Metabolism provides a basis for using first principles of physics, chemistry, and biology to link the biology of individual organisms to the ecology of populations, communities, and ecosystems. Metabolic rate, the rate at which organisms take up, transform, and expend energy and materials, is the most fundamental biological rate. We have developed a quantitative theory for how metabolic rate varies with body size and temperature. Metabolic theory predicts how metabolic rate, by setting the rates of resource uptake from the environment and resource allocation to survival, growth, and reproduction, controls ecological processes at all levels of organization from individuals to the biosphere. Examples include: (1) life history attributes, including devel- opment rate, mortality rate, age at maturity, life span, and population growth rate; (2) population interactions, including carrying capacity, rates of competition and predation, and patterns of species diversity; and (3) ecosystem processes, including rates of biomass production and respiration and patterns of trophic dynamics. Data compiled from the ecological literature strongly support the theoretical predictions. Even- tually, metabolic theory may provide a conceptual foundation for much of ecology, just as genetic theory provides a foundation for much of evolutionary biology.

/pdf/toward-a-metabolic-theory-of-ecology-1dxmg8xr3n.pdf

Toward a metabolic theory of ecology

Cellular carbon and nitrogen content and cell volume of nutritionally and morphologically diverse dinoflagellate species were measured to determine carbon to volume (C : vol) and nitrogen to volume (N : vol) relationships. Cellular C and N content ranged from 48 to 3.0 3 10 4 pgC cell 21 21 5

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2000.45.3.0569

Carbon to volume relationships for dinoflagellates, diatoms, and other protist plankton

The biomass of marine “oligotri chous” ciliates has often been estimated by measuring the cell volume of preserved samples and converting to units of carbon based on theoretical carbon: volume (C: vol) ratios of 007–011 pg µm−3 Using laboratory cultures of several strains of Laboea strobila, Strombidium spp, and Strobilidium spiralis, we experimentally derived a C: vol conversion factor of 019 pg µm−3 for cells preserved with 2% vol : vol Lugol’s iodine Cell volume estimates of Lugol’s-preserved cells averaged 76% of cell volume estimates of Formalin-preserved cells Hence a C : vol ratio of 014 pg µm−3 applies to Formalin-preserved cells Our study indicates that the biomass of oligotrichous ciliates in marine systems has been significantly underestimated by the use of inappropriate C: vol ratios

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1989.34.6.1097

An experimentally determined carbon : volume ratio for marine “oligotrichous” ciliates from estuarine and coastal waters

We present an analysis of the global impact of microplanktonic grazers on marine phytoplankton and its implications for remineralization processes in the microbial community. The data were obtained by an extensive literature search that yielded 788 paired rate estimates of autotrophic growth (mu) and microzooplankton grazing (m) from dilution experiments. From studies in which phytoplankton standing stock was measured in terms of carbon equivalents, we show that the production estimate from dilution experiments is a reasonable proxy (r = 0.89) for production determined by the standard C-14 method. The ratio m: mu, the proportion of primary production (PP) consumed by micrograzers, shows that microzooplankton consumption is the main source of phytoplankton mortality in the oceans, accounting for 67% of phytoplankton daily growth for the full data set. This ratio varies modestly among various marine habitats and regions, with data averages ranging from 60% for coastal and estuarine environments to 70% for the open oceans, and from similar to59% for temperate-subpolar and polar systems to 75% for tropical-subtropical regions. Given estimates for the metabolic requirements of micrograzers and assuming they consume most bacterial production, regionally averaged estimates of the protistan respiration are 35-43% of daily PP for the first level of consumer or 49-59% of PP for three trophic transfers. The estimated contributions of microbial grazers to total community respiration are of the same magnitude as bacterial respiration. Consequently, potential ecosystem differences in micrograzer activity or trophic structure are a large uncertainty for biogeochemical models that seek to predict the microbial community role in carbon cycling from bacterial parameters alone.

