Seasonal variability in the feeding ecology of an oceanic predator.

Complementary approaches (stomach contents, DNA barcoding, and stable isotopes) were used to examine seasonal shifts in the feeding ecology of an oceanic predator, yellowfin tuna (Thunnus albacares, n = 577), in the northern Gulf of Mexico. DNA barcoding greatly enhanced dietary resolution and seasonally distinct prey assemblages were observed for both sub-adults and adults. In general, diet was characterized by ommastrephid squids and exocoetids in spring, juvenile fishes (i.e., carangids and scombrids) in summer, migratory coastal fishes during fall, and an increased consumption of planktonic prey (e.g., amphipods) in winter. Seasonal variability in bulk stable isotope values (δ13C, δ15N, and δ34S) was also observed, with low δ15N values and high δ34S values during late summer/early fall and high δ15N values (low δ34S) during late winter/early spring. Bayesian stable isotope mixing models corroborated seasonal diet shifts, highlighting the importance of oceanic nekton in spring/summer, coastal nekton during fall, and oceanic plankton during winter. Seasonal shifts in diet appeared to be influenced by prey reproductive cycles, habitat associations, and environmental conditions. Findings highlight the complex food web dynamics supporting an opportunistic oceanic predator and the importance of seasonal cycles in prey availability to predator resource utilization in open-ocean ecosystems.

Assessing microplastics contamination in unviable loggerhead sea turtle eggs.

Sea turtles, in comparison with marine mammals, sea birds, and fishes, are the most affected by microplastics in terms of number of individuals impacted and concentration within each organism. The ubiquitous nature and persistence of microplastics in the environment further compromises sea turtles as many species are currently vulnerable, endangered, or critically endangered. The objective of this study was to quantify microplastic contamination in unviable loggerhead sea turtle eggs (Caretta caretta). Eggs were collected from seven locations along the northwest coast of Florida. A total of 70 nests and 350 eggs were examined. Microplastics (n = 510) were found in undeveloped loggerhead sea turtle eggs across all seven sites, suggesting that maternal transference and/or exchange between the internal and external environment were possible. The frequency found was 7.29 ± 1.83 microplastic pieces per nest and 1.46 ± 0.01 per egg. Microplastics were categorized based on color, shape, size, and type of polymer. The predominant color of microplastics were blue/green (n = 236), shape was fibers (n = 369), and length was 10-300 µm (n = 191). Identified fragments, films, beads and one foam (n = 187) had the most common area of 1-10 µm2 (n = 45). Micro-Fourier Transform Infrared (µ-FTIR) spectroscopy analysis demonstrated that polyethylene (11 %) and polystyrene (7 %) were the main polymer types. For the first time microplastics were found in unviable, undeveloped loggerhead sea turtle eggs collected in northwest Florida. This work provides insight into the distribution patterns of microplastic pollutants in loggerhead sea turtle eggs and may extend to other species worldwide.

Quantifying microplastics in fjords along the Western Antarctic Peninsula.

Microplastics are ubiquitous around the world. Microplastics have been documented around the Southern Ocean, in coastal sediments and in Antarctic marine organisms, however microplastics data for Antarctic waters remain scarce. Microplastics concentrations were characterized from fjord habitats on the Western Antarctic Peninsula where most glaciers are rapidly retreating. Water samples were collected from 2017 to 2020 from surface and benthos, vacuum-filtered, quantified to determine the classification of microplastic, color, and size. Micro-FTIR spectrophotometry was utilized to confirm chemical composition. Comparisons over time and location were made for average microplastic per liter. Despite the new emergent youth and remoteness of these habitats, it was determined that all fjord habitats had microplastics present each year sampled and increased from 2017 to 2020 in each fjord. Despite physical 'barriers' such as the Antarctic Circumpolar Current (and particularly its strongest jet, the Polar Front), microplastics are clearly present and increasing in even recent habitats.

Detection of the threatened snail darter Percina tanasi in the Tennessee River system using environmental DNA.

The distribution of many fishes that occupy large rivers is poorly known, in part due to the difficulties of sampling for them. This is especially true for small-bodied or rare species, such as the snail darter Percina tanasi, 44, 469-488; 1976). This federally listed (threatened) species has a limited distribution in the Tennessee River system in Alabama and Tennessee, where it is known from a few large tributaries or small rivers. In Alabama, P. tanasi was previously known from only one locality, but has recently been found in two additional, widely separated systems. These new records raise questions regarding the accuracy of our current understanding of the range for this species. Particularly, is P. tanasi present throughout the main stem Tennessee River, and is this species dispersing into new areas from source populations in the river? To clarify the distribution of P. tanasi in Alabama, 83 unique sites were surveyed using environmental DNA analysis. This cost-effective detection tool reduces the difficulty associated with empirically sampling large rivers for small fishes. Approximately 42% of sites sampled were positive for P. tanasi DNA. This study confirmed the known localities of P. tanasi in the Bear Creek, Elk River and Paint Rock River. Several new localities were also discovered throughout the main stem Tennessee River and in Shoal Creek, near Florence, Alabama. These findings can inform biologists about where to prioritize conservation efforts and further could lead to studies assessing movement and relatedness between populations in this system.

