The Complementary Niches of Anthropocentric and Biocentric Conservationists

A divergence of values has become apparent in recent debates between conservationists who focus on ecosystem services that can improve human well‐being and those who focus on avoiding the extinction of species. These divergent points of view fall along a continuum from anthropocentric to biocentric values, but most conservationists are relatively closer to each other than to the ends of the spectrum. We have some concerns with both positions but emphasize that conservation for both people and all other species will be most effective if conservationists focus on articulating the values they all share, being respectful of divergent values, and collaborating on common interests. The conservation arena is large enough to accommodate many people and organizations whose diverse values lead them to different niches that can, with good will and foresight, be far more complementary than competitive. Los Nichos Complementarios de los Conservacionistas Antropocéntricos y Biocéntricos     

DISCHARGE AND SUSPENDED SEDIMENT PATTERNS OF AN INTERMITTENT COLD DESERT STREAM1

Sage Creek in south‐central Wyoming is listed as impaired by the U.S. Environmental Protection Agency (USEPA) due to its sediment contribution to the North Platte River. Despite the magnitude of sediment impacts on streams, little research has been conducted to characterize patterns of sediment transport or to model suspended sediment concentration in many arid western U.S. streams. This study examined the relationship between stream discharge and suspended sediment concentration near the Sage Creek and North Platte River confluence from 1998 through 2003. The objectives were to determine patterns of stream discharge and suspended sediment concentration, produce a sediment prediction model, and compare sediment concentrations for the six‐year period. Stream discharge and suspended sediment transport responded rapidly to convective storms and spring runoff events. During the study period, events exceeding 0.23 m³/s accounted for 92 percent of the sediment load, which is believed to originate from erodible headwater uplands. Further analysis of these data indicates that time series modeling is superior to simple linear regression in predicting sediment concentration. Significant increases in suspended sediment concentration occurred in all years except 2003. This analysis suggests that a six‐year monitoring record was insufficient to factor out impacts from climate, geology, and historical sediment storage.     

Why geodiversity matters in valuing nature's stage

Geodiversity—the variability of Earth's surface materials, forms, and physical processes—is an integral part of nature and crucial for sustaining ecosystems and their services. It provides the substrates, landform mosaics, and dynamic physical processes for habitat development and maintenance. By determining the heterogeneity of the physical environment in conjunction with climate interactions, geodiversity has a crucial influence on biodiversity across a wide range of scales. From a literature review, we identified the diverse values of geodiversity; examined examples of the dependencies of biodiversity on geodiversity at a site‐specific scale (for geosites <1 km² in area); and evaluated various human‐induced threats to geosites and geodiversity. We found that geosites are important to biodiversity because they often support rare or unique biota adapted to distinctive environmental conditions or create a diversity of microenvironments that enhance species richness. Conservation of geodiversity in the face of a range of threats is critical both for effective management of nature's stage and for its own particular values. This requires approaches to nature conservation that integrate climate, biodiversity, and geodiversity at all spatial scales.     

Clutch size as an optimal foraging problem for insects

Summary Many insects oviposit on food patches (e. g., hosts) that represent a finite resource. Competition for food may occur among the developing progeny with the effect of reducing their survivorship, size, and/or some other aspect of fitness. Here a simple, but general, equation is given that captures tures some of the possible relationships between the number of progeny on a host and their fitness. This in turn specifies the clutch size that maximizes the fitness of a female ovipositing on a single host (the Lack clutch size). The equation is then used in an optimal foraging type model to specify optimal clutch sizes when a female searches for and oviposits on a series of hosts. The model makes three general predictions: (1) for a constant host size (or value), optimal clutch size varies directly with the inter-host search time, (2) for a constant search time, optimal clutch size varies directly with host value, and, (3) females should never lay more than the Lack clutch size. The model is then extended to include optimal clutch size in superparasitism.     

Feeding and reproductive behaviour and their effect on catchability of the spanner crab Ranina ranina

The behaviour of 16 adult (8 male and 8 female) spanner crabs (Ranina ranina), collected off southern Queensland, Australia, was monitored continuously in captivity by closed-circuit television for fifteen months from September 1982. Spanner crabs spent most of the time buried in the substrate, emerging mainly only when food became available. They remained emerged for twice as long on feeding days as on days without food. Females responded significantly faster than males to the presence of food. Response was slowest in October and November. There was no correlation between temperature and response time. The average feeding time was 2.0 min (SE=0.12), with no significant difference between males and females. Crabs without food were aggressive towards crabs with food, which sometimes led to fighting and wounding. These interactions also could result in food being transferred from one individual to another. When males interacted, food was transferred more often than when either females, or males and females interacted. Around moulting, male crabs did not feed for 52 d (SE=9.0) and females for 22 d (SE=2.2). This habit would reduce the frequency with which newly moulted crabs are caught in the baited tangle nets used by commercial fishermen. In mating interactions, copulation was always initiated by the males. Males dug up other crabs but, apparently unable to distinguish the sex of these individuals, attempted copulation with either sex. The majority of copulations occurred between midday and midnight and in the period August to December. The frequency of copulations with a female increased 10 d before she extruded eggs, after which it dropped to zero for the following 41 to 50 d. Eggs were carried for 39 to 44 d in the period September to November. The females remained emerged for long periods before extruding their eggs, but the period shortened immediately afterwards. This behaviour would lead to low catchability of ovigerous females. Because females respond more rapidly than males to a food stimulus, they may be more catchable in baited nets than are males. It is concluded that seasonal changes in the behaviour of spanner crabs could affect the number caught by baited tangle nets and may influence the sex ratio in catches.     

Prehistoric Decline in Freshwater Mussels Coincident with the Advent of Maize Agriculture

Abstract:  During late prehistory, high population densities and intensive agricultural practices of Native American societies had profound effects on the pre-Columbian landscape. The degree to which Native American land use affected aquatic ecosystems is unknown. Freshwater mussels are particularly sensitive harbingers of modern-day ecosystem deterioration. We used data from prehistoric Native American shell middens to examine prehistoric trends in abundance of freshwater mussels of the genus Epioblasma in North America during the last 5000 years. The relative abundance of Epioblasma declined steadily during this period, a result that could be explained either by an increase in human impacts to streams or by long-term climatic changes unrelated to human activities. The rate of decline of Epioblasma increased significantly, however, after the advent of large-scale maize agriculture in the southeastern United States about 1000 years before the present. Our results suggest that human land-use activities in prehistory caused changes in freshwater mussel communities that were lower in magnitude but similar in direction to changes caused by recent activities.     

Thermal impact evaluation for brunner Island steam electric station: Toward a more realistic assessment

A realistic approach to thermal impact assessment is presented which employs a two-dimensional thermal plume model, a large data base for river flow and temperature, and accounts for nonuniform spatial distribution of habitats and seasonal differences in fish behavior. The end result portrays real effects of the thermal impact rather than an artificially constructed worst-case scenario.