Plankton production in the Bay of Villefranche was relatively constant during March and April 1986 but the particle size at which the production occurred was more variable. At the beginning of the study, production was dominated by the larger (ca. 6 μm) flagellates but towards the end it was more or less equally divided between the nano- and picoplankton. There were considerable differences in the estimates of population growth rates, depending on the methods used, but on average the population doubling times were close to 12 hours for autotrophs and 24 hours for heterotrophs. As autotrophs do not grow during the night, each population was therefore doubling once per day. It seemed that each of the nanoor picoplankton populations could adversely affect the growth of the others. This could be either by simple predation or by some form of inhibition. Although nutrient levels in the bay were uniformly low, the addition of nutrients did not always stimulate algal growth. The plankton populations seemed to be both in a state of equilibrium and intense ecological competition.

In a series of midocean stations extending from high northern to high southern latitudes in both the Pacific and Atlantic Oceans we found that 14C dark uptake followed a definite geographic pattern. In temperate and equatorial regions the dark uptake was normally ≾ 10% of that in the light, but in the subtropical gyres and at high southern latitudes the average dark uptake varied from 10 to >50% of the light uptake. There was a significant and complex relationship between dark uptake, production, and standing stock that seemed to depend on the structure of the plankton community, but a relatively simple pattern could also be discerned. At production levels of > l µg C liter−1 h−1 or at standing stock levels of >40 µg C liter−1, the average dark uptake was low. At lower levels the average dark uptake was high.

Food size-range for 13 species of Tintinnina and 18 species of Oligotrichina were studied using electronic particle counting and in situ observation of food vacuole contents. Tintinnids consume nanoplankton in the size range 2–20 μm. Oligotrichous naked ciliates consume particles in the size range 0.5–10 μm. Ciliates smaller than 30 μm take 72% picoplankton and 28% nanoplankton. For ciliates between 30 μm and 50 μm the proportions are reversed (30% pico- and 70% nanoplankton), while the larger ciliates (> 50 μm) take nanoplankton almost exclusively (95% nano- and 5% picoplankton). A seasonal study of total Oligotrichida grazing showed that natural particles were consumed at rates that varied from 1 to 20 μg C 1−1 day−1. This included between 1 and 38% of the bacterioplankton production and 9 to 52% of the nanoplankton production. In the N-W Mediterranean the total ciliate production varied from 0.4 to 8.2 μg C 1−1 day−1.

Predation by copepods (Euterpina acutifrons) on ciliates (Lohmanniella spiralis) and by ciliates on flagellates was followed during a 12‐day experiment in a small enclosed ecosystem (100 liters). For a period of about 4 days the three populations seemed to exist in a state of quasi‐equilibrium with growth balanced by predation. During this time, material transfer from prey to predator was taking place with an efficiency of 30–40%.

Population interactions between nanoplankton and bacteria were investigated by means of long (ca. 5 day) incubations of prescreened seawater samples. Evidence is presented to show that population development is controlled by the predation of larger organisms on smaller ones. The development of the bacterial populations seems to be totally controlled by predation by nano‐sized organisms (flagellates and ciliates) and by picoflagellates. It is possible, though less certain, that picoflagellate development is controlled by nanociliate predation.

Limnology and OceanographyVolume 29, Issue 6 p. 1342-1346 CommentsFree Access Phytoplankton growth rates in the tropical ocean R. W. Sheldon, R. W. Sheldon Marine Ecology Laboratory Bedford Institute of Oceanography P.O. Box 1006 Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this author R. W. Sheldon, R. W. Sheldon Marine Ecology Laboratory Bedford Institute of Oceanography P.O. Box 1006 Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this author First published: November 1984 https://doi.org/10.4319/lo.1984.29.6.1342Citations: 18AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume29, Issue6November 1984Pages 1342-1346 RelatedInformation

Growth of phytoplankton in the presence of detritus will follow an asymptotic function. It is theoretically possible to estimate the phytoplankton and detrital standing stock and the phytoplankton growth rates from serial measurements of particle concentration, but the measurements must be very precise, and in practice this is rarely attainable. Small errors in measurement produce large errors in the plankton and detrital estimates. To measure phytoplankton growth, the phytoplankton must be identified relative to its place on the size spectrum. Within a restricted size range particle growth is exponential and represents phytoplankton growth.

Microplankton growth rates were determined from biomass (ATP) increase of incubated samples from near‐surface waters at two locations in the Sargasso Sea. Measured growth rates were quite variable but the results tended to cluster around a generation time of 3 h. Estimates of primary production derived from these growth rates are roughly an order of magnitude greater than those derived from measurements of 14C uptake.

Limnology and OceanographyVolume 23, Issue 6 p. 1264-1267 CommentFree Access Population densities of euphausiids off Nova Scotia as indicated by net samples, whale stomach contents, and sonar P. F. Brodie, P. F. Brodie Department of Fisheries and Environment Fisheries and Marine Service Marine Ecology Laboratory Bedford Institute of Oceanography Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this authorD. D. Sameoto, D. D. Sameoto Department of Fisheries and Environment Fisheries and Marine Service Marine Ecology Laboratory Bedford Institute of Oceanography Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this authorR. W. Sheldon, R. W. Sheldon Department of Fisheries and Environment Fisheries and Marine Service Marine Ecology Laboratory Bedford Institute of Oceanography Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this author P. F. Brodie, P. F. Brodie Department of Fisheries and Environment Fisheries and Marine Service Marine Ecology Laboratory Bedford Institute of Oceanography Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this authorD. D. Sameoto, D. D. Sameoto Department of Fisheries and Environment Fisheries and Marine Service Marine Ecology Laboratory Bedford Institute of Oceanography Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this authorR. W. Sheldon, R. W. Sheldon Department of Fisheries and Environment Fisheries and Marine Service Marine Ecology Laboratory Bedford Institute of Oceanography Dartmouth, Nova Scotia B2Y 4A2Search for more papers by this author First published: November 1978 https://doi.org/10.4319/lo.1978.23.6.1264Citations: 53AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume23, Issue6November 1978Pages 1264-1267 RelatedInformation

