Nutritional constraints on mountain baboons (Papio ursinus): Implications for baboon socioecology

Summary Populations of baboon (Papio sp.) at geographic and climatic extremes for the genus show a tendency to one-male organization, whereas most baboons live in multimale social groups; this effect has been attributed largely to limitation of food supply, but baboons' complex diet has hindered proper nutritional analyses. To test these optimal-diet explanations of social variation, we quantified intake and used phytochemical analysis of foods to compare the nutrition, during seasonal changes, of two groups of mountain baboons (P. ursinus) living at different altitudes of a continuous grassland habitat. The majority of plant foods were eaten uniquely by one or other group, though their altitudinal separation was only 400 m, and the time budget of feeding choices varied with age-sex class as well as season. Converting to a common currency of nutrients reveals that baboons gained the same yield from a unit time spent foraging (whether this is measured in edible dry weight, or simply protein) in both groups, despite their differing mean altitude, whereas seasonal variation was large and statistically significant. Increased feeding time at the winter bottleneck made no effective compensation for the poorer food yields: in late winter there was a minimum for daily nutrient gain at both altitudes. Apparently this population is already at an extreme for the time animals devote to foraging in winter, when they rely on inconspicuous and slow-to-harvest swollen shoot bases and underground plant storage organs. Since an individual's nutrient yield does not vary with altitude, we conclude that socioecological parameters are effectively optimized for feeding. Since contest competition is absent, this adjustment of foraging efficiency is largely through the effect of differential density on scramble competition. Differences in social structure are considered to be a secondray consequence of optimal foraging, mediated through altitudinal variation in either population density or in day range limits.     

Impact of ocean acidification on marine ecosystems: educational challenges and innovations

Population growth and social/technological developments have resulted in the buildup of carbon dioxide (CO₂) in the atmosphere and oceans to the extent that we now see changes in the earth’s climate and ocean chemistry. Ocean acidification is one consequence of these changes, and it is known with certainty that it will continue to increase as we emit more CO₂ into the atmosphere. Ocean acidification is a global issue likely to impact marine organisms, food webs and ecosystems and to be most severely experienced by the people who depend on the goods and services the ocean provides at regional and local levels. However, research is in its infancy and the available data on biological impacts are complex (e.g., species-specific response). Educating future generations on the certainties and uncertainties of the emerging science of ocean acidification and its complex consequences for marine species and ecosystems can provide insights that will help assessing the need to mitigate and/or adapt to future global change. This article aims to present different educational approaches, the different material available and highlight the future challenges of ocean acidification education for both educators and marine biologists.     

Biological impacts of ocean acidification: a postgraduate perspective on research priorities

Research into the effects of ocean acidification (OA) on marine organisms has greatly increased during the past decade, as realization of the potential dramatic impacts has grown. Studies have revealed the multifarious responses of organisms to OA conditions, indicating a high level of intra- and interspecific variation in species’ ability to accommodate these alterations. If we are to provide policy makers with sound, scientific input regarding the expected consequences of OA, we need a broader understanding of these predicted changes. As a group of 20 multi-disciplinary postgraduate students from around the globe, with a study focus on OA, we are a strong representation of ‘next generation’ scientists in this field. In this unique cumulative paper, we review knowledge gaps in terms of assessing the biological impacts of OA, outlining directions for future research.     

The lead content and isotopic composition of british coals and their implications for past and present releases of lead to the UK environment

More than 60 coal samples, predominantly from the principal coalfields of England and Wales (25) and Scotland (30), were analysed for lead by AAS and for stable lead isotopes by ICPMS. While the average lead content of Scottish coal, 23.9mg kg^–1, was more than double that of coal from England and Wales, 11.0mg kg^–1, the corresponding mean ²⁰⁶Pb/²⁰⁷Pb ratios (± 1 s.d.) were nearly identical, at 1.181±0.011 and 1.184±0.006, respectively. In the light of the lead isotopic signatures of British coals and of both indigenous (²⁰⁶Pb/²⁰⁷Pb 1.17) and imported Australian (²⁰⁶Pb/²⁰⁷Pb 1.04) lead ores, an approach based on estimated lead emissions from these sources and the deconvolution of the historical lead and ²⁰⁶Pb/²⁰⁷Pb records preserved in lake sediments, peat bogs and archival herbage material indicates that coal combustion became an increasingly significant contributor to atmospheric lead deposition in the UK during the period 1830–1930, especially after the onset of Englands decline as a major location of lead mining and smelting in the late19th Century. Since 1930 and the introduction of leaded petrol, the atmospheric ²⁰⁶Pb/²⁰⁷Pb ratio in the UK has been strongly influenced by carexhaust emissions of comparatively ²⁰⁶Pbdepleted lead of predominantly Australian origin, counterbalanced to some extent by coalcombustion emissions of lead, although these have fallen dramatically since the mid1950s. Nevertheless, with the introduction and substantial uptake of unleaded petrol in the UK during the last decade, even the declining releases from coal, along with contributions from other sources, are continuing to affect the atmospheric lead content and ²⁰⁶Pb/²⁰⁷Pb ratio.     

