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# Abundance and patchiness of Chrysaora quinquecirrha medusae from a high-frequency time series in the Choptank River, Chesapeake Bay, USA

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## Abstract and Figures

Despite strong control over marine plankton dynamics and negative impacts on human activities, jellyfish are not well quantified due primarily to sampling difficulties with nets. Therefore, some of the longest records of jellyfish are visual shore-based surveys. As surface counting is inexpensive and simple, it is of interest to determine what can be learned from such records as well as the usefulness of the method. We analyzed a 4-year high-frequency time series of Chrysaora quinquecirrha medusa counts collected using three sampling methods in the Choptank River, Chesapeake Bay. Medusa abundance was modeled by change points and was highly correlated between the sampling methods. The remaining signal was random, and indices of aggregation [fit to the Poisson distribution, Taylor’s Power Law (TPL), and Morisita’s Index] indicated that medusae were aggregated. TPL suggested that patches grew in the number of individuals as abundance increased. Additionally, a simple conceptualization of where the time series sampled in space revealed that the upper bound of patch size was on the order of kilometers. Our results enhance the knowledge of local C. quinquecirrha abundance and patchiness, alluding to processes that generate these patterns. This study also provides direction for improving population monitoring from visual shore-based surveys.
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PRIMARY RESEARCH PAPER
Abundance and patchiness of Chrysaora quinquecirrha
medusae from a high-frequency time series
in the Choptank River, Chesapeake Bay,
USA
Jacqueline Tay .Raleigh R. Hood
Received: 19 May 2016 / Revised: 18 October 2016 / Accepted: 16 November 2016 / Published online: 7 December 2016
ÓSpringer International Publishing Switzerland 2016
Abstract Despite strong control over marine plank-
ton dynamics and negative impacts on human activ-
ities, jellyﬁsh are not well quantiﬁed due primarily to
sampling difﬁculties with nets. Therefore, some of the
longest records of jellyﬁsh are visual shore-based
surveys. As surface counting is inexpensive and
simple, it is of interest to determine what can be
learned from such records as well as the usefulness of
the method. We analyzed a 4-year high-frequency
time series of Chrysaora quinquecirrha medusa
counts collected using three sampling methods in the
Choptank River, Chesapeake Bay. Medusa abundance
was modeled by change points and was highly
correlated between the sampling methods. The
remaining signal was random, and indices of aggre-
gation [ﬁt to the Poisson distribution, Taylor’s Power
Law (TPL), and Morisita’s Index] indicated that
medusae were aggregated. TPL suggested that patches
grew in the number of individuals as abundance
increased. Additionally, a simple conceptualization of
where the time series sampled in space revealed that
the upper bound of patch size was on the order of
kilometers. Our results enhance the knowledge of
local C. quinquecirrha abundance and patchiness,
alluding to processes that generate these patterns. This
study also provides direction for improving population
monitoring from visual shore-based surveys.
Keywords Abundance Aggregation Patchiness
Jellyﬁsh Gelatinous zooplankton Time series
Introduction
There is growing interest in jellyﬁsh, among the
scientiﬁc community as well as the general public, as
plankton dynamics (Richardson et al., 2009; Robinson
et al., 2014) and as their negative impacts on human
commercial and recreational activities increase (Pur-
cell et al., 2007; Purcell, 2012). In Chesapeake Bay,
the scyphozoan medusa, Chrysaora quinquecirrha
(Desor, 1848), is a keystone predator that consumes
crustacean mesozooplankton, ﬁsh eggs and larvae, and
ctenophores (Feigenbaum & Kelly, 1984; Purcell
et al., 1994; Purcell & Cowan, 1995; Purcell, 1997;
Purcell & Decker, 2005), strongly impacting the ﬂow
of carbon within the food web (Baird & Ulanowicz,
1989; Libralato et al., 2006). Aside from the conse-
quences for ﬁsheries, C. quinquecirrha is a common
nuisance to swimmers and watermen, and their blooms
Handling editor: Jo
¨rg Dutz
Electronic supplementary material The online version of
mentary material, which is available to authorized users.
J. Tay (&)R. R. Hood
Horn Point Laboratory, University of Maryland Center for
Environmental Science, 2020 Horns Point Road,
Cambridge, MD 21613, USA
e-mail: jtay@umces.edu
123
Hydrobiologia (2017) 792:227–242
DOI 10.1007/s10750-016-3060-8
... Due to their gelatinous nature, medusae are difficult to sample by net and may be injured if not handled with care (Tay and Hood, 2017). Some of the longest records of jellyfish abundance are shore-based surveys that may not be representative of the entire water column, especially in deeper water and when there are distinct hydrological features such as pycnoclines that may aggregate or restrict the vertical distribution of medusae (Graham et al., 2003;Rakow and Graham, 2006;Suzuki et al., 2016;Tay and Hood, 2017). ...
