Relearning the ABC: taxonomic changes and abundance/biomass relationships in disturbed benthic communities

Abstract

Abstract. For marine macrobenthic communities, a shift from higher biomass dominance with increasing levels of disturbance can be determined by the abundance/biomass comparison (ABC) method. This response results from (i) a shift in the proportions of different phyla present in communities, some phyla having larger-bodied species than others, and (ii) a shift in the relative distributions of abundance and biomass among species within the Annelida (specifically Polychaeta) but not within any of the other major phyla (Mollusca, Crustacea, Echinodermata). The shift within polychaetes reflects the substitution of largerbodied by smaller-bodied species, and not a change in the average size of individuals within a species. In most instances the phyletic changes reinforce the trend in species substitutions within the polychaetes, to produce the overall ABC response, but in some cases they may work against each other. Indications of pollution or disturbance detected by this method should be viewed with caution if the species responsible for the polluted configurations are not polychaetes. These observations provide an aid to interpretation of the ABC plots, especially in some situations where they have been deemed to give a false impression of the disturbance status of a community.

Assessment Level of Severity of Environmental Disturbance Caused by Aquaculture Activities Using Abundance-Biomass Curves of Macrobenthic Assemblages

“…The changes in the dominance pattern of macrobenthic assemblages based on both abundance and biomass were assessed using the Abundance/Biomass Comparison (ABC) method [1], [3]. The ABC method was used to determine a shift in the proportions of different phyla and in relative distributions of abundance and biomass among taxa between reference sites and fish farming sites, and over time.…”

“…The ABC method was used to determine a shift in the proportions of different phyla and in relative distributions of abundance and biomass among taxa between reference sites and fish farming sites, and over time. The "W" plotted in graphs is Clarke"s W statistic describing the degree and direction of separation of the curves [1], [3] and is calculated as shown in a formula (1):…”

“…The value of W is in the range between -1 and +1, where W → +1 for even abundances across species but biomass is dominated by a single species (undisturbed), and W → -1 in the converse case (severely disturbed) [1], [3].…”

“…Therefore, an increasing level of disturbance may either decrease or increase diversity or it may even remain the same [1], a condition that may not be easily detected by univariate statistical techniques [2]. In order to assess the rates and degree of environmental disturbance, multivariate techniques have been developed and widely used, as they are considered more sensitive for detecting community changes than univariate techniques [3].…”

“…Graphical methods, such as abundance biomass comparison (ABC), have been introduced and applied to assess the level of environmental disturbance [1], [3]. The method has been illustrated initially in a graphical model by [11] in assessing the changes in numbers of species, abundance, and biomass (SAB) in response to organic enrichment applicable to all habitats where organic enrichment occurs.…”