11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 4: Coral Reef Organisms as Recorders of Local and Global Environmental Change
4-5
Coral Record of Ba/Ca from the Southern Gulf of Mexico and its Relationship to
Fluvial Discharge
Guillermo HORTA-PUGA* 1 , José D. CARRIQUIRY 2
1 Facultad de Estudios Superiores Iztacala, UBIPRO, Universidad Nacional Autónoma de
México, Tlalnepantla, México, Mexico, 2 Instituto de Investigaciones Oceanológicas,
Universidad Autónoma de Baja California, Ensenada, Baja California, Mexico
The Ba/Ca ratio in the annual growth bands of Montastraea faveolata from the Veracruz
Reef System was used to record long-term environmental change associated to
anthropogenic activity in the Southern Gulf of Mexico (SGM). Annual samples, from
cores of two colonies collected at Anegada de Adentro and Isla Verde reefs, were cleaned
to quantify both the total and the Ca-sustitutive Ba/Ca ratios by ICP-OES. The total and
the Ca-sustitutive Ba/Ca records from the Anegada de Adentro reef were similar for the
period 1835-2002, ranging from 5.9 to 10.2 µmol/mol with averages of 7.8 µmol/mol. As
no significant statistical differences were found between records, it is concluded that
almost all Ba is incorporated in the Ca-sustitutive fraction. The Ba/Ca ratio average
increased from 7.4 µmol/mol in the 1835-1920 period to 8.2 µmol/mol in the 1920-2002
period. As the human population in the SGM increased >600% in the last period, it is
probable that the sediment load of river waters also increased due to higher erosion rates
enhanced by human activities, which also caused and increase of about 10% in the
concentration of Ba in the seawater of the SGM. The 62-yr record of Ba/Ca from Isla
Verde reef (1941-2002), showed a significant correlation with the Jamapa River total
annual discharge for the periods 1957-1974 (r=0.78, p