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Journal ArticleDOI

Predictability of patches of neritic salps and doliolids (Tunicata, Thaliacea)

01 Dec 2009-Journal of Plankton Research (Oxford University Press)-Vol. 31, Iss: 12, pp 1571-1579
TL;DR: An evaluation of data and published results on abundances of doliolids and salps from ocean margins reveals that a considerable degree of prediction is possible, based upon meteorological and boundary current intrusion dynamics.
Abstract: The occurrence of large patches of gelatinous zooplankton has for decades been considered to be unpredictable. An evaluation of our own data and published results on abundances of doliolids and salps from ocean margins reveals that a considerable degree of prediction is possible, based upon meteorological and boundary current intrusion dynamics.

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Citations
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Journal ArticleDOI
TL;DR: It is shown that salps play a major role in carbon sequestration and are key components of marine food webs as a food source for at least 202 species including fish, turtles, and crustaceans.
Abstract: Salps are barrel-shaped, gelatinous zooplankton that regularly form large swarms. They have historically been ignored because they are difficult to sample and their gelatinous body structure suggests that they are unimportant in food webs and biogeochemical cycles. We collate evidence to overturn several common misconceptions about salps that have hampered research. We show that salps play a major role in carbon sequestration and are key components of marine food webs as a food source for at least 202 species including fish, turtles, and crustaceans. The future of salps in the Anthropocene is uncertain, and therefore further research into areas such as basic rate processes and their biogeochemical impact through new and innovative laboratory and field methods is needed.

135 citations

Journal ArticleDOI
19 Mar 2014-PLOS ONE
TL;DR: High-use habitat for leatherbacks in this study occurred in coastal waters of the North American eastern seaboard and eastern Caribbean, putting turtles at heightened risk from land- and ocean-based human activity.
Abstract: Leatherback sea turtles, Dermochelys coriacea, are highly migratory predators that feed exclusively on gelatinous zooplankton, thus playing a unique role in coastal and pelagic food webs. From 2007 to 2010, we used satellite telemetry to monitor the movements and dive behavior of nine adult and eleven subadult leatherbacks captured on the Northeast USA shelf and tracked throughout the Northwest Atlantic. Leatherback movements and environmental associations varied by oceanographic region, with slow, sinuous, area-restricted search behavior and shorter, shallower dives occurring in cool (median sea surface temperature: 18.4°C), productive (median chlorophyll a: 0.80 mg m−3), shallow (median bathymetry: 57 m) shelf habitat with strong sea surface temperature gradients (median SST gradient: 0.23°C km−1) at temperate latitudes. Leatherbacks were highly aggregated in temperate shelf and slope waters during summer, early fall, and late spring and more widely dispersed in subtropical and tropical oceanic and neritic habitat during late fall, winter and early spring. We investigated the relationship of ecoregion, satellite-derived surface chlorophyll, satellite-derived sea surface temperature, SST gradient, chlorophyll gradient and bathymetry with leatherback search behavior using generalized linear mixed-effects models. The most well supported model showed that differences in leatherback search behavior were best explained by ecoregion and regional differences in bathymetry and SST. Within the Northwest Atlantic Shelves region, leatherbacks increased path sinuosity (i.e., looping movements) with increasing SST, but this relationship reversed within the Gulf Stream region. Leatherbacks increased path sinuosity with decreasing water depth in temperate and tropical shelf habitats. This relationship is consistent with increasing epipelagic gelatinous zooplankton biomass with decreasing water depth, and bathymetry may be a key feature in identifying leatherback foraging habitat in neritic regions. High-use habitat for leatherbacks in our study occurred in coastal waters of the North American eastern seaboard and eastern Caribbean, putting turtles at heightened risk from land- and ocean-based human activity.

