Latest Research on Copepod: Feb 2021

The insidious effect of diatoms on copepod reproduction

The productive regions of the ocean are characterized by seasonal blooms of phytoplankton which are generally dominated by diatoms. This algal class has, therefore, traditionally been regarded as providing the bulk of the food that sustains the marine food chain to top consumers and important fisheries. However, this beneficial role has recently been questioned on the basis of laboratory studies showing that although dominant zooplankton grazers such as copepods feed extensively on diatoms, the hatching success of eggs thus produced is seriously impaired1. Here we present evidence from the field showing that the hatching success of wild copepods feeding on a diatom-dominated bloom is also heavily compromised, with only 12% of the eggs hatching compared with 90% in post-bloom conditions. We report on the structure of the three aldehydes isolated from diatoms that are responsible for this biological activity, and show that these compounds arrest embryonic development in copepod and sea urchin bioassays and have antiproliferative and apoptotic effects on human carcinoma cells. [1]

Reorganization of North Atlantic Marine Copepod Biodiversity and Climate

We provide evidence of large-scale changes in the biogeography of calanoid copepod crustaceans in the eastern North Atlantic Ocean and European shelf seas. We demonstrate that strong biogeographical shifts in all copepod assemblages have occurred with a northward extension of more than 10° latitude of warm-water species associated with a decrease in the number of colder-water species. These biogeographical shifts are in agreement with recent changes in the spatial distribution and phenology detected for many taxonomic groups in terrestrial European ecosystems and are related to both the increasing trend in Northern Hemisphere temperature and the North Atlantic Oscillation. [2]

Copepod feeding currents: Food capture at low Reynolds number

High‐speed motion pictures of dye streams around feeding calanoid copepods revealed that these important planktonic herbivores do not strain algae out of the water as previously described. Rather, a copepod flaps four pairs of feeding appendages to propel water past itself and uses its second maxillae to actively capture parcels of that water containing food particles. The feeding appendages of Eucalanus pileatus operate at Reynolds numbers of only 10−2 to 10−1. In the viscous world of a feeding copepod, water flow is laminar, bristled appendages behave as solid paddles rather then open rakes, particles can neither be scooped up nor left behind because appendages have thick layers of water adhering to them, and water and particle movement stops immediately when an animal stops beating its appendages. [3]

Lernaeid Copepod Parasitic on the Freshwater Fishes of Godavari River, Rajahmundry, Andhra Pradesh, India with Description of a New Species, Lernaea notopteri n.sp. from Notopterus notopterus

Lernaeid copepods are one of the most detrimental and ubiquitous ectoparasites of cultured and wild variety freshwater fishes. River Godavari offers a dynamic habitat to a wide variety of fishes which are in turn infected by endo and ectoparasites. In a copepod parasitic survey on various species of freshwater fishes of River Godavari, Rajahmundry from 2007-2009, a total of 5 freshwater fishes were parasitized by copepods of the genus Lernaea. Four different adult species of Lernaea were found clinging to the skin of Channa punctatus, Catla catla, Barbus sp., Macrognathus aculeatus and Notopterus notopterus i.e., Lernaea bengalensis Gnanamuthu, [17], Lernaea cyprinacea Linnaeus, 1758, Lernaea cyprinacea mastacembeli Hu, [13] and a new species, Lernaea notopteri n.sp. The new lerneaid copepod, Lernaea notopteri was reported from Notopterus notopterus showed variations in cephalic arms, antenna, maxillipede and Leg-V from the other closely related species and hence was designated as new species. [4]

A Morphological Study of Kroyeria minuta Pillai, 1968 (Copepoda: Eudactylinidae) Infecting the Milk Shark, Rhizoprionodon acutus Rüppell, 1937 off Nellore Coast, Bay of Bengal, India

Copepods of the genus Kroyeria Van Beneden, 1853 (Eudactylinidae) are ectoparasites of Elasmobranchs frequently infecting the gill filaments. Eudactylinid parasites were sampled from 152 milk sharks, Rhizoprionodon acutus collected from the Nellore coast, Bay of Bengal. With the application of scanning electron microscopy (SEM) and light microscopy we identified Kroyeria minuta Pillai, 1968, which is a new geographical record for the east coast of India. Fifteen parasites were acquired from the gill filaments of 9 infected fishes and its main morphological characteristics include minute structure, long dorsal stylets not extending beyond the hind border of the 4th thoracic segment, thoracic segments with interpodal bars, short 3-segmented abdomen, uniseriate egg sacs, 8-jointed antennule, robust antenna, slender maxilla with apically forked claw and two segmented maxillipede. [5]

Reference

[1] Miralto, A., Barone, G., Romano, G., Poulet, S.A., Ianora, A., Russo, G.L., Buttino, I., Mazzarella, G., Laabir, M., Cabrini, M. and Giacobbe, M.G., 1999. The insidious effect of diatoms on copepod reproduction. Nature, 402(6758), pp.173-176.

[2] Beaugrand, G., Reid, P.C., Ibanez, F., Lindley, J.A. and Edwards, M., 2002. Reorganization of North Atlantic marine copepod biodiversity and climate. Science, 296(5573), pp.1692-1694.

[3] Koehl, M.A.R. and Strickier, J.R., 1981. Copepod feeding currents: Food capture at low Reynolds number 1. Limnology and Oceanography, 26(6), pp.1062-1073.

[4] Prasanna Vankara, A., Gudivada, M. and Chikkam, V. (2016) “Lernaeid Copepod Parasitic on the Freshwater Fishes of Godavari River, Rajahmundry, Andhra Pradesh, India with Description of a New Species, Lernaea notopteri n.sp. from Notopterus notopterus”, Journal of Applied Life Sciences International, 9(3), pp. 1-13. doi: 10.9734/JALSI/2016/30123.

[5] Kalyan, C. S. and Anuprasanna, V. (2016) “A Morphological Study of Kroyeria minuta Pillai, 1968 (Copepoda: Eudactylinidae) Infecting the Milk Shark, Rhizoprionodon acutus Rüppell, 1937 off Nellore Coast, Bay of Bengal, India”, Journal of Applied Life Sciences International, 9(1), pp. 1-10. doi: 10.9734/JALSI/2016/29012.

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