Impact of a simulated oil spill on benthic phototrophs and nitrogen‐fixing bacteria in mudflat mesocosms

Abstract

Coastal and estuarine ecosystems are highly susceptible to crude oil pollution. Therefore, in order to examine the resilience of benthic phototrophs that are pivotal to coastal ecosystem functioning, we simulated an oil spill in tidal mesocosms consisting of intact sediment cores from a mudflat at the mouth of the Colne Estuary, UK. At day 21, fluorescence imaging revealed a bloom of cyanobacteria on the surface of oiled sediment cores, and the upper 1.5 cm thick sediment had 7.2 times more cyanobacterial and 1.7 times more diatom rRNA sequences when treated with oil. Photosystem II operating efficiency (Fq'/Fm') was significantly reduced in oiled sediments at day 7, implying that the initial diatom-dominated community was negatively affected by oil, but this was no longer apparent by day 21. Oil addition significantly reduced numbers of the key deposit feeders, and the decreased grazing pressure is likely to be a major factor in the increased abundance of both diatoms and cyanobacteria. By day 5 concentrations of dissolved inorganic nitrogen were significantly lower in oiled mesocosms, likely resulting in the observed increase in nifH-containing, and therefore potentially dinitrogen-fixing, cyanobacteria. Thus, indirect effects of oil, rather than direct inhibition, are primarily responsible for altering the microphytobenthos.

Role of environmental factors and microorganisms in determining the fate of polycyclic aromatic hydrocarbons in the marine environment

“…2012; Chronopoulou et al. 2013), coral reefs (Burns 2014; Ko, Chang and Cheng 2014; Guigue et al. 2015) and even Arctic coasts with increasing traffic due to the diminution of the polar ice cap (Jörundsdóttir et al.…”

Selection of Diazotrophic Bacterial Communities in Biological Sand Filter Mesocosms Used for the Treatment of Phenolic-Laden Wastewater

“…It has previously been reported that diazotrophs are selected in organic-contaminated sediments [2]. Such adaptive traits indicate that bioavailable N is of pivotal importance for the bioremediation of organic-rich effluents and/or for organic-contaminated whole-ecosystems to function effectively.…”

The Variable Influence of Dispersant on Degradation of Oil Hydrocarbons in Subarctic Deep-Sea Sediments at Low Temperatures (0–5 °C)

“…During DWH, approximately 4.9 million barrels of crude oil were released at depth and it has been estimated that between 2–15% of this oil was deposited onto deep-sea sediments by sedimentation of oil-contaminated marine snow 2, 3 . Once in contact with the sediment, hydrocarbons can become entrapped for long periods via absorption into sediment organics 4–7 and impact sediment ecosystem function services 8–13 . The persistence in sediments of hydrocarbons recalcitrant to degradation may also have negative impacts on sediment communities biodiversity and pose significant health risks as accumulated hydrocarbons slowly enter the food web 14 .…”