Steve W. Ross

Global Trophic Position Comparison of Two Dominant Mesopelagic Fish Families (Myctophidae, Stomiidae) Using Amino Acid Nitrogen Isotopic Analyses

The δ15N values of organisms are commonly used across diverse ecosystems to estimate trophic position and infer trophic connectivity. We undertook a novel cross-basin comparison of trophic position in two ecologically well-characterized and different groups of dominant mid-water fish consumers using amino acid nitrogen isotope compositions. We found that trophic positions estimated from the δ15N values of individual amino acids are nearly uniform within both families of these fishes across five global regions despite great variability in bulk tissue δ15N values. Regional differences in the δ15N values of phenylalanine confirmed that bulk tissue δ15N values reflect region-specific water mass biogeochemistry controlling δ15N values at the base of the food web. Trophic positions calculated from amino acid isotopic analyses (AA-TP) for lanternfishes (family Myctophidae) (AA-TP ∼2.9) largely align with expectations from stomach content studies (TP ∼3.2), while AA-TPs for dragonfishes (family Stomiidae) (AA-TP ∼3.2) were lower than TPs derived from stomach content studies (TP∼4.1). We demonstrate that amino acid nitrogen isotope analysis can overcome shortcomings of bulk tissue isotope analysis across biogeochemically distinct systems to provide globally comparative information regarding marine food web structure.

Deep-water antipatharians: Proxies of environmental change

Deep-water (307-697 m) antipatharian (black coral) specimens were collected from the southeastern continental slope of the United States and the north-central Gulf of Mexico. The sclerochronology of the specimens indicates that skeletal growth takes place by formation of concentric coeval layers. We used 210 Pb to estimate radial growth rate of two specimens, and to establish that they were several centuries old. Bands were delaminated in KOH and analyzed for carbon and nitrogen stable isotopes. Carbon values ranged from -16.4‰ to -15.7‰; the oldest specimen displayed the largest range in values. Nitrogen values ranged from 7.7%c to 8.6‰. Two specimens from the same location and depth had similar 15 N signatures, indicating good reproducibility between specimens.

Further Evidence for the Invasion and Establishment of Pterois volitans (Teleostei: Scorpaenidae) Along the Atlantic Coast of the United States

Abstract We document the continued population expansion of red lionfish, Pterois volitans, the first documented successful introduction of an invasive marine fish species from the western Pacific to Atlantic coastal waters of the United States. Red lionfish are indigenous to the Indo-Pacific and have apparently established one or more breeding populations on reefs off the southeastern United States. Fifty-nine specimens, most presumably adult red lionfish, were documented or collected on live-bottom reefs off North Carolina, South Carolina, and Florida, and on a manmade structure off Georgia. Observation/collection depths and bottom water temperatures for these fish ranged from 40–99 m and 13.8–24.4°C, respectively. Eleven juvenile lionfish, believed to be expatriated from southeastern waters, were collected in estuaries along the coast of Long Island, NY, at depths of 0–5 m and water temperatures ranging from 13.8–16.5 °C. Twelve of the total 70 specimens collected or observed were positively identified as red lionfish. Based on histological assessment of gonad tissue, two reproductively-active males and one immature female were collected. The life history of red lionfish, especially their reproductive biology and food habits, should be investigated along the east coast of the US to determine the potential impacts of this species on ecosystems they have invaded.

Coral-associated bacterial diversity is conserved across two deep-sea Anthothela species

