Comparative phototaxis of calanoid and harpacticoid copepods

Ma, Xiao; Johnson, Kevin B.

doi:10.1007/s00227-016-3054-0

Cited by 7 publications

(3 citation statements)

References 49 publications

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“…Although no such in vivo behavioral clues were presented here, the large amount of luminous prey in M. pelagios stomach contents (i.e. Euphausia pacifica, Nematoscelis difficilis, Thysanopoda genus, Atolla genus, copepods [8,49,50]), and positive phototactism of some of them [51][52][53], adds support to this assumption. This strategy consisting to use bioluminescence of other organisms to attract prey is similar to the one suggested for the sperm whale, Physeter microcephalus.…”

Section: Discussionmentioning

confidence: 83%

The megamouth shark, Megachasma pelagios, is not a luminous species

et al. 2020

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Despite its five meters length, the megamouth shark (Megachasma pelagios Taylor, Compagno & Struhsaker, 1983) is one of the rarest big sharks known in the world (117 specimens observed and documented so far). This filter-feeding shark has been assumed to be a luminous species, using its species-specific white band to produce bioluminescence as a lure trap. Another hypothesis was the use of the white band reflectivity to attract prey or for social recognition purposes. However, no histological study has ever been performed to confirm these assumptions so far. Two hypotheses about the megamouth shark's luminescence arose: firstly, the light emission may be intrinsically or extrinsically produced by specific light organs (photophores) located either on the upper jaw white band or inside the mouth; secondly, the luminous appearance might be a consequence of the reflection of prey luminescence on the white band during feeding events. Aims of the study were to test these hypotheses by highlighting the potential presence of specific photophores responsible for bioluminescence and to reveal and analyze the presence of specialized light-reflective structures in and around the mouth of the shark. By using different histological approaches (histological sections, fluorescent in situ hybridization, scanning electron microscopy) and spectrophotometry, this study allows to unravel these hypotheses and strongly supports that the megamouth shark does not emit bioluminescence, but might rather reflect the light produced by bioluminescent planktonic preys, thanks to the denticles of the white band.

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Section: Discussionmentioning

confidence: 83%

The megamouth shark, Megachasma pelagios, is not a luminous species

et al. 2020

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“…It is a small (∼2 mm long), holoplanktonic, calanoid copepod that dwells in the upper 6-20 m of tropical and subtropical estuarine, coastal, and oceanic waters (Milstein, 1979;Turner and Dagg, 1983;Wong et al, 1993;Tang et al, 1994;Almeida et al, 2012;Sun et al, 2012;Liu et al, 2013). It is common for this species and other calanoid copepods to reside permanently in the mid-to upper water column (Ma and Johnson, 2017), where they feed on microalgae and nanoplankton. These cosmopolitan copepods have been shown to tolerate a wide range of temperatures (15-31 • C), salinities (20-37), and eutrophic or turbid conditions (Milstein, 1979;Wong et al, 1993;Almeida et al, 2012).…”

Section: Culturing Copepods and Algaementioning

confidence: 99%

Grazing by the Copepod Parvocalanus crassirostris on Picochlorum sp. at Harmful Bloom Densities and the Role of Particle Size

Jacoby

Johnson

2021

Front. Mar. Sci.

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Harmful blooms of nanophytoplankton (2–20 μm) are increasingly common and sometimes severe, but requirements and controls of such blooms (e.g., water quality constraints, requirements for nutrients, and the presence of different guilds of grazers) are poorly understood. Laboratory grazing experiments were conducted to evaluate the potential for top-down control by the copepod Parvocalanus crassirostris on a small harmful algal species (an unidentified chlorophyte Picochlorum, 1–4 μm) and to test the effects of cell sizes on grazing rates. The Picochlorum sp. is a strain isolated from a long-lasting harmful algal bloom in the Indian River Lagoon that reached high densities (>1 × 106 cells ml–1). Experiments contrasted grazing on Picochlorum sp. with grazing on the palatable prymnesiophyte Isochrysis galbana (4–6 μm) in monocultures and mixed cultures. When presented in monocultures, grazing rates on Picochlorum sp. were lower than grazing rates on the palatable alternative. When Picochlorum sp. were presented alongside I. galbana, copepods essentially ceased feeding on the former. In additional experiments, P. crassirostris were fed plastic beads with diameters of 2.0–17.9 μm to control for differences in taste, toxicity, production of mucilage and shape of potential food. Paracalanus crassirostris fed most efficiently on beads with diameters of 7.0–7.9 μm. Results revealed that P. crassirostris can consume Picochlorum sp., but small size and the presence of palatable cells reduces the likelihood of top-down control of blooms of Picochlorum sp.

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“…The grazer selected for this study is Parvocalanus crassirostris, a small (∼2 mm long), holoplanktonic, calanoid copepod that dwells in the upper 6-20 m of tropical and subtropical estuarine, coastal, and oceanic waters (Milstein, 1979;Turner and Dagg, 1983;Wong et al, 1993;Tang et al, 1994;Almeida et al, 2012;Sun et al, 2012;Liu et al, 2013). It is common for calanoid copepods to reside permanently in the mid-to upper water column (Ma and Johnson, 2017), where they feed on microalgae and nanoplankton. P. crassirostris is a cosmopolitan copepod and tolerates a wide range of temperatures (15-31 • C), salinities (20-37), and eutrophic or turbid conditions (Milstein, 1979;Wong et al, 1993;Almeida et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

High Densities of a Prochlorophyte (Unresolved Species) Inhibit Grazing by the Herbivorous Copepod Parvocalanus crassirostris

Jacoby

Johnson

2021

Front. Mar. Sci.

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Harmful algal blooms (HABs) are increasing in frequency and severity, underscoring the importance of understanding potential top-down controls of blooms. In the Indian River Lagoon (IRL), a shallow subtropical estuary, one harmful bloom was co-dominated by an unresolved prochlorophyte in the Family Prochlorothricaceae, which reached densities of > 106 cells ml–1 engendering the term “Superbloom.” Experiments were conducted to evaluate grazing rates and the potential for top-down control by an abundant herbivorous copepod, Parvocalanus crassirostris, on the prochlorophyte. Those grazing rates were lower than the rates on a palatable alternative algal food, Isochrysis galbana, when both algal species were presented in monocultures with identical densities. Grazing on the prochlorophyte decreased or ceased at densities over 4.8 × 105 cells ml–1. When the prochlorophyte and the palatable alternative each comprised half of the total density, both species were consumed, but grazing on I. galbana was reduced compared to the grazing rates in a monoculture of this species, especially at higher cell densities. Copepod mortality was observed in treatments with high concentrations of the prochlorophyte, and these treatments contained mucilage. Experiments simulating viscosities produced by prochlorophyte mucilage yielded results consistent with the original grazing experiments (i.e., copepods showed lower grazing rates and higher mortality rates in higher viscosity treatments). Results reveal potential limitations of top-down controls by this grazer on prochlorophyte blooms and HABs that produce mucilage.

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Comparative phototaxis of calanoid and harpacticoid copepods

Cited by 7 publications

References 49 publications

The megamouth shark, Megachasma pelagios, is not a luminous species

The megamouth shark, Megachasma pelagios, is not a luminous species

Grazing by the Copepod Parvocalanus crassirostris on Picochlorum sp. at Harmful Bloom Densities and the Role of Particle Size

High Densities of a Prochlorophyte (Unresolved Species) Inhibit Grazing by the Herbivorous Copepod Parvocalanus crassirostris

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