T226 Cushman Foundation Symposium: Microfossil Mayhem—Murder, Misfortune, and More

Tuesday, 24 October 2017
1:30 PM - 5:30 PM
Room 611

A BASELINE STUDY FOR ASSESSING LAND-USE CHANGES ALONG THE CARIBBEAN COAST OF PANAMA

Paper number: T226-13
Program: Technical Sessions
Time: 4:35 PM – 4:50 PM

Authors

Abstract

Land-use changes along Caribbean coastlines have caused declines in marine communities. We are using environmental indicator species of benthic foraminifera to compare modern marine coastal habitats of Bocas del Toro, Panama, to the presumably pristine state of a mid-Holocene coral reef. Herein we establish the distribution and community structure of benthic foraminiferal assemblages from reef-associated facies, and compare them with measurements of carbon and grain size to assess habitats. Samples were collected ~7m below mean sea level from ~3ha of an excavated ~6-ka-old Acropora cervicornis-dominated reef. Relative abundance, richness, evenness and wall type indicate salinity levels. The distribution of taxa and habitats are being used to build a baseline for future comparisons with their modern equivalents.

Foraminiferal wall types, with the exception of one mud sample, are indicative of normal salinity. The mud sample has low diversity, with Ammonia parkinsoniana and Elphidium species including E. poeyanum and E. gunteri, composing ~90%, consistent with brackish/low salinity habitats, whereas other samples contain normal marine diversities. Assemblages with an approx. 50-50 split of hyaline and porcellaneous wall types agree with typical coral reef assemblages. Seagrass-associated species such as Archaias angulatus, Peneropolis pertusus and Articulina mexicana were present in some samples, although their low relative abundances do not strongly indicate habitat type. Preliminary foraminiferal taxonomic identifications group assemblages into reefal, seagrass and muddy/fringing reef facies. Reefal and seagrass biofacies are dominated by inorganic carbon, a result of nearby coral rubble. Grain sizes range from fine to coarse sands with no clear association with biofacies. Initial results comparing grain size, carbon and foraminiferal taxa do not suggest a correlation between benthic foraminiferal assemblages, not unusual in this mixed siliciclastic-carbonate depositional setting. Ongoing analysis of benthic foraminifera and physical data will further assess habitats for comparison to those of nearby modern habitats to determine changes in coastal habitats over the past ~6,000 years.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-308139

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