Geology topics

Cheryl Morrison

Publications and source records attributed to Cheryl Morrison.

9 recordsLinked to original sources

USGS2024

Population structure of Desmophyllum pertusum found along the United States eastern continental margin

Objective The connectivity and genetic structuring of populations throughout a region influence a species’ resilience and probability of recovery from anthropogenic impacts. By gaining a comprehensive understanding of population connectivity, more effective management can be prioritized. To assess the connectivity and population genetic structure of a common cold-water coral species, Desmophyllum pertusum ( Lophelia pertusa ), we performed Restriction-site Associated DNA Sequencing (RADseq) on individuals from nine sites ranging from submarine canyons off New England to the southeastern coast of the United States (SEUS) and the Gulf of Mexico (GOM). Fifty-seven individuals and 3,180 single-nucleotide polymorphisms (SNPs) were used to assess genetic differentiation. Results High connectivity exists among populations along the SEUS, yet these populations were differentiated from those to the north off New England and in Norfolk Canyon along the North Atlantic coast of the United States, as well as those in the GOM. Interestingly, Norfolk Canyon, located just north of North Carolina, and GOM populations exhibited low levels of genetic differentiation, corroborating previous microsatellite analyses and signifying gene flow between these populations. Increasing sample sizes from existing populations and including additional sampling sites over a larger geographic range would help define potential source populations and reveal fine-scale connectivity patterns among D. pertusum populations.

Atlantic coastal margin↗

USGS2024

How long have we been mistaken? Multi-tools shedding light into the systematics of the widespread deep-water genus Madrepora Linnaeus, 1758 (Scleractinia)

Deep-water coral reefs are found worldwide and harbor biodiversity levels that are comparable to their shallow-water counterparts. However, the genetic diversity and population structure of deep-water species remain poorly explored, and historical taxonomical issues still need to be resolved. Here we used microsatellite markers as well as ultraconserved elements (UCE) and exons to shed light on the population structure, genetic diversity, and phylogenetic position of the genus Madrepora , which contains M. oculata , one of the most widespread scleractinian species. Population structure of 107 samples from three Southwestern Atlantic sedimentary basins revealed the occurrence of a cryptic species, herein named M. piresae sp. nov. (authored by Kitahara, Capel and Zilberberg), which can be found in sympatry with M. oculata . Phylogeny reconstructions based on 134 UCEs and exon regions corroborated the population genetic data, with the recovery of two well-supported groups, and reinforced the polyphyly of the family Oculinidae. In order to better accommodate the genus Madrepora , while reducing taxonomical confusion associated with the name Madreporidae, we propose the monogeneric family Bathyporidae fam. nov. (authored by Kitahara, Capel, Zilberberg and Cairns). Our findings advance the knowledge on the widespread deep-water genus Madrepora , resolve a long-standing question regarding the phylogenetic position of the genus , and highlight the need of a worldwide review of the genus.

Molecular Phylogenetics and Evolution↗

USGS2024

National Aquatic Environmental DNA Strategy

Aquatic life is the engine of ecosystems and economies. In environments ranging from freshwater through marine, this biodiversity underpins the health, culture, opportunities, and economic wellbeing of the Nation -- from local communities to the entire country. The ability to evaluate the status, trends, and future projections of nature is key to maintaining national prosperity, and this requires timely and trusted information about the condition of aquatic biodiversity on a vast scale. With one of the largest Exclusive Economic Zones in the world and extensive estuaries, lakes, rivers and streams, it is a grand challenge for the United States to explore, monitor, and understand aquatic life.

Report↗

USGS2022

Genetic diversity and connectivity of chemosynthetic cold seep mussels from the U.S. Atlantic margin

Background Deep-sea mussels in the subfamily Bathymodiolinae have unique adaptations to colonize hydrothermal-vent and cold-seep environments throughout the world ocean. These invertebrates function as important ecosystem engineers, creating heterogeneous habitat and promoting biodiversity in the deep sea. Despite their ecological significance, efforts to assess the diversity and connectivity of this group are extremely limited. Here, we present the first genomic-scale diversity assessments of the recently discovered bathymodioline cold-seep communities along the U.S. Atlantic margin, dominated by Gigantidas childressi and Bathymodiolus heckerae . Results A Restriction-site Associated DNA Sequencing (RADSeq) approach was used on 177 bathymodiolines to examine genetic diversity and population structure within and between seep sites. Assessments of genetic differentiation using single-nucleotide polymorphism (SNP) data revealed high gene flow among sites, with the shallower and more northern sites serving as source populations for deeper occurring G. childressi . No evidence was found for genetic diversification across depth in G. childressi , likely due to their high dispersal capabilities. Kinship analyses indicated a high degree of relatedness among individuals, and at least 10–20% of local recruits within a particular site. We also discovered candidate adaptive loci in G. childressi and B. heckerae that suggest differences in developmental processes and depth-related and metabolic adaptations to chemosynthetic environments. Conclusions These results highlight putative source communities for an important ecosystem engineer in the deep sea that may be considered in future conservation efforts. Our results also provide clues into species-specific adaptations that enable survival and potential speciation within chemosynthetic ecosystems.

