Subsistence productivity and hunting effort in native South America

The question of why people work more or less at various activities is an old one in anthropology and recently has surfaced in studies of native South American societies. Growing out of debates about protein scarcity, arguments have arisen over the reasons why people spend time on hunting and fishing. Some authors suggest that labor allocation and other societal features can be explained with reference to absolute minimum requirements for specific nutrients (e.g., protein). This study presents data from four native Central Brazilian societies on the time spent at various subsistence tasks and the productivity of those tasks. The evidence suggests that decisions to allocate labor to hunting and fishing are influenced more by the overall possibilities for production in an area than by the availability of animal proteins alone. Satisfaction of calorie requirements appears to take precedence over satisfaction of protein requirements. In those societies in which gardening is highly productive, people can spend more time on hunting and fishing and improve the overall quality of their diet.     

7. Mire Straldza (Southeastern Bulgaria): Late Holocene vegetation history

Aeroallergens of the southeastern Missouri region were determined by skin test frequencies of 817 consecutive individuals and compared and contrasted with five years of air sampling using the Rotorod sampler. Household inhalants were found to induce the most frequently positive skin tests, especially house dust, feathers, house dust mite, wool, cat epithelium, tobacco, dog epithelium, and horse epithelium. Among the trees, pollen extracts of Acer saccharum (maple), Acer negundo (box-elder), Carya ovata/C. illinoensis (hickory/pecan), Juglans nigra (walnut), and Ulmus americana (elm) were the most commonly positive. A slightly higher level of skin reactivity was found to grass pollen extracts with Anlhoxanthum odoralum (sweet vernal), Phleum pratense (timothy), Cynodon dactylon (Bermuda), Agrostis alba (red top) and Festuca elatior (meadow fescue), all being quite similar in incidence, but Sorghum halepense (Johnson grass) was clearly less important. Ambrosia spp. (ragweed) and Xanthium commune (cocklebur) were the most frequent weed reactions with ragweed the most prominent allergen of outside environmental origin. Of the genera of fungi, skin tests to Epicoccum were most frequently positive. When reactivity level is considered, the other important fungi are Alternaria, Candida, Cladosporium, Curvularia, and Fusarium. Air sampling data generally correlates well with the positive skin tests frequencies i.e., the most numerous pollen, ragweed, has the highest skin test frequency and reactivity level. Similarly among the fungi the most numerous spores, Cladosporium, Alternaria, Fusarium, and Epicoccum have the highest frequencies and reactivity levels. Certain species appear to be able to sensitize patients in lower concentrations, such as box-elder and the grasses. Oak pollen and Cladosporium spores appear in large numbers, but seem less sensitizing.     

Late Glacial and Holocene environmental and climatic changes from a limnological transect through Colombia, northern South America

We present a synthesis of the palaeolimnological and palaeoclimatic reconstructions of four sites in Colombia. The record from Lake El Caimito, the westernmost site on the Pacific Coast, dates from the Late Holocene and shows lacustrine sedimentation frequently interrupted by fluvial pulses. These pulses probably reflect periods of increased precipitation related to La Niña phases. East of El Caimito site is the Patía swamp, situated between the Western and Central Andean Cordilleras. The Patía records the dynamics of forest expansion/reduction and changes in water levels. Although the climatic signal of the Patia core is difficult to reconstruct, there is a clear increase in humidity in the Mid-Holocene. The Fúquene Lake record, on the Eastern Andean Cordillera, records dry and cold conditions during the Late Pleistocene, very humid conditions for the early Mid-Holocene, and dry conditions during the mid-Late Holocene. Las Margaritas site, on the eastern savannas, records dry conditions during the Early Holocene and overall humid conditions for the Mid- and Late Holocene. Climate conditions from the Fuquene and Las Margaritas sites seem to reflect the Holocene movements of the Intertropical Convergence Zone (ITCZ); the latter site being more affected by humidity coming from the Amazon region.     

