Summary

Turf, turf-forming, or mat-forming algae occur in coastal waters throughout the world, but they have particular significance on coral reefs, including those of the Great Barrier Reef of Australia. Although almost ubiquitous on coral reefs, they are comparatively inconspicuous in many habitats. Nevertheless, they are now considered the most important group of free-living algae with respect to primary production (Larkum 1983, Klumpp & McKinnon 1989) and serve as the major food source for the large populations of herbivorous reef animals, especially fishes (Hatcher 1983, Russ & St. John 1988).

The need for a detailed, comprehensive work to enable ready and consistent identifications of the turf algal species occurring on coral reefs has become increasingly evident in recent years. This has resulted from the great expansion in scientific research on reefs in the last few decades, with increasing emphasis on programs to assess and minimize undesirable human impacts, and also from recognition of the great ecological significance of the turf algae. However, because of the difficulties involved in studying this diverse group of minute algae, taxonomic knowledge has lagged behind that of certain other reef organisms such as the nongeniculate coralline algae, corals and fishes. The lack of a detailed turf algal Flora has, in turn, restricted detailed research on many aspects of the biology and ecology of these important reef organisms.

Because of their small size and generally simple morphology, the identification of turf algal species provides a considerable challenge. Field identification of many species remains difficult or even impossible. On the other hand, these organisms exhibit a remarkable diversity of structural and reproductive organization, particularly at the microscopic level.

In contrast with the situation in many temperate and tropical areas, there are relatively few detailed publications dealing with the taxonomy, distribution and ecology of the marine algae of tropical Australia. For the Great Barrier Reef region the single major contribution to date is Cribb's (1983) handbook of the intertidal Rhodophyta of the southernmost reefs. Many of the species described in the present work were also recorded by Cribb. Due to the general paucity of detailed information in the literature concerning many species of turf algae occurring on coral reefs in the Indo-West Pacific region, and constraints on the present study, this Turf Algal Flora must to some degree be considered preliminary. It represents a synthesis of our present knowledge of the structure, taxonomy and distribution of these algae, and should provide a stimulus for expanded research on their biology and ecology. Although based largely on material collected in the Great Barrier Reef region, the Flora should prove useful in other parts of northern Australia, in neighbouring tropical regions and, if used with caution, throughout the tropical Indo-West Pacific biogeographical region.

This work will most readily be used by phycologists, but should also provide interested biologists with ready identifications in many cases. For the non-phycologist, a guide to using the Flora and methods for collecting specimens and preparing material for study and reference purposes are given in the Introduction. The present volume covers only the 74 species of Rhodophyta (red algae) recorded; it is planned to treat other groups of turf algae in subsequent publications.