Incipient speciation in allopatric Etheostoma rupestre (Percidae: Etheostomatinae) lineages, with the description of three new subspecies.

In recent years, new species descriptions for the North American darters have proliferated. Most species concepts accepted by contemporary ichthyologists require that a valid species be both monophyletic and diagnoseable, yet many lineages exhibit modal or range differences in morphological characteristics without individuals being diagnosable. Such scenarios present difficulties with regards to proper taxonomic recognition of divergent lineages and often prohibit appropriate conservation action. Following the example of recent authors, we provide meristic, geometric morphometric, and pigmentation data to support the recognition of three subspecies of Etheostoma rupestre, a species endemic to the Mobile Basin. These morphological data cohere with previous genetic work for E. rupestre. The nominate subspecies Etheostoma rupetsre rupestre (Tsais Rock Darter) is endemic to the Tombigbee River and Black Warrior River watersheds in Alabama and Mississippi and is characterized by having lower numbers of lateral blotches, lower range and mean of lateral line scales, lower modal number of scales above the lateral line, and lower degrees of nape squamation than other subspecies. Etheostoma rupestre piersoni (Shamrock Darter), ssp. nov., is endemic to the Cahaba and Alabama River Watersheds in Alabama and is characterized by intermediate counts of lateral blotches and higher scale counts and nape squamation than E. r. rupestre. Etheostoma rupestre uphapeense (Jade Darter), ssp. nov., is restricted to several small, disjunct populations in the Coosa and Tallapoosa watersheds in Alabama, Georgia, and Tennessee. Etheostoma r. uphapeense is characterized by having a higher mean number of lateral blotches than both other subspecies and higher scale counts than E. r. rupestre. While E. r. rupestre and E. r. piersoni are widespread and abundant within their respective ranges, E. r. uphapeense has a disjunct range and is often uncommon where it occurs. Etheostoma r. uphapeense should be monitored where it occurs to discern population trends.

The complete mitochondrial genome of the marine feather duster, Bispira melanostigma (Annelida: Sabellidae).

The marine feather duster, Bispira melanostigma (Schmarda, 1861), is a tube-dwelling annelid that contributes to ecological and biogeochemical processes in benthic communities. Due to the lack of scientific data, B. melanostigma is often difficult to distinguish from other species of marine worms through morphological characteristics alone. In this study, we report the complete mitochondrial genome of Bispira melanostigma. The complete mitogenome contained 20,624 bp length with a total of 13 protein-encoding genes, 21 tRNA, and 2 rRNA genes. Phylogenetic analysis of the complete mitochondrial DNA of B.melanostigma can aid in the understanding of evolutionary relationships within Sabellidae.

Characterization of the complete mitochondrial genome of Spheciospongia vesparium (Demospongiae, Clionaida, Clionaidae).

The Loggerhead sponge (Spheciospongia vesparium) is an ecologically important marine species of sponge that provides habitat and food sources to biodiversity hotspots in the Caribbean Sea and along the coasts of Florida. In this study, the complete mitochondrial genome of the sponge, S. vesparium was sequenced and reported. The mitochondrial genome of S. vesparium was 21,763 base pairs, and consisted of 14 protein-coding genes, 26 tRNA genes, and two rRNA genes. The total nucleotide content comprised 31.01% A, 36.04% T, 11.08% C, and 21.88% G, with a lower GC content of 32.95%. This study provides a phylogenetic analysis of S. vesparium and relative sponges in Demospongiae.

The complete mitochondrial genome of the plumed worm Diopatra cuprea (Annelida: Onuphidae).

In this study, we describe the complete mitochondrial genome of Diopatra cuprea (Bosc, 1802). The mitogenome was found to contain 14,990 base pairs (67.53% A + T content), with a total of 37 genes (13 protein coding, 22 transfer RNAs, and 2 ribosomal RNAs). This study also examined mitogenome phylogenetics relationships of closely related species and recovered that D. cuprea is closely related to eunicids. This work has added to the genetic resources for furthering evolutionary studies of Annelida.

Characterization of the complete mitochondrial genome of Thyonella gemmata (Echinodermata: Cucumariidae).

