Thermal conditions determine lizards' response to oil contamination in a desert habitat

A unique, hyper-arid habitat in southern Israel was polluted by crude oil in 2014. Surveys following the event found that some species of local lizards avoid the oil, while other species were found more frequently in polluted plots. These results raised the question: why do species react differently to oil-polluted soil? We evaluated how soil type, thermal conditions, and food availability interacted to shape habitat preferences of three lizard species. Generally, thermal conditions determined habitat selection and preferences for contaminated or clean soils, while the effects of food availability were weak. The diurnal Acanthodactylus opheodurus avoided artificial heating sources, perhaps to avoid hot soil during warm hours. Both nocturnal Stenodactylus species showed a preference for higher temperature treatments. While crude oil is considered harmful, ectotherms may not recognize it as a danger and may be attracted to it due to its thermal properties, which may create an ecological trap.

Disturbance legacies and shifting trajectories: Marsh soil strength and shoreline erosion a decade after the Deepwater Horizon oil spill

Marsh resilience post disturbance is strongly dependent on the belowground dynamics affecting the emergent plants aboveground. We investigated the long-term impacts at the marsh-water interface in coastal wetlands of south Louisiana after the 2010 Deepwater Horizon oil spill with a combination of fieldwork (2010-2018) and spatial analysis (1998-2021). Data were collected on shoreline erosion rates, marsh platform elevation heights and cantilever overhang widths, and soil strength up to 1 m depth. Oil concentration in the top 5 cm of the marsh soil were determined using gas chromatography/mass spectrometry and were 1000 times higher than before the spill and remained 10 times higher eight years post-oiling. The oiling initially caused the marsh edge to subside, and chronic effects lowered soil strength, creating a faster erosion rate and deeper water within 150 cm of the shoreline. Soil strength declined by 50% throughout the 1 m soil profile after oiling and has not recovered. The mean erosion rate for 11 years post-spill was double that before oiling and there was an additive impact on erosion rates after Hurricane Isaac. Erosion appeared to have recovered to pre-spill rates by 2019, however from 2019 to 2021, the rate increased by 118% above the pre-spill rate. The continuing loss of soil strength indicates that the belowground biomass was seriously compromised by oiling. The perpetuation of oil in the remaining marsh may have set a new baseline for soil strength and subsequent storm induced erosional events. The remaining marsh soils retain chronic physical and biological legacies compromising recovery for more than a decade that may be evident in other marsh habitats subject to oiling and other stressors.

Comparative Analysis of Microbial Consortiums and Nanoparticles for Rehabilitating Petroleum Waste Contaminated Soils

Nano-bioremediation application is an ecologically and environmentally friendly technique to overcome the catastrophic situation in soil because of petroleum waste contamination. We evaluated the efficiency of oil-degrading bacterial consortium and silver nanoparticles (AgNPs) with or without fertilizer to remediate soils collected from petroleum waste contaminated oil fields. Physicochemical characteristics of control soil and petroleum contaminated soils were assessed. Four oil-degrading strains, namely Bacillus pumilus (KY010576), Exiguobacteriaum aurantiacum (KY010578), Lysinibacillus fusiformis (KY010586), and Pseudomonas putida (KX580766), were selected based on their in vitrohydrocarbon-degrading efficiency. In a lab experiment, contaminated soils were treated alone and with combined amendments of the bacterial consortium, AgNPs, and fertilizers (ammonium nitrate and diammonium phosphate). We detected the degradation rate of total petroleum hydrocarbons (TPHs) of the soil samples with GC-FID at different intervals of the incubation period (0, 5, 20, 60, 240 days). The bacterial population (CFU/g) was also monitored during the entire period of incubation. The results showed that 70% more TPH was degraded with a consortium with their sole application in 20 days of incubation. There was a positive correlation between TPH degradation and the 100-fold increase in bacterial population in contaminated soils. This study revealed that bacterial consortiums alone showed the maximum increase in the degradation of TPHs at 20 days. The application of nanoparticles and fertilizer has non-significant effects on the consortium degradation potential. Moreover, fertilizer alone or in combination with AgNPs and consortium slows the rate of degradation of TPHs over a short period. Still, it subsequently accelerates the rate of degradation of TPHs, and a negligible amount remains at the end of the incubation period.