/pdf/phytoplankton-growth-microzooplankton-grazing-and-carbon-4we9j3gjyq.pdf

Phytoplankton growth, microzooplankton grazing, and carbon cycling in marine systems

The full suite of carbon exchanges among the 36 most important components of the Chesapeake Bay mesohaline ecosystem is estimated to examine the seasonal trends in energy flow and the trophic dynamics of the ecosystem. The networks provide information on the rates of energy transfer between the trophic components in a system wherein autochthonous production is dominated by phytoplankton production. A key seasonal feature of the system is that the summer grazing of primary producers by zooplankton is greatly reduced due to top—down control of zooplankton by ctenophores and sea nettles. Some of the ungrazed phytoplankton is left to fuel the activities of the pelagic microbial community, and the remainder falls to the bottom where it augments the deposit—feeding assemblage of polychaetes, amphipods, and blue crabs. There is a dominant seasonal cycle in the activities of all subcommunities, which is greatest in the summer and least in the cold season. However, the overall topology of the ecosystem does not ap...

The Seasonal Dynamics of The Chesapeake Bay Ecosystem

Lorica volume, carbon, nitrogen, and ATP content were measured in nine species of tintinnid ciliates spanning a size range of two orders of magnitude. Tintinnid carbon was linearly related to both lorica volume and ATP content. The mean C:ATP ratio was 65. Tintinnid ATP as a percentage of total ATP in the < 153 /un fraction averaged 7% over an annual cycle in Narragansett Bay. It is concluded that ATP is a useful indicator of living phytoplankton carbon in pre-screened, smallvolume samples during periods of moderate to high phytoplankton biomass, but that protozoan microzooplankton interference is significant when phytoplankton standing stocks are low.

Relationships between lorica volume, carbon, nitrogen, and ATP content of tintinnids in Narragansett Bay

Clearance, ingestion, and growth rates of two coastal tintinnid ciliates were measured in batch culture as a function of temperature and phytoplankton concentration. Oxygen consumption and ammonium excretion rates were determined at food concentrations which supported maximum growth rates at each temperature. Clearance, ingestion, respiration, excretion, and growth rates of both species increased with temperature. Clearing rates declined with increasing phytoplankton abundance. Ingestion and growth rates increased asymptotically with phytoplankton abundance and declined at high food concentrations. Gross growth efficiency was highest at phytoplankton concentrations which supported maximum growth rates. Over a range of temperatures, respiration and excretion were linearly related and exhibited significant linear relationships with ingestion and curvilinear relationships with growth. 0 : N ratios were 4-7, assuming an RQ of 1 .O. The metabolic data were combined with previous measurements of in situ production by tintinnids to estimate their potential carbon requirements and NH,+ regeneration in Narragansett Bay, Rhode Island. Tintinnids ingested a carbon equivalent of 16-26% of the total annual net primary production and 32-52% of < IO-urn nanonlankton oroduction. Nitrogen excretion was sufficient to support 1 l18% of net primary production.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1985.30.6.1268

Grazing, respiration, excretion, and growth rates of tintinnids1

Egg production, dry weight, cephalothorax length, and condition factor were measured for adult Acartia tonsa females collected twice weekly from Narragansett Bay, R.I., during summer 1979 and incubated in ambient bay water and in ambient bay water enriched with laboratorycultured algae. Egg production, dry weight, and condition factor of copepods in the ambient bay water fluctuated considerably (ranges 1.6-51.6 eggsafemale-‘*d-l, 7.37-16.60 fig dry wt, and 1.09-2.37 condition factor) and closely followed the seasonal trends in Chl a and particulate carbon and nitrogen. Cephalothorax length remained fairly constant during the study. The overall mean egg production rate, dry weight, and cephalothorax length of the copepods after incubation for 48 h in the algae-enriched water were significantly greater than for copepods incubated in ambient bay water (mean values 45.9 vs. 25.3 eggsafemale-‘*d-l, 13.2 vs. 11.8 kg dry wt, and 901.7 vs. 891.8 pm long). Since body size and egg production in adult A. tonsa responded rapidly to a change in food availability, the copepods must have been continuously food limited in Narragansett Bay during summer.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1983.28.6.1199

Peter G. Verity

Papers

Relationships between lorica volume, carbon, nitrogen, and ATP content of tintinnids in Narragansett Bay

Grazing, respiration, excretion, and growth rates of tintinnids1

Food limitation of production by adult Acartia tonsa in Narragansett Bay, Rhode Island1

The relative food value of diatoms, dinoflagellates, flagellates, and cyanobacteria for tintinnid ciliates

Effects of temperature, irradiance, and daylength on the marine diatom Leptocylindrus danicus Cleve, IV. Growth