Seasonal changes in the phytoplankton as indicated by spectrophotometric chlorophyll estimations 1952-53
Jenkins, P.G. (1955). Seasonal changes in the phytoplankton as indicated by spectrophotometric chlorophyll estimations 1952-53, in: Papers in Marine Biology and Oceanography. Dedicated to Henry Bryant Bigelow, By His Former Students and Associates on the occasion of The Twenty-fifth Anniversary of the Founding of The Woods Hole Oceanographic Institution 1955. Deep-Sea Research (1953), 3(Supplement): pp. 58-67 In: (1955). Papers in Marine Biology and Oceanography. Dedicated to Henry Bryant Bigelow, By His Former Students and Associates on the occasion of The Twenty-fifth Anniversary of the Founding of The Woods Hole Oceanographic Institution 1955. Deep-Sea Research (1953), 3(Supplement). Pergamon Press: London & New York. 498 pp., more In: Deep-Sea Research (1953). Pergamon: Oxford; New York. ISSN 0146-6291; e-ISSN 1878-2485, more |   |
| Abstract | Estimations of the chlorophyll content of the phytoplankton in the English Channel at station E1 were continued from September 1952 until August 1953 at ten depths from to 70 m. As before, the species of the phytoplankton were identified by a culture method. Minima of about 2 mg/m² occur in winter and in June. Maxima at particular depths can occur in March, April or May, thus in 1952 the maximum was in a March surface sample, 34.2 mg/m², whereas in 1953 sinking of the cells gave, in May, 78.8 mg/m². The quantity found can be much influenced by the date of sampling. An autumn maximum late in September 1952 gave 21.1 mg/m² at the surface. The collodion filter disks varied in colour from dark grey or chocolate to a light sandy colour and examination with a low-power microscope shows phytoplankton, stray fibres and sometimes copepods and other animals. Copepods were counted in spring and summer, a maximum of 24 on one disk being found at 25 m on April 27, got from two litres of water. The figures for the column indicate about 300,000 per square metre down to 70 m. The botanical composition of the phytoplankton was studied by the repeated examination, from first signs of growth onwards, of the chemically enriched samples placed in diffuse daylight. Fiftyfour species of Bacillariphyceae were recorded. As before Skeletonema costatum, a Navicula sp. and Nitzschia closterium were the most common. Many species of Chaetoceros were identified in the autumn of 1952. Six species of the Chlorophyceae, five of the Chrysophyceae, one of the Cyanophyceae and three of the Cryptophyceae were recorded. The most common species of the first class was a Chlorella, and of the second a species of Coccolithophora grew in each sample. Phaeocystis globosa grew from January to May. The member of the Cyanophyceae was an Oscillatoria. Neither this nor Phaeocystis was recorded for E1 in the previous year. Hemiselmis rufescens appeared once more. |
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