... Due to their gelatinous nature, medusae are difficult to sample by net and may be injured if not handled with care (Tay and Hood, 2017). Some of the longest records of jellyfish abundance are shore-based surveys that may not be representative of the entire water column, especially in deeper water and when there are distinct hydrological features such as pycnoclines that may aggregate or restrict the vertical distribution of medusae (Graham et al., 2003;Rakow and Graham, 2006;Suzuki et al., 2016;Tay and Hood, 2017). Many surveys also use fixed stations, that may provide only a limited view of the population as changes in flow will change the observable population, causing observer bias to pick out patterns that may not actually exist (Tay and Hood, 2017). ...
... Some of the longest records of jellyfish abundance are shore-based surveys that may not be representative of the entire water column, especially in deeper water and when there are distinct hydrological features such as pycnoclines that may aggregate or restrict the vertical distribution of medusae (Graham et al., 2003;Rakow and Graham, 2006;Suzuki et al., 2016;Tay and Hood, 2017). Many surveys also use fixed stations, that may provide only a limited view of the population as changes in flow will change the observable population, causing observer bias to pick out patterns that may not actually exist (Tay and Hood, 2017). Long-term records of medusa presence and abundance are necessary to determine whether populations cycles are changing in response to environmental drivers. ...
Thesis
Jellyfish population cycles and bloom events occur at global, regional, and local scales. Understanding what causes these cycles now and in the future is a major question in jellyfish bloom research, because of the potential impacts on ecosystem function and services. Most bloom forming scyphozoan jellyfish have complex life histories involving a long-lived asexually reproducing benthic polyp and a sexually reproducing pelagic medusae. Environmental and climate factors affect each life stage, but we do not fully understand how these variables drive life stage transition, or how demographic differences in survival, growth and fecundity translate into visible jellyfish outbreaks. We undertook a comprehensive laboratory and field-based study of the physicochemical conditions that control survival, fecundity and phase transition of the different life stages of scyphozoan jellyfish. Through this research, we examine the effects of environmental drivers on jellyfish population cycles and life stage transition. Modifications to estuaries through the construction of barrages alter the natural dynamics of inhabitant species by controlling freshwater inputs into those systems, driving the presence and absence of medusae from estuaries. As well as this, we explore how environmental conditions translate into reproductive success or failure in temperate populations from the medusa to the polyp life stage, demonstrating that early polyp growth rates are strongly linked to their thermal environment and highlighting a potential marine heatwave event. We examine not only the effects of temperature and other climate drivers on scyphozoan jellyfish growth, survival and reproduction, but also whether epigenetic transgenerational effects can drive acclimation to warmer summer temperatures in the short term in the context of a warming ocean. No parental effects were observed in the first or second generation, and in the third generation the transgenerational effects of temperature were subtle and appeared most strongly in cooling scenarios. Finally, within the setting of anthropogenically-driven climate change, we demonstrate for the first time that A. aurita polyps require a minimum period of cooler temperatures to strobilate, contradicting claims that jellyfish populations will be more prevalent in warming oceans, specifically in the context of warmer winter conditions. To answer these questions, we chose the common, or moon jellyfish Aurelia aurita as our primary experimental organism. However, we expanded our research to other species to demonstrate how they may vary in both environment and response to forcing factors as compared to a ‘typical’ model species. This thesis highlights the importance of examining each population within the context of their environment, and advances our understanding of how the climate and environment affect jellyfish life stage transition.
... Time series of abundance (Breitburg & Fulford, 2006;Feigenbaum & Kelly, 1984;Sexton et al., 2010;Tay & Hood, 2017) reveal that both C. chesapeakei and A. aurita become abundant during summer when temperatures rise above 17°C and are largely absent in the winter (Table 6.1). In the case of C. chesapeakei, the appearance of medusae in early summer is related to temperature-controlled triggering of strobilation of benthic polyps (Decker et al., 2007;Loeb, 1972), whereas the disappearance in the fall is related to temperature-controlled declines in pulsation rate below 15°C, which causes the medusa to Aurelia aurita * *** *** ** * Chrysaora chesapeakei + + + + + + *** *** *** ** ** Cyanea capillata ** ** ** ** ** Nemopsis bachei *** *** ** Mnemiopsis leidyi ** ** ** ** *** *** ** ** *** ** ** ** Beroe ovata ** ** ** *** sink (Sexton et al., 2010). ...
... Rhopilema verrilli and S. meleagris are both uncommon visitors to lower CB from coastal waters during fall and winter (Calder, 1972). Interannual to decadal time series of C. chesapeakei from the estuarine reaches of the Patuxent River (Breitburg & Fulford, 2006;Cargo & King, 1990) and Choptank (Sexton et al., 2010;Tay & Hood, 2017) reveal strong episodic and interannual variability in medusa abundance that appear to be related to freshwater flow, with high-flow years often associated with lower overall medusa abundance (Cargo & King, 1990). Observations from 2018 reveal a complete collapse of the C. chesapeakei medusa population in CB, which could be related to unusually high precipitation and freshwater flow in late spring and early summer (R. Hood, unpublished observations). ...