Biodiversity influences the effects of oil disturbance on coastal ecosystems

Biodiversity can enhance the response of ecosystems to disturbance. However, whether diversity can reduce the ecological effect of human-induced novel and extreme disturbances is unclear. In April 2010, the Deepwater Horizon (DwH) platform exploded, allowing an uncontrolled release of crude oil into the northern Gulf of Mexico. Initial surveys following the spill found that ecological impacts on coastal ecosystems varied greatly across habitat-type and trophic group; however, to date, few studies have tested the influence of local biodiversity on these responses. We used a meta-analytic approach to synthesize the results of 5 mesocosm studies that included 10 independent oil experiments and 5 independent oil + dispersant experiments. We tested whether biodiversity increased the resistance and/or resilience of coastal ecosystems to oil disturbance and whether a biodiversity effect depended on the type of diversity present (taxonomic or genetic) and/or the response type measured (population, community, or ecosystem level). We found that diversity can influence the effects of oiling, but the direction and magnitude of this diversity effect varied. Diversity reduced the negative impact of oiling for within-trophic-level responses and tended to be stronger for taxonomic than genetic diversity. Further, diversity effects were largely driven by the presence of highly resistant or quick to recover taxa and genotypes, consistent with the insurance hypothesis. However, we found no effect of diversity on the response to the combination of oil and dispersant exposure. We conclude that areas of low biodiversity may be particularly vulnerable to future oil disturbances and provide insight into the benefit of incorporating multiple measures of diversity in restoration projects and management decisions.

Stable isotope analyses identify trophic niche partitioning between sympatric terrestrial vertebrates in coastal saltmarshes with differing oiling histories

Bioindicator species are commonly used as proxies to help identify the ecological effects of oil spills and other stressors. However, the utility of taxa as bioindicators is dependent on understanding their trophic niche and life history characteristics, as these factors mediate their ecological responses. Seaside sparrows (Ammospiza maritima) and marsh rice rats (Oryzomys palustris) are two ubiquitous terrestrial vertebrates that are thought to be bioindicators of oil spills in saltmarsh ecosystems. To improve the utility of these omnivorous taxa as bioindicators, we used carbon and nitrogen stable isotope analysis to quantify their trophic niches at saltmarshes in coastal Louisiana with differing oiling histories. We found that rats generally had lower trophic positions and incorporated more aquatic prey relative to seaside sparrows. The range of resources used (i.e.,trophic niche width) varied based on oiling history. Seaside sparrows had wider trophic niches than marsh rice rats at unoiled sites, but not at oiled sites. Trophic niche widths of conspecifics were less consistent at oiled sites, although marsh rice rats at oiled sites had wider trophic niches than rats at unoiled sites. These results suggest that past oiling histories may have imparted subtle, yet differing effects on the foraging ecology of these two co-occurring species. However, the temporal lag between initial oiling and our study makes identifying the ultimate drivers of differences between oiled and unoiled sites challenging. Even so, our findings provide a baseline quantification of the trophic niches of sympatric seaside sparrows and marsh rice rats that will aid in the use of these species as indicators of oiling and other environmental stressors in saltmarsh ecosystems.

Dietary Exposure to Low Levels of Crude Oil Affects Physiological and Morphological Phenotype in Adults and Their Eggs and Hatchlings of the King Quail (Coturnix chinensis)

Despite the current knowledge of the devastating effects of external exposure to crude oil on animal mortality, the study of developmental, transgenerational effects of such exposure has received little attention. We used the king quail as an animal model to determine if chronic dietary exposure to crude oil in a parental population would affect morpho-physiological phenotypic variables in their immediate offspring generation. Adult quail were separated into three groups: (1) Control, and two experimental groups dietarily exposed for at least 3 weeks to (2) Low (800 PAH ng/g food), or (3) High (2,400 PAH ng/g food) levels of crude oil. To determine the parental influence on their offspring, we measured metabolic and respiratory physiology in exposed parents and in their non-exposed eggs and hatchlings. Body mass and numerous metabolic (e.g., O₂ consumption, CO₂ production) and respiratory (e.g., ventilation frequency and volume) variables did not vary between control and oil exposed parental groups. In contrast, blood PO₂, PCO₂, and SO₂ varied among parental groups. Notably, water loss though the eggshell was increased in eggs from High oil level exposed parents. Respiratory variables of hatchlings did not vary between populations, but hatchlings obtained from High oil-exposed parents exhibited lower capacities to maintain body temperature while exposed to a cooling protocol in comparison to hatchlings from Low- and Control-derived parents. The present study demonstrates that parental exposure to crude oil via diet impacts some aspects of physiological performance of the subsequent first (F₁) generation.

