[Advances in Marine Biology] Advances in Marine Biology Volume 15 Volume 15 || The Biology of Pseudocalanus

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<ul><li><p>Adv. mar. Biol., Vol. 16. 1978 pp. 1-231. </p><p>THE BIOLOGY OF PSEUDOCALANUS </p><p>CHRISTOPHER J. CORKETT and IAN A. MCLAREN Dalhousie University, Halifax, Nova Xcotia, Canada </p><p>I. Introduction . . .. .. .. .. .. 11. Systematics . . .. .. .. .. .. </p><p>A. Nomenclature . . .. .. .. B. " Physiological " Species . . .. .. C. Variations in DNA Content . . .. .. D. Retrospects and Prospects . . .. .. </p><p>111. Distribution and Abundance. . . . . . .. A. Geographical Distribution . . .. . . B. Abundance . . . . .. .. .. C. Temporal Variations . . .. .. .. D. Vertical Distribution . . .. .. .. E. Sampling Problems and Microdistribution . . F. Physical-chemical Limits to Distribution . . G. Retrospects and Prospects . . .. .. </p><p>IV. Morphology . . .. . . .. . . .. A. Embryo .. .. .. .. .. .. B. Nauplii . . .. .. .. .. .. C. Copepodids (C I-C V) . . . . . . .. D. Adults (C VI) . . .. .. .. .. E. Retrospects and Prospects . . .. .. </p><p>v. ResDiration . . .. . . . . . . .. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. . . . . .. .. .. .. . . .. .. .. .. .. .. .. .. </p><p>A. Factors Influencing Rate of Oxygen Consumption. . B. Respiration and Food Requirements C. Retrospects and Prospects . . .. </p><p>.. </p><p>VI. Excretion . . .. .. .. A. Nitrogen .. .. .. B. Phosphorus . . .. .. C. Retrospects end Prospects . . </p><p>VII. Locomotion . . .. .. .. A. Routine Swimming . . .. B. Escape Reaction . . . . C. Retrospects and Prospects . . </p><p>VIII. Nutrition . . .. .. .. A. Feeding Mechanism . . .. B. FoodEaten . . . . .. C. Feeding Rate . . . . .. D. Die1 Feeding Rhythms .. E. Assimilation . . .. .. F. Food Requirements for Sustenance G. Retrospects and Prospects . . </p><p>$.3f.U.--15 1 </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. . . .. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>.. I . .. </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. . . .. .. .. .. .. .. . . . . .. .. .. .. . . . . .. .. . . .. .. .. .. .. . . .. .. </p><p>.. 2 </p><p>.. 3 </p><p>.. 3 </p><p>.. 9 </p><p>. I 9 </p><p>.. 11 </p><p>.. ' 11 </p><p>.. 11 </p><p>. . 17 </p><p>. . 18 </p><p>. . 20 </p><p>. . 22 </p><p>. . 23 </p><p>. . 26 </p><p>.. 27 </p><p>.. 29 </p><p>.. 29 </p><p>.. 29 </p><p>.. 31 </p><p>.. 37 .. 37 . . 38 .. 42 .. 43 .. 43 .. 44 .. 49 .. 61 .. 61 .. 61 . . 63 .. 63 .. 64 . . 64 .. 68 . . 64 . . 72 .. 16 .. 76 .. I9 </p><p>2 </p></li><li><p>2 CHRISTOPHER J. CORKETT AND IAN A. MCLAREN </p><p>IX. Reproduction .. I . .. .. .. .. .. A. SexRatio . . .. .. .. .. .. B. Oogenesis and Egg Laying . . .. . . . . C. Sperm and Spermatophore Production . . .. D. Mating . . .. . . . . .. .. . . E. Reproductive Rate . . .. . . .. . . F. Retrospects and Prospects . . .. . . . . </p><p>X. Development and Growth . . .. . . .. .. A. Embryonic Development Rate . . .. .. R. Hatching . . . . .. . . . . . . </p><p>D. Longevity of Adults . . .. .. .. .. E. Body Size . . . . . . . . . . .. F. Body Composition and Weights . . .. . . G. Oil Storage . . . . . . . . . . . . H. Growth Rates . . . . . . . . . . .. I. Rate of Production of Egg Matter . . . . .. J. The Balance Equation and Growth Efficiencies K. Retrospects and Prospects . . . . .. </p><p>C. Development Rate of Nauplii and Copepodids . . </p><p>XI. Life Cycles in Nature .. .. . . . . A. General Features, Terminology and Approaches </p><p>V </p><p>B. Representative Life Cycles . . C. Retrospects and Prospects . . </p><p>A. Ontogenetic Migrations . . XII. Vertical Migration . . .. .. </p><p>B. Seasonal Migrations . . .. C. Die1 Migrations . . . . D. Retrospects and Prospects . . </p><p>XIII. Production . . . . . . . . A. General Methods . . . . B. Production Estimates . . C. Retrospects and Prospects . . </p><p>XIV. Parasites . . . . .. .. A. Dinoflagellates . . .. .. B. Gregarines . . . . . . C. Trematodes . . .. . . D. Nematodes . . .. .. E. Crustaceans . . . . . . F. Retrospects and Prospects . . </p><p>XV. Role in the Food Web .. . . A. Effect on Phytoplankton . . B. Predators . . . . . . C. Significance in the Food Web. . D. Retrospects and Prospects . . </p><p>XVI. Acknowledgemonts . . ,. .. XVII. References . . .. . . .. </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>. . </p><p>. . </p><p>. . </p><p>.. </p><p>.. </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>.. </p><p>. . </p><p>.. </p><p>. . </p><p>.. </p><p>. . </p><p>.. ,. .. . . .. .. .. .. . . . . . . .. . . . . . . . . . . .. .. . . .. . . .. .. .. .. .. . . . . .. .. . . . . . . </p><p>.. 80 </p><p>. . 80 </p><p>.. 81 </p><p>.. 81 </p><p>. . 83 </p><p>.. 85 </p><p>.. 99 </p><p>.. 100 </p><p>.. 101 </p><p>.. 107 </p><p>.. 107 </p><p>.. 114 </p><p>. . 115 </p><p>. . 124 </p><p>.. 128 </p><p>.. 129 </p><p>.. 131 </p><p>. . 132 </p><p>.. 134 </p><p>.. 135 </p><p>. . 135 </p><p>. . 136 </p><p>.. 155 </p><p>. . 158 </p><p>. . 158 </p><p>. . 161 </p><p>.. 163 </p><p>.. 179 </p><p>.. 179 </p><p>. . 179 </p><p>. . 182 </p><p>. . 188 </p><p>.. 190 </p><p>.. 190 </p><p>.. 197 </p><p>.. 197 </p><p>.. 197 </p><p>.. 198 </p><p>.. 199 </p><p>. . 199 </p><p>. . 199 </p><p>.. 201 </p><p>. . 208 </p><p>. . 210 </p><p>.. 210 </p><p>.. 211 </p><p>I. INTRODUCTION </p><p>Over forty years ago, at a conference sponsored by the National Research Council of Canada, Russell (1934) put our subject into context: intensive study of the plankton in northern waters . . . supplemented </p></li><li><p>THE BIOLOGY OF PSEUDOCALANUS 3 </p><p>by recent observations on the food of plankton-feeding fish have all pointed to the economic importance of a few species only. In first rank can be placed Calanus Jinmarchicus, Temora longicornis, and Pseudocalanus elongatus . . , These three genera have all been extensively studied since, and Calanus has been admirably ( booked (Marshall and Orr, 1955). Perhaps because of its relatively large size, Calanus has been most favoured as an experimental animal and is much the best known copepod in a number of ways. Our knowledge of Pseudocalanus is somewhat complementary to that of Calanus. Out of an awareness, expressed even in the earliest copepod literature, of the extreme variability of size of PseudocaZanus in nature, has grown a rather precise set of ( rules concerning its development, growth, and reproductive rates. Perhaps it can also be said that there has been more concern with the mean response to environmental variables in studies of Calanus and more interest in individual variation in studies of Pseudocalanus. </p><p>The reader should be aware that we have generally avoided using papers in the vast copepod literature that make no direct reference to Pseudocalanua. This may disappoint readers who feel that a more complete or deeper account might have been inferred from systematic relationships. For example, the swimming of Calanus nauplii has been well described, and there is no reason to suppose that the morpho- logically very similar nauplii of Pseudocalanus would behave differently. However, since we can find no description of swimming of Pseudoculanus nauplii, we do not cover the subject. </p><p>We have attempted to be analytical and synthetical where possible in our review, and do not simply summarize the observations and conclusions of other authors. Some readers may feel that on occasion we have selected or even abused the writings of others in the search for patterns and regularities. However, we have reserved our most personal assessments of research on Pseudocalanus for the sections in each subsection that we call ( retrospects and prospects . Therein we broadly assess what has been done and suggest promising (and un- promising) lines for future investigation. Some of our suggestions for future research may