Diversity of tropical macroalgae in the New Zealand marine aquarium trade

Exotic species often slip through international borders undetected. Increased global trade has increased the frequency of species introductions. The marine aquarium trade is a significant vector of species introductions, including algal introductions. Molecular barcoding of tropical macroalgae entering the New Zealand aquarium trade was implemented using various molecular markers. Both NCBI BLAST searches and maximum-likelihood phylogenies were used to identify the isolates. A total of 62 species of tropical macroalgae were identified from coral rocks. Some species found are known as invasive elsewhere, for example, Caulerpa cylindracea, C. racemosa, C. sertularioides, Ulva ohnoi and Chaetomorpha vieillardii. All three major groups of algae were well represented with 26 species of red algae, 24 species of green algae and 12 species of brown algae. Temperature tolerance of some of these algae to minimum sea surface temperatures was tested. Results show that one species Chaetomorpha vieillardii can survive at Auckland minimum winter sea surface temperatures. Our findings have important implications for New Zealand biosecurity, as not only are a large diversity of exotic macroalgae entering the New Zealand marine aquarium trade unregulated, but there is also the potential for them to survive in New Zealand waters.