Macroinfauna responses and recovery trajectories after an oil spill differ from those following saltmarsh restoration

Given the severity of injuries to biota in coastal wetlands from the Deepwater Horizon oil spill (DWH) and the resulting availability of funding for restoration, information on impacted salt marshes and biotic development of restored marshes may both help inform marsh restoration planning in the near term and for future spills. Accordingly, we performed a meta-analysis to model a restoration trajectory of total macroinfauna density in constructed marshes (studied for ~30 y), and with a previously published restoration trajectory for amphipods, we compared these to recovery curves for total macroinfauna and amphipods from DWH impacted marshes (over 8.5 y). Total macroinfauna and amphipod densities in constructed marshes did not consistently reach equivalency with reference sites before 20 y, yet in heavily oiled marshes recovery occurred by 4.5 y post spill (although it is unlikely that macroinfaunal community composition fully recovered). These differences were probably due to initial conditions (e.g., higher initial levels of belowground organic matter in oiled marshes) that were more conducive to recovery as compared to constructed marshes. Furthermore, we found that amphipod trajectories were distinctly different in constructed and oiled marshes as densities at oiled sites exceeded that of reference sites by as much as 20x during much of the recovery period. Amphipods may have responded to the rapid increase and high biomass of benthic microalgae following the spill. These results indicate that biotic responses after an oil spill may be quantitatively different than those following restoration, even for heavily oiled marshes that were initially denuded of vegetation. Our dual trajectories for oil spill recovery and restoration development for macroinfauna should help guide restoration planning and assessment following the DWH as well as for restoration scaling for future spills.

A review on the environmental impacts of shipping on aquatic and nearshore ecosystems

There are several environmental and ecological effects of shipping. However, these are rarely assessed in total in the scientific literature. Thus, the aim of this study was to summarize the different impacts of water-based transport on aquatic and nearshore ecosystems and to identify knowledge gaps and areas for future research. The review identified several environmental and ecological consequences within the main impact categories of water discharges, physical impacts, and air emissions. However, although quantitative data on these consequences are generally scarce the shipping contribution to acidification by SO_x- and NO_x-emissions has been quantified to some extent. There are several knowledge gaps regarding the ecological consequences of, for example, the increasing amount of chemicals transported on water, the spread of non-indigenous species coupled with climate change, and physical impacts such as shipping noise and artificial light. The whole plethora of environmental consequences, as well as potential synergistic effects, should be seriously considered in transport planning.

Oiling of the continental shelf and coastal marshes over eight years after the 2010 Deepwater Horizon oil spill

We measured the temporal and spatial trajectory of oiling from the April, 2010, Deepwater Horizon oil spill in water from Louisiana's continental shelf, the estuarine waters of Barataria Bay, and in coastal marsh sediments. The concentrations of 28 target alkanes and 43 target polycyclic aromatic hydrocarbons were determined in water samples collected on 10 offshore cruises, in 19 water samples collected monthly one km offshore at 13 inshore stations in 2010 and 2013, and in 16-60 surficial marsh sediment samples collected on each of 26 trips. The concentration of total aromatics in offshore waters peaked in late summer, 2010, at 100 times above the May, 2010 values, which were already slightly contaminated. There were no differences in surface or bottom water samples. The concentration of total aromatics declined at a rate of 73% y^-1 to 1/1000th of the May 2010 values by summer 2016. The concentrations inside the estuary were proportional to those one km offshore, but were 10-30% lower. The oil concentrations in sediments were initially different at 1 and 10 m distance into the marsh, but became equal after 2 years. Thus, the distinction between oiled and unoiled sites became blurred, if not non-existent then, and oiling had spread over an area wider than was visible initially. The concentrations of oil in sediments were 100-1000 times above the May 2010 values, and dropped to 10 times higher after 8 years, thereafter, demonstrating a long-term contamination by oil or oil residues that will remain for decades. The chemical signature of the oil residues offshore compared to in the marsh reflects the more aerobic offshore conditions and water-soluble tendencies of the dissolved components, whereas the anaerobic marsh sediments will retain the heavier molecular components for a long time, and have a consequential effect on the ecosystems.

