Ecological Archives E092-144-D1
Cathy H. Lucas, Kylie A. Pitt, Jennifer E. Purcell, Mario Lebrato, and Robert H. Condon. 2011. What's in a jellyfish? Proximate and elemental composition and biometric relationships for use in biogeochemical studies. Ecology 92:1704.
Abstract: Many marine organisms have gelatinous bodies, but the trait is most common in the medusae (phylum Cnidaria), ctenophores (phylum Ctenophora), and the pelagic tunicates (phylum Chordata, class Thaliacea). Although there are taxonomic and trophic differences between the thaliaceans and the other two closely related phyla, the collective term "jellyfish" has been used within the framework of this article. Because of the apparent increase in bloom events, jellyfish are receiving greater attention from the wider marine science community. Questions being posed include: (1) what is the role of jellyfish in pelagic food webs in a changing environment, and (2) what is the role of jellyfish in large-scale biogeochemical processes such as the biological carbon pump? In order to answer such questions, fundamental data on body composition and biomass are required. The purpose of this data set was to compile proximate and elemental body composition and length–mass and mass–mass regressions for jellyfish (i.e., medusae, siphonophores, ctenophores, salps, doliolids, and pyrosomes) to serve as a baseline data set informing studies on biogeochemical cycling, food web dynamics, and ecosystem modeling, and physiology. Using mainly published data from 1932 to 2010, we have assembled three data sets: (1) body composition (wet, dry, and ash-free dry mass, C, N, P as a percentage of wet and dry mass, and C:N), (2) length–mass biometric equations, and (3) mass–mass biometric equations. The data sets represent a total of 102 species from six classes (20 Thaliacea, 2 Cubozoa, 33 Hydrozoa, 26 Scyphozoa, 17 Tentaculata, 4 Nuda) in three phyla. Where it exists, we have included supplementary data on location, salinity, whole animal or tissue type, measured size range, and where appropriate, the regression type with values of sample size, correlation coefficients (r, r2), and level of significance for the relationship. In addition to the raw unpublished data, we have provided summary tables of mean (± SD) body composition for the main taxonomic groups.
Key words: biometric relationships; carbon; ctenophores; dry mass; Medusae; nitrogen; organic mass; proximate composition; salps.
INTRODUCTION
Several marine taxa have a gelatinous body, in particular the medusae and siphonophores (phylum Cnidaria), ctenophores (phylum Ctenophora) and the pelagic tunicates - salps, doliolids and pyrosomes (phylum Chordata, sub-phylum Thaliacea). While it is known that the thaliaceans are rather different from the cnidarians and ctenophores which are closely-related in taxonomic and trophic terms, there is scope for them to be included in the collective terms ‘jellies’, ‘jellyfish’ or ‘gelatinous zooplankton’, due to their watery bodies, low carbon content, ability to reproduce rapidly and form extensive bloom populations, and potential impact on marine plankton communities and biogeochemical cycling. Within the framework of this article the collective term ‘jellyfish’ will be used.
Jellyfish are found throughout the world’s oceans, from the surface to great depths, and from estuaries to the open ocean. In the short term, numbers can increase rapidly in a matter of weeks or months under conditions that favour rapid growth and reproduction (Lucas 2001, Madin et al. 2006). Over longer time-scales outbreaks can become more frequent or persistent in response to large-scale variability in climate (e.g., North Atlantic Oscillation, El Niño) (Kogovšek et al. 2010, Licandro et al. 2010) and oceanic (Lynam et al. 2010) influences; or they can in fact decline (Dawson et al. 2001, Brodeur et al. 2008). Locally, these naturally occurring episodic bloom events can be exacerbated by anthropogenic impacts such as overfishing, translocations, eutrophication, alterations to coastal geomorphology and climate warming (Mills 2001, Lynam et al. 2006, Purcell et al. 2007, Richardson et al. 2009, Dong et al. 2010, Reusch et al. 2010).
