Comparison of Different Methods to Assess Macrobenthic Biomass within an Anti-Estuarine Zostera Marina Meadow in Baja California, Mexico

Abstract

Biomass is a fundamental variable to estimate benthic secondary production. Currently, the loss-on-ignition (LOI) technique is the most used method for biomass assessment, although it is expensive, time consuming, and subject to error due to the volatilization of the samples in the muffle. Moreover, samples are lost for subsequent taxonomic identification. Alternative methods for biomass evaluation, such as conversion factors, are fast, easy, reliable, and the samples are preserved for species identification. In the present study, we took benthic macrofauna samples at bimonthly intervals from August 2009 to May 2011 in a Zostera marina meadow at Estero Punta Banda, Mexico. We compared biomass estimations of the main benthic taxa between the LOI method and five conversion factors. The total mean biomass assessed with the LOI method was 45.14 ± 13.56 g ash-free dry weight (AFDW) m⁻², while the values of the alternative estimation methods ranged from 63.12 ± 13.56 g AFDW m⁻² to 39.25 ± 9.35 g AFDW m⁻². There were no significant differences among mean biomass values estimated with the different methods (two way ANOVA, p = 0.49), indicating that all methods are valuable alternatives. The two conversion factors showing the highest correlation with the LOI method were chosen as the most reliable alternatives to estimate biomass (BREY and R&B).