PRIMARY PRODUCTIVITY OF MARINE MACROALGAL FUNCTIONAL‐FORM GROUPS FROM SOUTHWESTERN NORTH AMERICA1

Abstract

New productivity data are given for 62 macroalgal species from 6 intertidal habitats spanning a latitudinal range of nearly twelve degrees on the Pacific Coast of south‐western North America. Our data, utilizing a functional‐form group approach, support an hypothesis relating morphological forms to photosynthetic performances. Specifically, the Sheet‐Group showed the highest productivity (mean apparent net photo synthetic performance = 5.16 mg C · g−1· h−1) with a reduction of ca. two‐fold between each of the following four groups: Filamentous‐Group (2.47), Coarsely Branched‐Group (1.30), Thick Leathery‐Group (0.76) and Jointed Calcareous‐Group (0.45). The Crustose‐Group had by far the lowest mean net productivity being only 0.07 mg C · g−1· h−1. The‐functional‐form group approach is a promising tool for predicting the outcome of productivity‐related ecological and evolutionary processes without being restricted temporally, geographically or taxonomically.