Atlantic Ocean, Baltimore Canyon Seep, Blake Ridge↗

USGS2019

Phenotypic plasticity or a reproductive dead end? Primnoa pacifica (Cnidaria: Alcyonacea) in the southeastern Alaska region

Red tree corals ( Primnoa pacifica ) are abundant in the eastern Gulf of Alaska, from the glacial fjords of Southeast Alaska where they emerge to as shallow as 6 m, to the continental shelf edge and seamounts where they are more commonly found at depths greater than 150 – 500 m. This keystone species forms large thickets, creating habitat for many associated species, including economically valuable fishes and crabs, and so are important benthic suspension feeders in this region. Though the reproductive periodicity of this species was reported in 2014 from a shallow fjord (Tracy Arm), this study examined reproductive ecologies from 8 sites – two within Glacier Bay National Park and Preserve, three on the continental shelf edge, one within Endicott Arm (Holkham Bay) and two time points from the Tracy Arm (Holkham Bay) study. Male reproductive traits were similar at all sites but there were distinct differences in oogenesis. Though per polyp fecundity mostly showed no significant difference between sites, there was a non-significant trend of increasing number of oocytes with depth. In addition, the average oocyte size from Tracy Arm (the shallowest site) was 105 μm, whereas from Shutter Ridge (one of the deepest sites) the average size was 309 μm. Moreover, the maximum oocyte size at Endicott Arm was 221 μm and at Tracy Arm was 802 μm (both shallow sites), whereas at Dixon Entrance (a deep site) it was 2120 μm, a difference not usually observed within a single species. We propose two theories to explain the observed differences, (a) this species shows great phenotypic plasticity in reproductive ecology, adjusting to different environmental variables based on energetic need and potentially demonstrating micro-evolution; or (b) the fjord sites are at a reproductive dead end, with the stress of shallow-water conditions effectively preventing gametogenesis reaching full potential and likely limiting successful reproductive events from occurring, at least on a regular basis.

Alaska↗

USGS2007

Alvin explores the deep northern Gulf of Mexico Slope

Many of the world's productive deepwater hydrocarbon basins experience significant and ongoing vertical migration of fluids and gases to the modern seafloor. These products, which are composed of hydrocarbon gases, crude oil, formation fluids, and fluidized sediment, dramatically change the geologic character of the ocean floor, and they create sites where chemosynthetic communities supported by sulfide and hydrocarbons flourish. Unique fauna inhabit these sites, and the chemosynthetic primary production results in communities with biomass much greater than that of the surrounding seafloor.

Gulf of Mexico↗

USGS2007

Exploration of the deep Gulf of Mexico slope using DSV Alvin: Site selection and geologic character

The Gulf of Mexico is well known for its hydrocarbon seeps, associated chemosynthetic communities, and gas hydrates. However, most direct observations and samplings of seep sites have been concentrated above water depths of approximately 3000 ft (1000 m) because of the scarcity of deep diving manned submersibles. In the summer of 2006, Minerals Management Service (MMS) and National Oceanic and Atmospheric Administration (NOAA) supported 24 days of DSV Alvin dives on the deep continental slope. Site selection for these dives was accomplished through surface reflectivity analysis of the MMS slope-wide 3D seismic database followed by a photo reconnaissance cruise. From 80 potential sites, 20 were studied by photo reconnaissance from which 10 sites were selected for Alvin dives. Four sites, found in Atwater Valley Lease Area, Block 340 (AT 340), Green Canyon Lease Area, Block 852 (GC 852), Alaminos Canyon Lease Area, Block 601 (AC 601), and Alaminos Canyon Lease Area, Block 818 (AC 818) had impressive and diverse chemosynthetic communities as well as well-defined fluid-gas expulsion geology. In addition to chemosynthetic communities, GC 852 had abundant hard and soft corals seated on substrates of exposed authigenic carbonate boulders. During the two dives at this site the water depths (WD) were approximately 4760 ft (1450 m), and the currents were estimated to be 1-1.5 kts ( approximately 50-80 cm/s). At AC 601 (WD approximately 7675 ft (2340 m)), a brine lake that was 13 ft (4 m) deep and 590 ft (180 m) wide with a salinity of approximately 90 per mil (parts per thousand) was investigated and sampled. White "flocs" floating in the brine and concentrated at the "shoreline" were found to be barite. No visible animal life was observed in the brine, but moribund fauna were found both in the lake and at the shoreline. Isolated living communities of mussels and urchins were found on the lake margins. Geochemically, the concentration of methane in the water column above the lake exceeded all their Alvin dive sites by one order of magnitude. Methane was supersaturated all the way to the surface, suggesting the site could be a source of methane to the atmosphere.

