Permutation Tests of Hierarchical Cluster Analyses of Carrion Communities and Their Potential Use in Forensic Entomology.

Forensic entomologists can use carrion communities' ecological succession data to estimate the postmortem interval (PMI). Permutation tests of hierarchical cluster analyses of these data provide a conceptual method to estimate part of the PMI, the post-colonization interval (post-CI). This multivariate approach produces a baseline of statistically distinct clusters that reflect changes in the carrion community composition during the decomposition process. Carrion community samples of unknown post-CIs are compared with these baseline clusters to estimate the post-CI. In this short communication, I use data from previously published studies to demonstrate the conceptual feasibility of this multivariate approach. Analyses of these data produce series of significantly distinct clusters, which represent carrion communities during 1- to 20-day periods of the decomposition process. For 33 carrion community samples, collected over an 11-day period, this approach correctly estimated the post-CI within an average range of 3.1 days.

Abundance and size of Gulf shrimp in Louisiana's coastal estuaries following the Deepwater Horizon oil spill.

The Deepwater Horizon oil spill impacted Louisiana's coastal estuaries physically, chemically, and biologically. To better understand the ecological consequences of this oil spill on Louisiana estuaries, we compared the abundance and size of two Gulf shrimp species (Farfantepeneus aztecus and Litopeneus setiferus) in heavily affected and relatively unaffected estuaries, before and after the oil spill. Two datasets were used to conduct this study: data on shrimp abundance and size before the spill were available from Louisiana Department of Wildlife and Fisheries (LDWF). Data on shrimp abundance and size from after the spill were independently collected by the authors and by LDWF. Using a Before-After-Control-Impact with Paired sampling (BACIP) design with monthly samples of two selected basins, we found brown shrimp to become more abundant and the mean size of white shrimp to become smaller. Using a BACIP with data on successive shrimp year-classes of multiple basins, we found both species to become more abundant in basins that were affected by the spill, while mean shrimp size either not change after the spill, or increased in both affected and unaffected basins. We conclude that following the oil spill abundances of both species increased within affected estuaries, whereas mean size may have been unaffected. We propose two factors that may have caused these results: 1) exposure to polycyclic aromatic hydrocarbons (PAHs) may have reduced the growth rate of shrimp, resulting in a delayed movement of shrimp to offshore habitats, and an increase of within-estuary shrimp abundance, and 2) fishing closures established immediately after the spill, may have resulted in decreased fishing effort and an increase in shrimp abundance. This study accentuates the complexities in determining ecological effects of oil spills, and the need of studies on the organismal level to reveal cause-and-effect relationships of such events.

A new Psammogammarus (Amphipoda: Eriopisidae) from anchialine pools on the Exuma Cays, Bahamas.

Psammogammarus lucayensis sp. nov. is described from anchialine pools on Little Iguana Cay (Exuma Cays, Great Bahama Bank). It can be easily distinguished from the other 14 members of the genus by the combination of: 1) carpus of G2 longer than broad; 2) male G2 palm margin non-excavated, evenly convex and devoid of strong mid-palmar robust setae; 3) basis of P7 with subparallel margins; 4) armature arrangement of ventral margin of epimeral plates as 0-2-3; 5) posteroventral angle of epimeral plate III strongly produced; 6) protopod of U2 with distomedial angle armed with comb of 3-4 robust setae; 7) U3 endopod as long as exp1; and 8) telson with robust setae on tip. The generic diagnosis is amended in order to allow the precise characterization of members of Psammogammarus compared to other eriopisids.

Exploring the utility of an indel-rich, mitochondrial intergenic region as a molecular barcode for bamboo corals (Octocorallia: Isididae).

The DNA barcoding initiative has advocated the use of the 5'-end (∼658bp) of mitochondrial (mt) cytochrome c oxidase subunit 1 (cox1) to genetically distinguish species. However, this has proven difficult within the subclass Octocorallia due to extraordinarily low substitution rates within mt protein-coding genes. Intergenic regions (IGRs), which have been little examined among octocorals, may be subject to high mutation rates and have proven useful target regions at both the interspecific and population levels of metazoans. Herein we examine a mt IGR (igr4) between the cytochrome b (cob) and NADH dehydrogenase subunit 6 (nad6) genes among species of the bamboo coral subfamily Keratoisidinae to evaluate its utility for barcoding and phylogenetic studies. Among 77 keratoisidin specimens, we found igr4 to vary in length between either 42bp (Acanella Gray, 1870 and Orstomisis Bayer, 1990) or 302-605bp (Isidella Gray, 1857, Lepidisis Verrill, 1883, Keratoisis Wright, 1869, and two undescribed genera). We interpreted the short igr4 sequence of Acanella eburnea (Pourtalès, 1868) as potentially indicative of additional mt genome-related novelties and thus sequenced its entire mt genome; gene content and gene order were the same as in a previously-sequenced bamboo coral mt genome. Alignment of the longer igr4 sequences included 108 parsimony-informative characters, as well as numerous indels ranging from 2-262bp in length. Uncorrected pairwise 'p' distances indicated sequence variation of 0-27.2%, as compared to 0-4.8% among the same specimens for the MutS homolog (msh1), currently the most widely sequenced octocorallian mt gene, and <0.4% for cox1 for a subset of the taxa. Despite the greater levels of variation, fewer unique haplotypes were observed at igr4 compared to msh1; however, in combination, the two gene regions revealed increased mt haplotype diversity relative to either gene region on their own.

Ultrastructure and functional morphology of glandular setae and distal claws of cephalic appendages of Speleonectes tanumekes (Crustacea: Remipedia).

Terminal pores on crustacean setae are commonly associated with chemoreception. In this study we present an exception to that association with the description of glandular setae on maxillulary and maxillary endites of the remipede Speleonectes tanumekes. This introduces a function associated with crustacean setae beyond the general functions currently assigned to crustacean setae: sensory functions, mechanical functions, or a combination of these two. Even though the functions of the secretory products are unclear, we suggest means by which these may contribute to feeding behaviors. In addition, we describe glandular features of maxillary and maxillipedal distal claws of the same remipede species. Glandular setae and distal claws appear to share several morphological homologies.