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Author

Gustav-Adolf Paffenhöfer

Other affiliations: University System of Georgia
Bio: Gustav-Adolf Paffenhöfer is an academic researcher from Skidaway Institute of Oceanography. The author has contributed to research in topics: Zooplankton & Copepod. The author has an hindex of 36, co-authored 69 publications receiving 3293 citations. Previous affiliations of Gustav-Adolf Paffenhöfer include University System of Georgia.


Papers
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Journal ArticleDOI
TL;DR: Direct observations using high-speed micro-cinematography indicate that planktonic calanoid copepods are “suspension-feeders”, actively using sensory inputs for detection, motivation to capture, and ingestion.
Abstract: Many planktonic calanoid copepods are commonly described as “filter-feeders”. Direct observations using high-speed micro-cinematography indicate that these animals are “suspension-feeders”. They capture and handle the food particles not passively according to size and shape but, in most cases, actively using sensory inputs for detection, motivation to capture, and ingestion.

185 citations

Journal ArticleDOI
TL;DR: Descriptions of selective feeding in grazing trials using Coulter Counter data are influenced by the size above which the copepods can detect individual cells and by the proportions of the pregrazing particle spectrum larger and smaller than this threshold.
Abstract: High-speed cinematography was used to observe adult female copepods feeding in pure cultures of roughly spherical algal cells ranging from 4.5 to 22.0 pm in diameter. Eucalanus pileatus and Puraculunus puruus detect and handle individual cells as small as 12 pm. Continuous low amplitude movement of the second maxillae and combing of the appendages is used by E. pileutus to capture cells smaller than the 12qm sensitivity threshold. Different energetic costs are probably associated with capturing small and large cells, and the probability of copepods encountering large cells should be greatly increased due to remote detection. The above suggests that descriptions of selective feeding in grazing trials using Coulter Counter data are influenced by the size above which the copepods can detect individual cells and by the proportions of the pregrazing particle spectrum larger and smaller than this threshold.

180 citations

Journal ArticleDOI
TL;DR: Juveniles and adult females were presented a food spectrum of three algae of different sizes and it is hypothesized that the algal cell size for maximum nitrogen ingestion in upwelled waters is relatively small, round or square and close to the size threshold below which adult females do not sense individual cells.
Abstract: Juveniles and adult females were presented a food spectrum of three algae of different sizes (4.5, 12 and 20 μm cell width). The increase in rate of ingestion of the medium-sized alga with an increase in copepod size was significantly greater than the increase in rate of ingestion of the small alga. It is hypothesized that the perception of chemical signals from the small alga by a copepod decreases as the copepod moults from stage to stage. The rate of ingestion of the large alga by copepod stage V (CV) and adult females was lower than the rate of ingestion of the medium-sized alga at mid- and high phytoplankton concentrations. The amount of nitrogen ingested when the medium-sized alga alone was offered was either higher than (≦stage C II) or not significantly different from that when the three algae were offered together (≧stage C IV). Ingestion rates are reduced when there is a multialgal food source. This implies that there is increased stability in the ocean because multiparticle food sources are more slowly depleted than unialgal foods. Weight-specific ingestion rates of copepods fed the three algae simultaneously increased from nauplius to stage C III and then decreased as adulthood approached. The contribution of the small alga to the total amount of nitrogen ingesied was greatest for naupliar stages while the contribution of the medium-sized cells was greater for later stages. The largest alga was readily ingested by stage C V and adult females but never contributed more than 25% of the nitrogen ingested. Eight to 12% of the nitrogen ingested by adult females was from the small alga. It is hypothesized that the algal cell size for maximum nitrogen ingestion in upwelled waters is relatively small, round or square and close to the size threshold below which adult females do not sense individual cells.

112 citations


Cited by
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30 Apr 1984
TL;DR: A review of the literature on optimal foraging can be found in this article, with a focus on the theoretical developments and the data that permit tests of the predictions, and the authors conclude that the simple models so far formulated are supported by available data and that they are optimistic about the value both now and in the future.
Abstract: Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

2,709 citations

Book
29 May 2006
TL;DR: Reynolds as discussed by the authors provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity.
Abstract: Communities of microscopic plant life, or phytoplankton, dominate the Earth's aquatic ecosystems. This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities in lakes and rivers and oceans. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity. Although focussed on one group of organisms, the book develops many concepts relevant to ecology in the broadest sense, and as such will appeal to graduate students and researchers in ecology, limnology and oceanography.

1,856 citations

Book ChapterDOI
TL;DR: A conceptual model of the spatial and temporal dominance of group-specific primary producers, and hence the basic fatty acid patterns available to higher trophic levels is presented and is based on stratification.
Abstract: Fatty acids have been used as qualitative markers to trace or confirm predator-prey relationships in the marine environment for more than thirty years. More recently, they have also been used to identify key processes impacting the dynamics of some of the world's major ecosystems. The fatty acid trophic marker (FATM) concept is based on the observation that marine primary producers lay down certain fatty acid patterns that may be transferred conservatively to, and hence can be recognized in, primary consumers. To identify these fatty acid patterns the literature was surveyed and a partial least squares (PLS) regression analysis of the data was performed, validating the specificity of particular microalgal FATM. Microalgal group specific FATM have been traced in various primary consumers, particularly in herbivorous calanoid copepods, which accumulate large lipid reserves, and which dominate the zooplankton biomass in high latitude ecosystems. At higher trophic levels these markers of herbivory are obscured as the degree of carnivory increases, and as the fatty acids originate from a variety of dietary sources. Such differences are highlighted in a PLS regression analysis of fatty acid and fatty alcohol compositional data (the components of wax esters accumulated by many marine organisms) of key Arctic and Antarctic herbivorous, omnivorous and carnivorous copepod species. The analysis emphasizes how calanoid copepods separate from other copepods not only by their content of microalgal group specific FATM, but also by their large content of long-chain monounsaturated fatty acids and alcohols. These monounsaturates have been used to trace and resolve food web relationships in, for example, hyperiid amphipods, euphausiids and fish, which may consume large numbers of calanoid copepods. Results like these are extremely valuable for enabling the discrimination of specific prey species utilized by higher trophic level omnivores and carnivores without the employment of invasive techniques, and thereby for identifying the sources of energetic reserves. A conceptual model of the spatial and temporal dominance of group-specific primary producers, and hence the basic fatty acid patterns available to higher trophic levels is presented. The model is based on stratification, which acts on phytoplankton group dominance through the availability of light and nutrients. It predicts the seasonal and ecosystem specific contribution of diatom and flagellate/microbial loop FATM to food webs as a function of water column stability. Future prospects for the application of FATM in resolving dynamic ecosystem processes are assessed.

1,357 citations

Journal ArticleDOI
TL;DR: An attempt is made to describe the motion of grouping individuals kinematically as distinct from simple diffusion or random walk, to model the grouping on the basis of dynamics of animal motion, and to interpret the grouping from the standpoint of advection-diffusion processes.

850 citations

Journal ArticleDOI
TL;DR: The role of large detrital particles in the downward vertical mass flux in the sea has been investigated in a variety of sources, including sediment trap data as mentioned in this paper, and it has been shown that the relatively rare, large particles sinking through the water column are responsible for the majority of the downward mass flux.

840 citations