seem a little vague ; perhaps they have to be since real discovery is by nature unpredictable. </p><p>11. SYSTEMATICS A. Nomenclature </p><p>1. The Genus The Genus was established by Boeck (1864) with the name Clausia, </p><p>in honour of the late C. Claus. Later Boeck (1872) discovered that the </p></li><li><p>4 CHRISTOPHER J. CORKETT AND IAN A. MCLAREN </p><p>name Glausia had been preoccupied by a parasitic copepod and there- fore substituted the name Glausia with the new name Pseudocalanus. </p><p>2. Described species (a) Pseudocalanus minutus (Kreryer, 1845) </p><p>The first description of a species of the genus was the publication of a plate by Kreryer (1842-45), on which the animal was given the binomen Calanus minutus. No description of the plate was pubIished a t the same time, but since the plate was published prior to 1931 the plate and accompanying binomen are sufficient to describe a new species (I.C.Z.N., Art. 16, a, vii). The original drawing is reproduced in Fig. 1 and is clearly a male copepodid V (see p. 30, Table I), although </p><p>FIQ. 1 . Calanus minutus Kreyer, 1845, the type species of Pseudocalanus. A male copepodid V. ( x 2.6 from original plate 41 in Kreyer, 1842-46.) </p><p>the diagram shows five thoracic segments and not the usual four. K r ~ y e r (1848) did publish, separate from the plate, a description of a male copepodid V of Calanus minutus in which he described the fifth thoracic segment as being rudimentary and free on its lateral and ventral sides. This evidence suggests that the fourth and fifth thoracic segments were incompletely fused or that the suture line of the fusion was still visible. This is not uncommon in Pseudocalanus and With (1915) illustrated copepodids V of both sexes showing small fifth thoracic segments. </p><p>A problem arises since the date of publication of the binomen Calanus minutus is the date of publication of Kreryers plate, and we have been unable to obtain this exact date. It is known that the date must have been during or before 1845, when the last plates of this </p></li><li><p>THE BIOLOGY O F PSEUDOCALANUS 5 </p><p>work were published (Sherborn and Woodward, 1901), and the date 1845 can therefore be used after the binomen (I.C.Z.N., Art. 21, f ) . According to de la Roquette (1842, p. 446), publication of the first plates had begun by 1842. We, therefore, cite both dates in our references except in purely nomenclatorial citations, </p><p>K r ~ y e r preserved some specimens which were examined by With (1915), who described them as belonging all to the penultimate stage (18 + 29) , presumably meaning one male copepodid V and two female copepodids V. However, Dr B. Frost (personal communication) has recently examined the same material and reports that it consists of three female copepodids V and one male copepodid IV. This appears to exclude the possibility that the holotype is extant. I n view of other taxonomic problems to be documented below, great care should be taken in any future designation of a neotype. </p><p>(b) Pseudocalanus elongatus (Boeck, 1864) P. elongatus was first given the binomen Clausia elongata by Boeck </p><p>(1864) in a short description of adult males and females, with the observation that females were common and males rare in Christiana (Oslo) Fjord. Boeck made no reference to the earlier publications of K r ~ y e r (1 842-45, 1848). </p><p>(c) Pseudocalanus clausii (Brady, 1865) Specimens of this species were originally found by Brady (1863) </p><p>in the North Sea and erroneously ascribed by him to a quite different genus and species, Phadnna spinifera. Later Brady (1865) gave his specimens the new binomen Calanus Clausii, after the carcinologist C. Claus. </p><p>(d) Pseudocalanus acuspes (Giesbrecht , 1 88 1 ) This species was originally described by Giesbrecht as Lucullus n. </p><p>gen. acuspes, from the Bay of Kiel, and later given a very thorough description with excellent