Correction: Coupled effects of oil spill and hurricane on saltmarsh terrestrial arthropods.

[This corrects the article DOI: 10.1371/journal.pone.0194941.]

First Record of Pyramica epinotalis (Hymenoptera: Formicidae) for the United States

Pyramica epinotalis is an arboreal dacetine ant previously known only from Brazil, Costa Rica, Ecuador, and southern Mexico. Here we report the first records of P. epinotalis for the United States. Collections were made in three parishes across southern Louisiana in cypress-tupelo swamps using floating pitfall traps placed in floating vegetation and arboreal pitfall traps placed on trunks and limbs of three wetland tree species. One additional specimen of this species was collected in Highlands County, Florida. Based on collections of specimens in Louisiana, including multiple dealate females at different localities, P. epinotalis appears to be well established in this state. We discuss the design and implementation of modified arboreal pitfall traps that were instrumental in this discovery

Coupled effects of oil spill and hurricane on saltmarsh terrestrial arthropods

<div><p>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 <i>Deepwater Horizon</i> (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.</p></div

Effect of treatment (heavily oil, lightly oiled, and reference), year (2013 and 2014) and their interaction (treatment*year) on the insects and spider (p values).

<p>The degree of freedom for treatment (df = 7), year (df = 47) and treatment*year interaction (df = 47) is same for all the arthropods.</p

Geographic coordinates for the treatment sites: heavily oiled, lightly oiled and reference sites.

<p>Geographic coordinates for the treatment sites: heavily oiled, lightly oiled and reference sites.</p

Mean ((±SE) diversity measurement in terms of Shannon and Weaver Index for treatments (reference, lightly oiled and heavily oiled) in 2013 (blue) and 2014 (orange).

<p>Mean ((±SE) diversity measurement in terms of Shannon and Weaver Index for treatments (reference, lightly oiled and heavily oiled) in 2013 (blue) and 2014 (orange).</p

Mean (±SE) abundance of individual group of arthropods collected per sweep net sample in reference, light oiled and heavily oiled sites in 2013 (blue) and 2014 (orange).

<p>Mean (±SE) abundance of individual group of arthropods collected per sweep net sample in reference, light oiled and heavily oiled sites in 2013 (blue) and 2014 (orange).</p

Mean (±SE) number of insects sorted per sweep net sample in all treatment sites (references, light oiled and heavily oiled sites) in 2013 (blue) and 2014 (orange).

<p>Mean (±SE) number of insects sorted per sweep net sample in all treatment sites (references, light oiled and heavily oiled sites) in 2013 (blue) and 2014 (orange).</p

Community structure analysis using Principal Component Analysis II excluding Delphacidae and Culicoidea (PCA II) a) Community structure analysis and (b) Component score for each individual family/order for the treatment sites and year.

<p>Community structure analysis using Principal Component Analysis II excluding Delphacidae and Culicoidea (PCA II) a) Community structure analysis and (b) Component score for each individual family/order for the treatment sites and year.</p

Principal Component Analysis (PCA); a) Community structure analysis and (b) Component score for each individual family/order for the treatment sites and year.

<p>Principal Component Analysis (PCA); a) Community structure analysis and (b) Component score for each individual family/order for the treatment sites and year.</p