Integrated ecological models: simulation of socio-cultural constraints on ecological dynamics

We suggest that general systems theory provides a common philosophical basis for dialog between ecological and social scientists interested in studying the reciprocal interactions of humans and their environment. We (1) provide a synopsis of the ‘systems approach' as viewed from the biological and social sciences, respectively; (2) develop a conceptual framework for the explicit linking of ecological and social variables, and (3) draw upon game theoretic results of the Prisoner's Dilemma to represent human decision-making quantitatively in a model that simulates the tragedy of the commons. The model consists of 5 submodels that represent the ‘observers world' and each of 4 ‘participant's worlds.' The observer's-world represents the decision processes, either Optimize or Tit-for-Tat, by which each of 2 users decides to add or remove animals. The 4 perceived worlds represent hypothetical situations in which (1) persons A and B both add an animal; (2) A adds and B does not; (3) B adds and A does not, and (4) neither A nor B add an animal. Simulation results indicate that net worth of the community and of each person individually under Tit-for-Tat is more than double the net worth attained under Optimize. Replacement of the static payoff matrix assumed in game theory with a dynamic quantitative model illustrates how ‘norm-based' approaches to ecosystem management can outperform optimizing approaches based on predicted outcomes. Although ‘soft systems' techniques may better help decision-makers reach norm-based agreements on ecosystem management, quantitative models have more explanatory value, and if developed sufficiently such models could incorporate complex social dimensions that would enhance further their explanatory value.     

Effects of incubation temperature on hatchling pine snakes: implications for survival

Incubation temperature in ectothermic vertebrates affects incubation periods, and in some reptiles it affects sex ratios and behavior. I present evidence that incubation temperature affects emergence and post-hatching behavior of pine snakes (Pituophis melanoleucus) that could influence survival in the weeks before hibernation. Hatchlings incubated at low temperatures remained in the nest longer, had fewer alternate nest openings, and fewer underground tunnels to hide in than did hatchlings from warmer temperatures. These conditions could render hatchlings from low-temperature nests more vulnerable to predation because, if a nest is opened, they are not inside tunnels where they would be protected. Hatchlings from nests incubated at low temperatures took longer to find shade during a thermoregulation test, and were less likely to move about in search of other cover than were those from higher-incubation-temperature artificial nests. Similarly, hatchlings from nests with low incubation temperatures were less responsive to a predatory stimulus and had a longer latency to strike than other hatchlings. Taken together, hatchlings from nests with low incubation temperatures might be less able to avoid predators and find shade than those from nests incubated at higher temperatures, and thus could be expected to have lower survival in nature. Received: 21 July 1997 / Accepted after revision: 15 February 1998     

A test for phylogenetic constraints on behavioral adaptation in a spider system

Summary A population of a desert spider species (Agelenopsis aperta) that is located in an unusually favorable thermal and feeding environment (AZ riparian), fails to exhibit territorial, foraging and antipredatory behaviors that are appropriate to its environment. Study of the behavior of this spider species is extended to another population that occupies a similar environment but where there is not potential gene flow from individuals occupying more arid habitats (TX riparian). The two populations are shown to experience similar prey availabilities and predation pressures when compared to a third more arid population (NM desert grassland). Analyses of the relevant behavior patterns demonstrate that the TX riparian population is well-adjusted to the ameliorated conditions. Thus, phylogenetic constraints do not appear to underlie the observed maladaptive behavior of the AZ riparian population and credibility is given to potential gene flow influences.     

