Anacortes, WA, United States
Anacortes, WA, United States

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Kolesar S.E.,University of Maryland Center for Environmental Science | Kolesar S.E.,Academy of Natural science Estuarine Research Center | Kolesar S.E.,Oregon State University | Breitburg D.L.,Academy of Natural science Estuarine Research Center | And 5 more authors.
Marine Ecology Progress Series | Year: 2010

Differences in predator and prey tolerances to low dissolved oxygen (DO) concentrations influence planktonic food web interactions in seasonally hypoxic environments. We examined low-DO effects on predation by hypoxia-tolerant ctenophores, Mnemiopsis leidyi, on less hypoxiatolerant ichthyoplankton prey in laboratory experiments. We also examined the relationship between bottom DO concentrations and vertical distributions, and considered potential effects of biotic (predators and competitors) versus abiotic factors (low DO concentration, temperature, salinity, time of day) on vertical habitat overlaps between gelatinous zooplankton and their prey during summer in a Chesapeake Bay subestuary. Laboratory clearance rates of M. leidyi feeding on bay anchovy (Anchoa mitchilli) eggs and yolk sac larvae, and naked goby (Gobiosoma bosc) larvae were as high at low DO (1.5 mg l-1) as at high DO concentrations (7 mg l-1). Multiple years of field sampling at 2 sites revealed that the proportions of motile species in the bottom layer of the water column, especially fish larvae and copepods, increased with increasing bottom DO concentrations during both day and night. Ctenophore densities remained high in the bottom layer even at low DO concentrations. Vertical habitat overlaps among 4 motile predator-prey pairs (M. leidyi-copepods, M. leidyi-naked goby larvae, bay anchovy larvae-copepods, and naked goby larvae-copepods) increased with increasing bottom DO concentrations (1st- or 2nd-order regression models). Vertical overlap between M. leidyi and fish eggs was significantly higher during the day than at night. Statistical models suggest that both bottom DO concentration and scyphomedusan predators influenced M. leidyi-fish egg nighttime and M. leidyi-copepod combined day-night overlaps. Hypoxia influences food web interactions more through altered habitat use and encounter rates than by directly affecting predation. Strong behavioral responses of larval fish and copepods to low bottom DO concentrations may decrease habitat overlap between M. leidyi predators and their prey. Copyright © 2010 Inter-Research.


Graham W.M.,University of Southern Mississippi | Gelcich S.,University of Santiago de Chile | Robinson K.L.,University of Southern Mississippi | Duarte C.M.,CSIC - Mediterranean Institute for Advanced Studies | And 12 more authors.
Frontiers in Ecology and the Environment | Year: 2014

Jellyfish are usually perceived as harmful to humans and are seen as "pests". This negative perception has hindered knowledge regarding their value in terms of ecosystem services. As humans increasingly modify and interact with coastal ecosystems, it is important to evaluate the benefits and costs of jellyfish, given that jellyfish bloom size, frequency, duration, and extent are apparently increasing in some regions of the world. Here we explore those benefits and costs as categorized by regulating, supporting, cultural, and provisioning ecosystem services. A geographical perspective of human vulnerability to jellyfish over four categories of human well-being (health care, food, energy, and freshwater production) is also discussed in the context of thresholds and trade-offs to enable social adaptation. Whereas beneficial services provided by jellyfish likely scale linearly with biomass (perhaps peaking at a saturation point), non-linear thresholds exist for negative impacts to ecosystem services. We suggest that costly adaptive strategies will outpace the beneficial services if jellyfish populations continue to increase in the future. © The Ecological Society of America.


Purcell J.E.,University of Cambridge | Purcell J.E.,Shannon Point Marine Center | Decker M.B.,University of Cambridge | Decker M.B.,Yale University | And 4 more authors.
Marine Ecology Progress Series | Year: 2014

Plankton concentrations near discontinuities in the water column (clines) are believed to be important for intensifying trophic interactions; however, evidence for increased feeding by predators at clines in situ is scarce. Here we demonstrate enhanced feeding near pycnoclines by a voracious planktivore, the ctenophore Mnemiopsis leidyi. To determine their feeding relative to stratification, we quantified temperature, salinity, dissolved oxygen concentration (DO), densities of ctenophores and copepods at 1 to 2 m depth intervals, and gut contents of ctenophores collected by depth layer at stations in a tributary and in the mainstem Chesapeake Bay during summer from 1999 to 2001. We tested the null hypotheses that patterns in the tributary and the bay were similar and that ctenophore vertical distributions and feeding were independent of the vertical distributions of the physical variables, stratification, and copepods. We rejected all null hypotheses. Ctenophores and copepods had peak densities below the pycnocline in the weakly stratified tributary, where DO was above 2 mg l-1 throughout the water column; by contrast, they were more concentrated above the strong pycnocline and near-anoxic waters at ∼11 m in the bay. Predation on copepods by ctenophores was highest where both populations were concentrated. Our results illustrate the importance of stratification to planktonic trophic interactions for M. leidyi, which thrives in anthropogenically degraded waters and now is established throughout European seas, where it can negatively affect planktonic food webs and fisheries. © Inter-Research 2014.


Condon R.H.,Dauphin Island Sea Laboratory | Condon R.H.,Global Jellyfish Group | Graham W.M.,University of Southern Mississippi | Duarte C.M.,Jellyfish Database Initiative | And 18 more authors.
BioScience | Year: 2012

During the past several decades, high numbers of gelatinous Zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to he heading toward being dominated by "nuisance" jellyfish. We question this current paradigm by presenting a broad overview of gelatinous Zooplankton in a historical context to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous Zooplankton blooms, the human frame of reference for changes in gelatinous Zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous Zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous Zooplankton blooms. © 2012 by American Institute of Biological Sciences. All rights reserved.


