The configuration of the seascape and the complexity of the habitats can affect where fish find food and were they hide from predators. This is part of what Maria Eggertsen, PhD candidate at DEEP, has studied while doing field work on Ningaloo reef, one of the most extensive fringing reefs in the world. The reef harbors large seaweed beds along the coastline that fascinates her. The seaweed beds are often used as nursery habitat for young fishes which migrate to the reef when they grow older. The field trip was coordinated by researchers from  the Australian National University (ANU), The Fulton Lab - Ecology and evolution of fishes.

 

 

The video is made by Communications and Marketing at ANU.

What is it like to do fieldwork on the Ningaloo reef?

- I dive and keep track of fish movements. I look at where they are feeding, how much they feed and on what they feed. I also note if they are travelling, searching or hiding.

 I follow one fish at the time, and it is difficult to keep track of them - they can swim really fast! When looking at the GPS after a dive, I can see that I have swum 700 meters while following one fish!  I also map the seaweed areas; how dense and tall they are and which species grow there.

PhD candidate Maria Eggertsen. Photo: Niklas Björling.

The fish need to get used to you in the beginning. Sometimes I get the impression the fish look back at me saying: “What are you doing?!” and then you need to back off a bit. But if you keep your distance you are able to observe them undisturbed in their “everyday life”. You can really see the different fish personalities. Some are nasty to their friends or they prefer to eat different things. My role within the research team is to focus on the moon wrasse (Thalassoma lunare), a common fish in Western Australia which exists around the world in tropical waters. It is an important link in the marine food web by feeding on smaller organisms and is preyed on by larger fish.

 

 
Moon wrasse (Thalassoma lunare). Photo: Maria Eggertsen.

What drives you to do research on seaweed?

- The literature today focuses on that seaweed outcompete corals and when corals die, seaweeds takes over. But there is more to seaweeds than that; there is a place for them in the seascape. They exist naturally in some areas where they are part of the ecosystem. When the seaweeds are in the right place, they are important for young fish.  Collaborating with other researchers working on seaweed helps me gain knowledge and to grow as a PhD student. Visitinganother lab and have them visit you is great!

How was the seaweed doing in Australia this year?

- This year was a fantastic seaweed year, with some plants reaching  two meters in height (!). The researchers I am collaborating with had never seen them this tall.  Probably, it is because of the lower water temperatures this year cause by La Niña. We saw the same pattern in Tanzania where we also do research. The seasonal seaweed thrives in cooler temperatures and climate change can potentially be harmful.

Why is the research you do there important?

- To increase knowledge of the seaweed-coral ecosystems in Ningaloo and how they interact with each other. They are linked to each other, so what happens in one place will affect the other and vice versa. At Ningaloo, it is important to study them together and not just focus on the coral reefs in order to protect and preserve a healthy coral reef ecosystem.

The problem is also that seaweed areas are neglected in research - coral is somehow more charismatic and fancy. And no one wants to snorkel in seaweed areas, but I think it’s nice!

Read another article about the work performed in Ningaloo.

Maria Eggertsen is part of Charlotte Berkström and the Christina Halling  research group at Department of Ecology, Environment and Plant Sciences.