Bayha K.M.,Dauphin Island Sea Laboratory |
Bayha K.M.,Gulf Coast Research Laboratory |
Chang M.H.,Yale University |
Mariani C.L.,Yale University |
And 10 more authors.
Biological Invasions | Year: 2014
The ctenophore Mnemiopsis leidyi is one of the most successful marine bioinvaders on record. Native to the Atlantic coast of the Americas, M. leidyi invaded the Black Sea, Caspian and Mediterranean Seas beginning the in late 1980s, followed by the North and Baltic Seas starting in 2006, with major concomitant alterations in pelagic ecology, including fishery collapses in some cases. Using extensive native range sampling (21 sites), along with 11 invasive sites in the Black, Caspian, Mediterranean, North and Baltic Seas, we examined M. leidyi worldwide phylogeographic patterns using data from mitochondrial cytochrome b (cytb) and six nuclear microsatellite loci. Cytb and microsatellite data sets showed different levels of genetic differentiation in the native range. Analyses of cytb data revealed considerable genetic differentiation, recovering three major clusters (northwestern Atlantic, Caribbean, and South America) and further divided northwestern Atlantic sampling sites into three groups, separated approximately at Cape Hatteras on the US Atlantic coast and at the Floridian peninsula, separating the Gulf of Mexico and Atlantic coasts. In contrast, microsatellite data only distinguished samples north and south of Cape Hatteras, and suggested considerable gene flow among native samples with clear evidence of isolation by distance. Both cytb and microsatellite data sets indicated that the northern invaders (North/Baltic Seas) originated from north of Cape Hatteras, with cytb data pointing to Delaware and north. Microsatellite data indicated a source for the southern invaders (Black, Caspian and Mediterranean Seas) to be south of Cape Hatteras, while cytb data narrowed the source location to the Gulf of Mexico region. Both cytb and microsatellite data sets suggested that the southern invasion was associated with genetic bottlenecks while evidence was equivocal for the northern invasion. By increasing the native range spatial sampling, our dataset was able to sufficiently characterize patterns and levels of genetic differentiation in the native range of M. leidyi and identify likely biogeographic boundaries, allowing for the most complete characterization of M. leidyi's invasion histories and most realistic estimates of its source region(s) to date. © 2014 Springer International Publishing Switzerland.
Gustafson K.D.,University of North Dakota |
Gustafson K.D.,Oklahoma State University |
Newman R.A.,University of North Dakota |
Pulis E.E.,University of North Dakota |
And 3 more authors.
Journal of Herpetology | Year: 2015
Amphibian parasite communities are often suggested to be dependent on host size. However, age-related differences in parasite exposure and susceptibility could lead to differences in parasitism unaccounted for by host size. To address these hypotheses, we determined the ages of Wood Frogs (Lithobates sylvaticus) using skeletochronology and assessed the relationships of host age and size with helminth infections. Neither age nor size was significantly related to helminth species richness. Total infection intensity increased with female age and generally increased with age and size in males. However, these overall measures may mask more complex dynamics with individual helminth species. Although the intensity of Alaria spp. increased in males initially, both the intensity and prevalence of Alaria spp. ultimately decreased with male age. The prevalence of both Fibricola sp. and Echinoparyphium rubrum increased with female age. The abundance of Fibricola sp. also increased with female age, whereas Fibricola sp. prevalence and intensity increased with male size. Rhabdias bakeri abundance increased with female size, but decreased with female age. These results suggest age and size are both related to some aspects of Wood Frog infection dynamics. We hypothesize that the absence of trematode metacercariae in young female frogs may be a result of delayed maturity because female Wood Frogs generally avoid water until they are reproductively mature. In contrast, male parasite-specific relationships may be the result of host immune response, host mortality, or parasite mortality. Because males and females were sampled at different times of the season, differences in parasitism based on host sex alone should be interpreted with caution. © 2015 Society for the Study of Amphibians and Reptiles.
Waldbusser G.G.,Oregon State University |
Powell E.N.,Rutgers University |
Powell E.N.,Gulf Coast Research Laboratory |
Mann R.,Virginia Institute of Marine Science
Ecology | Year: 2013
Disease, overharvesting, and pollution have impaired the role of bivalves on coastal ecosystems, some to the point of functional extinction. An underappreciated function of many bivalves in these systems is shell formation. The ecological significance of bivalve shell has been recognized; geochemical effects are now more clearly being understood. A positive feedback exists between shell aggregations and healthy bivalve populations in temperate estuaries, thus linking population dynamics to shell budgets and alkalinity cycling. On oyster reefs a balanced shell budget requires healthy long-lived bivalves to maximize shell input per mortality event thereby countering shell loss. Active and dense populations of filter-feeding bivalves couple production of organic-rich waste with precipitation of calcium carbonate minerals, creating conditions favorable for alkalinity regeneration. Although the dynamics of these processes are not well described, the balance between shell burial and metabolic acid production seems the key to the extent of alkalinity production vs. carbon burial as shell. We present an estimated alkalinity budget that highlights the significant role oyster reefs once played in the Chesapeake Bay inorganic-carbon cycle. Sustainable coastal and estuarine bivalve populations require a comprehensive understanding of shell budgets and feedbacks among population dynamics, agents of shell destruction, and anthropogenic impacts on coastal carbonate chemistry. © 2013 by the Ecological Society of America.
