Introduction

Benthic marine habitats are those found on the sea floor (benthic means "bottom"). They are made up mainly by macroalgae (plants) but also some sessile (attached) invertebrates. Two survey methods are used to sample them:

• Line Intercept Transect (LIT) - a weighted one metre steel ruler is placed in a number of consecutive locations on a bottom contour and the points along one edge (in cm) at which the lifeforms change are recorded. This is the same method used in studies commissioned every few years by the EPA. The method used is described more fully in the Reef Watch LIT Survey Manual, which should be read in conjunction with the Reef Watch Site Manual.
   
• Quadrat - a one square metre quadrat is placed randomly on the bottom and the approximate percentage cover and/or count of the different lifeforms within it are recorded using codes. The method is described more fully in the Reef Watch Quadrat Survey Manual.
  
  Datasheets for both Quadrat and LIT surveys are available from Reef Watch, but if you have waterproof paper you can download and print your own:
   
  • LIT datasheet
  • Quadrat datasheet
   
  

Given that there are more than a thousand species of algae, and that even the experts can't identify them all without laboratory equipment, Reef Watch provides a simple yet scientifically useful set of lifeform codes that are based on appearance. The same codes are used for both survey methods.These codes are described in the Reef Watch Benthic Identification Manual.

The benthic identification manual is best read with the book Australian Marine Life - The Plants and Animals of Temperate Waters, by Graham Edgar (either the first edition by Reed books in 1997, or the second, paperback edition by Reed New Holland in 2000 will do). Although it contains only a relatively small proportion of the known southern Australian benthic species, it covers those most commonly observed by divers. Graham has generously allowed us to use images from this book for our on-line identification guides and quizzes.

Here is a list of Reef Watch and other resources that can assist you with the identification of benthic organisms (both algae and invertebrates), and provide further information:

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