Late Pleistocene and Holocene environments of the Southeastern United States from the stratigraphy and pollen content of a peat deposit on the Georgia Coastal Plain

A 5.4 m peat core from the Sandy Run Creek (SRC) valley in the upper Coastal Plain of Georgia shows that before 30 ka the valley had an aggradational sandy floor with shallow swales and low ridges of 1–2 m amplitude suggesting a braided stream pattern and a low water table. The climate from 30–25 ka was cool and dry and the vegetation open grassland with stands of pine and spruce that produced few fires. At ca. 16 ka a warmer, wetter climate caused SRC to meander and incise the valley fill removing some previously deposited sediment at the site of our peat core so that sediments of 13 ka rest directly on sediments deposited at 25 ka. After ca. 13 ka higher groundwater levels initiated vertical accretion of floodplains allowing peat accumulation in shallow depressions across the valley. Pollen from the Younger Dryas period (ca. 13–11 ka) indicates a cool, moist environment of open oak woodland, mesic trees, riparian populations of alder, and reduced levels of pine. By the early to mid Holocene, tupelo and oak dominated over pine indicating wetter conditions, while sand stringers in peat record periodic heavy rains, an elevated water table, and intervals of substantial runoff. Cooling after ca. 4.5 ka brought drier and more variable conditions. Fires increased and southern pine replaced tupelo and oak. The absence of sand stringers in peat younger than 4.5 ka indicates fewer intense rainfall events.     

Late Holocene sea level and reef-flat progradation, Phuket, South Thailand

 Fringing reefs growing in the muddy waters of SE Phuket contain fossil, former reef-front, massive corals that protrude above the intertidal reef flat. The top surfaces of some of these massive fossil corals have been dated and surveyed. The results indicate that these reefs commenced growth 6000 y ago when the sea level (low spring tide) was 1 m above present and that the average rate of reef-front progradation was 1.7 cm per year. Accepted: 22 May 1998     

Deer fauna from Pleistocene and Holocene localities of Ecuador (South America)

Late Pleistocene and Holocene deer remains from Ecuadorian sites have been analysed. Most of the material belongs to Odocoileus virginianus ustus, which is documented in latest Pleistocene deposits, in the Interandean Depression. Coastal sediments referred to the Holocene bear remains of Odocoileus salinae. O. v. ustus and O. salinae differ in size and in the morphology of the antlers and of the dentitions. In the present work, O. salinae is postulated to have derived from O. v. ustus during an arid climatic phase in the latest Pleistocene.     

Long-Term Effects of Frequent Low-Intensity Burning on the Abundance of Litter-Dwelling Invertebrates in Coastal Blackbutt Forests of Southeastern Australia

Low-intensity fire is extensively used in Australian dry eucalypt forests to reduce fuel levels. The long-term impact of this management practice on terrestrial invertebrates is, however, unknown and is of concern given their contribution to ecosystem function and forest biodiversity. This study found that areas subjected to frequent low-intensity fire had significantly lower numbers of spiders, ticks and mites, pseudoscorpions, woodlice, springtails, bugs, beetles, ants and insect larvae in the leaf litter compared with adjacent unburnt areas. Taxa numbers were between 41 and 82% lower and these reductions in abundance have led to an overall decline in taxon richness. This decrease was attributed to a reduction in the amount of litter and associated moisture levels, and a simplification of habitat structure. The extent of local and regional extinctions will depend upon the scale of this disturbance, with future studies investigating the impact on individual species within these communities. A comparison of two sampling techniques, pitfall-trapping and litter extraction, highlighted important considerations for spatial components of invertebrate sampling designs.     

Holocene Human Footprints in North America

Reports of human footprints from North American archaeological sites are summarized and described. Although some human footprints have been claimed to be of Pleistocene and earlier ages, the earliest authenticated prints in America north of Mexico, as distinct from Central or South America, date to the Holocene. The earliest of these prints is at least 5,070 years old, and the youngest are late prehistoric period, only about 400 years old. Footprint sites are reported in the U.S. Southeast, Southwest, and California. Activities indicated by ancient North American human footprints include the mundane, such as daily tasks in a riparian zone and domestic behaviors inside a habitation. Footprints were also left by prehistoric peoples undertaking more esoteric activities deep in cave interiors, including exploration, mineral extraction, and ritual.     

Cladocera response to Late Glacial to Early Holocene climate change in a South Carpathian mountain lake

