Modeling population dynamics of scyphozoan jellyfish (Aurelia spp.) in the Gulf of Mexico

Henschke, Natasha; Stock, Charles A.; Sarmiento, Jorge L.

doi:10.3354/meps12255

Cited by 25 publications

(11 citation statements)

References 66 publications

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“…m is the mortality rate such that mortality is 1% d -1 at low densities (S C = 0.577 mg C m −3 ) and reaches 5% d −1 at high densities (S C = 1.291 mg C m −3 ; Table 1). Similar density-dependent mortality rates have been assumed for other gelatinous zooplankton (Oviatt and Kremer, 1977;Henschke et al, 2018) and mesozooplankton (Ohman et al, 2002) based on the assumption that the biomass of unresolved predators scales in proportion to the biomass of unresolved prey (Steele and Henderson, 1993). Starvation occurs when respiratory needs exceed available food for consumption (i.e.…”

Section: Mortalitymentioning

confidence: 76%

Modelling the life cycle of Salpa thompsoni

Henschke

Pakhomov

Groeneveld

et al. 2018

Ecological Modelling

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Salpa thompsoni is an important grazer in the Southern Ocean. It is found from the Subtropical Convergence southward to the coastal Antarctic Seas but being most abundant in the Antarctic Polar Frontal Zone. Low temperatures appear to negatively affect their development, limiting their ability to occur in the krill dominated high Antarctic ecosystems. Yet reports indicate that with ocean warming S. thompsoni have experienced a southward shift in their distribution. As they are efficient filter feeders, this shift can result in large-scale changes in the Southern Ocean ecosystem by increasing competitive or predatory interactions with Antarctic krill. To explore salp bloom dynamics in the Southern Ocean a size-structured S. thompsoni population model was developed with growth, consumption, reproduction and mortality rates dependent on temperature and chlorophyll a conditions. The largest uncertainties in S. thompsoni population ecology are individual and population growth rates, with a recent study identifying the possibility that the life cycle could be much shorter than previously considered. Here we run a suite of hypothesis scenarios under various environmental conditions to determine the most appropriate growth rate. Temperature and chlorophyll a were sufficient drivers to recreate seasonal and interannual dynamics of salp populations at two locations. The most suitable growth model suggests that mean S. thompsoni growth rates are likely to be ∼1 mm body length d −1 , 2-fold higher than previous calculations. S. thompsoni biomass was dependent on bud release time, with larger biomass years corresponding to bud release occurring during favorable environmental conditions; increasing the survival and growth of blastozooids and resulting in higher embryo release. This model confirms that it is necessary for growth and reproductive rates to be flexible in order for the salp population to adapt to varying environmental conditions and provides a framework that can examine how future salp populations might respond to climate change. carbon to the seafloor than in areas without salp swarms (Fischer et al., 1988). However, this contribution is sporadic, and as the majority of studies are based on "potential" estimates there is uncertainty surrounding the total export flux produced by salps. A recent study suggests that recycling of salp faecal pellets in the epipelagic layer may be more common than previously believed, with only ∼13% of produced pellets captured in sediment traps at 300 m (Iversen et al., 2017). Salpa thompsoni is the most prominent pelagic tunicate in the Southern Ocean, found from the Subtropical Convergence southward to the coastal Antarctic Seas but being most abundant in the Antarctic

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Section: Mortalitymentioning

confidence: 76%

Modelling the life cycle of Salpa thompsoni

Henschke

Pakhomov

Groeneveld

et al. 2018

Ecological Modelling

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“…The individual GZ taxa predation levels varied, from 36% to 60% of production (global mean); these values were constrained by other requirements from the MC and the single‐point validation. We recognize that there are many unknowns with respect to GZ predation, and other factors that were excluded from consideration (e.g., life history; Henschke et al, 2018), but these global GZ production and predation levels represent initial values upon further work can be done, and the discrepancies between literature and model parameters highlight areas where additional experiments are needed.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, one 2‐day jelly‐fall event in the Arabian Sea produced over an order of magnitude more particulate organic carbon (POC) flux to the benthos than annual fluxes measured by sediment traps, which do not typically capture jelly‐falls (Billett et al, 2006). However, since GZ have only been included in a few regional (Henschke et al, 2018; Heymans & Baird, 2000; Stone & Steinberg, 2016; Vasas et al, 2007) but no global biogeochemical models, an understanding of the global impact of these events, and other GZ‐associated fluxes (e.g., fecal production), on carbon export is lacking. Most recently, Lebrato et al (2019) used the biomass estimates from Lucas et al (2014) to estimate the impact of GZ on the transfer efficiency (T eff ) of the biological pump if the annual GZ standing stock were to sink with observed GZ sinking rates (Lebrato, Mendes, et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Gelatinous Zooplankton‐Mediated Carbon Flows in the Global Oceans: A Data‐Driven Modeling Study