Cold-water corals, similar to tropical corals, contain diverse and complex microbial assemblages. These bacteria provide essential biological functions within coral holobionts, facilitating increased nutrient utilization and production of antimicrobial compounds. To date, few cold-water octocoral species have been analyzed to explore the diversity and abundance of their microbial associates. For this study, 23 samples of the family Anthothelidae were collected from Norfolk (n = 12) and Baltimore Canyons (n = 11) from the western Atlantic in August 2012 and May 2013. Genetic testing found that these samples comprised two Anthothela species (Anthothela grandiflora and Anthothela sp.) and Alcyonium grandiflorum. DNA was extracted and sequenced with primers targeting the V4–V5 variable region of the 16S rRNA gene using 454 pyrosequencing with GS FLX Titanium chemistry. Results demonstrated that the coral host was the primary driver of bacterial community composition. Al. grandiflorum, dominated by Alteromonadales and Pirellulales had much higher species richness, and a distinct bacterial community compared to Anthothela samples. Anthothela species (A. grandiflora and Anthothela sp.) had very similar bacterial communities, dominated by Oceanospirillales and Spirochaetes. Additional analysis of core-conserved bacteria at 90% sample coverage revealed genus level conservation across Anthothela samples. This core included unclassified Oceanospirillales, Kiloniellales, Campylobacterales, and genus Spirochaeta. Members of this core were previously recognized for their functional capabilities in nitrogen cycling and suggest the possibility of a nearly complete nitrogen cycle within Anthothela species. Overall, many of the bacterial associates identified in this study have the potential to contribute to the acquisition and cycling of nutrients within the coral holobiont.

Deep‐sea coral record of human impact on watershed quality in the Mississippi River Basin

One of the greatest drivers of historical nutrient and sediment transport into the Gulf of Mexico is the unprecedented scale and intensity of land use change in the Mississippi River Basin. These landscape changes are linked to enhanced fluxes of carbon and nitrogen pollution from the Mississippi River, and persistent eutrophication and hypoxia in the northern Gulf of Mexico. Increased terrestrial runoff is one hypothesis for recent enrichment in bulk nitrogen isotope (δ15N) values, a tracer for nutrient source, observed in a Gulf of Mexico deep-sea coral record. However, unambiguously linking anthropogenic land use change to whole scale shifts in downstream Gulf of Mexico biogeochemical cycles is difficult. Here we present a novel approach, coupling a new tracer of agro-industrialization to a multiproxy record of nutrient loading in long-lived deep-sea corals collected in the Gulf of Mexico. We found that coral bulk δ15N values are enriched over the last 150–200 years relative to the last millennia, and compound-specific amino acid δ15N data indicate a strong increase in baseline δ15N of nitrate as the primary cause. Coral rhenium (Re) values are also strongly elevated during this period, suggesting that 34% of Re is of anthropogenic origin, consistent with Re enrichment in major world rivers. However, there are no pre-anthropogenic measurements of Re to confirm this observation. For the first time, an unprecedented record of natural and anthropogenic Re variability is documented through coral Re records. Taken together, these novel proxies link upstream changes in water quality to impacts on the deep-sea coral ecosystem.

MARINE FISHES NEW TO CONTINENTAL UNITED STATES WATERS, NORTH CAROLINA, AND THE GULF OF MEXICO

Abstract Along the southeastern coast of the United States, hardground systems support a high diversity of sub-tropical and tropical fishes. Many of these hardgrounds occur in deep (ca. ≥ 50 m) waters and their fauna is still poorly described; however, with concentrated sampling in these deeper areas, new records of fishes continue to emerge. In the northeastern Gulf of Mexico and off North Carolina, we used the Johnson-Sea-Link submersible, remotely operated vehicles, trawling gear, and angling gear to sample deep reef systems (38–248 m). We document five records of fishes new to continental United States waters, including Liopropoma aberrans, Parasphyraenops incisus, Lipogramma regia, Apogon gouldi, and Prognathodes guyanensis. We also report range extensions for eleven species: Gymnothorax hubbsi, Gymnothorax vicinus, Lepophidium staurophor, Cypselurus comatus, Liopropoma mowbrayi, Serranus annularis, Rypticus saponaceus, Caranx lugubris, Prognathodes aculeatus, Centropyge argi, and Canthigaster jamestyleri.

