REVIEW: New Zealand Seaweeds: An Illustrated Guide
by Wendy Nelson
Te Papa Press, 2013
NZ RRP: $79.99
Despite their prominence in many coastal habitats, New Zealand seaweeds have until now lacked a photographic handbook of the type available for our marine invertebrates, fishes and birds. This gap has now been filled with an excellent book by New Zealand’s resident seaweed authority, Prof. Wendy Nelson of the National Institute of Water and Atmospheric Research and the University of Auckland.
The temperate coastal waters of New Zealand are home to a seaweed flora that is every bit as interesting as our better-known terrestrial flora. Like land plants, seaweeds generate oxygen through photosynthesis and are important food and habitat for a variety of animals. However, living in the ocean imposes unique challenges on seaweeds.
Light is absorbed very rapidly underwater, so seaweeds are restricted to the shallows where water motion is often strong. Moderate water movement enables rapid growth by replenishing nutrients, but violent wave action abrades seaweeds against rocks and sometimes rips whole individuals loose. To resist these forces, seaweeds need to be streamlined, flexible, tough, and well attached to a firm substrate, while still presenting plenty of surface area for absorbing light and nutrients. Within these constraints a great variety of morphologies are possible, and seaweeds with the right formula for a particular location can be very abundant and productive.
This is the first substantial guide to our seaweeds since the similarly-titled Seaweeds of New Zealand: An Illustrated Guide (Canterbury University Press) by the late Nancy Adams came out in 1994. Prof. Nelson covers the most common third of our 787 known seaweed species, in a reasonably-sized and priced paperback format. Adams’ award-winning book covered the entire flora (over 600 species at the time), which required 360 pages in hardcover A4 format. It was illustrated with watercolour paintings and pencil drawings. While these are useful for highlighting taxonomically important characteristics, a good photograph can better represent the organism as it is likely to be encountered in the field.
Subtidal seaweeds, in particular, often look very different underwater when upright and expansive than they do as the dry pressed specimens that presumably were the basis for many of Adams’ illustrations. Prof. Nelson has obtained fine in situ images from a number of photographers throughout the country, and has supplemented these with watercolour paintings from Adams’ book and/or photomicrographs. Together they showcase the full range of seaweed diversity found on our shores.
Following some introductory material on the biology of seaweeds and their role in coastal ecosystems, the majority of Prof. Nelson’s book consists of species accounts. These are organised taxonomically within the broad groupings of “greens” (Chlorophyta), “browns” (Ochrophyta), and “reds” (Rhodophyta). The colours are a function of the major photosynthetic pigments possessed by seaweeds within each division, and a matching-coloured square at the top corner of each page helps to narrow down the options when attempting to identify a specimen.
Each species is described in enough detail to identify it (cautiously, bearing in mind that not all known species are covered), with pointers given to key characters. In many cases keys are included to help distinguish the species. A few non-indigenous species are included. New Zealand’s seaweed flora is relatively “uninvaded” compared to our terrestrial flora, but we do have the Asian kelp Undaria pinnatifida, which is spreading around our coastline with uncertain consequences for native seaweeds and animals.
The guide will enable any interested person to identify most of the seaweeds they find growing on rocks or washed up on the beach. I wouldn’t risk damaging my copy by taking it onto the shore, but there is no real need to do so given the amenability of seaweeds to being photographed or collected for later identification. In conclusion, Prof. Nelson’s book is a valuable addition to any New Zealander’s natural history library.
Dr Richard Taylor is Senior Lecturer in Marine Ecology at the University of Auckland’s Leigh Marine Laboratory. He studies the relationships between seaweeds and the animals that live on and eat them.