Oil spill effects on macrofaunal communities and bioturbation of pristine marine sediments (Caleta Valdés, Patagonia, Argentina): experimental evidence of low resistance capacities of benthic systems without history of pollution

Abstract

The Patagonian coast is characterized by the existence of pristine ecosystems which may be particularly sensitive to oil contamination. In this study, a simulated oil spill at acute and chronic input levels was carried out to assess the effects of contamination on the macrobenthic community structure and the bioturbation activity of sediments sampled in Caleta Valdés creek. Superficial sediments were either noncontaminated or contaminated by Escalante crude oil and incubated in the laboratory for 30 days. Oil contamination induced adverse effects on macrobenthic community at both concentrations with, for the highest concentration, a marked decrease of approximately 40 and 55 % of density and specific richness, respectively. Besides the disappearance of sensitive species, some other species like Oligochaeta sp. 1, Paranebalia sp., and Ostracoda sp. 2 species have a higher resistance to oil contamination. Sediment reworking activity was also affected by oil addition. At the highest level of contamination, nearly no activity was observed due to the high mortality of macroorganisms. The results strongly suggest that an oil spill in this protected marine area with no previous history of contamination would have a deep impact on the non-adapted macrobenthic community.

Distribution of oil products in bottom sediments of the Irtysh River in the urban area

“…population -a decrease in fertility, a change in biomass, abundance, in particular, an abnormal "outbreak" of a species as an indicator of stability disturbances, changes in the sizeweight, sexual, generative and spatial structure, death of the least stable individuals in the population [8,10,11,28,31,32,[37][38][39][40][41][42][43][44][45][46][47][48];…”

“…biocenotic -a change in the species, size and trophic structure, type of dominance, violation of interspecific relationships and interpopulation relations [5,8,9,11,25,38,[40][41][42][43][44][45][47][48][49][50][51];…”

Microbial ecology of hydrocarbon-polluted coastal sediments

“…Gilbert et al (2014) showed that the macrofaunal community structure was not affected by an oil contamination in a historically hydrocarbon-contaminated sediment but the sedimentreworking activity was characterized by a deeper particle burial. In contrast, Ferrando et al (2015) demonstrated the deleterious effect of crude oil on macrofaunal community structure and reworking activity in a pristine sediment without pollution history suggesting that macrofaunal species could serve as bioindicators of pollution. The paper by Louati et al (2014b) confirms the negative impact of PAHs on macrofaunal communities and further demonstrates the capacity of bioremediation strategies (biostimulation and/ or bioaugmentation) to mitigate the effects of PAHs on macrofauna diversity.…”

Bioturbation functional roles associated with mangrove development in French Guiana, South America

“…One may therefore expect that the ex situ measurements quantified the maximum biological sediment transports. Such ex situ measurements with a natural benthic community have been widely used in the literature (Duport et al, 2007;Cuny et al, 2015;Ferrando et al, 2015). Although the absolute values must be interpreted with caution, the relative comparisons between the stages of mangrove development remain valid.…”

“…The presence and intensity of biodiffusive mixing and non-local transport may vary substantially according to the structure of the benthic communities (species richness, density, biomass, and biovolume; Sandnes et al, 2000;Duport et al, 2006;Gilbert et al, 2007;Majdi et al, 2014) which in turn depends on the environmental variables (temperature, organic matter or pollutant inputs, vegetation; Duport et al, 2007;Bernard et al, 2014;Cuny et al, 2015;Ferrando et al, 2015). Previous studies in ecology have shown that the productivity of an ecosystem is more dependent on its bioturbation functional richness than on its species richness (Solan et al, 2004;Mermillod-Blondin et al, 2005;Michaud et al, 2006;Norling et al, 2007).…”