Primary Productivity Distributions Along the River-Dominated Shoreline of the Bay of St. Louis, MS Estuary

Potential primary production was measured for six consecutive months (July 2010 to December 201 0) at selected stations along the shoreline of the Bay of Saint Louis (BSL) estuary. Monthly surface and a series of subsurface (0.5 m) samples were taken to observe the temporal (monthly and short-term) and spatial variability in production relative to environmental variables that potentially could influence phytoplankton photosynthesis. Daily areal primary production, PP was modeled using photosynthesis-irradiance (P-E) parameters in conjunction with in situ irradiance measurements and biomass data collected during sampling. Although spatial variability was not observed, PP varied seasonally and ranged from 1.90 g C m-2 d-1 in July to 0.06 g C m-2 d-1 in December. Short-term variability also was observed. Production ranged from 0.25 to 0.84 g C m-2 d-1 over the course of a week and within-day values ranged from 0.36 to 0. 72 g C m-2 d-1 with peak production occurring at midday. Temporal variability was attributed primarily to changes in temperature (seasonal), river discharge (week-long), and incident irradiance (diurnal). Annual production for the BSL estuary was estimated at 197.3 g C m-2 d-1 and is comparable to other temperate, mesotrophic estuaries. The results from this study provide the first modeled estimates of primary production within the BSL system and will facilitate ecological research and monitoring efforts within this locally important estuary

Microplankton Dynamics in the River-Dominated Mississippi Bight

The Mississippi Bight (MSB) is a river-dominated continental margin influenced by multiple large river systems, including the Mississippi River, Alabama and Tombigbee rivers via Mobile Bay, and numerous smaller rivers, creeks, and bayous. This is part of a biologically-rich ecosystem that supports the second largest fishery industry by volume in the United States. Despite our understanding of the linkages between primary production with higher trophic levels, there remains limited studies quantifying these trophic interactions in this system. Microplankton (µm) community dynamics and trophic connectivity between primary producers and heterotrophic protists represent a critical nexus influencing overall biological productivity in this region. These processes were examined using a combination of a novel morphological-based (MBFG) classification system derived from in-flow plankton imaging (i.e. FlowCAM), a suite of in situ biogeochemical and biological measurements, and multivariate statistics to describe patterns of microplankton community composition, biomass, primary productivity, and microzooplankton grazing relative to prevailing physicochemical conditions. Results indicated that the MSB is a highly productive ecosystem, oscillating from a mesotrophic state under reduced river discharge and nutrients to eutrophic conditions during high discharge and elevated nutrient concentrations. Microplankton communities shifted under differing environmental conditions, though diatoms and nanoplankton were predominant throughout the study. Both size fractions (0.6-5 µm and \u3e 5 µm) contributed nearly equivalent proportions to biomass and productivity during low discharge, whereas \u3e5 µm size fraction contributed more biomass and productivity during the spring freshet. Microzooplankton grazing (i.e. ciliates) exerted a significant top-down control on phytoplankton biomass (30-60%) and productivity (\u3e 60%), despite enhanced phytoplankton growth in spring. The effects of environmental variability on biological productivity and ecological resilience in the MSB is best understood within the context of microplankton community dynamics among primary producers and their trophic intermediaries. Results from this research highlight these key ecological relationships that are fundamental to ecosystem function, productivity, and resilience in this system

Dyadic inter-group cooperation in shotgun hunting activities in a Congo Basin village.

Understanding the dynamics of inter-group cooperation in human adaptation has been the subject of recent empirical and theoretical studies in evolutionary anthropology, beginning to fill gaps in our knowledge of how interactions across political, economic and social domains can - and often do - lead to stable, large-scale cooperation. Here we investigate dyadic intergroup cooperation in shotgun hunting in the Republic of the Congo. In the Congo Basin, inter-group cooperation between foragers and farmers is at the centre of an exchange system maintained by traditional norms and institutions such as fictive kinship. Here, we focused on what factors predict cooperative shotgun hunting exchanges between BaYaka and Yambe. We conducted structured interviews with 48 BaYaka hunters and 18 Yambe men who organise hunts in a village along the Motaba River. We used Bayesian multilevel regression models to investigate the influence of Yambe and BaYaka attributes on probability of dyadic cooperation. We found that BaYaka men's reputations as skilled hunters and their family size each predicted cooperation in shotgun hunting, whereas there was no effect of Yambe attributes (status, wealth, family size). We discuss the results in terms of evolutionary models of men as hunters and inter-group cooperation, as well as biodiversity conservation implications

