TY - JOUR
T1 - Nutrient enrichment caused by in situ fish farms at Eilat, Red Sea is detrimental to coral reproduction
AU - Loya, Y.
AU - Lubinevsky, H.
AU - Rosenfeld, M.
AU - Kramarsky-Winter, E.
N1 - Funding Information:
We would like to acknowledge the Inter-University Institute at Eilat (IUI) for the use of their facilities. Special thanks are due to Drs. B. Willis, P. Harrison, K. Sakai, A. Hayward and C. Downs for their constructive comments on the ms.; Ms. Naomi Paz for editorial help and N. Siboni for technical help. This study was partially supported by the monitoring program of the Jordanian–Israeli Red Sea Marine Peace Park Program, the Israeli Science Foundation (ISF) and the Raynor Chair for Environmental Conservation Research (YL).
PY - 2004/8/1
Y1 - 2004/8/1
N2 - Recent studies report conflicting results concerning the effects of eutrophication on coral reproduction. The present study examines reproductive effort in the brooding coral Stylophora pistillata exposed to chronic eutrophication caused by in situ fish cages (FC) in the northern Gulf of Eilat (Aqaba). Histological studies of 20 S. pistillata colonies transplanted to each of two study sites, one close to the nutrient enriched FC site and the other at a reference site (IUI), 8 km southwest of the FC site, show that, overall, corals from the FC site have a significantly higher percentage of polyps containing oocytes and testes than corals from the IUI site. However, average oocyte size and the percentage of oocytes reaching the size at which fertilization occurs (i.e., >200 μm) were both significantly greater in colonies at the IUI site compared to the FC site. As the reproductive season progressed, colonies at the IUI site exhibited a decrease in the percentage of polyps containing oocytes, concomitant with an increase in the number of polyps containing planulae, indicating successful development of oocytes into planulae. In contrast, in colonies at the FC site oocyte numbers were greatest at the end of the reproductive season, and overall, numbers of planulae were significantly lower compared with the IUI colonies, suggesting relative failure of oocyte maturation, fertilization and ensuing larval development. The significantly higher lipid content found during the reproduction season in IUI colonies compared with FC colonies corroborates this assertion. This data strongly suggest that nutrients released from the fish farms have adverse effects on successful production of larvae of S. pistillata. In view of the recent severe deterioration of the coral reefs of Eilat and their present critical state of health, the only chance for their renewal is the use of immediate, prudent and rational protection measures against all man-made perturbations.
AB - Recent studies report conflicting results concerning the effects of eutrophication on coral reproduction. The present study examines reproductive effort in the brooding coral Stylophora pistillata exposed to chronic eutrophication caused by in situ fish cages (FC) in the northern Gulf of Eilat (Aqaba). Histological studies of 20 S. pistillata colonies transplanted to each of two study sites, one close to the nutrient enriched FC site and the other at a reference site (IUI), 8 km southwest of the FC site, show that, overall, corals from the FC site have a significantly higher percentage of polyps containing oocytes and testes than corals from the IUI site. However, average oocyte size and the percentage of oocytes reaching the size at which fertilization occurs (i.e., >200 μm) were both significantly greater in colonies at the IUI site compared to the FC site. As the reproductive season progressed, colonies at the IUI site exhibited a decrease in the percentage of polyps containing oocytes, concomitant with an increase in the number of polyps containing planulae, indicating successful development of oocytes into planulae. In contrast, in colonies at the FC site oocyte numbers were greatest at the end of the reproductive season, and overall, numbers of planulae were significantly lower compared with the IUI colonies, suggesting relative failure of oocyte maturation, fertilization and ensuing larval development. The significantly higher lipid content found during the reproduction season in IUI colonies compared with FC colonies corroborates this assertion. This data strongly suggest that nutrients released from the fish farms have adverse effects on successful production of larvae of S. pistillata. In view of the recent severe deterioration of the coral reefs of Eilat and their present critical state of health, the only chance for their renewal is the use of immediate, prudent and rational protection measures against all man-made perturbations.
KW - Eutrophication
KW - Fish farms
KW - Red Sea
KW - Reproductive effort
KW - Stylophora pistillata
UR - http://www.scopus.com/inward/record.url?scp=4043137290&partnerID=8YFLogxK
U2 - 10.1016/j.marpolbul.2004.06.011
DO - 10.1016/j.marpolbul.2004.06.011
M3 - Article
C2 - 15341829
AN - SCOPUS:4043137290
SN - 0025-326X
VL - 49
SP - 344
EP - 353
JO - Marine Pollution Bulletin
JF - Marine Pollution Bulletin
IS - 4
ER -