Medusae and ctenophores are voracious predators, consuming a wide range of zooplankton prey, and in some ecosystems acting as important ‘keystone’ species (Pauly et al. 2009). Many species consume fish eggs and larvae and/or are competitors with fish larvae for the same food resources. Thus, in some regions of the world’s oceans, jellyfish and fish stocks have been inextricably linked, for example, the Benguela (Lynam et al. 2006), southeast Asia (Uye 2008, Dong et al. 2010), and Bering Sea (Brodeur et al. 2008). Pelagic tunicates (e.g., salps) are efficient filter-feeders, removing small particles such as bacteria and phytoplankton (Madin et al. 2006). At times they can contribute significantly to the cycling of organic matter in the oceans, packaging and exporting primary organic carbon principally out of the euphotic zone via the production of large and rapidly sinking faecal pellets (Wiebe et al. 1979, Madin and Diebel 1998, Phillips et al. 2009). Thus, it is believed that jellyfish populations play an important role in ecosystem diversity and function and in biogeochemical cycling. Bloom populations could potentially alter trophic pathways in the following ways. Firstly, increased conversion of primary and secondary production into gelatinous biomass (Condon and Steinberg 2008, Pitt et al. 2009) may limit carbon bioavailability to higher trophic levels, including fish, and promote a microbially-dominated food web through release of labile organic matter (Condon et al., in press). Increased carbon export and transfer efficiency of the biological carbon pump through sinking of carcasses and faecal pellet production (Billett et al. 2006, Madin et al. 2006, Lebrato and Jones 2009, Pitt et al. 2009) would supply the benthos with an increased food supply. This is particularly important in the deep-sea, which by definition is a food-limited environment (Gage and Tyler 1991). However, large accumulations of dead jellyfish (e.g., Billett et al. 2006) could potentially cause hypoxic events and alter the oxygen exchange flux with sediments as a result of the high oxygen demand for the mineralization of carbon during decomposition (West et al. 2009, Sexton et al. 2010). Finally, blooms can cause trophic cascades in estuarine and coastal systems (Purcell and Decker 2005, Pitt et al. 2007), altering ecosystem services in unknown ways.
Apparent increases in jellyfish bloom events in several regions of the world (e.g., the Giant jellyfish Nemopilema nomurai in the Sea of Japan (Uye 2008), the ctenophore Mnemiopsis leidyi in the Black Sea (Kovalev and Piontkovski 1998), Chrysaora hysoscella and Aequorea forskalea in the Benguela upwelling (Lynam et al. 2006) and the Mauve stinger Pelagia noctiluca in the Mediterranean (Licandro et al. 2010)), has resulted in jellyfish receiving increased attention from the wider marine science community, including biogeochemists, fisheries scientists and ecosystem modelers (Daskalov et al. 2007, Pauly et al. 2009). Ecosystems experiencing shifting baselines or alternative stable states may result in jellyfish having greater influence on ecosystem function. Thus, the need to understand and quantify the role of jellyfish in pelagic and benthic food webs and in biogeochemical cycling in these changing environments gains prominence.
[Editor's note: "weight" has been changed to "mass" throughout per our style regarding SI units, but the abbreviations using "w" for "weight", as in "DW" have not been changed so as to match the data files.]
In order to answer such questions we require data on the spatial and temporal extent of populations, knowledge of trophic ecology and metabolic processes, as well as fundamental data on body composition size to mass conversions. Two commonly applied measures of biomass and production are dry mass (DW) and ash-free dry mass (AFDW), as both these mass types are relatively simple to determine. However, neither DW nor AFDW truly reflect jellyfish biomass when compared with non-gelatinous groups. In the latter group, carbon (C) accounts for 30–60% of DW (Harris et al. 2000), whereas in jellyfish it is typically <15% (Larson 1986). As part of a multinational project studying the magnitude, causes, and consequences of jellyfish blooms globally, data of body composition and biometric equations have been assembled for salps, pyrosomes, doliolids, medusae (including siphonophores), and ctenophores. Data have been compiled primarily from the peer-reviewed literature, spanning the period 1932 to the end of 2010, and covering a wide range of marine ecosystems (e.g., estuaries, coastal seas, oceanic) from the poles to the subtropics. In addition, summary tables have also been compiled using the data set. Where available, data on the salinity of the sample location have been included. It is well established that values of DW and AFDW are affected by ‘water of hydration’, i.e., bound water that is not removed during the drying process at 50–70°C, but which is driven off during the ashing process at 500–600°C, and which is influenced by the ambient salinity and body size (Larson 1986, Hirst and Lucas 1998). Detailed analyses of the effects of salinity and body size on body composition in the ubiquitous scyphozoan Aurelia are given in Hirst and Lucas (1998).