Positive buoyancy in eel leptocephali: an adaptation for life in the ocean surface layer

Many planktonic organisms have adaptations such as floats or lighter substances to obtain buoyancy to help them remain in the surface layer of the ocean where photosynthetic primary production occurs and food is most abundant. The almost totally transparent eel larvae, called leptocephali, are a unique member of the planktonic community of the surface layer, but their ecology and physiology are poorly understood. We conducted a comparative study on the specific gravity of planktonic animals including 25 taxa of 7 phyla of marine invertebrates and 6 taxa of leptocephali (vertebrate) to gain a broad perspective on the buoyancy of the eggs and larval stages of the Japanese eel. The specific gravity values of the various freshly caught marine invertebrate taxa varied widely from 1.020 to 1.425, but leptocephali had some of the lowest values (1.028–1.043). Artificially cultured live leptocephali had even greater buoyancies with specific gravities of 1.019–1.025 that were close to or lower than seawater, and their buoyancy showed ontogenetic changes among the different early life history stages. Leptocephali appear to have a unique mechanism of buoyancy control by chloride cells all over body surface through osmoregulation of body fluid contained in the extracellular matrix of transparent gelatinous glycosaminoglycans filling their bodies. This adaptation is likely a key factor for their survival by helping them to remain in the surface layer where food particles are the most abundant, while being transparent for predator avoidance. The ontogenetic change in buoyancy of eel eggs, leptocephali and glass eels likely enhances their larval survival, transport, and recruitment to terrestrial freshwater habitats.     

Cadmium levels in Europe: implications for human health

In this study we used the Forum of European Geological Surveys geochemical baseline data to examine the distribution of cadmium (Cd) in Europe, with a particular reference to the international soil and water guideline values. The highest cadmium levels were found to occur in topsoil and to follow closely the distribution of P₂O₅, suggesting that the contamination was from the use of rock phosphate fertilizer in intensive arable agriculture. In terms of human health impacts, food (up to several hundred μg/day) was found as the only major route of exposure to Cd for the non-smoking general population. It appeared that low levels of chronic exposure to Cd resulted in completely different human health impacts than those high levels that had caused the ‘itai–itai’ disease. Some correlations were suggested between cadmium levels and the age-adjusted prostate or breast cancer rates distributed in the European countries under study.     

Impact of ocean warming on the early ontogeny of cephalopods: a metabolic approach

The impact of a realistic warming scenario on the metabolic physiology of early cephalopod (squid Loligo vulgaris and cuttlefish Sepia officinalis) life stages was investigated. During exposure to the warming conditions (19 °C for the western coast of Portugal in 2100), the increase in oxygen consumption rates throughout embryogenesis was much steeper in squid (28-fold increase) than in cuttlefish (11-fold increase). The elevated catabolic activity–accelerated oxygen depletion within egg capsules, which exacerbated metabolic suppression toward the end of embryogenesis. Squid late-stage embryos appear to be more impacted by warming via metabolic suppression than cuttlefish embryos. At all temperature scenarios, the transition from encapsulated embryos to planktonic paralarvae implied metabolic increments higher than 100 %. Contrary to the nektobenthic strategy of cuttlefish newborns, the planktonic squid paralarvae rely predominantly on pulsed jet locomotion that dramatically increases their energy requirements. In the future, hatchlings will require more food per unit body size and, thus, feeding intake success will be crucial, especially for squid with high metabolic rates and low levels of metabolic reserves.     

Population-level effects of augmented herbivory on Lespedeza cuneata: implications for biological control.

Invasive species pose significant ecological costs, and therefore successful management techniques are important. One commonly employed method is biological control. The success of biological control depends largely on whether additional inflicted damage can successfully reduce the fitness and population growth rate of a target species. Here, we simulate herbivory on the invasive Lespedeza cuneata and create stage-structured projection models to determine if augmented herbivory by a leaf-chewing biological control agent would regulate the population growth rate of this species. We found that augmented herbivory influenced stage transitions of plants in the smallest stage class, causing higher mortality and reduced growth. No other effect was found on stage transitions or fecundities, despite manipulation of herbivory at exceptionally high levels (up to 80% leaf loss). None of the clipping treatments significantly reduced the population growth rate of L. cuneata. We conclude that biological control by a leaf chewing herbivore would not likely be successful, even if an exceptionally large amount of each plant were consumed. We suggest that this approach, a combination of simulated herbivory and demographic modeling, will provide essential information for understanding the utility of biological control to curb the population growth of invasive plant species.     