Bacterial Community Diversity Of The Deep-sea Octocoral Paramuricea Placomus

Compared to tropical corals, much less is known about deep-sea coral biology and ecology. Although the microbial communities of some deep-sea corals have been described, this is the first study to characterize the bacterial community associated with the deep-sea octocoral, Paramuricea placomus. Samples from five colonies of P. placomus were collected from Baltimore Canyon (379–382 m depth) in the Atlantic Ocean off the east coast of the United States of America. DNA was extracted from the coral samples and 16S rRNA gene amplicons were pyrosequenced using V4-V5 primers. Three samples sequenced deeply (>4,000 sequences each) and were further analyzed. The dominant microbial phylum was Proteobacteria, but other major phyla included Firmicutes and Planctomycetes. A conserved community of bacterial taxa held in common across the three P. placomus colonies was identified, comprising 68–90% of the total bacterial community depending on the coral individual. The bacterial community of P. placomus does not appear to include the genus Endozoicomonas, which has been found previously to be the dominant bacterial associate in several temperate and tropical gorgonians. Inferred functionality suggests the possibility of nitrogen cycling by the core bacterial community.

δ13C and δ15N in deep-living fishes and shrimps after the Deepwater Horizon oil spill, Gulf of Mexico

The blowout of the Deepwater Horizon (DWH) drill-rig produced a surface oil layer, dispersed micro-droplets throughout the water column, and sub-surface plumes. We measured stable carbon and nitrogen isotopes in mesopelagic fishes and shrimps in the vicinity of DWH collected prior to, six weeks after, and one year after the oil spill (2007, 2010 and 2011). In 2010, the year of the oil spill, a small but significant depletion of δ(13)C was found in two mesopelagic fishes (Gonostoma elongatum and Chauliodus sloani) and one shrimp (Systellaspis debilis); a significant δ(15)N enrichment was identified in the same shrimp and in three fish species (G. elongatum, Ceratoscopelus warmingii, and Lepidophanes guentheri). The δ(15)N change did not suggest a change of trophic level, but did indicate a change in diet. The data suggest that carbon from the Deepwater Horizon oil spill was incorporated into the mesopelagic food web of the Gulf of Mexico.

Aspects of the Reproductive Biology of the Skate Fenestraja plutonia (Garman) off North Carolina

Abstract Fenestraja plutonia is an abundant member of the slope community in the western North Atlantic, occurring at depths of 293-1042 m. Aspects of the reproductive biology of F. plutonia were examined for specimens collected off North Carolina, in the summer-fall of 2001, 2002, and 2006. Male-to-female sex ratios were not significantly different from 1:1. The smallest mature male was 215 mm TL, and the smallest mature female was 230 mm TL. Length at 50% maturity was estimated at 231 mm TL for females and 233 mm TL for males, 89 and 90% of maximum TL, respectively. Deposited egg cases (n = 107; six containing embryos), three egg-bearing females, and 11 newly hatched juveniles were collected. It appears that the upper slope off Cape Lookout, NC, at the northern end of the species range, constitutes both an egg-laying area and possibly a nursery area for this species.

The utility of museum records for documenting distributions of deep-sea corals off the southeastern United States

Abstract Museum records can enhance distribution maps of deep-sea corals (DSC), but museum data usually acquired from online internet catalogues may be of uncertain quality. Also, many museum records are unavailable through online sources. Holdings of four structure-forming DSC species (Lophelia pertusa, Madrepora oculata, Enallopsammia profunda, Enallopsammia rostrata) collected from off the southeastern US were evaluated from the US National Museum of Natural History (NMNH), Harvard Universitys Museum of Comparative Zoology (MCZ), University of Miamis Marine Invertebrate Museum, and Yale Universitys Peabody Museum of Natural History. Data were gathered from online sources, selected publications, and personal visits to the MCZ and NMNH. Each record was located, if possible, specimens were photographed and additional data obtained, including whether the specimen was collected alive or dead. The resulting database was imported into ArcGIS to examine coral distributions. Museums yielded 304 records: 126 L. pertusa, 62 M. oculata, 113 E. profunda, 3 E. rostrata. Most (87%) records occurred between 400 and 900 m depths; some were <300 m (46–248 m) and >900 m (965–2195 m). Museum records confirmed geographic and bathymetric ranges of these corals and suggested areas for further exploration. Problems encountered in the museum data were varied but generally minor. Museum collections are useful for investigating DSC distributions; however, these data require more scrutiny than they usually receive. Visits to museums and/or interaction with museum staff are recommended to improve museum data utility.