Gulf of Mexico↗

USGS2006

Phylogeographic analyses suggest multiple lineages of Crystallaria asprella (Percidae: Etheostominae)

The crystal darter, Crystallaria asprella , exists in geographically isolated populations that may be glacial relicts from its former, wide distribution in the Eastern U.S. An initial phylogeographic survey of C. asprella based upon the mitochondrial cytochrome b (cyt b ) gene indicated that there were at least four distinct populations within the species: Ohio River basin, Upper Mississippi River, Gulf coast, and lower Mississippi River. In particular, the most divergent population was the most recently discovered, from the Elk River, WV, in the Ohio River basin, and it was postulated that this population represents an undescribed, potentially threatened species. However, differentiation observed at a single gene region is generally not considered sufficient evidence to establish taxonomic status. In the present study, nucleotide variation at the mitochondrial control region and a nuclear S7 ribosomal gene intron were compared to provide independent verification of phylogeographic results between individuals collected from the same five disjunct populations previously surveyed. Variation between populations at the control region was substantial (except between Gulf drainages) and was concordant with patterns of sequence divergence from cyt b . Only the Elk River population was resolved as monophyletic based upon nuclear S7, but significant differences based upon Φ ST statistics were observed between most populations. Morphometric data were consistent with molecular data regarding the distinctiveness of the Elk River population. It is proposed that populations of C. asprella consist of at least four distinct population segments, and that the Elk River group likely constitutes a distinct species.

Alabama, Arkansas, Georgia, Louisiana, Mississippi↗

USGS2005

Molecular identification of cypripedioid orchids in international trade

Two cypripedioid orchid genera, Paphiopedilum and Phragmipedium, are listed in Appendix I of CITES and are restricted from international trade. Because of their morphological similarity to other genera, however, they may be disguised as belonging to one of the other cypripedioids listed along with other orchids in Appendix II of CITES. Sequence analysis was performed on the internal transcribed spacer region (ITS) of ribosomal DNA of cypripedioid orchids to develop a molecular marker system capable of discriminating among rare species in trade. Molecular analyses concentrated on rare cypripedioid orchids from the genera Paphiopedilum and Phragmipedium, which are known to be poached from the wild and smuggled across international borders disguised as common species. A total of 48 taxa representing two genera {Paphiopedilum, N = 43; Phragmipedium, N = 5) have been sequenced and compared for distinc- tiveness. Phylogenetic analyses clearly distinguish between these two genera and among other cypripedioid genera, with 5-10 fixed nucleotide differences reported between genera. Within a genus, sections of closely related taxa are recoverable in phylogenetic analyses, in most cases, with low sequence divergence within sections. ITS sequences available in GenBank have been aligned with data generated for this project, resulting in a comprehensive sequence library of 151 sequences representing all genera of cypripedioid orchids: 70 Paphiopedilum taxa, 16 Phragmipedium taxa, and 14 Cypripedium taxa, as well as represen- tatives from Selenipedium and the monotypic genus Mexipedium (Phragmipedium) xerophyticum. Addi- tionally, several organelle intron regions have been screened for variation among genera and species. Both the chloroplast řrnS-M and the mitochondrial NAD1 intron regions, which varied between genera in nu- cleotide substitutions and indels, hold promise for increasing ability to distinguish between these orchids. The set of DNA markers examined for this project are diagnostic of these genera, appear to be robust, and are suitable for rapid assay to avoid unnecessary complication in the legitimate trade of orchids listed in CITES Appendix

Selbyana↗