It’s pretty in pink and it doesn’t stink!

It’s pretty in pink and it doesn’t stink!

NIWA scientists are in the pink! They’re studying the deep candy pink or purple coralline algae, abundant around the New Zealand shoreline and throughout the world, which play a vital role in marine ecosystems.

To the untrained eye, some of these species look identical to others. A splash or crust of pink along the NZ coastline, they can be found in almost all marine habitats where there is sunlight and something to attach to. Their habitat ranges from high intertidal pools through to subtidal waters. In fact, there are more than 30 known species that occur in New Zealand, and NIWA scientists estimate that there are at least a dozen more species they can recognise, which are either new to science, or new to New Zealand.

Initially it was thought that these red algae, which have calcium carbonate in their cell walls, were animals. “When you look at them and feel them, they are hard and you don’t think algae, because they’re more like a shell or a coral. That’s why they are called coralline algae; algae that are like coral,” says NIWA biodiversity scientist, Tracy Farr. It wasn’t until the mid 1800s that their plant-like nature was established.

Coralline algae are either jointed (geniculate) or not jointed (non-geniculate). The jointed species have branches, and can be quite fine, and their joints give them flexibility. They’re often known as “coralline turf”, and can form a dense carpet in intertidal and deeper waters. Non-jointed species – often called “encrusting”, or “crustose” – are completely calcified. They may feel “warty” or “lumpy” to touch; some grow in complex and beautiful layered or folded forms, like a rose carved from chalk. But across all of these different growth forms, all of them are pink!

NIWA scientists begun studying them in 2002, armed with chisels and hammers, prising them off rocks. The scientists are currently focusing on one form of coralline algae, rhodoliths, literally “pink rocks,” which roll around on the sea floor. “These algae play key roles in the lives of invertebrates, fishes, and other algae. They provide a three-dimensional structure which is a habitat for organisms, a place where things can hide, a hard substrate where seaweeds can attach,” says Farr.

Some coralline algae produce chemicals which actively promote both settlement and early development of paua and other invertebrate larvae. Research overseas, and in New Zealand, indicates that some algae species are more attractive to paua than others. There is also some evidence that post-settlement survival may vary on different species or growth forms of corallines.

Crustose coralline algae are important to the construction and ecology of coral reefs, acting as the main cementing agent and providing strength for the reef. Research so far suggests that the calcium carbonate in the cell walls of the non-geniculate coralline algae species are a major store of carbon in the near-shore environment.

These coralline algae represent great biodiversity and the individual species are really important. “It’s difficult to tell some of them apart, but when you look at their DNA sequences, they are very different. There are very clear differences, and when you have the clue of the DNA you can look for other differences and find them,” says Farr.

The impact of ocean acidification on coralline algae is also the subject of current research. “We are measuring what happens when we grow coralline algae under more acidic conditions, to look at the impact on their growth rate, health and their structure,” says Farr.

Farr has been studying coralline algae since 2001. She is a scientist in marine biodiversity and biosecurity group at NIWA.

The Ministry of Fisheries recognises the importance of coralline algae to the ecosystem, and has funded three research projects since 2001.

ENDS