Grantee Research Project Results

1998 Progress Report: Framework for Predicting the Effects of Environmental Change on Populations

EPA Grant Number: R823588
Title: Framework for Predicting the Effects of Environmental Change on Populations
Investigators: Nisbet, Roger M. , Murdoch, William W.
Institution: University of California - Santa Barbara
EPA Project Officer: Hahn, Intaek
Project Period: August 15, 1995 through August 14, 1998
Project Period Covered by this Report: August 15, 1997 through August 14, 1998
Project Amount: $360,037
RFA: Exploratory Research - Environmental Biology (1995) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Biology/Life Sciences , Human Health

Objective:

The research is part of a larger program that aims to produce mathematical models that can translate the effects of environmental stress on individual aquatic organisms to the dynamics of populations. Specifically we aim to develop testable, individual-based models capable of predicting population response to environmental insults. We focus on an ecologically important genus, Daphnia, for which sufficient empirical data are available, or can be obtained from well-chosen experiments to permit powerful tests of models.

We have a subcontract with Dr. E. McCauley (University of Calgary) who with previous EPA support conducted experiments on the response of individual Daphnia to varied environmental conditions (temperature and pH). His current experiments aim: (i) to determine Daphnia population dynamics, when faced with contrasting environments and food schedules, (ii) to follow cohorts of individuals within a population, with the aim of estimating fecundity, growth rates and mortality rates for individuals within a population.

The primary objective of our modeling is to determine whether the results of these experiments are predictable using individual-based models parameterized using previous data on individuals grown in isolation.

Progress Summary:

All planned experimental work is either completed or will be completed by September 1998. We have completed the collection and preliminary analysis of replicated data from population experiments with three treatments where food was supplied at the same average rate but at different time intervals. These experiments will allow us to test model predictions that take account of food dynamics and not just the average environment.

We have made the following progress with modeling: (i) Formulation of dynamic energy budget (DEB) models describing growth and reproduction of individual organisms, so as to permit parameter identification and model testing from McCauley's experiments on individual Daphnia. Some estimated parameters (for example those describing feeding) can be compared with independent data in the literature. (ii) Formulation and testing of simple models describing the biomass changes in laboratory populations.

Future Activities:

The "cohort" experiments described above are near completion. These will give strong indications on whether individuals in populations grow, reproduce and survive in accordance with the same rules as individuals grown in isolation. During a "no-cost" extension of the grant (to August 1999), we shall complete our modeling of the effects of a dynamic food environment on population dynamics. We shall complete our modeling of changes the lab population dynamics in response to temperature.

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Publications Views
Other project views:	All 12 publications	11 publications in selected types	All 8 journal articles

Publications
Type	Citation	Project	Document Sources
Journal Article	Murdoch WW, Nisbet RM, McCauley E, deRoos AM, Gurney WSC. Plankton abundance and dynamics across nutrient levels: tests of hypotheses. Ecology 1998;79(4):1339-1356.	R823588 (1998)	Abstract: ESA Journals Abstract Exit Other: UVA PDF Exit
Journal Article	Noonburg EG, Nisbet RM, McCauley E, Gurney WSC, Murdoch WW, De Roos AM. Experimental testing of dynamic energy budget models. Functional Ecology 1998;12(2):211-222.	R823588 (1998)	Abstract: Blackwell-Synergy Abstract Exit Other: STAMS PDF Exit

Supplemental Keywords:

RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, Ecological Indicators, Ecosystem Protection, Chemistry, Ecology, Biology, Ecosystem/Assessment/Indicators, exploratory research environmental biology, Monitoring/Modeling, Ecological Effects - Environmental Exposure & Risk, Ecological Effects - Human Health, Chemical Mixtures - Environmental Exposure & Risk, ecosystem health, predictive model, population level response, environmental monitoring, predicting environmental change, environmental impact , exposure, population, ecological exposure, ecological impacts, anthropogenic stress, population models

Progress and Final Reports:

Original Abstract

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.