This study explores changes in cladoceran composition in a high mountain lake of the Retezat (Lake Brazi), the South Carpathian Mountains of Romania, during the Late Glacial–Early Holocene (14,500–11,600 cal. yr. bp) transition using a paleolimnological approach. The lake had a species poor cladoceran community throughout this period. Daphnia longispina, Chydorus sphaericus and Alona affinis were the most common, showing marked fluctuations in their relative abundances through time. Distinct faunal response to warming at the Younger Dryas (YD)/Preboreal transition was recorded by increasing fossil densities and distinct community composition change: Alona affinis became dominant while numbers of Chydorus sphaericus dramatically decreased. In the Early Holocene, the productivity of Lake Brazi seem to have increased as reflected by higher numbers of Cladocera due to appearance of new species (Alona rectangula, A. quadrangularis and A. guttata) which are common in productive waters. Significant negative correlation was found between average dorsal length of daphnid ephippia and the NGRIP ^δ18O isotope values. Given the absence of fish predation, changes in Daphnia ephippia size were taken to indicate climatic change: larger ephippium size inferred cold conditions during the Late Glacial, while smaller size reflected climate warming during the Early Holocene. We conclude that Cladocera fossils are good indicators of climatic change that happened during the transition from the Late Glacial to the Holocene. We found that climatic conditions can be tracked either by size distribution of Daphnia ephippia (larger ephippium size under colder climate) and/or by community change of cladocerans.     

Avoiding Competition: the Ecological History of Late Cenozoic Metatherian Carnivores in South America

The ecological interaction between small and medium sized South American metatherian carnivores, from the Miocene to Recent, has been analyzed with the objective to understand the ecological interactions between the Hathliacynidae (Sparassodonta) and some Didelphoidea (Didelphimorphia). The species richness through time for these two groups, along with the body mass, diet, and several morphofunctional variables has been analyzed here. The results show a double-wedge geometry of the diversity curve. The climax of the Hathliacynidae took place during the Santacrucian mammal-age with a subsequent decline, in the species richness of this family, followed by the extinction of the family at the Barrancalobian subage. Carnivorous Didelphoidea show a first maximum species richness during the Chapadmalalan followed by a decline and a new rise during Recent times. The coexistence of these mentioned groups took place from the Chasicoan to the Chapadmalalan mammal-ages covering a time span of around 6,000,000 years. The multivariate and univariate analyses of morphofunctional variables suggest a restriction of the Hathliacynidae to hypercarnivory while the Didelphoidea occupied the niche of meso- and hypocarnivory. The body mass analyses show some overlap in small sizes but it is not correlated with any superposition in the morphospace of functional variables. In summary, any passive replacement or active displacement between the Hathliacynidae and carnivorous Didelphoidea are supported by the fossil record. In turn, a partition of the metatherian carnivorous guild seems to have occurred through to the Neogene. The extinction of the Hathliacynidae seems to be a result of environmental change.     

Late Holocene reef growth and relative sea-level changes in Atol das Rocas, equatorial South Atlantic

Shallow drilling provided the first detailed record of vertical reef accretion rates for the last 4,000 years from the oceanic atoll Atol das Rocas. Six cores up to1-m long from windward, leeward, and intertidal hardground environments were radiocarbon dated. Frameworks are dominated by the coralline alga Porolithon cf. pachydermum with minor contributions of Lithophyllum sp. Coralline bindstone and framestone facies were identified. Vertical accretion rates (VAR) form three groups: group A frameworks were formed between 3,490±45 years BP and 2,770±45 years BP, and VAR are 0.85, 1.4, and 1.6 mm/year; group B frameworks were formed between 2,510±45 year BP and 490±45 year BP, and VAR are 0.25, 0.46, and 0.42 mm/year; group C frameworks were formed between 900±50 year BP and 655±45 year BP, and VAR are 3.2, 9.75, and 18.4 mm/year. Results indicate that coralline-algal reefs may display a catch-down response to a falling sea level similar to the way corals respond to a rising sea level. In this case, present day reef topography may be the result of late Holocene SW Atlantic sea-level changes. The calculated VAR of 18.4 mm/year is the highest rate known to date for a coralline-algal reef and close to the maximum rates recorded for corals.     

Late Holocene flooding in the Ecuadorian rain forest

SUMMARY 1. The stratigraphy, radiocarbon chronology, sedimentary pigment, and cation records of sediment cores from four lakes in the Ecuadorian rain forest show that regional flooding occurred from about 1300 to 800 'BP. Each core contains a stratum of alluvial clay, silt and sand overlain by lacustrine deposits of peat, gyttja or clayey gyttja. Radiocarbon dates show that the onset and termination of the alluvial event was synchronous across the sites. Short-term, possibly regional, flooding occurred at each of the sites at least once since the major flood.
2. A core from Anangucocha, a black-water lake, records the geoche- mical signature of white-water incursion during this flooding interval. Sedimentary pigments show that aquatic production at Anañgucocha was low during the lotic interval but rose sharply and remained high within the modern lake period.
3. The Amazon's dynamic river system may have been an important force in promoting and maintaining high floral and faunal diversity.     