Further observations on the standing stocks of pelagic organisms confirm the occurrence of approximately equal biomass over logarithmically equal size ranges. A simple theoretical framework is developed that shows that the structural elements of the pelagic ecosystem can be described in terms of the sizes of predator and prey and of the efficiencies of their interactions. In practice this means that if the standing stock at any size range is known, the standing stock at any other size can be estimated, and if the growth rate at this size is known, the production can be estimated. The theory is tested on three fisheries. For the Gulf of Maine and the North Sea, phytoplankton production is estimated from fishery production. For the area off Peru the fishery production is estimated from the plankton production. Key words: pelagic ecosystem, predator–prey relationships, plankton production, marine fisheries, Peru, North Sea, Gulf of Maine

In the surface waters of the ocean particle production and consumption are in balance. The structure of the pelagic food chain and the morphological limitations dictated by the environment are such that, in general, large particles have to consume smaller ones. If the large particles are removed the small particles cannot be consumed and their production rate can be measured. A state of exponential growth seems to be normal. The rate of production, as revealed by small particle growth following predation release, is much greater than the apparent rate of primary production indicated by radiocarbon uptake.

Limnology and OceanographyVolume 18, Issue 2 p. 345-346 CommentFree Access The Loch Ness monster: Reply to comments of C. H. Mortimer R. W. SHELDON, R. W. SHELDON Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova ScotiaSearch for more papers by this authorS. R. KERR, S. R. KERR Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova ScotiaSearch for more papers by this author R. W. SHELDON, R. W. SHELDON Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova ScotiaSearch for more papers by this authorS. R. KERR, S. R. KERR Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova ScotiaSearch for more papers by this author First published: March 1973 https://doi.org/10.4319/lo.1973.18.2.0345Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume18, Issue2March 1973Pages 345-346 RelatedInformation

Estimates of living mass and respiratory rate were made by several methods on large water samples taken at several depths at each of two ocean stations. Total microbial biomass estimates based on ATP determinations gave reasonable results in relation to phytoplankton biomass, total particulate organic carbon, and total particulate volume as determined by an electronic particle counter. Respiratory rate estimates based on O2 uptake, electron transport system activity, and ATP were in moderately good agreement in surface water but diverged widely in deep water. Heterotrophic uptake of specific organic compounds seems to be related to numbers of active bacteria and not related to total microbial respiration. Photosynthetic rates and release of dissolved photosynthate are reported for both stations.

Frequency distributions of particle size between sizes of about 1 and 100 µ are given for both surface and deep water of the Atlantic and Pacific Oceans. The form of the size spectra varies predictably both geographically and with depth. A hypothesis is presented to show that, to a first approximation, roughly equal concentrations of material occur at all particle sizes within the range from 1 µ to about 108 µ, i.e. from bacteria to whales.

The average minimum sizes of particles retained by metal membranes (Selas Flotronics) and perforated polycarbonate membranes (General Electric Nuclepore) were similar to the stated pore sizes when relatively small seawater samples with moderate concentrations of particles were filtered. When large samples or high concentrations were filtered, the average retention size was less than the stated pore size. All cellulose ester membranes (Millipore) retained particles much smaller than the stated pore size, even from small samples with low particle concentrations. Glass‐fiber filters had retention characteristics similar to membrane filters.

Limnology and OceanographyVolume 17, Issue 5 p. 796-798 CommentFree Access THE POPULATION DENSITY OF MONSTERS IN LOCH NESS1 R. W. SHELDON, R. W. SHELDON Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute of Oceanography, Dartmouth, Nova Scotia.Search for more papers by this authorS. R. KERR, Corresponding Author S. R. KERR Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute of Oceanography, Dartmouth, Nova Scotia. Present address: Ministry of Natural Resources, Research Branch, Maple, Ontario.Search for more papers by this author R. W. SHELDON, R. W. SHELDON Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute of Oceanography, Dartmouth, Nova Scotia.Search for more papers by this authorS. R. KERR, Corresponding Author S. R. KERR Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute of Oceanography, Dartmouth, Nova Scotia. Present address: Ministry of Natural Resources, Research Branch, Maple, Ontario.Search for more papers by this author First published: September 1972 https://doi.org/10.4319/lo.1972.17.5.0796Citations: 24 † Bedford Institute of Oceanography Contribution. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Citing Literature Volume17, Issue5September 1972Pages 796-798 RelatedInformation

Limnology and OceanographyVolume 14, Issue 3 p. 441-444 Notes and CommentFree Access RETENTION OF MARINE PARTICLES BY SCREENS AND FILTERS1 R. W. SHELDON, R. W. SHELDON Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova Scotia.Search for more papers by this authorW. H. SUTCLIFFE JR., W. H. SUTCLIFFE JR. Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova Scotia.Search for more papers by this author R. W. SHELDON, R. W. SHELDON Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova Scotia.Search for more papers by this authorW. H. SUTCLIFFE JR., W. H. SUTCLIFFE JR. Fisheries Research Board of Canada, Marine Ecology Laboratory, Bedford Institute, Dartmouth, Nova Scotia.Search for more papers by this author First published: May 1969 https://doi.org/10.4319/lo.1969.14.3.0441Citations: 62 †Contribution No. 149 of the Bedford Institute and No. 460 of the Bermuda Biological Station. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume14, Issue3May 1969Pages 441-444 RelatedInformation