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- W1878391385 abstract "Ecosystems are complex adaptive systems because their living components are capable of adapting to environmental change, be it biotic or abiotic change. Organisms however can experience adverse consequences if environmental change exceeds levels they can tolerate by relying on their adaptive capabilities. Hence, our ability to understand, predict and mitigatethe effects of ecological stressors, such as those associated with global climate change, pollution, and harvesting, depends largely on how we incorporate organismic adaptation into ecological investigations.This is true for trophic ecology as for any other aspect of ecology, because animals demonstrate varying feeding regulation mechanisms in order to satisfy their demands for energy and chemical substances. Most can preferentially feed on prey organisms that promote fitness against disadvantageous ones, and those incapable of prey selection are endowed (by evolution) with physiological capabilities for dealing with disadvantageous food constituents. Hence, trophic adaptation among consumers does not only help define the structure of food webs and thus the complexity of ecological communities, it also determines the fate as well as the ecological transfer efficiency of biomass (and carbon). Adaptive trophic behaviour is however ignored or poorly represented in ecosystem models because a realistic framework, for effecting trophic behaviour, that incorporates relevant natural history details and is capable of providing mechanistic understanding of trophic processes is lacking.Currently in aquatic ecology, trophic behaviour is assumed to be mainly dictated by food quality (Q), which is determined by employing food quality models (FQMs) that mimic consumers’ mechanism for anticipating the fitness consequences for feeding on specific prey items. Heuristically however, progress has been limited because previous FQMs are based onframeworks that a priori identify specific food components, usually nitrogen, phosphorus, and/or essential compounds, as pre-eminent or limiting. This suppresses trophic adaptability by negating the effect of habitat conditions (fluctuating temperature, etc), as well as that of consumers’ behaviour and physiology on food quality.This thesis addresses the shortfalls in existing models by proposing a new FQM. The model determines food quality by considering (i) the biochemical characteristics of prey items, (ii) consumers’ demand for energy and structural constituents, and (iii) consumers’ capacity for food intake and metabolism based on physiological principles. It employs parameters that areadaptive to the relevant habitat conditions encountered by consumers. The model relies on the balance between the biochemical composition of prey items and consumer’s requirements to determine the potential fate and utilisation efficiencies of acquired chemical substances. The yardstick for food quality is the potential growth performance of consumers. The form of themodel makes it applicable to all heterotrophs. Here, the focus is on copepod consumers because of the critical role they play in aquatic ecosystems. The model has been used to evaluate the growth performance of Acartia tonsa (Copepoda: Calanoida) over wide range of food conditions and the results are consistent with experimental observations. It predicts Acartia’s response to changes in prey biochemical composition to be unimodal, with growthbeing highest only when the biochemical composition of the prey imposes no constrain on egg production. This is consistent with experimental observations. Existing food quality models are incapable of this prediction. Hence, the FQM here is a better alternative, which, when employed could help in understanding substrate acquisition and utilisation for growth and reproduction by heterotrophs. This was demonstrated by embedding the FQM here in a secondary production model for a consumer whose food intake and metabolic capabilities are bounded within a maximum threshold needed for growth and maintenance when food is “nutritionally good”, and a minimum threshold needed for only maintenance when food is “nutritionally poor”. Theconsumer relies on the food quality model to evaluate the growth limiting potentials of individual prey constituents. This information then dictates its regulatory response, in terms of feeding and metabolism, to the available prey. The demonstration was used to re-evaluate the hypothesis that carbon (C), relative to nitrogen (N), is a non-limiting resource for egg production by marine copepods. The results here challenge the hypothesis, and revealpotential causes for carbon limitation that previous models do not predict because they suffer from the above-stated shortfalls. Within the range of ecologically realistic algal C:N < 17, C-limitation was determined to be higher than that of N, due partly to the low metabolic availability of C associated with cellulose and structural carbohydrates. This result emphasizes the importance of biochemical substances in animal nutrition and production.The dynamics of zooplankton production may be determined by the interaction between ambient temperature and prey biochemical composition. While this has been documented in experiments, previous zooplankton models contain no explicit description of it. Chapter 4 of this thesis shows how this could be done. It makes the new food quality model adaptive tochanges in ambient temperature by making animals’ demand for energy and structural constituents temperature dependent. This was then integrated into a model framework that allows consumers to regulate food ingestion, assimilation and metabolism based on their temperature-specific needs. Using this approach, growth rate, growth efficiency, as well as optimum temperatures for egg production by two copepod species with significantly different ranges of thermal tolerance were realistically simulated. Consistent with the results from other studies, the results here show that the growth response of copepods to changes in ambient temperature is driven mainly by temperature-induced changes in animals’ demand for maintenance. This observation emphasizes the cost of maintenance as a major constraint onzooplankton production.Food quality models suffer from an important practical problem: it is difficult to define the biochemical traits of organisms and how those traits are dependent on the several relevant environmental conditions. To tackle this problem, published data on the proteins, carbohydrates, lipids, essential amino and fatty acids composition of microalgae (68 species belonging to 7 taxonomic classes species) and marine zooplankton (female: 42 species, eggs: 29 species) cultured under diverse conditions were reviewed. From the results, robust parameters, not restricted to specific species or habitat conditions, were determined. They have been employed for this study and could be used by others to characterize the biochemical composition of algae and zooplankton, independent of the environment. In addition, an experiment was conducted to investigate the impact of food availability on the reproductive strategy of copepods, in terms of females’ biochemical investment into eggsproduction. No food availability effect on the biochemical composition of females was observed. However, protein composition of eggs was higher in food-limited females. It has been argued that the production of protein-rich eggs by food-limited copepods is a reproductive strategy for ensuring the survival of offspring during poor feeding conditions.In conclusion, this thesis provides realistic conceptual and mathematical frameworks for modelling trophic behaviour. It contributes to our understanding of trophic processes and their implications for nutrient cycling by grounding food quality on the behaviour, physiology, and habitat conditions of consumers. The model has been successfully integrated into an eggproduction model for copepods and implemented under variable temperature and food conditions." @default.