Drivers of diatom production and the legacy of eutrophication in two river plume regions of the northern Gulf of Mexico

In the northern Gulf of Mexico (nGoM), the Louisiana Shelf (LS) and Mississippi Bight (MB) subregions are influenced by eutrophication to varying degrees. Despite recognition that dissolved silicon may regulate diatom productivity in the nGoM, there is only one published data set reporting biogenic silica (bSiO2) production rates for each subregion. We report that bSiO2 production rates on the LS and MB are high and appear to be controlled by different nutrients among seasons. Despite exceptional upper trophic level biomass regionally, which suggests significant primary production by diatoms (as in other systems), gross euphotic-zone integrated bSiO2 production rates are lower than major bSiO2 producing regions (e.g. upwelling systems). However, when normalizing to the depth of the euphotic zone, the bSiO2 production rates on the LS are like normalized rates in upwelling systems. We suggest local river-plume influenced hydrography concentrates diatom productivity within shallow euphotic zones, making production more accessible to higher trophic organisms. Comparison of rates between the LS and MB suggest that the fluvial nitrate within the LS stimulates bSiO2 production above that in the MB, which has a smaller watershed and is less eutrophic (relatively). Beyond understanding the factors controlling regional bSiO2 production, these data offer the most comprehensive Si-cycle baseline to date as the LS and MB will likely exchange freely in the mid to late century due to land subsidence of the Mississippi River delta and/or sea-level rise

Functioning of Coastal River-Dominated Ecosystems and Implications for Oil Spill Response: From Observations to Mechanisms and Models

Coastal river-dominated oceans are physically complex, biologically productive, and intimately connected to human socioeconomic activity. The Deepwater Horizon blowout and subsequent advection of oil into coastal waters of the northern Gulf of Mexico (nGOM) highlighted the complex linkages among oceanographic processes within this river-dominated system and knowledge gaps about it that resulted in imprecise information on both oil transport and ecosystem consequences. The interdisciplinary research program implemented through the CONsortium for oil exposure pathways in COastal River-Dominated Ecosystems (CONCORDE) is designed to identify and quantitatively assess key physical, biological, and geochemical processes acting in the nGOM, in order to provide the foundation for implementation of a synthesis model (coupled circulation and biogeochemistry) of the nGOM shelf system that can ultimately aid in prediction of oil spill transport and impacts. CONCORDE field and modeling efforts in 2015–2016 focused on defining the influence of freshwater input from river plumes in the nGOM. In situ observations, combined with field-deployed and simulated drifters, show considerable variability in the spatial extent of freshwater influence that is related to wind direction and strength. Increased primary production and particle abundance (a proxy for secondary production) was observed during the spring when nGOM shelf waters were becoming stratified. Zooplankton and marine snow displayed intense vertical and horizontal patchiness during all seasons, often aggregating near the halocline. Simulations of a neutrally buoyant tracer released offshore of the Mississippi Bight showed surface advection of low tracer concentrations onto the inner shelf under high river discharge, high stratification, and variable wind conditions compared to almost no advection onto the inner shelf under low discharge, negligible stratification, and generally northeasterly winds. The interconnectedness of environmental variables and biological activity indicate that multiple factors can affect the transport of oil and the resulting ecological impacts. The process-oriented understanding provided by CONCORDE is necessary to predict ecosystem-level impacts of oil spills, and these results are applicable to other river-dominated coastal systems worldwide that often support oil extraction activities

Women’s subsistence strategies predict fertility across cultures, but context matters

While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activities—incorporating market integration—are associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as “farmers” did not have higher fertility than others, while “foragers” did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence

Human preferences for sexually dimorphic faces may be evolutionarily novel

A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data come from large-scale, industrialized, urban populations. Here, we report the results for 12 populations with very diverse levels of economic development. Surprisingly, preferences for exaggerated sex-specific traits are only found in the novel, highly developed environments. Similarly, perceptions that masculine males look aggressive increase strongly with development and, specifically, urbanization. These data challenge the hypothesis that facial dimorphism was an important ancestral signal of heritable mate value. One possibility is that highly developed environments provide novel opportunities to discern relationships between facial traits and behavior by exposing individuals to large numbers of unfamiliar faces, revealing patterns too subtle to detect with smaller samples

Scientific assessment of the use of sugars as cigarette tobacco ingredients: A review of published and other publicly available studies