Thermal and energetic constraints on ectotherm abundance: a global test using lizards

Population densities of birds and mammals have been shown to decrease with body mass at approximately the same rate as metabolic rates increase, indicating that energetic needs constrain endotherm population densities. In ectotherms, the exponential increase of metabolic rate with body temperature suggests that environmental temperature may additionally constrain population densities. Here we test simple bioenergetic models for an ecologically important group of ectothermic vertebrates by examining 483 lizard populations. We find that lizard population densities decrease as a power law of body mass with a slope approximately inverse to the slope of the relationship between metabolic rates and body mass. Energy availability should limit population densities. As predicted, environmental productivity has a positive effect on lizard density, strengthening the relationship between lizard density and body mass. In contrast, the effect of environmental temperature is at most weak due to behavioral thermoregulation, thermal evolution, or the temperature dependence of ectotherm performance. Our results provide initial insights into how energy needs and availability differentially constrain ectotherm and endotherm density across broad spatial scales.     

The sea-skater Halobates micans: an open ocean bioindicator for cadmium distribution in Atlantic surface waters

Our knowledge of the horizontal distribution of heavy metals in the open ocean with time and space is still very incomplete. Complementary to chemical water analyses suitable biological indicator species may be used to fill this gap. The pleuston organism Halobates micans was collected from 1966 to 1987 at 151 sampling stations of the tropical and subtropical Atlantic Ocean. The cadmium data from more than 1000 individuals analysed display a chemicaloceanographic meaningful distribution in surface waters and compare favourably to primary production values. Chemical analysis of individual plankton species offer a new tool for a better understanding of geochemical cycling of heavy metals in the ocean.     

Advanced age for sexual maturity in the ocean quahog Arctica islandica (Mollusca: Bivalvia)

A study of gonadal state in 39 small specimens of Arctica islandica Linné collected in April 1976 from the Middle Atlantic shelf of North America suggests that sexual maturity is reached at a later age than has been reported for other shelf bivalves. Eight of the specimens had gonads in the undifferentiated state. On the basis of annual internal growth banding in the shells of these immature specimens, age ranged between 4 and 14 years. Average age was 9.38 years (standard deviation, s,= 3.54). Shell length ranged from 24 to 47 mm (average 38.85 mm, s=9.25). Differentiated gonads were found in specimens as young as 6 years. Age of maturity shows a wide range and may be dependent upon growth rate and locality.     

Filter feeding by Oikopleura vanhoeffeni: grazing impact on suspended particles in cold ocean waters

Because of the abundance and size of Oikopleura vanhoeffeni its quantitative role as a suspension feeder in cold ocean waters needs to be defined. To minimize the effect of manipulation and containment, and to assess the effect of naturally occurring factors on clearance rate, I used an in situ latex microbead technique in Logy Bay, Newfoundland, from February 1985 to June 1986. Individual clearance rates ranged from 8–944 ml h^-1, increasing exponentially with increasing trunk length. Partial correlation and principal components analysis indicated that trunk length and the concentration of ingestible chlorophyll a accounted for a majority of the variation in clearance rate. At densities of 4–110 m^-3, O. vanhoeffeni populations removed from >1 to 13% of the standing stock of ingestible food particles each day. Grazing by near-surface populations was lowest during the spring diatom bloom (>1.4% of daily particle production removed per day), and was highest in June during the post-bloom crash (4 to 10% of daily production removed). Some populations in mid-depth waters had much higher population clearance rates (ca. 50% of daily production removed) because of a greater proportion of large animals. The median percentage daily ration (g Cxg C^-1xd^-1x100%) of 64% accounted for observed house production rates (1 to 2 d^-1, with each house=23% of body carbon).     

Parasite distribution and virulence: implications for parasite-mediated sexual selection

The Hamilton-Zuk hypothesis states that females choosing males with more developed secondary sexual traits, i.e. brighter males, achieve greater fitness if variability in brightness reflects heritable variation in resistance to parasites. However, several factors will affect the likelihood that parasites play a role in sexual selection in given species. Here, using simple models, we show that because of parasite aggregation on a few hosts, only few breeding males would suffer from reductions in brightness due to parasites. Only in cases where parasites are abundant and show low levels of aggregation among their hosts would there be sufficient variability in brightness among breeding males for female choice of bright, resistant males to evolve. In addition, sufficient parasite-induced variability in brightness among breeding males will only occur in host-parasite systems where pathology is linearly related to the number of parasites per host. The presence of males that are uninfected and bright but genetically susceptible to parasites will also influence the fitness advantages obtained by females choosing bright males. If genetic immunity against parasites is rare in the host population, females can probably only benefit from choosing bright males if parasites are common and little aggregated among males. These results greatly limit the generality of the Hamilton-Zuk hypothesis, and suggest that only a small fraction of host-parasite associations could promote the evolution of host mate choice for resistance based on brightness. Correspondence to: R. Poulin     