The data sets provide easy access to the most comprehensive compilation of published data of proximate and elemental body composition, and size–mass and mass–mass regression equations in jellyfish. It will serve as a baseline data set for use in a wide range of subject areas, including biogeochemical cycling, food web dynamics, population ecology, ecosystem modeling, as well as rate measurements of feeding, metabolism, and growth.
METADATA
CLASS I. DATA SET DESCRIPTORS
A. Data set identity: What’s in a jellyfish? Proximate and elemental composition and biometric relationships for use in biogeochemical studies.
B. Data set identification code: Jellyfish_body_composition_and_biometry
C. Data set description
Principal Investigator: Cathy Lucas, National Oceanography Centre Southampton, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH, UK.
Abstract: see above.
D. Key words: see above.
CLASS II. RESEARCH ORIGIN DESCRIPTORS
A. Overall project description
Identity: Global expansion of jellyfish blooms: magnitude, causes and consequences.
Originators: Robert H. Condon, Dauphin Island Sea Lab, Dauphin Island, AL, 36528 USA
Carlos M. Duarte, Department of Global Change Research, IMEDEA (UIB-CSIC), Instituto Mediterráneo de Estudios Avanzados, Esporles, 07190, Spain.
William M Graham, Dauphin Island Sea Lab, Dauphin Island, AL, 36528 USA
Period of Study: 2009– due to end late 2011
Objectives:To provide a global synthesis of reports of jellyfish abundance to achieve four main objectives: (1) to examine the hypothesis of a global expansion of jellyfish blooms, and to explore the possible drivers for this expansion; (2) to examine the effects of jellyfish blooms on the ecosystem, addressing in particular, carbon cycling, and food webs; (3) to identify current and future consequences of jellyfish blooms for tourism, industry, and fisheries, including ecosystem-based management on regional and global scales; and (4) to inform the public at large of the project results. The centerpiece of this project is a scientifically-coordinated global jellyfish and environmental database (JEDI, JEllyfish Database Initiative) based on published and unpublished data sets from coastal, estuarine, and open-ocean regions.
Abstract: Jellyfish are an important and often conspicuous component of oceanic food webs. During the past several decades, dramatic spatial increases and temporal shifts in jellyfish distributions have been reported around the world. Undoubtedly there are associated ecological ramifications such as food web and biogeochemical pathway alterations. Moreover, socio-economic impacts include damage to fisheries, industry and tourism. However, reports have remained local in scope, and scientists agree that a composite understanding of the extent of the problem is still lacking. The bottle-neck is the lack of synthetic analyses across marine ecosystems, due to the present fragmentation of data sources. In 2009, a research project entitled “Global expansion of jellyfish blooms: magnitude, causes, and consequences” started with the aim of providing a global synthesis of jellyfish abundance to achieve the objectives outlined above.
Sources of funding: National Center for Ecological Analysis and Synthesis (NCEAS), a Center supported by NSF (Grant #DEB-94-21535), the University of California at Santa Barbara, and the State of California. Data sourced and provided by M. Lebrato were carried out while working on an IFM-funded project under the ‘Future Oceans Cluster’.
