Editing Coccolithophore (section)

===Defence against predation===

Currently, the evidence supporting or refuting a protective function of the coccosphere against predation is limited. Some researchers found that overall microzooplankton predation rates were reduced during blooms of the coccolithophore ''[[Emiliania huxleyi]]'',<ref>{{cite journal |doi = 10.1017/S0025315402005593|title = Microplankton community structure and the impact of microzooplankton grazing during an Emiliania huxleyi bloom, off the Devon coast|year = 2002|last1 = Fileman|first1 = E.S.|last2 = Cummings|first2 = D.G.|last3 = Llewellyn|first3 = C.A.|journal = Journal of the Marine Biological Association of the United Kingdom|volume = 82|issue = 3|pages = 359–368| bibcode=2002JMBUK..82..359F |s2cid = 85890446}}</ref><ref>{{cite journal |doi = 10.1016/S0967-0645(02)00329-6|title = Phytoplankton growth, microzooplankton herbivory and community structure in the southeast Bering Sea: Insight into the formation and temporal persistence of an Emiliania huxleyi bloom|year = 2002|last1 = Olson|first1 = M.Brady|last2 = Strom|first2 = Suzanne L.|journal = Deep Sea Research Part II: Topical Studies in Oceanography|volume = 49|issue = 26|pages = 5969–5990|bibcode = 2002DSRII..49.5969O}}</ref> while others found high microzooplankton grazing rates on natural coccolithophore communities.<ref>{{cite journal |doi = 10.1016/j.pocean.2018.02.024|title = Growth and mortality of coccolithophores during spring in a temperate Shelf Sea (Celtic Sea, April 2015)|year = 2019|last1 = Mayers|first1 = K.M.J.|last2 = Poulton|first2 = A.J.|last3 = Daniels|first3 = C.J.|last4 = Wells|first4 = S.R.|last5 = Woodward|first5 = E.M.S.|last6 = Tarran|first6 = G.A.|last7 = Widdicombe|first7 = C.E.|last8 = Mayor|first8 = D.J.|last9 = Atkinson|first9 = A.|last10 = Giering|first10 = S.L.C.|journal = Progress in Oceanography|volume = 177|page = 101928|bibcode = 2019PrOce.17701928M|s2cid = 135347218|doi-access = free}}</ref> In 2020, researchers found that ''in situ'' ingestion rates of microzooplankton on ''E. huxleyi'' did not differ significantly from those on similar sized non-calcifying phytoplankton.<ref>{{cite journal |doi = 10.3389/fmars.2020.569896|doi-access = free|title = The Possession of Coccoliths Fails to Deter Microzooplankton Grazers|year = 2020|last1 = Mayers|first1 = Kyle M. J.|last2 = Poulton|first2 = Alex J.|last3 = Bidle|first3 = Kay|last4 = Thamatrakoln|first4 = Kimberlee|last5 = Schieler|first5 = Brittany|last6 = Giering|first6 = Sarah L. C.|last7 = Wells|first7 = Seona R.|last8 = Tarran|first8 = Glen A.|last9 = Mayor|first9 = Dan|last10 = Johnson|first10 = Matthew|last11 = Riebesell|first11 = Ulf|last12 = Larsen|first12 = Aud|last13 = Vardi|first13 = Assaf|last14 = Harvey|first14 = Elizabeth L.|journal = Frontiers in Marine Science|volume = 7|hdl = 1912/26802|hdl-access = free}}</ref> In laboratory experiments the heterotrophic dinoflagellate ''[[Oxyrrhis marina]]'' preferred calcified over non-calcified cells of ''E. huxleyi'', which was hypothesised to be due to size selective feeding behaviour, since calcified cells are larger than non-calcified ''E. huxleyi''.<ref>{{cite journal |doi = 10.3354/ame010307|title = Grazing in the heterotrophic dinoflagellate Oxyrrhis marina: Size selectivity and preference for calcified Emiliania huxleyi cells|year = 1996|last1 = Hansen|first1 = FC|last2 = Witte|first2 = HJ|last3 = Passarge|first3 = J.|journal = Aquatic Microbial Ecology|volume = 10|pages = 307–313|doi-access = free}}</ref> In 2015, Harvey et al. investigated predation by the dinoflagellate ''O. marina'' on different genotypes of non-calcifying ''E. huxleyi'' as well as calcified strains that differed in the degree of calcification.<ref name=Harvey2015>{{cite journal |doi = 10.1093/plankt/fbv081|title = Consequences of strain variability and calcification in ''Emiliania'' huxleyion microzooplankton grazing|year = 2015|last1 = Harvey|first1 = Elizabeth L.|last2 = Bidle|first2 = Kay D.|last3 = Johnson|first3 = Matthew D.|journal = Journal of Plankton Research|pages = fbv081|doi-access = free|hdl = 1912/7739|hdl-access = free}}</ref> They found that the ingestion rate of ''O. marina'' was dependent on the genotype of ''E. huxleyi'' that was offered, rather than on their degree of calcification. In the same study, however, the authors found that predators which preyed on non-calcifying [[genotype]]s grew faster than those fed with calcified cells.<ref name=Harvey2015 /> In 2018, Strom et al. compared predation rates of the dinoflagellate ''[[Amphidinium|Amphidinium longum]]'' on calcified relative to naked ''E. huxleyi'' prey and found no evidence that the coccosphere prevents ingestion by the grazer.<ref name=Strom2018>{{cite journal |doi = 10.1002/lno.10655|title = Phytoplankton defenses: Do Emiliania huxleyi coccoliths protect against microzooplankton predators?|year = 2018|last1 = Strom|first1 = Suzanne L.|last2 = Bright|first2 = Kelley J.|last3 = Fredrickson|first3 = Kerri A.|last4 = Cooney|first4 = Elizabeth C.|journal = Limnology and Oceanography|volume = 63|issue = 2|pages = 617–627|bibcode = 2018LimOc..63..617S| s2cid=90415703 |doi-access = free}}</ref> Instead, ingestion rates were dependent on the offered genotype of E. huxleyi.<ref name=Strom2018 /> Altogether, these two studies suggest that the genotype has a strong influence on ingestion by the microzooplankton species, but if and how calcification protects coccolithophores from microzooplankton predation could not be fully clarified.<ref name=Haunost2021 />