Non-selectivity in extinction of bivalves in the Late Cretaceous of the Atlantic and Gulf Coastal Plain of North America

It has been suggested that the biogeographic and clade-level characteristics of marine invertebrate groups important in survival through mass extinctions are different from those important in survival during normal times. The role played by ecologically important characters in survival across mass extinctions, however, has not been well-studied. We obtained information from the literature about the feeding mode and morphology, burrowing habits, size and depth below sea-level inhabited, temperature range, shell thickness, species richness and abundance of bivalve genera present in the Late Cretaceous of the Atlantic and Gulf Coastal Plain of North America. Non-parametric analysis revealed that there were no significant associations between any of these characteristics and survival across the Cretaceous-Tertiary boundary. This lack of selectivity may be due to varying local conditions, which favor different ecological characteristics in each area and produce no overall pattern of selectivity. It might also be indicative of the severity of this extinction on bivalves — differences in ecological habits may have been virtually irrelevant to survivorship through this event.     

Loss of Resilience, Crisis, and Institutional Change: Lessons from an Intensive Agricultural System in Southeastern Australia

Linked social-ecological systems in which surprise and crisis are interspersed with periods of stability and predictability are inherently difficult to manage. This condition, coupled with the legacies of past management actions, typically leaves policy and decision makers few options other than to incrementally adapt and reinforce the current trajectory of the system. Decision making becomes increasingly reactive and incremental as the system moves from one crisis to another. Eventually the system loses its capacity to cope with perturbations and surprise. Using a combination of dynamical-systems modeling and historical analysis, we studied a process of this kind as it developed in the Goulburn Broken Catchment in southeastern Australia over the past 150 years. Using the model to simulate trajectories of the biohydrological system, we correlate the state of the physical system to historical events and management action. We show how sequential management decisions have eroded the resilience of the system (its ability to cope with shocks and surprises) and reduced options for future change. Using the model in a forward-looking mode, we explore future management options and their implications for the resilience of the system.     

Processes Contributing to Resilience of Coastal Wetlands to Sea-Level Rise

The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to rising sea levels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-level rise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-level rise. We identified fundamental differences in how resilience is maintained across wetland community types, which have important implications for management activities that aim to restore or conserve resilient systems. We showed that the relative importance of surface and subsurface processes in controlling wetland surface elevation change differed between TFFWs and oligohaline marshes. The marshes had significantly higher rates of surface accretion than the TFFWs, and in the marshes, surface accretion was the primary contributor to elevation change. In contrast, elevation change in TFFWs was more heavily influenced by subsurface processes, such as root zone expansion or compaction, which played an important role in determining resilience of TFFWs to rising sea level. When root zone contributions were removed statistically from comparisons between relative sea-level rise and surface elevation change, sites that previously had elevation rate deficits showed a surplus. Therefore, assessments of wetland resilience that do not include subsurface processes will likely misjudge vulnerability to sea-level rise.     

Macrofaunal Functional Diversity Provides Resilience to Nutrient Enrichment in Coastal Sediments

The degradation of ecosystems is often associated with losses of large organisms and the concomitant losses of the ecological functions they mediate. Conversely, the resilience of ecosystems to stress is strongly influenced by faunal communities and their impacts on processes. Denitrification in coastal sediments is a process that may provide ecosystem resilience to eutrophication by removing excess bioavailable nitrogen. Here, we conducted a large-scale field experiment to test the effect of macrofaunal community composition on denitrification in response to two levels of nutrient enrichment at 28 sites across a biologically heterogeneous sandflat. After 7 weeks of enrichment, we measured denitrification enzyme activity (DEA) along with benthic macrofaunal community composition and environmental variables. We normalised treatment site specific DEA values by those in ambient sediments (DEA_CN) to reveal the underlying response across the heterogeneous landscape. Nutrient enrichment caused reductions in DEA_CN as well as functional changes in the community; these were both more pronounced under the highest level of nutrient loading (on average DEA_CN was reduced by 34%). The degree of suppression of DEA_CN following moderate nitrogen loading was mitigated by a key bioturbating species, but following high nitrogen loading (which reduced the key species density) the abundance and diversity of other nutrient processing species were the most important factors alleviating negative effects. This study provides a prime example of the context-dependent role of biodiversity in maintaining ecosystem functioning, underlining that different elements of biodiversity can become important as stress levels increase. Our results emphasise that management and conservation strategies require a real-world understanding of the community attributes that facilitate nutrient processing and maintain resilience in coastal ecosystems.