- W1878391385 created "2016-06-24" @default.
- W1878391385 creator A5028436018 @default.
- W1878391385 date "2011-11-16" @default.
- W1878391385 modified "2023-09-27" @default.
- W1878391385 title "Copepod production : The interplay between abiotic environment, prey biochemical composition and consumers' requirements" @default.
- W1878391385 cites W127661644 @default.
- W1878391385 cites W1497256448 @default.
- W1878391385 cites W1503832382 @default.
- W1878391385 cites W1522296012 @default.
- W1878391385 cites W1533564470 @default.
- W1878391385 cites W1544145404 @default.
- W1878391385 cites W1658772620 @default.
- W1878391385 cites W1780044675 @default.
- W1878391385 cites W1964101184 @default.
- W1878391385 cites W1968176058 @default.
- W1878391385 cites W1968834637 @default.
- W1878391385 cites W1969370910 @default.
- W1878391385 cites W1972358325 @default.
- W1878391385 cites W1975272502 @default.
- W1878391385 cites W1977475664 @default.
- W1878391385 cites W1977558737 @default.
- W1878391385 cites W1977879753 @default.
- W1878391385 cites W1977984278 @default.
- W1878391385 cites W1981082370 @default.
- W1878391385 cites W1982021944 @default.
- W1878391385 cites W1982097199 @default.
- W1878391385 cites W1982233439 @default.
- W1878391385 cites W1982975169 @default.
- W1878391385 cites W1983707917 @default.
- W1878391385 cites W1983994785 @default.
- W1878391385 cites W1984565788 @default.
- W1878391385 cites W1985024171 @default.
- W1878391385 cites W1991637872 @default.
- W1878391385 cites W1991725465 @default.
- W1878391385 cites W1992671708 @default.
- W1878391385 cites W1994917180 @default.
- W1878391385 cites W1997856240 @default.
- W1878391385 cites W1999803304 @default.
- W1878391385 cites W2002336569 @default.
- W1878391385 cites W2002951050 @default.
- W1878391385 cites W2004230099 @default.
- W1878391385 cites W2004678133 @default.
- W1878391385 cites W2005852296 @default.
- W1878391385 cites W2006809571 @default.
- W1878391385 cites W2007378999 @default.
- W1878391385 cites W2008654855 @default.
- W1878391385 cites W2012921095 @default.
- W1878391385 cites W2013728972 @default.
- W1878391385 cites W2015438692 @default.
- W1878391385 cites W2016469924 @default.
- W1878391385 cites W2017322631 @default.
- W1878391385 cites W2017857047 @default.
- W1878391385 cites W2018395328 @default.
- W1878391385 cites W2018636798 @default.
- W1878391385 cites W2021551441 @default.
- W1878391385 cites W2022928943 @default.
- W1878391385 cites W2023014060 @default.
- W1878391385 cites W2023381896 @default.
- W1878391385 cites W2024117379 @default.
- W1878391385 cites W2025514545 @default.
- W1878391385 cites W2027948329 @default.
- W1878391385 cites W2030955147 @default.
- W1878391385 cites W2031921850 @default.
- W1878391385 cites W2034972539 @default.
- W1878391385 cites W2035195157 @default.
- W1878391385 cites W2035551420 @default.
- W1878391385 cites W2036203627 @default.
- W1878391385 cites W2036993233 @default.
- W1878391385 cites W2038521189 @default.
- W1878391385 cites W2039005078 @default.
- W1878391385 cites W2040488499 @default.
- W1878391385 cites W2040984893 @default.
- W1878391385 cites W2043479278 @default.
- W1878391385 cites W2044129239 @default.
- W1878391385 cites W2044810031 @default.
- W1878391385 cites W2044929988 @default.
- W1878391385 cites W2046141744 @default.
- W1878391385 cites W2048489567 @default.
- W1878391385 cites W2053765399 @default.
- W1878391385 cites W2057651895 @default.
- W1878391385 cites W2057692213 @default.
- W1878391385 cites W2058129085 @default.
- W1878391385 cites W2060012482 @default.
- W1878391385 cites W2060191522 @default.
- W1878391385 cites W2060313313 @default.
- W1878391385 cites W2061150550 @default.
- W1878391385 cites W2061792168 @default.
- W1878391385 cites W2062259609 @default.
- W1878391385 cites W2063566802 @default.
- W1878391385 cites W2068401874 @default.
- W1878391385 cites W2069074024 @default.
- W1878391385 cites W2070198008 @default.
- W1878391385 cites W2071415447 @default.
- W1878391385 cites W2072512857 @default.
- W1878391385 cites W2073408936 @default.
- W1878391385 cites W2075655582 @default.
- W1878391385 cites W2077188313 @default.
- W1878391385 cites W2077769416 @default.
- W1878391385 cites W2080879490 @default.