Scientists survey vulnerable marine ecosystems

Scientists survey vulnerable marine ecosystems

NIWA’s flagship research vessel Tangaroa has returned from a five-week voyage to the Louisville Seamount Chain after completing an extensive biological survey of this rarely sampled area.

The voyage was one of the first of its kind aimed at giving scientists a better understanding about marine ecosystems vulnerable to commercial fishing in the region.

The main goal of the voyage was to verify the models developed by scientists that predict the whereabouts of various sea animals that indicate the presence of a vulnerable marine ecosystem.

Voyage leader and NIWA Principal Scientist Malcolm Clark said this “ground-truthing” provided confidence that the models can be used for management of fishing industry practices to mitigate the impacts of bottom trawling on the seamounts.

The Louisville Seamount Chain is about 1000km northeast of New Zealand and extends more than 4000km through the western South Pacific.

Dr Clark said a combination of techniques such as detailed mapping, towed cameras to take photographs of the seafloor, and sampling some of the animals proved very effective.

“We had to be adaptable during the survey, as the size and shape of the seamounts differed from expected, as did the location of the animals.”

Dense patches of live stony corals were quite localised, not on the summits as is common with many seamounts around New Zealand, but on the hard and steep flanks and ridges down the side of the seamounts. They were also much deeper than expected, Dr Clark said.

Samples of some animals were captured using small seafloor sleds. These included about 80 species of invertebrate and fish.

“These specimens will be used to improve our knowledge of deep-sea biodiversity in the region, to study the genetic connectivity of populations on the seamounts, and to understand the associations between corals and the animals like brittlestars that live on them,” Dr Clark said.

Some live corals were also recovered that will be analysed at NIWA in Wellington to determine the effect of ocean acidification on coral growth and survival.

Data from the survey will be used to refine the scientific models and improve the confidence of fishery managers that the maps correctly predict the distribution of vulnerable marine ecosystems when they are designing protective measures.

Dr Ashley Rowden, Principal Scientist at NIWA and the project leader, said "The survey is one of the first to ground-truth large-scale models of habitat suitability for fishery management purposes, and represents an important contribution by New Zealand to improving the techniques that are now being used to protect marine ecosystems worldwide."

The survey is part of a three-year research project on the vulnerable marine ecosystems of the South Pacific funded by NIWA, the Ministry of Business, Innovation and Employment and the Ministry for Primary Industries.

The study involves US-based scientists under a bilateral agreement to improve scientific and technical collaboration between NZ and the US. Scientists from Australia are also involved in the project.

ENDS

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