Sugars, such as sucrose or invert sugar, have been used as tobacco ingredients in American-blend cigarettes to replenish the sugars lost during curing of the Burley component of the blended tobacco in order to maintain a balanced flavor. Chemical-analytical studies of the mainstream smoke of research cigarettes with various sugar application levels revealed that most of the smoke constituents determined did not show any sugar-related changes in yields (per mg nicotine), while ten constituents were found to either increase (formaldehyde, acrolein, 2-butanone, isoprene, benzene, toluene, benzo[k]fluoranthene) or decrease (4-aminobiphenyl, N-nitrosodimethylamine, N-nitrosonornicotine) in a statistically significant manner with increasing sugar application levels. Such constituent yields were modeled into constituent uptake distributions using simulations of nicotine uptake distributions generated on the basis of published nicotine biomonitoring data, which were multiplied by the constituent/nicotine ratios determined in the current analysis. These simulations revealed extensive overlaps for the constituent uptake distributions with and without sugar application. Moreover, the differences in smoke composition did not lead to relevant changes in the activity in in vitro or in vivo assays. The potential impact of using sugars as tobacco ingredients was further assessed in an indirect manner by comparing published data from markets with predominantly American-blend or Virginia-type (no added sugars) cigarettes. No relevant difference was found between these markets for smoking prevalence, intensity, some markers of dependence, nicotine uptake, or mortality from smoking-related lung cancer and chronic obstructive pulmonary disease. In conclusion, thorough examination of the data available suggests that the use of sugars as ingredients in cigarette tobacco does not increase the inherent risk and harm of cigarette smoking

Observations of Cooperative Pond Fishing by the Bayaka and Bantu People in the Flooded Forest of the Northern Republic of Congo

The subsistence techniques of the Congo Basin peoples are diverse and well-adapted to local ecological and socio-cultural contexts. Besides well-known fishing techniques using dams, nets, barriers, or poison, the BaYaka and Bantu in the northern Republic of Congo use ponds dug by humans, called mosongo. In the flooded forest, the ponds function as fish traps when fish seek refuge there at the end of the dry season. In March 2020, the authors conducted participant observation and interviews with the BaYaka and Bantu who engaged in pond fishing. Some mosongo were inherited from and managed by informants’ grandmothers or mothers. Generally, the Bantu fisher-farmers visit this area once a year to make money with the catch from pond fishing. As in a variety of foraging activities, the Bantu recruit the BaYaka for labor and compensate them with some fish. Much surplus catch is sold in markets. For the BaYaka, pond fishing was one of their important seasonal subsistence activities. Yet, the BaYaka also sold surplus fish to the Bantu. This report provides additional evidence for the diversity in subsistence techniques in the Congo Basin, and reaffirms the importance of inter-ethnic relationships in the subsistence strategies in this region

SOCIAL LEARNING DURING MIDDLE CHILDHOOD AMONG AKA FORAGERS AND NGANDU FARMERS OF THE CENTRAL AFRICA REPUBLIC

Homo sapiens are uniquely characterized by a lengthy juvenile period we call childhood and a pronounced reliance on social learning for the acquisition of an adaptive behavioral repertoire, commonly referred to as culture. Anthropologists have been long been interested in children's social learning, but recent interest in cultural transmission by other disciplines, notably biology and psychology, offers an important opportunity for interdisciplinary integration. This manuscript is the first systematic, comparative study of children's social learning in two small-scale societies: the Aka forest foragers and Ngandu farmers of the Central African Republic. Herein, I review the social learning process and cultural transmission modes argued to make the transmission of complex, cumulative human culture possible and culture as a distinct inheritance system evolve. I then build a set of hypotheses derived from evolutionary models of social learning and cultural transmission theory, and informed by a developmental niche perspective. I find that evolutionary models of optimal social learning schedules, and adaptive cultural transmission modes generally hold, but vary in ways predicted by core cultural differences between foragers and farmers.Among my major results are: Each social learning process decreases with age, trading off with individual learning as predicted by evolutionary theory; Same-sex cultural transmission of work behavior is associated with cultural variations in the sexual division of labor; Social play is a major social learning process for child-to-child transmission of foundational cultural schema such as competition versus cooperation; Teaching is present among both foragers and farmers but consists of at least three different social learning processes, and teaching via vertical transmission is of less importance during middle childhood among foragers than among farmers; Food sharing norms are transmitted to Aka forager children through multiple social learning process and cultural transmission modes, but Ngandu farmers rarely have the opportunity to observe food sharing.The results of these novel analyses provide new insights into the culture learner-culture teacher interface, and help to better characterize the dynamic interplay between childhood and culture in human adaptation