Bingham B.L.,Western Washington University | Freytes I.,University of Puerto Rico at San Juan | Emery M.,Western Washington University | Dimond J.,Shannon Point Marine Center | Muller-Parker G.,National Science Foundation
Invertebrate Biology | Year: 2011

The sea anemone Anthopleura elegantissima is a common member of intertidal communities along the west coast of North America, and can experience extended periods of increased temperature during summertime low tides. Internal body temperatures of emersed individuals of A. elegantissima were monitored in a laboratory wind tunnel and in the field, and factors influencing the anemones' thermal experience were examined. Larger body size and aggregation with conspecifics slowed body temperature increases in controlled wind tunnel conditions. In the field, anemones in the interior of an aggregation stayed cooler than those on the edges, and microhabitat features related to light exposure and surface orientation overshadowed any direct effects of body size. In the warmest month only (July), aggregations of A. elegantissima were significantly larger at the upper limit of their distribution than they were at the mid and lower limits, suggesting aggregation in high intertidal zones may be a behavioral response to desiccation and temperature stress. As this sea anemone can host multiple species of symbiotic algae with different thermal tolerances, the ability to slow body heating may affect the type of algae hosted and thus the potential contribution of this abundant anemone to primary production in the intertidal zone. © 2011, The American Microscopical Society, Inc.


Miner B.G.,Western Washington University | Miner B.G.,Shannon Point Marine Center | Donovan D.A.,Western Washington University | Donovan D.A.,Shannon Point Marine Center | And 6 more authors.
Marine Ecology Progress Series | Year: 2013

The whelk Nucella lamellosa displays phenotypic plasticity in the presence of the sea star Pisaster ochraceus by becoming more retractable. In this study, we directly tested whether this response is an inducible defense, and looked for evidence of phenotypic costs associated with the induced phenotype. We found that whelks held in the presence of sea stars consuming conspecific whelks became more retractable, while whelks that were not exposed to sea stars became less retractable - indicating that this is a reversible and symmetric (i.e. similar magnitude of change) response. We did not find changes in aspect ratio of the shell or size of the whelks. Following the induction experiment, whelks were fed to sea stars. In this predation experiment, sea stars were much less likely to consume whelks previously exposed to sea stars compared to whelks not exposed to sea stars. There was a strong relationship between mortality and retractability relative to shell length, and individuals that could retract 50% of their shell length had relatively little chance of being consumed during the predation experiment. These results support the hypothesis that increased retractability is an inducible defense. We also conducted field surveys of N. lamellosa populations and found differences in retractability among populations, most of which were more retractable than the whelks in our induction experiment. For these field-collected individuals, we found evidence of phenotypic costs, with a negative relationship between retractability and tenacity. Thus, N. lamellosa responds to a sea star predator by becoming more retractable but at the cost of becoming less tenacious. © Inter-Research 2013.


Grason E.W.,Western Washington University | Grason E.W.,Shannon Point Marine Center | Miner B.G.,Western Washington University | Miner B.G.,Shannon Point Marine Center
PLoS ONE | Year: 2012

Top-down effects of predators in systems depend on the rate at which predators consume prey, and on predator preferences among available prey. In invaded communities, these parameters might be difficult to predict because ecological relationships are typically evolutionarily novel. We examined feeding rates and preferences of a crab native to the Pacific Northwest, Cancer productus, among four prey items: two invasive species of oyster drill (the marine whelks Urosalpinx cinerea and Ocenebra inornata) and two species of oyster (Crassostrea gigas and Ostrea lurida) that are also consumed by U. cinerea and O. inornata. This system is also characterized by intraguild predation because crabs are predators of drills and compete with them for prey (oysters). When only the oysters were offered, crabs did not express a preference and consumed approximately 9 juvenile oysters crab-1 day-1. We then tested whether crabs preferred adult drills of either U. cinerea or O. inornata, or juvenile oysters (C. gigas). While crabs consumed drills and oysters at approximately the same rate when only one type of prey was offered, they expressed a strong preference for juvenile oysters over drills when they were allowed to choose among the three prey items. This preference for oysters might negate the positive indirect effects that crabs have on oysters by crabs consuming drills (trophic cascade) because crabs have a large negative direct effect on oysters when crabs, oysters, and drills co-occur. © 2012 Grason, Miner.


Grason E.W.,Western Washington University | Grason E.W.,Shannon Point Marine Center | Grason E.W.,University of Washington | Miner B.G.,Western Washington University | Miner B.G.,Shannon Point Marine Center
Oecologia | Year: 2012

Inducible defenses have the potential to affect both invasion success and the structure of invaded communities. However, little is known about the cues used for risk-recognition that influence the expression of inducible defenses in invasive prey, because they involve a novel threat. In laboratory experiments, we investigated behavioral defenses induced by a native crab on two invasive oyster drills (marine whelks Urosalpinx cinerea and Ocinebrina inornata). Both drills hid more often and reduced their feeding rates when they detected predators consuming conspecific prey. Examination of the responses of U. cinerea to specific cue sources (predator kairomones, conspecific alarm cues) indicated that this species had the strongest responses to cues from injured conspecifics, but that it did recognize the novel crab predator. Our observation of native predator (per se) recognition by an invasive marine prey is novel. In addition, we observed that neither species of drill reduced their defensive behavior to reflect predation risk shared by a group of prey. The lack of density dependence in risk-assessment could cause populations of invasive prey to transmit both quantitatively and qualitatively different community effects over the course of an invasion as abundance changes. Together, these findings demonstrate several ways that the risk-assessment strategies could be important in establishment and post-establishment dynamics of invasive prey. © 2011 Springer-Verlag.

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