Revisiting Copano Bay, Texas: an exceptional long-term record of ecological communities and their associated death assemblages

Abstract

Thanks to previous work conducted by Staff et al. (1986), Copano Bay on the Texas coast presents an exceptional research area for studying 1) the effect of living volatility on death assemblage diversity and composition and 2) the stability of death assemblage diversity. Staff et al. (1986) revisited one site in Copano Bay every six weeks for 18 months in 1981-1982. In order to test the variability of both the live and dead assemblages of Copano Bay, Texas, the transect originally established by Staff et al. (1981) in 1981-1983, was reestablished in 2004 and sampled every six weeks for a duration of one year. Taxonomic abundance, diversity, and composition of these assemblages were compared to each other and those of Staff et al. (1981) in order to understand how both the living and dead assemblages have changed in the intervening 22 years. Important findings include: 1. Death assemblage composition in Copano Bay changed over 22 years more than expected based on short-term variation; 2. The death assemblages in Copano Bay reflected changes in taxonomic composition of the corresponding living community; 3. The death assemblages of Copano Bay were found to predominantly reflect the local, rather than the entire regional, species pool; and 4. Variation in diversity occurred at both six-week and 22-year time scales, indicating that the death assemblages at the study site are variable. Understanding time averaging and its effects on death assemblages will not only aid in paleocommunity reconstruction, but also aid in the construction of modern ecologic baselines.