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.

Covariations in ecological scaling laws fostered by community dynamics

“…9 of main text to this case cannot be computed analytically. Some empirical studies [10,11] found a P (m|A) similar to a log-normal. We can describe this case as P (m|A) = m −δ F 2 m A λ where F 2 (x) is such that lim x→0,∞ x j F 1 (x) = 0 ∀j.…”

“…Precise estimates of the scaling exponents' values are thus crucial. Empirical evidence, however, shows that they vary considerably across ecosystems [9,10,11], suggesting that exponents of scaling ecological laws are far from universal, although the power-law form proves remarkably robust ( Fig. 1).…”

Body size variation in polyplacophoran molluscs: Geographical clines and community structure along the south‐eastern Pacific

“…Aguilera et al, 2015, 2019; Fenberg et al., 2015; Fenberg & Rivadeneira, 2019; Ibáñez, Waldisperg, et al., 2019; Moreno et al., 2006). In addition, for marine vertebrates and invertebrates it has been evidenced that body size distribution shows a correlation with species richness at different spatial scales (Barneche et al., 2019; Labra et al., 2015). Particularly along the south‐east Pacific coast (SEP), latitudinal clines of body size have been detected at intraspecific level in several invertebrates (Camus et al., 2012; Ibáñez, Waldisperg, et al., 2019; Jaramilllo et al, 2017; Lardies et al., 2010; Sepúlveda et al., 2016).…”

“…Aguilera et al, 2015Aguilera et al, , 2019Fenberg et al, 2015;Fenberg & Rivadeneira, 2019;Ibáñez, Waldisperg, et al, 2019;Moreno et al, 2006). In addition, for marine vertebrates and invertebrates it has been evidenced that body size distribution shows a correlation with species richness at different spatial scales (Barneche et al, 2019;Labra et al, 2015).…”

Short-term alteration of biotic and abiotic components of the pelagic system in a shallow bay produced by a strong natural hypoxia event

“…Off the south-central coast of Chile in the first days of January 2008, there was an intense and extensive upwelling event that involved a spatial scale of hundreds of kilometers. This produced an intrusion into the coastal area of ESSW from the oxygen minimum zone (OMZ), and produced massive mortality and beaching of fish, crustaceans and molluscs in Coliumo Bay [ 18 – 21 ], as well as zooplankton (see Fig 1 ). The OMZ in the Humboldt Current System is characterized by an oxygen concentration of <20 μmol kg −1 (0.5 mL O 2 L -1 ) ( e .…”