... Rhopilema verrilli and Stomolophus meleagris are found only in the polyhaline reach. In addition, the 4-year Choptank River time series has been used to identify aggregation behavior and quantify patch size of C. chesapeakei (Tay & Hood, 2017). Indices of aggregation calculated from the time series indicate that medusae were aggregated and suggested that patches grew in the number of individuals as abundance increased. ...
Chapter
Mesozooplankton and gelatinous zooplankton communities in Chesapeake Bay (CB) and the northern Adriatic Sea (NAS) have been subject to similar stressors over recent decades, including warming waters, overfishing, urbanization, and eutrophication. Direct comparisons between the systems are clouded by the lack of standardized and sustained long‐term monitoring programs in both, which have covered different temporal and spatial scales, and employed different methodologies. Data that are available show that the systems differ in community composition, with CB having fewer species compared with the more diverse NAS. Both systems have seen an altered gelatinous zooplankton community over recent decades. In the NAS, these changes in part have been due to the recent introduction of nonindigenous species, a phenomenon not yet documented in CB. Chesapeake Bay has seen a long‐term decline in the abundance of the dominant copepod taxa, attributed to increases in ctenophore abundance and/or increased seasonal hypoxia. Given the importance of mesozooplankton and gelatinous organisms in marine food webs, it is imperative that future ecosystem‐based management efforts for marine resources include coordinated, consistent, and standardized monitoring of mesozooplankton and gelatinous zooplankton. Such data would allow for the development of robust indices to help achieve management goals for water quality, ecosystem health, and marine resources.
... Time series of abundance (Breitburg & Fulford, 2006;Feigenbaum & Kelly, 1984;Sexton et al., 2010;Tay & Hood, 2017) reveal that both C. chesapeakei and A. aurita become abundant during summer when temperatures rise above 17°C and are largely absent in the winter (Table 6.1). In the case of C. chesapeakei, the appearance of medusae in early summer is related to temperature-controlled triggering of strobilation of benthic polyps (Decker et al., 2007;Loeb, 1972), whereas the disappearance in the fall is related to temperature-controlled declines in pulsation rate below 15°C, which causes the medusa to Aurelia aurita * *** *** ** * Chrysaora chesapeakei + + + + + + *** *** *** ** ** Cyanea capillata ** ** ** ** ** Nemopsis bachei *** *** ** Mnemiopsis leidyi ** ** ** ** *** *** ** ** *** ** ** ** Beroe ovata ** ** ** *** sink (Sexton et al., 2010). ...
... Rhopilema verrilli and S. meleagris are both uncommon visitors to lower CB from coastal waters during fall and winter (Calder, 1972). Interannual to decadal time series of C. chesapeakei from the estuarine reaches of the Patuxent River (Breitburg & Fulford, 2006;Cargo & King, 1990) and Choptank (Sexton et al., 2010;Tay & Hood, 2017) reveal strong episodic and interannual variability in medusa abundance that appear to be related to freshwater flow, with high-flow years often associated with lower overall medusa abundance (Cargo & King, 1990). Observations from 2018 reveal a complete collapse of the C. chesapeakei medusa population in CB, which could be related to unusually high precipitation and freshwater flow in late spring and early summer (R. Hood, unpublished observations). ...
... Rhopilema verrilli and Stomolophus meleagris are found only in the polyhaline reach. In addition, the 4-year Choptank River time series has been used to identify aggregation behavior and quantify patch size of C. chesapeakei (Tay & Hood, 2017). Indices of aggregation calculated from the time series indicate that medusae were aggregated and suggested that patches grew in the number of individuals as abundance increased. ...
... Results from our study revealed similar patterns of C. chesapeakei abundance and seasonality compared to previous studies conducted in the Patuxent River tributary (Cargo and Schultz 1966, Cones and Haven 1969, Loeb 1972, Calder 1974, Baird and Ulanowicz 1989, Purcell 1992, Suchman and Sullivan 1998, Brown et al. 2002, Breitburg and Fulford 2006, Decker et al. 2007, Breitburg and Burrell 2014, Tay and Hood 2017. Fig. 8. Relative Chrysaora chesapeakei density noted between years and across transects. ...
... This was not the case during the peak week of 18 July 2017, when a relatively similar number of medusae were found in the creek and channel. The difference in the observed dispersion patterns is not clear, and advective factors such as wind, river discharge, and geomorphology of sites may have resulted in more dispersal out of the source regions (Purcell et al. 2000, Graham et al. 2001, Suchman and Brodeur 2005, Decker et al. 2007, Hamner and Dawson 2009, Kaneshiro-Pineiro and Kimmel 2015, Tay and Hood 2017. However, there were no significant differences in Patuxent River discharge from June to August when comparing 2016 to 2017. ...
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