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Comparisons of macrophyte cover and community primary productivity on two southern california shores
Author(s) -
Bullard A. M.,
Murray S. N.
Publication year - 2003
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.2003.03906001_16.x
Subject(s) - crustose , macrophyte , coralline algae , productivity , fucales , algae , intertidal zone , biology , ecology , botany , economics , macroeconomics
Light‐saturated net photosynthetic rates and cover of rocky intertidal macrophytes were determined between January and March 2003 at two southern California sites characterized by different macrophyte standing stocks. Overall macrophyte cover at Little Corona del Mar was low (75.4%) and was dominated by articulated corallines, and small, turf‐forming crustose algae that provide little habitat structure. Macrophyte cover was higher at Dana Point (99.4%), where larger, frondose seaweeds were more abundant (34% vs < 5% cover). Our light‐saturated photosynthetic rates for Little Corona del Mar and Dana Point macrophytes were similar to values for the same species obtained during the 1970s and 1980s. Highest photosynthetic rates were obtained for thinner, sheet‐like, and branched, frondose seaweeds, while lowest rates were found for articulated coralline and crustose algae. We estimated the net community productivity of the two sites using photosynthetic rates (calculated as mg C m −2 · h −1 ) and percent cover data for the most abundant populations. We also compared our community productivity estimates for Little Corona del Mar and Dana Point with values for the same sites calculated using macrophyte cover values obtained during the mid‐1970s. Re‐sampling studies of these and other regional sites reveal that lower‐producing, crustose and coralline algae have become increasingly abundant while the cover of higher‐producing, frondose algae has declined on many southern California shores. Our studies at Little Corona del Mar and Dana Point, indicate that changing macrophyte abundances can have significant effects on the primary productivity of rocky intertidal communities.