title: Dynamic relationships between body size, species richness, abundance, and energy use in a shallow marine epibenthic faunal community.
abstract: We study the temporal variation in the empirical relationships among body size (S), species richness (R), and abundance (A) in a shallow marine epibenthic faunal community in Coliumo Bay, Chile. We also extend previous analyses by calculating individual energy use (E) and test whether its bivariate and trivariate relationships with S and R are in agreement with expectations derived from the energetic equivalence rule. Carnivorous and scavenger species representing over 95% of sample abundance and biomass were studied. For each individual, body size (g) was measured and E was estimated following published allometric relationships. Data for each sample were tabulated into exponential body size bins, comparing species-averaged values with individual-based estimates which allow species to potentially occupy multiple size classes. For individual-based data, both the number of individuals and species across body size classes are fit by a Weibull function rather than by a power law scaling. Species richness is also a power law of the number of individuals. Energy use shows a piecewise scaling relationship with body size, with energetic equivalence holding true only for size classes above the modal abundance class. Species-based data showed either weak linear or no significant patterns, likely due to the decrease in the number of data points across body size classes. Hence, for individual-based size spectra, the SRA relationship seems to be general despite seasonal forcing and strong disturbances in Coliumo Bay. The unimodal abundance distribution results in a piecewise energy scaling relationship, with small individuals showing a positive scaling and large individuals showing energetic equivalence. Hence, strict energetic equivalence should not be expected for unimodal abundance distributions. On the other hand, while species-based data do not show unimodal SRA relationships, energy use across body size classes did not show significant trends, supporting energetic equivalence.
authors.affiliation: Centro de Investigación e Innovación para el Cambio Climático, Facultad de Ciencias, Universidad Santo Tomas Ejercito 146, Código Postal, 8370003, Santiago, Chile.
authors.forename: Fabio A
authors.initials: FA
authors.lastname: Labra
authors.affiliation: Programa de Investigación Marina de Excelencia (PIMEX), Facultad de Ciencias Naturales & Oceanográficas, Universidad de Concepción Concepción, Chile ; Interdisciplinary Center for Aquaculture Research (INCAR), Casilla 160-C, Universidad de Concepción Concepción, Chile.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Hernández-Miranda
authors.affiliation: Programa de Investigación Marina de Excelencia (PIMEX), Facultad de Ciencias Naturales & Oceanográficas, Universidad de Concepción Concepción, Chile ; Interdisciplinary Center for Aquaculture Research (INCAR), Casilla 160-C, Universidad de Concepción Concepción, Chile.
authors.forename: Renato A
authors.initials: RA
authors.lastname: Quiñones
keywords: Coliumo bay; energetic equivalence; humboldt current system; hypoxia; macroecological dynamics; south eastern pacific