In light of rapid shifts in biodiversity associated with human impacts, there is an urgent need to understand how changing patterns in biodiversity impact ecosystem function. Functional redundancy is hypothesized to promote ecological resilience and stability, as ecosystem function of communities with more redundant species (those that perform similar functions) should be buffered against the loss of individual species. While functional redundancy is being increasingly quantified, few studies have linked differences in redundancy across communities to ecological outcomes. We conducted a review and meta‐analysis to determine whether empirical evidence supports the asserted link between functional redundancy and ecosystem stability and resilience. We reviewed 423 research articles and assembled a data set of 32 studies from 15 articles across aquatic and terrestrial ecosystems. Overall, the mean correlation between functional redundancy and ecological stability/resilience was positive. The mean positive effect of functional redundancy was greater for studies in which redundancy was measured as species richness within functional groups (vs. metrics independent of species richness), but species richness itself was not correlated with effect size. The results of this meta‐analysis indicate that functional redundancy may positively affect community stability and resilience to disturbance, but more empirical work is needed including more experimental studies, partitioning of richness and redundancy effects, and links to ecosystem functions.

The Deepwater Horizon (DWH) incident resulted in extensive oiling of the pelagic zone and shoreline habitats of many commercially important fish species. Exposure to the water-accommodated fraction (WAF) of oil from the spill causes developmental toxicity through cardiac defects in pelagic fish species. However, few studies have evaluated the effects of the oil on near-shore estuarine fish species such as red drum (Sciaenops ocellatus). Following exposure to a certified weathered slick oil (4.74 μg/L ∑PAH) from the DWH event, significant sublethal impacts were observed ranging from impaired nervous system development [average 17 and 22% reductions in brain and eye area at 48 h postfertilization (hpf), respectively] to abnormal cardiac morphology (100% incidence at 24, 48, and 72 hpf) in red drum larvae. Consistent with the phenotypic responses, significantly differentially expressed transcripts, enriched gene ontology, and altered functions and canonical pathways predicted adverse outcomes in nervous and cardiovascular systems, with more pronounced changes at later larval stages. Our study demonstrated that the WAF of weathered slick oil of DWH caused morphological abnormalities predicted by a suite of advanced bioinformatic tools in early developing red drum and also provided the basis for a better understanding of molecular mechanisms of crude oil toxicity in fish.

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The 2010 Deepwater Horizon (DWH) oil spill in the Gulf of Mexico was the largest spill in recent history and led to the exposure of many commercially and ecologically important fish species. Crude-oil exposure is known to result in compromised cardiorespiratory function and swim performance of fishes, presumably altering ecological performance by impairing the ability to capture prey or evade predators. However, this has yet to be empirically tested. This study assessed the impacts of oil exposure on thigmotaxis (avoidance of exposed areas), routine activity, and prey-capture ability in larval red drum (Sciaenops ocellatus) by using environmentally relevant concentrations of weathered-oil water-accommodated fractions (0–55.9µgL–1 of total polycyclic aromatic hydrocarbons, ΣPAH). Oil exposure caused a dose-dependent increase in time spent in the exposed area of the arena, with an average three-fold increase at the highest dose, suggesting increased risk-taking. Although increased risk-taking resulted in 14% more area explored, oil-exposed individuals were significantly slower to catch prey and caught 67% less prey overall. Prey-capture ability did not appear to be related to cardiorespiratory or swimming impairments, because oil-exposed fish exhibited routine swim speeds and the distance travelled similar to those of the control, suggesting an alternate route of toxicity, such as cognitive impairments.