Effect of nutrient enrichment in the field on the biomass, growth and calcification of the giant clam Tridacna maxima
| Main Authors: | Ambariyanto, A, Hoegh-Guldberg, O |
|---|---|
| Format: | Article PeerReviewed application/pdf |
| Terbitan: |
, 1997
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| Subjects: | |
| Online Access: |
http://eprints.undip.ac.id/540/1/37._AMBARIYANTO_AND_HOEGH_GULDB.PDF http://eprints.undip.ac.id/540/ |
Daftar Isi:
- Nutrients were added separately and combined to an initial concentration of 10 lM(ammonium) and/or 2 lM (phosphate) in a series of experiments carried out with the giant clam Tridacna maxima at 12 microatolls in One Tree Island lagoon, Great Barrier Reef, Australia (ENCORE Project). These nutrient concentrations re- mained for 2 to 3 h before returning to natural levels. The additions were made every low tide (twice per day) over 13 and 12 mo periods for the ®rst and second phase of the experiment, respectively. The nutrients did not change the wet tissue weight of the clams, host C:N ratio, protein content of the mantle, calci®cation rates or growth rates. However, ammonium (N) enrichment alone signi®cantly increased the total population density of the algal sym- biont (Symbiodinium sp.: C . 3.6 á 108 cell clam)1, N . 6.6 á 108 cell clam)1, P.5.7 á 108 cell clam)1, N + P . 5.7 á 108 cell clam)1; and C.4.1 á 108 cell clam)1,N . 5.1 á 108 cell clam)1, P . 4.7 á 108 cell clam)1, N + P . 4.5 á 108 cell clam)1, at the end of the ®rst and second phases of the experiment, respectively), although no di€erences in the mitotic index of these populations were detected. The total chlorophyll a (chl a) content per clam but not chlorophyll a per cell also increased with ammonium addition (C . 7.0 mg chl a clam)1, N . 13.1 mg chl a clam)1, P . 12.9 mg chl a clam)1, N + P . 11.8 mg chl a clam)1; and C . 8.8 mg chl a clam)1, N . 12.8 mg chl a clam)1; P . 11.2 mg chl a clam)1, N+P . 11.3 mg chl a clam)1, at the end of the ®rst and second phases of the experiment, respec- tively). The response of clams to nutrient enrichment was quantitatively small, but indicated that small changes in inorganic nutrient levels a€ect the clam±zooxanthellae association.