Beach sand oil spills select for generalist microbial populations

Area of Science:

• Microbial Ecology
• Environmental Microbiology
• Ecosystem Dynamics

Background:

• The specialization-disturbance hypothesis suggests generalist species thrive and specialists decline following environmental disturbances.
• This hypothesis lacks rigorous testing in microbial systems, particularly regarding microbial community succession after perturbations.
• Previous field studies on Deepwater Horizon oil spill-affected sands showed support, but confounding factors like storms and ecological drift were possible.

Purpose of the Study:

• To rigorously test the specialization-disturbance hypothesis in a controlled laboratory setting using microbial communities from oil-impacted beach sands.
• To investigate microbial community succession patterns following crude oil disturbance in a simulated beach environment.
• To validate or refute the applicability of the specialization-disturbance hypothesis to microbial ecosystems.

Main Methods:

• Beach sands experimentally disturbed with Deepwater Horizon crude oil were incubated in laboratory advective-flow chambers mimicking saturated beach sediments.
• Control chambers with unamended sand were used for comparison.
• Shotgun metagenomic and 16S rRNA gene amplicon sequencing were performed over a two-month incubation period to analyze microbial community structure and function.

Main Results:

• Microbial functional diversity significantly increased over the two-month incubation period.
• Microbial taxonomic diversity significantly declined, indicating a reduction in specialist taxa.
• The observed decrease in specialists and increase in generalists supports the specialization-disturbance hypothesis.

Conclusions:

• Laboratory results corroborate previous field observations, confirming the specialization-disturbance hypothesis applies to microbial succession in crude oil-impacted beach sands.
• The study provides strong evidence that disturbance selects against microbial specialists and favors generalists in these environments.
• Controlled experiments are crucial for validating ecological hypotheses in microbial systems, minimizing confounding environmental factors.