Primary productivity of marine macrophytes in the coral reef lagoon of theKadmat Island, Lakshadweep

In situ primary productivity measurements were, carried out with different macrophyte species (belonging to four groups) dominating the benthic commun ities in the coral reef lagoon of the Kadmat Island of the Lakshadweep Arch ipelago. The photosynthetic productivity and respiratory requirements in ni ne macrophytes were determined by measuring changes in dissolved oxygen con centration in light and dark bottles. The highest net productivity was reco rded in Laurencia papillosa (Forsk.) Greville while the lowest was in Dicty ota bartayresiana Lamour. More than 75% of the macrophytes studied had net photosynthetic productivity higher than 15 mg C (g dry wt)(-1) d(-1) and on ly one macrophyte, Boergesenia forbesii had net production and respiration ratio higher than 10. The results indicated that macrophyte species under i nvestigation are most productive and both macroalgae and sea-grasses contri bute equally to the carbon production of the coral reef lagoon of the Kadma t Island.