Thyonella gemmata , also known as the Green sea cucumber, is a biomedically and ecologically important species. In this study, the complete mitogenome of T. gemmata (Echinodermata: Holothuroidea) collected from the Florida Panhandle, USA is reported. The mitochondrial genome of T. gemmata consisted of 15,696 base pairs, and was composed of 36.10% A, 28.27% T, 23.18% C, and 12.45% G. There were 13 protein coding genes, 22 tRNA genes, and 2 rRNA genes within the mitogenome of T. gemmata. Mapping out the complete mitochondrial genome of T. gemmata, will help aid in future evolutionary studies and can be applied to future phylogenetic research of holothurians and related species.

The complete mitochondrial genome of the peppermint shrimp Lysmata wurdemanni (Decapoda: Lysmatidae).

In this study, the complete 16,979 bp mitochondrial genome of Lysmata wurdemanni (Gibbes, 1850) was determined from a specimen collected from Apalachee Bay, U.S. The mitogenome contains 37 genes, and consists of 32.33% A, 35.01% T, 19.55% C, and 13.10% G, with a total G + C content of 32.65%. A maximum likelihood phylogenetic tree based on mitochondrial protein-coding genes suggested L. wurdemanni is clustered with Lysmata vittata and Lysmata amboinensis, based on available mitochondrial sequences of relatives. These data are useful in determining phylogenetic relationships between Lysmatidae and Thoridae. The sequenced mitochondrial genome may also assist in understanding evolutionary distinctions and breeding strategies in hermaphroditic species.

The complete mitochondrial genome of the chocolate chip sea cucumber Isostichopus badionotus (Echinodermata: Holothuroidea).

The chocolate chip sea cucumber, Isostichopus badionotus (Selenka 1867), is an ecologically and biomedically important species. In this study, we report the complete mitogenome sequence of the sea cucumber, I. badionotus (Echinodermata: Holothuroidea). The mitochondrial genome consisted of 16,319 bp, with 13 protein-coding genes, 22 tRNA genes, and 2 rRNA genes. The total nucleotide composition consisted of 31.61% A, 29.20% T, 23.48% C, 15.71% G, with a high A + T content of 60.81%. Phylogenetic analysis using the complete mitochondrial genome of I. badionotus is helpful in studying the evolution of beneficial adaptations to aid in bioremediation and biomedical research and development.

Unrecognized Antarctic biodiversity: a case study of the genus Odontaster (Odontasteridae; Asteroidea).

Antarctica has a complex and multifaceted geologic and oceanographic history that has influenced and shaped patterns of marine invertebrate diversity. This evolutionary history consists of major events on a wide range of time scales such as the formation of the Antarctic Polar Front (25-41 million years ago) to repeated glacial cycles during the past million years. These factors variably influenced genetic connectivity of fauna to produce a highly unique, but incredibly diverse marine community. Use of molecular phylogeographic methods is creating the need to revise our understanding of Antarctic patterns of biodiversity. In particular, almost every phylogeographic study carried out to date, suggests that the biodiversity of Antarctic marine shelf fauna is considerably underestimated. In discovering this diversity, some lineages (i.e., cryptic lineages) show no diagnostic morphological differences whereas others (i.e., unrecognized species) show differences that were unknown to science. The sea star genus Odontaster is among the best-studied of Antarctic invertebrate groups. Nonetheless, two unrecognized lineages were recently discovered along the Antarctic Peninsula, which is one of the best-studied regions in Antarctica. Herein, we elucidate the molecular and morphological uniqueness of these species and name them O. roseus and O. pearsei. The latter is in honor of John Pearse, an Antarctic biologist, as well as past President and long-time member of the Society of Integrative and Comparative Biology.

A review of molecular markers used for Annelid phylogenetics.

Annelida, one of the most successful animal phyla, exhibits an amazing variety of morphological forms. Disparity between some of the forms is so great that until molecular tools were used, some annelid lineages (for example, echiurids and pogonophorans) were not commonly recognized as belonging to the group. Although it is easy to assign annelids to a given family, understanding the deeper relationships within the group has been difficult. The main working hypothesis for annelid phylogeny is based on morphological cladistic analysis. However, the recent work using molecular tools has caused a revision of our view of annelid evolutionary history. For example, Scolecida and Palpata appear not to be natural groups, and the phylogenetic positions of some aberrant taxa (for example, Siboglinidae, Poeobius, Pisione) have been determined. Herein, we discuss some of the main molecular markers that have been used to elucidate annelid phylogeny and the contribution that such work is making to our understanding. A table highlighting the molecular literature and the genes used is included.