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Short‐term responses of coral reef microphytobenthic communities to inorganic nutrient loading
Author(s) -
Dizon Romeo M.,
Yap Helen T.
Publication year - 1999
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1999.44.5.1259
Subject(s) - nutrient , reef , water column , seawater , coral reef , coral , photosynthesis , chlorophyll a , phosphorus , sediment , nitrogen , carbonate , biology , irradiance , environmental chemistry , zoology , botany , chemistry , ecology , paleontology , physics , organic chemistry , quantum mechanics
The responses of coral reef flat microphytobenthos to short‐term exposure to elevated levels of inorganic nitrogen (N) and phosphorus (P) were investigated in 1994 and 1995. Sand samples collected from the reef flat were maintained over 7 d in triplicate cultures with N‐enriched (100 µM NO 3 ), P‐enriched (10 µM PO 4 ), and ambient seawater. A fourth experiment used a treatment of combined N and P enrichment. The sediment samples were assessed for chlorophyll a (Chl a ) content and photosynthesis‐irradiance (P‐I) responses. P‐I curves, constructed from area‐and Chl a ‐specific metabolic rates, showed consistently higher maximal rates in the nutrient enriched samples. Sediments exposed to enhanced levels of N exhibited the highest Chl a content while both N‐ and P‐enriched samples showed increased photosynthetic yield. Very little depletion of nutrients in the water column was detected over time in the batch cultures except in the N:P‐enriched treatments where nutrient values dropped to near‐ambient levels. Results from these experiments point to N and P colimitation in tropical carbonate sediments.