple of octopuses including a blue-ringed individual.

We put most of the catch straight back in the water but brought the octopus to shore so I could photograph it with one of the LIRS microscopes.

On the second morning I was helping Chris, we were working under a picturesque sky full of swooping terns, and on a recent evening, another flock was feeding on a school of fish, with a rainbow in the background.

There is so much to see and learn here, I can’t imagine ever being bored.

Nicola Fraser

Undergraduate intern
Southern Cross University

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