Temporal and spatial variation in the delta super(15)N and delta super(13)C of coral tissue and zooxanthellae in Montastraea faveolata collected from the Florida reef tract

• Published in: Limnology and oceanography 2005-07, Vol.50 (4), p.1049-1058
• Main Authors: Swart, Peter K, Saied, Amel, Lamb, Kathryn
• Format: Article
• Language: English
• Subjects: Marine; Montastraea faveolata
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.2005.50.4.1049

Tissues were collected from Montastraea faveolata at five locations on the Florida Reef tract representing both nearshore and offshore environments. The tissue and zooxanthellae were removed from the skeletons, separated, and subsequently analyzed for delta super(15)N and delta super(13)C. The mean delta super(15)N value in the coral tissue was +6.6 ( plus or minus 0.6ppt) while the delta super(13)C was -13.3 ( plus or minus 0.5ppt) (n = 197). The delta super(15)N and delta super(13)C of the zooxanthellae were +4.7 ( plus or minus 1.1ppt) and -12.2 ( plus or minus 1.0ppt), respectively (n = 147). The differences in the delta super(15)N and delta super(13)C between the zooxanthellae and the tissue were statistically significant. No statistically significant differences were observed between nearshore and offshore stations in either delta super(15)N or delta super(13)C. The absence of a difference casts doubt on both whether the delta super(15)N of the coral tissues is related to anthropogenic influences and/or whether the delta super(15)N value itself can be used as an indicator of sewage contamination in corals. Between 1995 and 1997, there was an increase of 1ppt in the delta super(13)C and a decrease of approximately 0.8pptin the delta super(15)N. The increase in the delta super(13)C of the organic material was mimicked in the delta super(13)C of the skeletal material from corals from two reefs in the area. There appears to be clear seasonal variations in the delta super(13)C of the coral tissue at certain locations with delta super(13)C of the coral tissues and the zooxanthellae becoming more positive between July and August. The difference between the delta super(13)C of the zooxanthellae and the coral tissue varies seasonally with the maximum difference occurring in July of each year. In contrast, the maximum delta super(13)C in the skeleton appears to occur later in the year, between September and November.