B. Specific subproject description
Study Region: Data of body composition and biometric relationships were obtained for a wide range of marine ecosystems, including estuaries, coastal lagoons and fjords, hyposaline seas, coastal and shelf seas, open oceans and the mesopelagic. In terms of climate, data were obtained from polar (e.g., sub-Arctic Pacific, Antarctic Peninsula, Southern Ocean), temperate (e.g., coastal and shelf Europe, North America, Australia) and some subtropic (e.g., Caribbean, Australia, SE Asia) regions. Although this is a global database, entries are most comprehensive for Europe, North America, the North Atlantic, and the Antarctic, reflecting where most of the research has been conducted over the last ~70 years.
Experimental or sampling design: Most data have been compiled, as published, from the primary articles in the peer-review literature. In a few cases where the primary article could not be accessed, we have cited the primary and secondary source. Shin-Ichi Uye, Kylie Pitt and Cathy Lucas have provided unpublished data (unpublished data) or data from a PhD thesis.
Research Methods:
Collation of data sets:
Data on body composition and biometric relationships were collected by the authors, primarily from the peer-reviewed literature. Where possible we have used the primary literature source so that as much detail and ancillary information can be gathered. In some instances the primary source could not be accessed, so we have cited both the primary and secondary source. The data collated and stored in the ESA Ecological Archives ( are as published (i.e., we have not carried out any data transformations). A total of 29 terms have been collated. Detailed information on the analytical methods used to determine size and mass can be found in the original publications, but brief summaries of the most common methods are included in the list of definitions of each term and how they were collected as set out below.
Phylum: The taxonomic phylum to which the animal belongs.
Class: The taxonomic class to which the animal belongs.
Order: The taxonomic order to which the animal belongs.
Genus: The taxonomic genus to which the animal belongs as published in the source reference.
Species: The taxonomic species that identifies the animal as published in the source reference.
Location: The location where the species was collected according to the source reference. This varies in resolution and detail from, for example, ‘Australia’ or ‘Southern Ocean’ to named bays and estuaries such as ‘Southampton Water’ or ‘Kiel Bight’.
Salinity: The salinity of the water from which the species was collected, as published in the source reference. The majority of salinity measurements are made using a CTD (Conductivity, Temperature, Density) sensor, YSI multi-parameter probe, or refractometer. Although salinity is known to affect dry mass and ash free dry mass values due to the effects of bound ‘water of hydration’ (Larson 1986, Hirst and Lucas 1998), we have not attempted to approximate salinity from other literature sources for those records where salinity has not been included in the primary source material.
Life stage: Where it has been stated, the life stage of the sampled animals has been included. Thaliaceans are classified as either solitary or aggregate, oozoids or blastozooids. The life stages of hydrozoans and scyphozoans are rarely described other than as, rather arbitrarily, medusae, immature, ephyrae, juveniles, adults, adults with gonads, and eudoxies (immature or mature males or females) in siphonophores. Similarly ctenophores may be described as larvae, young or mature. In all groups, nd (no data) indicates where no life stage has been recorded.
Tissue type: The great majority of body composition and biometric data are for whole animals. In the cnidarians (principally the scyphozoans) there are some data for separate tissues – umbrella, gonad, oral arm, or tentacle.
Size: (Body composition) The size of individuals used in the analyses of body composition, if available. Sizes are published as either the minimum to maximum range, range (and average), mean ± standard deviation, and less than (<) or more than (>) a numeric value. Most sizes are expressed as linear measures, but some entries have reported mass or biovolume.
Size range: (Biometric equations) The size range of individuals used in the analysis of size–mass and mass–mass regressions. Most sizes are expressed as linear measures, but some entries have reported mass or biovolume.
Units: Standard SI units used to measure size (as length, height, mass, volume, age), as published in the source material. Size definitions are as follows: Thaliaceans – mm3 or mL biovolume, length defined as either oral-aboral (O-A) length or just length, individual wet mass or dry mass; Cnidarians – bell diameter (BD), coronal diameter (CD) for coronate scyphozoans, diameter, disc diameter, interradalia diameter, arm tips, bell height, individual wet mass or dry mass, age in days; Ctenophores – length, oral-apical (O-A) length, gut length, individual wet mass or dry mass.