Patch choice under perceptual constraints: a cause for departures from an ideal free distribution

Summary A review of tests of ideal free distribution (IFD) theory reveals a characteristic bias: patches with a small proportion of the resources are relatively overused and patches with a larger proportion of the resources are relatively underused. A model is developed to examine how animals with limited abilities to perceive differences in patch quality affect an IFD by foragers. This constraint produces the observed bias, a bias that is exaggerated as the number of patches increases. Sutherland (1983) has developed a model based on interference which can also explain the observed bias. The two models can be differentiated in that only the perception limit model (this paper) is sensitive to absolute changes in overall resource availability and to increases in the number of animals. Additionally, Sutherland's model predicts that when deviations away from an IFD occur there will be no differences in intake rates, while the perception limit model predicts that intake rates should vary between patches.     

A simple plankton model for the Oregon upwelling ecosystem: Sensitivity and validation against time-series ocean data

Simple plankton models serve as useful platforms for testing our understanding of the mechanisms underlying ecosystem dynamics. A simple, one-dimensional plankton model was developed to describe the dynamics of nitrate, ammonium, two phytoplankton size-classes, meso-zooplankton, and detritus in the Oregon upwelling ecosystem. Computational simplicity was maintained by linking the biological model to a one-dimensional, cross-shelf physical model driven by the daily coastal upwelling index. The model sacrificed resolution of regional-scale and along-shore (north to south) processes and assumed that seasonal productivity is primarily driven by local cross-shelf Ekman transport of surface waters and upwelling of nutrient-rich water from depth.Our goals were to see how well a simple plankton model could capture the general temporal and spatial dynamics of the system, test system sensitivity to alternate parameter set values, and observe system response to the effective scale of potential retention mechanisms. Model performance across the central Oregon shelf was evaluated against two years (2000-2001) of chlorophyll and copepod time-series observations. While the modeled meso-zooplankton biomass was close in scale to the observed copepod biomass, phytoplankton was overestimated relative to that inferred from the observed surface chlorophyll concentration. Inshore, the system was most sensitive to the nutrient uptake kinetics of diatom-size phytoplankton and to the functional grazing response of meso-zooplankton. Meso-zooplankton was more sensitive to alternate parameter values than was phytoplankton. Reduction of meso-zooplankton cross-shelf advection rates (crudely representing behavioral retention mechanisms) reduced the scale of model error relative to the observed seasonal mean inshore copepod biomass but had little effect of the modeled meso-zooplankton biomass offshore nor upon phytoplankton biomass across the entire shelf.     

Institutional deficiencies and capacity building constraints: the dilemma for environmentally sustainable development in Africa

SUMMARY

The authors question Africa's ability to achieve sustainable development in view of the erosion of its institution building capacity, a problem compounded by the alarming rate of Africa's continuing marginalisation in the world economy. The situation has been provoked by inappropriate domestic policies which have not only compromised Africa's competitiveness, but also made it particularly vulnerable given the increasing globalisation of markets and factors of production. The benefits associated with effective global economic participation transcend direct financial gains and include technology transfers, technical and managerial skills transfers, and other skills transfers associated with the ‘learning and doing’ process. These benefits are instrumental in the development of the economic, administrative, legislative and social institutions that prescribe the organisational and managerial structure of an economy and define its capacity for sustainable growth. In Africa, the absence of such structures has undermined development efforts and created large impoverished populations. But poverty in living standards is not only prevalent, there is also the acute poverty in knowledge and skills which is so damaging to institution building capacity. The socio-economic impact is manifest in dilapidated infrastructure, decaying institutions, the exodus of the professional and managerial cadre, and the almost total disintegration of society. It is within this context that Africa's ability to evolve and effectively manage sustainable development policies is questioned. The study concludes that the continent's capacity to initiate sound environmental and sustainable development policies depends crucially on its ability to develop appropriate and functional institutions.