Ammonium loading disturbed the microbial food webs in biofilms attached to submersed macrophyte Vallisneria natans

The knowledge about the impacts of ammonium loading on microbial food webs in biofilms attached to submersed macrophytes is limited. In the present study, Illumina sequencing method was employed to investigate bacterial and eukaryotic communities in biofilms attached to leaves of Vallisneria natans (V. natans) exposed to 1-16 mg L^-1 NH₄⁺-N for 10 days, and 8 mg L^-1 NH₄⁺-N for 21 days. Ammonium loading stimulated biofilms growth, enhanced the relative abundance of nitrifying genus Nitrospira and several denitrifying genera. Eukaryotic kingdom Metazoa, Viridiplantae, Chromista, Fungi and super group SARNU (Stramenopiles, Alveolata, Rhizaria, Nucleariidae and Fonticula group and unknown eukaryotes) were obtained. Relative abundance of Metazoa decreased with the increased ammonium concentration and exposure time. Redundancy analysis revealed that ammonium, dissolved oxygen (DO) and pH had a key role in determining microbial community structure. Network analyses revealed that there were complex interactions including feeding, parasitism and predatism among organism in biofilms, and the microbial food webs were disturbed by inhibiting metazoan growth but stimulating bacteria and algae growth. These results suggest that ammonium-disturbed microbial food webs in biofilms may contribute to the growth of biofilms and algae, and thus contribute to the decline of submersed macrophyte and provide "algal seeds" for the algae burst in water column. These data will be helpful in understanding the macrophytic region transform into algal region in water column polluted by ammonium.

Partitioning the effects of regional, spatial, and local variables on beta diversity of salt marsh arthropods in Chile

AIM

We examined the influence of regional, spatial, and local variables (edaphic characteristics and vegetation structure) on patterns of arthropod variation along the Chilean coast by partitioning beta diversity into its turnover and nestedness components.

LOCATION

2,000 km along the coast of Chile.

METHODS

We collected ground-dwelling arthropod samples from nine marshes during two seasons. A clustering method was used to examine patterns of arthropod similarity across salt marshes. We also calculated multiple-site beta diversity and partitioned it into its turnover and nestedness components. Variation partitioning was then used to identify the major drivers of their variation (regional, spatial, and local variables). We compared results for the whole arthropod community and for the most abundant, speciose, and functionally different groups, Crustacea, Coleoptera, and Araneae.

RESULTS

Salt marsh arthropod similarities did not depend on the geographic proximity of sites. Arthropod beta diversity was mainly determined by its turnover component. A significant fraction of community variation was related to the spatially structured variation of climate or edaphic factors. However, the exclusive contribution of spatial variables had also a role.

MAIN CONCLUSIONS

Each salt marsh on the Chilean coast has the capacity to accommodate unique invertebrate taxa. Species sorting along the climatic gradient together with dispersal-based processes seems the key structuring force of the arthropods and Crustacean variation in the marshes we studied, while species sorting alone might be more important for Coleoptera variation.

eDNA-based bioassessment of coastal sediments impacted by an oil spill

Oil spills offshore can cause long-term ecological effects on coastal marine ecosystems. Despite their important ecological roles in the cycling of energy and nutrients in food webs, effects on bacteria, protists or arthropods are often neglected. Environmental DNA (eDNA) metabarcoding was applied to characterize changes in the structure of micro- and macro-biota communities of surface sediments over a 7-year period since the occurrence of Hebei Spirit oil spill on December 7, 2007. Alterations in diversities and structures of micro- and macro-biota were observed in the contaminated area where concentrations of polycyclic aromatic hydrocarbons were greater. Successions of bacterial, protists and metazoan communities revealed long-term ecological effects of residual oil. Residual oil dominated the largest cluster of the community-environment association network. Presence of bacterial families (Aerococcaceae and Carnobacteriaceae) and the protozoan family (Platyophryidae) might have conferred sensitivity of communities to oil pollution. Hydrocarbon-degrading bacterial families (Anaerolinaceae, Desulfobacteraceae, Helicobacteraceae and Piscirickettsiaceae) and algal family (Araphid pennate) were resistant to adverse effects of spilt oil. The protistan family (Subulatomonas) and arthropod families (Folsomia, Sarcophagidae Opomyzoidea, and Anomura) appeared to be positively associated with residual oil pollution. eDNA metabarcoding can provide a powerful tool for assessing effects of anthropogenic pollution, such as oil spills on sediment communities and its long-term trends in coastal marine environments.