illustrations, by Giesbrecht (1 882). </p><p>(e) Pseudocalanus major G. 0. Sars, 1900 This species was described by Sars (1900) as so very resembling </p><p>the type species [by this he meant P. elongatus] that I should have been very much inclined to regard it as only a large variety if both forms were not found together in the very same samples, without exhibiting any transitions . </p><p>Sars (1900) did not refer to the publications of Krayer (1842-45, 1848), but does refer to Boeck (1864) and, implicitly, Boeck (1872), </p></li><li><p>6 CHRISTOPHER J. CORKETT AND IAN A. MCLAREN </p><p>so that clearly he assumed that prior to his work the genus contained only P. elongatus (Boeck, 1864). </p><p>( f ) Pseudocalanus gracilis G. 0. Sars, 1903 The classic work of Sars (1903) contains a description and figures of </p><p>P. gracilis in the supplement at the end of the volume. He described the females of P. gracilis as being more slender than those of P. elongatus, as having a more conspicuously projecting frontal region and as having longer and narrower caudal rami. When females were placed on their side, the flexed first antenna was said to reach the end of the third urosome segment in P. gracilis, whereas in P. elongatus the first antenna reached only to the end of the genital segment. </p><p>The male of P. gracilis was said by Sars (1 903) to resemble that of P. elongatus, the only distinction between them being the longer first antenna of the former. </p><p>3. Subsequent delimitations of described species Pseudocalanus has been referred to under a variety of species names </p><p>in the subsequent literature. Clearly the designation of at least some of the species has been less than satisfactory. We are concerned here with those papers that have attempted to clarify the status and characters of species. </p><p>Much of the difficulty in subsequent work on the nomenclature of Pseudocalanus comes from the fact that Boeck, Brady, Giesbrecht, and G. 0. Sars did not mention the work of Krrayer in relation to the genus Pseudocalanus. </p><p>Brady (1878) synonymizes his Calanus Clausii, 1865, with Pseudo- calanus elongatus (Boeck, 1864). Giesbrecht (1882, addendum p. 167) admits the synonymy of Lucullus acuspes Giesbrecht, 1881, with Pseudocalanus elongatus (Boeck, 1864) and P. clausii (Brady, 1865). Giesbrecht (1882) says that he had not previously been aware of the identity of the species he described due to the poor original accounts given by Boeck and Brady. Giesbrecht also lists in his bibliography Kraryers (1848) text description of P. minutus, but not Krayers (1842-45) plate. Giesbrecht was thus clearly aware of Krrayers work, but probably did not consider the description to be detailed enough to be worthy of comments in connection with the genus Pseudocalanus. </p><p>It seems inconceivable that Sars did not know of the work of his compatriot, H. Kraryer, but since Kraryer described an immature specimen, Sars may not have viewed it as Pseudocalanus. Clearly the species name minutus is available for a species of Pseudocalanus, and </p></li><li><p>THE BIOLOGY OF PSEUDOGALANUS 7 </p><p>the question arises: is the form that Krayer described synonymous with P. elongatus (Boeck), P. major, G. 0. Sam, or P. gracilis, G. 0. Saw? </p><p>With (1915) considered this question in detail and examined what he referred to as Kraryers original specimens, and was of the opinion that the three species described by Boeck and G. 0. Sars were synonymous, since he found transition specimens in shape of head, length of first antenna, and size. With did, however, state that Krayers specimens ( were in shape of the head most like P. gracilis, and were of middle size ,. With (1915) therefore recognized only one species: Pseudocalanus minutus (Krcryer). </p><p>Wiborg (1954) considered that G. 0. Sars was right in establishing three specie...</p></li></ul>

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