Saillant E.,Gulf Coast Research Laboratory |
Bradfield S.C.,Texas A&M University |
Gold J.R.,Texas A&M University
ICES Journal of Marine Science | Year: 2010
Temporal and spatial genetic variations at 18 nuclear-encoded microsatellites were assayed among age-0 Gulf red snapper (Lutjanus campechanus), sampled from the 2004 and 2005 cohorts in each of five regions in the northern Gulf of Mexico (Gulf) and from a mixed-age group sampled off northwest Florida. Hierarchical analysis of molecular variance revealed genetic heterogeneity among habitat patches within regions, but not among regions. A significant, positive spatial autocorrelation of microsatellite genotypes among fish sampled within the geographic range 50-100 km was detected. Bayesian coalescent analysis of historical demography indicated a decline of nearly an order of magnitude in the effective population size for red snapper across the area surveyed. The highest posterior probability for the current effective population size was 2163, approximately four orders of magnitude smaller than the estimates of red snapper census size. The results of the study demonstrate that spatial genetic structuring among young-of-the-year red snapper in the Gulf occurs at small geographic scales and is consistent with a metapopulation stock-structure model of partially connected populations. This accentuates the importance of maintaining healthy local spawning populations of red snapper in all regions across the northern Gulf. © 2010 United States Government, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center.
Pulis E.E.,University of North Dakota |
Pulis E.E.,Gulf Coast Research Laboratory |
Tkach V.V.,University of North Dakota |
Newman R.A.,University of North Dakota
Wetlands | Year: 2011
Parasites are ubiquitous members of biotic communities. Because their persistence and abundance is closely tied to other taxa and numerous environmental factors, information about parasite diversity may provide unique insights into ecosystem health. Parasites may also impact host health and population dynamics. Because they are relatively inconspicuous, however, little is known about parasite diversity and prevalence in specific host species in most geographic regions. We sampled parasites from wood frogs in the ecologically unique Prairie Pothole Region of North Dakota, USA. Most frogs were infectedwith helminths. We found a minimum of 7 species of trematodes, 3 of nematodes, and 1 cestode. Two species had prevalence >50%: the lung nematode Rhabdias bakeri and the trematode Echinoparyphium rubrum. Helminth species richness ranged from 0 to 6 taxa per host, with a median of 2. Total helminth abundance within infected frogs ranged from 1 to 503 worms. Males caught during the spring breeding season were infected with more taxa of helminths than either recent metamorphs or frogs captured later in the summer. The total abundance of helminths was also greater in breeding frogs. These data provide the foundation for further analyses of the ecology of amphibian-parasite interactions on the Northern Plains. © Society of Wetland Scientists 2011.
Dippold D.A.,University of Southern Mississippi |
Leaf R.T.,University of Southern Mississippi |
Hendon J.R.,Gulf Coast Research Laboratory |
Franks J.S.,Gulf Coast Research Laboratory
Transactions of the American Fisheries Society | Year: 2016
Spotted Seatrout Cynoscion nebulosus are a highly valued recreational inshore species in Mississippi coastal waters. The accurate description of the length-at-age relationship is critical for assessment efforts of the stock. Because Spotted Seatrout exhibit small-scale movements, the stocks in the Gulf of Mexico are managed as state-specific units. Therefore, local demographic estimates of length at age are needed for assessment. We estimated the length-at-age relationship of Spotted Seatrout in Mississippi by using tag recapture records and otolith-derived age estimates. Three nonlinear length-at-age models were fit to sex-aggregated, tag recapture data and four nonlinear length-at-age models were fit to sex-specific, otolith-derived age data. For each suite of models, model support was determined using Akaike information criteria. The Francis (1988a) GROTAG method had the greatest support of the three models fit to the tag recapture data, and the resulting parameter estimates from the model were L∞ = 550.8 mm and k = 0.45/year. The three-parameter logistic model had the greatest support of the four models fit to the otolith-derived age data for both males and females and the resulting parameter estimates of L∞ were 605.3 mm TL for females and 574.9 mm TL for males. The results of this study indicate that (1) the Francis (1988a) GROTAG model was the best-supported method for the determination of the von Bertalanffy growth function parameters from tag recapture information, and (2) the von Bertalanffy growth function may not be the best model to describe the length-at-age relationship of Mississippi's Spotted Seatrout. This work highlights the utility of using multiple sources of length-at-age information and fitting multiple models to enhance both the description of the length-at-age relationship and to determine biases that occur in both. Received July 13, 2015; accepted November 3, 2015 © 2016, © American Fisheries Society 2016.