No abstract

Estimating the production of marine copepods depends on measuring two key variables: biomass and growth rate. The major difficulty in estimating production of marine copepods and other zooplankton has been the inability to obtain precise, rapid measurements. In practice the variability in measurement of biomass greatly exceeds that in growth rate. It is shown here that individual growth rates of copepods can be accurately estimated from data on generation times and the weights of eggs and adults. Analysis of 181 separately published estimates of generation time for 33 species of copepods at environmental temperatures ranging from -1.7 degrees to 30.7 degrees C shows that temperature alone explains more than 90% of the variance in growth rate. Temperature dependence of growth rate transcends species differences. Weight-specific growth rate appears to be independent of body size. We hypothesize that food may not be limiting to growth in nature; the impression that food is limiting may be due to sampling at the wrong scales. Another possible cause of the apparent maximum growth rates of copepods in nature is predation mortality, which could selectively remove slower-growing individuals from the population. The temperature-dependent model developed here predicts the phenomenon of decreasing body size with increasing environmental temperature, often observed for single species of copepods. A method is suggested for making more accurate estimates of secondary production by using modern instrumentation to make quasi-synoptic measurements of biomass and temperature and using the temperature-dependent model to estimate individual growth rates.

No abstract

This techno-economic analysis/life-cycle assessment is based on actual production by the Cornell Marine Algal Biofuels Consortium with biomass productivity > 23 g/m 2-d. Ten distinct cases are presented for two locations, Texas and Hawaii, based on a 100-ha production facility with end-to-end processing that yields fungible co-products including biocrude, animal feed, and ethanol. Several processing technologies were evaluated: centrifugation and solvent extraction (POS Biosciences), thermochemical conversion (Valicor), hydrothermal liquefaction (PNNL), catalytic hydrothermal gasification (Genifuel), combined heat and power, wet extraction (OpenAlgae), and fermentation. The facility design was optimized by co-location with waste CO 2 , a terraced design for gravity flow, using renewable energy, and low cost materials. The case studies are used to determine the impact of design choices on the energy return on investment, minimum fuel and feed sale prices, discounted payback period, as well as water depletion potential, human health, ecosystem quality, non-renewable resources, and climate change environmental indicators. The most promising cases would be economically competitive at market prices around $2/L for crude oil, while also providing major environmental benefits and freshwater savings. As global demands for fuels and protein continue rising, these results are important steps towards economical and environmentally sustainable production at an industrial scale.

Thirteen species of dinoflagellates, ranging in size from 16 to 48 pm, were tested for particle rejection behavior in the copepods Calanuspacificusand Paracalanusparvus. Five dinoflagellates were rejected as food: Gonyaulax tamarensis (429). G. tamarensis (Ipswich), Ptychodiscus brev~s, Scrippsiella trochoidea and Protoceratium reticulatum. The response of copepods to P. reticulatum was examined in detail. Starved copepods could not b e induced to feed on this species; C. pacificus maintained in bloom concentrations ceased reproduction and had high mortality. Both the cells themselves and filtrate from the cell culture suppressed feeding on normally edible dinoflagellates.Direct observations showed that P. reticulatum cells cause reverse peristalsis and regurgitation, and that Ptychodiscus brevis cells cause elevated heart rate and loss of motor control by C. pacificus We conclude the particle rejection behaviour we observed is chemically mediated, and that it may b e a n important factor in formation and maintenance of monospecific dinoflagellate blooms. We suggest chemicals produced by the dinoflagellate cause an acute physiological response which renders the herbivore incapable of ingesting more than required for its respiratory needs. Secondary effects of starvation, suspended reproduction and mortality further reduce the predation pressure of both present and future generations of predators. These factors aid in development of the bloom. Chemical defense may confer a competitive advantage, but rejected dinoflagellates pay the price in the form of reduced growth rates.

No abstract

Analysis of data on the hydrodynamics of swimming by 100 species, ranging in body mass (M ) from bacteria to blue whales, leads to a model of animal-induced turbulence in the ocean. Swimming speeds and Reynolds number (Re) are strongly correlated with body mass, both at typical cruising speeds and at escape speeds associated with predator-prey interactions. We find that animals operating at Re > 1000 typically form schools that are concentrated by many orders of magnitude above their average abundance. We calculate the rate of kinetic energy production by 11 representative species of schooling animals ranging in size from euphausiids to whales, and find it to be of the order of 10 -5 W kg -1, regardless of animal size. Animal-induced turbulence is comparable in magnitude to rates of turbulent energy dissipation (ε) that result from major storms. The horizontal length scale (10 to 1000 m) of energy production rate by animal schools is comparable to the observed fine-scale variability in ε. We present detailed case studies of 4 species -Atlantic bluefin tuna, Norwegian herring, northern anchovy and Antarctic krill -all of which have schooling behavior that places them within the zone of maximum seasonal stratification where their energy production rate would be 3 to 4 orders of magnitude greater than the background average rate of turbulent energy dissipation. We conclude that schooling animals are an important source of fine-scale turbulent mixing in the ocean, especially in coastal regions during summer. KEY WORDS: Turbulence · Animal swimming · EpsilonResale or republication not permitted without written consent of the publisher

No abstract