Luo

Condon²,

Stock

et al. 2020

Global Biogeochemical Cycles

130

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Among marine organisms, gelatinous zooplankton (GZ; cnidarians, ctenophores, and pelagic tunicates) are unique in their energetic efficiency, as the gelatinous body plan allows them to process and assimilate high proportions of oceanic carbon. Upon death, their body shape facilitates rapid sinking through the water column, resulting in carcass depositions on the seafloor ("jelly-falls"). GZ are thought to be important components of the biological pump, but their overall contribution to global carbon fluxes remains unknown. Using a data-driven, three-dimensional, carbon cycle model resolved to a 1°global grid, with a Monte Carlo uncertainty analysis, we estimate that GZ consumed 7.9-13 Pg C y −1 in phytoplankton and zooplankton, resulting in a net production of 3.9-5.8 Pg C y −1 in the upper ocean (top 200 m), with the largest fluxes from pelagic tunicates. Non-predation mortality (carcasses) comprised 25% of GZ production, and combined with the much greater fecal matter flux, total GZ particulate organic carbon (POC) export at 100 m was 1.6-5.2 Pg C y −1 , equivalent to 32-40% of the global POC export. The fast sinking GZ export resulted in a high transfer efficiency (T eff) of 38-62% to 1,000 m and 25-40% to the seafloor. Finally, jelly-falls at depths >50 m are likely unaccounted for in current POC flux estimates and could increase benthic POC flux by 8-35%. The significant magnitude of and distinct sinking properties of GZ fluxes support a critical yet underrecognized role of GZ carcasses and fecal matter to the biological pump and air-sea carbon balance. Plain Language Summary Marine ecosystems play a critical role in the global carbon cycle through food web regulation of air-sea carbon fluxes and the transfer of organic carbon from the upper oceans to the deep sea. The carcasses of gelatinous zooplankton (GZ), which include jellyfish and salps, have been found in mass seafloor depositions ("jelly-falls") in many locations. These jelly-falls are thought to be a fast mechanism for carbon sequestration, yet no global studies on their overall impact have been done. Using a database of GZ observations, we suggest that the inclusion of previously unaccounted for GZ carbon in seafloor carbon deposition could increase current estimates by 8-35%. This previously unconsidered flux represents a substantial amount of carbon sequestered in the deep sea.

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“…Data on the polyp stage of jellyfish is largely focussed on common species and almost exclusively lab-based, with the patterns observed being locale-and species-dependant. Modelling of jellyfish life cycles is still relatively new, with the focus of previous modelling studies also being locale-and species-dependant (Henschke et al, 2018;Schnedler-Meyer et al, 2018). Higher temperature within PlankTOM11 increases the growth rate, which translates into increased biomass if there is sufficient food, thus providing a representation of an increasing medusa population.…”

Section: Discussionmentioning

confidence: 99%

Unique role of jellyfish in the plankton ecosystem revealed using a global ocean biogeochemical model

Wright¹,

Quéré²,

Buitenhuis³

et al. 2020

Preprint

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Abstract. Jellyfish are increasingly recognised as important components of the marine ecosystem, yet their specific role is poorly defined compared to that of other zooplankton groups. This paper presents the first global ocean biogeochemical model that includes an explicit representation of jellyfish, and uses the model to gain insight into the influence of jellyfish on the plankton community. The PlankTOM11 model groups organisms into Plankton Functional Types (PFT). The jellyfish PFT is parameterised here based on our synthesis of observations on jellyfish growth, grazing, respiration and mortality rates as functions of temperature and on jellyfish biomass. The distribution of jellyfish is unique compared to that of other PFTs in the model. The jellyfish global biomass of 0.13 PgC is within the observational range, and comparable to the biomass of other zooplankton and phytoplankton PFTs. The introduction of jellyfish in the model has a large direct influence on the crustacean macrozooplankton PFT, and influences indirectly the rest of the plankton ecosystem through trophic cascades. The zooplankton community in PlankTOM11 is highly sensitive to the jellyfish mortality rate, with jellyfish increasingly dominating the zooplankton community as its mortality diminishes. Overall the results suggest that jellyfish play an important and unique role in regulating marine plankton ecosystems, which has been neglected so far.

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Modeling population dynamics of scyphozoan jellyfish (Aurelia spp.) in the Gulf of Mexico

Cited by 25 publications

References 66 publications

Modelling the life cycle of Salpa thompsoni

Modelling the life cycle of Salpa thompsoni

Gelatinous Zooplankton‐Mediated Carbon Flows in the Global Oceans: A Data‐Driven Modeling Study

Unique role of jellyfish in the plankton ecosystem revealed using a global ocean biogeochemical model

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