59 citations

Journal ArticleDOI
TL;DR: Mixing model results suggest that leatherbacks foraging off Massachusetts primarily consume the scyphozoan jellyfishes, Cyanea capillata and Chrysaora quinquecirrha, and ctenophores, while a smaller proportion of their diet comes from holoplanktonic salps and sea butterflies (Cymbuliidae).
Abstract: Leatherback turtles, Dermochelys coriacea, are highly migratory, spending most of their lives submerged or offshore where their feeding habits are difficult to observe. In order to elucidate the foraging ecology of leatherbacks off Massachusetts, USA, stable isotope analyses were performed on leatherback tissues and prey collected from 2005 to 2009. Stable isotope ratios of nitrogen and carbon were determined in whole blood, red blood cells, blood plasma, muscle, liver, and skin from adult male, female, and subadult leatherbacks. Isotopic values were analyzed by body size (curved carapace length) and grouped by sex, and groups were tested for dietary differences. Gelatinous zooplankton samples were collected from leatherback foraging grounds using surface dip nets and stratified net tows, and prey contribution to leatherback diet was estimated using a two-isotope Bayesian mixing model. Skin and whole blood δ13C values and red blood cell δ15N values were correlated with body size, while δ13C values of red blood cells, whole blood, and blood plasma differed by sex. Mixing model results suggest that leatherbacks foraging off Massachusetts primarily consume the scyphozoan jellyfishes, Cyanea capillata and Chrysaora quinquecirrha, and ctenophores, while a smaller proportion of their diet comes from holoplanktonic salps and sea butterflies (Cymbuliidae). Our results are consistent with historical observations of leatherback turtles feeding on scyphozoan prey in this region and offer new insight into size- and sex-related differences in leatherback diet.

54 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the physical and biogeochemical properties of two contrasting cyclonic eddies in the East Australian Current (EAC) and found that the frontal eddies are significantly more ageostrophic, energetic and productive than the mesoscale cyclone, despite its small size and short life (∼4 weeks).
Abstract: Mesoscale cyclonic eddies are known to be highly productive. Less well-known are the dynamics and productivity of smaller cyclonic eddies, known as frontal eddies, that form on the landward side of western boundary currents. In this study we investigate the physical and biogeochemical properties of two contrasting cyclonic eddies in the East Australian Current (EAC). The first (“Murphy”), a mesoscale cyclonic eddy that formed at ∼28°S with a diameter of ∼160 km and high surface chlorophyll-a concentrations, which lived ∼47 days. The second (“Freddy”), a smaller frontal eddy (∼35 km diameter) that formed from a shelf water billow ∼7 days prior to sampling at ∼31.5°S and was advected off the shelf along the EAC front (from ∼200m to 4000m of water). Both eddies were at least 1000m deep with a similar steric height anomaly. We introduce and employ ‘the method of closest approach' using shipboard ADCP velocities to estimate the eddy centers, which reveals significant tilting through the water column. We estimate rotation rates of 4-10 days and 1-9 days and Rossby numbers 0.25-0.1 and 0.6-0.1, from the surface to 600m for Murphy and Freddy respectively. High-resolution altimetry measurements from the SARAL/AltiKA satellite provide estimates of the ageostrophic component of rotation. Our results show that the frontal eddy is significantly more ageostrophic, energetic and productive than the mesoscale cyclone, despite its small size and short life (∼4 weeks). We suggest that frontal eddies have potential to contribute significantly to the net productivity of the Tasman Sea region. This article is protected by copyright. All rights reserved.

52 citations


Cites background or methods or result from "Predictability of patches of neriti..."

  • ...Using satellite remote sensed ocean color data to survey more than 2400 cyclonic eddies, Everett et al. [2012] found a mean chl....

    [...]

  • ...A numerical modeling investigation into a cyclonic eddy (diameter 60–120 km) that formed in the region showed that proximity to the shelf was essential for entrainment of shelf waters [Everett et al., 2015]. Using a dye tracer, Everett et al. [2015] showed that surface waters within the cyclonic eddy (top 50 m) were almost entirely of shelf origin. Using in situ mooring data on the continental shelf at 308S, Schaeffer et al. [2014] showed that onshore fluctuations in the EAC and encroachment of eddies on shelf (which occurred at periods of 90–100 days) can drive onshore bottom boundary layer transport across the shelf, bringing an injection of cold (nutrient-richer) bottom water....

    [...]