Coupled effects of oil spill and hurricane on saltmarsh terrestrial arthropods

Terrestrial arthropods play an important role in saltmarsh ecosystems, mainly affecting the saltmarsh’s primary production as the main consumers of terrestrial primary production and decomposition. Some of these arthropods, including selected insects and spiders, can be used as ecological indicators of overall marsh environmental health, as they are differentially sensitive to ecological stressors, such as land loss, erosion, oil spills, and tropical storms. In the present study, we used terrestrial arthropods collected from seven (three lightly-oiled, four heavily-oiled) sites in Barataria Bay and from three unoiled reference sites in Delacroix, Louisiana, to determine the impacts of the distribution and re-distribution of Deepwater Horizon (DWH) oil on these saltmarsh ecosystems. A total of 9,476 and 12,256 insects were collected in 2013 and 2014, respectively. The results show that the terrestrial arthropods were negatively affected by the re-distribution of DWH oil by Hurricane Isaac in 2012, although the level of impacts varied among the arthropod groups. Moreover, the mean diversity index was higher (>1.5) in 2014 than in 2013 (<1.5) for all sites, suggesting a recovery trajectory of the saltmarsh arthropod population. The higher taxonomic richness observed in the reference sites compared to the oiled sites for both years also indicated long-term impacts of DWH oil to the saltmarsh arthropod community. Whereas a slow recovery of certain terrestrial arthropods was observed, long-term monitoring of arthropod communities would help better understand the recovery and succession of the marsh ecosystems.

Methodology for exposing avian embryos to quantified levels of airborne aromatic compounds associated with crude oil spills

Oil spills on birds and other organisms have focused primarily on direct effects of oil exposure through ingestion or direct body fouling. Little is known of indirect effects of airborne volatiles from spilled oil, especially on vulnerable developing embryos within the bird egg. Here a technique is described for exposing bird embryos in the egg to quantifiable amounts of airborne volatile toxicants from Deepwater Horizon crude oil. A novel membrane inlet mass spectrometry system was used to measure major classes of airborne oil-derived toxicants and correlate these exposures with biological endpoints. Exposure induced a reduction in platelet number and increase in osmolality of the blood of embryos of the chicken (Gallus gallus). Additionally, expression of cytochrome P4501A, a protein biomarker of oil exposure, occurred in renal, pulmonary, hepatic and vascular tissues. These data confirm that this system for generating and measuring airborne volatiles can be used for future in-depth analysis of the toxicity of volatile organic compounds in birds and potentially other terrestrial organisms.

Advances in Understanding the Fate and Effects of Oil from Accidental Spills in the United States Beginning with the Exxon Valdez

Scientific studies of the environmental effects of oil spills in the United States have produced a steady stream of unexpected discoveries countering prior and often simplistic assumptions. In this brief review, I present how major discoveries from scientific studies of oil spill effects on marine ecosystems and environments, beginning with the 1989 Exxon Valdez, have led to a more informed appreciation for the complexity and the severity of the damage that major spills can do to marine ecosystems and to an increasing recognition that our ability to evaluate those damages is very limited, resulting in a structural bias toward underestimation of adverse environmental effects.

Environmental effects of the Deepwater Horizon oil spill: A review

The Deepwater Horizon oil spill constituted an ecosystem-level injury in the northern Gulf of Mexico. Much oil spread at 1100-1300m depth, contaminating and affecting deepwater habitats. Factors such as oil-biodegradation, ocean currents and response measures (dispersants, burning) reduced coastal oiling. Still, >2100km of shoreline and many coastal habitats were affected. Research demonstrates that oiling caused a wide range of biological effects, although worst-case impact scenarios did not materialize. Biomarkers in individual organisms were more informative about oiling stress than population and community indices. Salt marshes and seabird populations were hard hit, but were also quite resilient to oiling effects. Monitoring demonstrated little contamination of seafood. Certain impacts are still understudied, such as effects on seagrass communities. Concerns of long-term impacts remain for large fish species, deep-sea corals, sea turtles and cetaceans. These species and their habitats should continue to receive attention (monitoring and research) for years to come.

Changes in the concentration and relative abundance of alkanes and PAHs from the Deepwater Horizon oiling of coastal marshes

We determined changes of 28 alkanes and 43 different PAHs in 418 wetland soil samples collected on ten sampling trips to three Louisiana estuaries before and after they were oiled from the 2010 Deepwater Horizon disaster. There was a significant decline in 22 of the 28 alkane analytes (0.42% day(-1)), no change in 6, over 2.5 years. The concentration of five aromatic petroleum hydrocarbons (PAHs) increased (range 0.25-0.70% day(-1)), whereas the total PAH pool did not change. Of these five, naphthalene and C-1-naphthalenes are suggested to be of higher toxicity than the other three because of their relatively higher volatility or solubility. The relative proportions of alkane analytes, but not PAHs, does not yet resemble that in the pre-oiled marshes after 3 years, The trajectories of nine indicators for degradation/weathering were either inconclusive or misleading (alkanes) or confirmed the relatively meager degradation of PAHs.