  • ...Both cyclonic and anticyclonic eddies are prolific in the EAC System, particularly downstream of the EAC separation point between 32 and 398S [Everett et al., 2012]. In this region, eddies have increased anomalies of sea level, surface temperature, and surface chlorophyll a (chl. a), and are associated with faster rotation rates [Everett et al., 2012, 2014]. Using the Chelton et al. [2011a,2011b] eddy database, Everett et al. [2012] showed that Tasman Sea eddies range in diameter from 100 to 300 km with a mean of 185 km in our region, with a mean sea level anomaly of 0....

    [...]

  • ...Our results showed that Murphy (diameter 160 km) is within the size range identified for OFES eddies, and by Everett et al. [2012], with diameters of <100–300 km, with a mean diameter of 164 km....

    [...]

  • ...A numerical modeling investigation into a cyclonic eddy (diameter 60–120 km) that formed in the region showed that proximity to the shelf was essential for entrainment of shelf waters [Everett et al., 2015]. Using a dye tracer, Everett et al. [2015] showed that surface waters within the cyclonic eddy (top 50 m) were almost entirely of shelf origin....

    [...]

Book ChapterDOI
01 Jan 2014
TL;DR: The evolutionary relationships among gelatinous zooplankton are summarized, biological factors that likely contribute to blooms are emphasized, and a population genetic framework for investigating the ecological causes of boom and bust population dynamics in the plankton is outlined.
Abstract: The jellyfishes and thaliaceans comprise primarily planktonic species of cnidarians, ctenophores (jellyfishes) and chordates (thaliaceans or pelagic tunicates). Grouped together because of their gelatinous bodies, these diverse species nonetheless differ in their evolutionary histories and may have distinct morphologies, life histories, ecologies and other traits. Subsets of these species occur at some times and places in highly elevated concentrations, i.e. they accumulate, aggregate, bloom or swarm. Why jellyfishes and thaliaceans occur in such masses is, however, somewhat unclear; the reasons obscured in part by a tendency to treat many gelatinous zooplankton, including jellyfishes and thaliaceans, as a single functional group. Here we summarize the evolutionary relationships among gelatinous zooplankton and review the characteristics of blooms, before focusing on comparing and contrasting medusae, ctenophores and thaliaceans. We highlight some substantial knowledge gaps, emphasize biological factors that likely contribute to blooms and outline a population genetic framework for investigating the ecological causes of boom and bust population dynamics in the plankton.

50 citations

References
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Journal ArticleDOI
TL;DR: How life cycle patterns are central in marine ecology, as are the pulses of gelatinous organisms, are described, and how such a dramatic lack of knowledge can affect the authors' understanding of the marine ecosystem as a whole is highlighted.
Abstract: In spite of being one of the most relevant components of the biosphere, the plank- ton-benthos network is still poorly studied as such. This is partly due to the irregular occurrence of driving phenomena such as gelatinous plankton pulses in this realm. Gelatinous plankters rely on their life cycles and histories to exploit temporarily abundant resources with an undeniable, but often overlooked, impact on marine food webs. Dramatic increases of gelatinous filter-feeders and/or carnivores (both native and nonindigenous species) are frequently observed, and explana- tions of these blooms alternatively invoke ecosystem variability, climate change, unspecified anthropogenic perturbation or removal of top predators from trophic networks. Gelatinous plank- ters, however, are not anomalies in plankton dynamics: the recognition of the ecological impor- tance of their pulses, based on their life cycle patterns (often involving benthic stages), is a critical breakthrough to understand the cycling diversity of plankton in space and time. The current study focuses on the many neglected aspects of the ecology and biology of gelatinous zooplankton, describes how life cycle patterns are central in marine ecology, as are the pulses of gelatinous organisms, and highlights how such a dramatic lack of knowledge can affect our understanding of the marine ecosystem as a whole.

327 citations

Book
01 Jan 1998
TL;DR: The relationships and systematics of the Thaliacea, with keys for identification, and the role of appendicularia in marine food webs are discussed.
Abstract: Introduction Chapter 1 - Anatomy of Thaliacea Chapter 2 - Anatomy of Appendicularia Chapter 3 - Locomotion, locomotor muscles and buoyancy Chapter 4 - Nervous system, sense organs and excitable epithelia Chapter 5 - Feeding and energetics of Thaliaceans Chapter 6 - The Appendicularian house Chapter 7 - Salp and pyrosomid blooms and their importance in biogeochemical cycles Chapter 8 - Feeding and metabolism of appendicularians Chapter 9 - Life history of the appendicularians Chapter 10 - The role of appendicularia in marine food webs Chapter 11 - The parasites and predators of Thaliacea Chapter 12 - Bioluminescence in the Appendicularia Chapter 13 - The cladistic biogeography of salps and pyrosomas Chapter 14 - Appendicularian distribution and zoogeography Chapter 15 - Molecular phylogeny of tunicates. A preliminary study using 28 Sribosomal RNA partial sequences: implications in terms of evolution and ecology Chapter 16 - The relationships and systematics of the Thaliacea, with keys for identification Chapter 17 - The classification of Appendicularia References Taxonomic Index Subject Index

251 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used hydrographic data collected during four cruises to evidence upwelling on the Yucatan Shelf, and describe its structure, which suggests that the YUW is probably caused by bottom friction or other topographical mechanisms.

184 citations

Journal ArticleDOI
TL;DR: The high Antarctic regions, particularly the Marginal Ice Zone, have effective physiological mechanisms that may provide protection against the salp invasion, and salps may become a more prominent player in the trophic structure of the Antarctic marine ecosystem.
Abstract: Available data on the spatial distribution and feeding ecophysiology of Antarctic krill, Euphausia superba, and the tunicate, Salpa thompsoni, in the Southern Ocean are summarized in this study. Antarctic krill and salps generally display pronounced spatial segregation at all spatial scales. This appears to be the result of a clear biotopical separation of these key species in the Antarctic pelagic food web. Krill and salps are found in different water masses or water mass modifications, which are separated by primary or secondary frontal features. On the small-scale (o100 km), Antarctic krill and salps are usually restricted to the specific water parcels, or are well segregated vertically. Krill and salp grazing rates estimated using the in situ gut fluorescence technique are among the highest recorded in the Antarctic pelagic food web. Although krill and salps at times may remove the entire daily primary production, generally their grazing impact is moderate (p50% of primary production). The regional ecological consequences of years of high salp densities may be dramatic. If the warming trend, which is observed around the Antarctic Peninsula and in the Southern Ocean, continues, salps may become a more prominent player in the trophic structure of the Antarctic marine ecosystem. This likely would be coupled with a dramatic decrease in krill productivity, because of a parallel decrease in the spatial extension of the krill biotope. The high Antarctic regions, particularly the Marginal Ice Zone, have, however, effective physiological mechanisms that may provide protection against the salp invasion. r 2002 Elsevier Science Ltd. All rights reserved.

174 citations

Journal ArticleDOI
TL;DR: Thytoplankton pigments and species were studied at a coastal station off Sydney over one annual cycle, and possible explanations as to alternation of diatom-dominated and nanoplankton-dominated floras are discussed.
Abstract: Phytoplankton pigments and species were studied at a coastal station off Sydney (New South Wales, Australia) over one annual cycle. Sudden increases in chlorophyll a (up to 280 mg m-2), due to short-lived diatom blooms, were found in May, July, September, January and February. These were superimposed upon background levels of chlorophyll a (20 to 50 mg m-2), due mostly to nanoplankton flagellates, which occurred throughout the year. The nanoplankton (<15 μm) accounted for 50 to 80% of the total phytoplankton chlorophyll, except when the diatom peaks occurred (10 to 20%). The annual cycle of populations of 16 dominant species-groups was followed. Possible explanations as to alternation of diatom-dominated and nanoplankton-dominated floras are discussed. Thin-layer chromatography of phytoplankton pigments was used to determine the distribution of algal types, grazing activity, and phytoplankton senescence in the water column. Chlorophyll c and fucoxanthin (diatoms and coccolithophorids) and chlorophyll b (green flagellates) were the major accessory pigments throughout the year, with peridinin (photosynthetic dinoflagellates) being less important. Grazing activity by salps and copepods was apparent from the abundance of the chlorophyll degradation products pheophytin a (20 to 45% of the total chlorophyll a) and pheophorbide a (10 to 30%). Chlorophyllide a (20 to 45%) was associated with blooms of Skeletonema costatum and Chaetoceros spp. Small amounts of other unidentified chlorophyll a derivatives (5 to 20%) were frequently observed.

170 citations