FACTORS THAT AFFECT ACTIVATED SLUDGE PHOSPHATE RELEASE1

The activated sludge process can remove significant amounts of phosphorus from sewage, but the removal efficiency is usually significantly reduced by the release of phosphate back to solution during subsequent treatment steps. This research presents a study of soluble phosphate release from activated sludge with emphasis on defining the factors that affect such release and the actual release mechanisms. Laboratory units were used for experimental purposes. The experiments were designed to study the relationship between soluble phosphate release and various environmental factors such as redox potential (ORP), dissolved oxygen (DO), pH, solids concentration, solids destruction, and sulfate salt addition. The effect of substrate utilization on phosphate uptake and the relationship between uptake characteristics and subsequent phosphate release were also studied. The results show that some phosphate storage occurs during aerobic substrate utilization. Following substrate utilization, activated sludge phosphate release is directly related to the amount of biological stress the organisms are subjected to, and the mechanism of release is primarily cell lysis. The phosphate released per unit sludge under anoxic conditions is relatively constant. Under normal environmental conditions, neither ORP or pH change have a significant affect on phosphate release.     

POLLUTIONAL ASPECTS OF PESTICIDES IN NATURAL STREAMS

The extensive use of synthetic organic pesticides in this country during the past twenty-five years has resulted in widespread pollution of our water resources. An obvious detrimental effect of such pollution has been observed in the numerous fish kills that have occurred. The most widely used pesticides, and the ones that have been implicated in the vast majority of the pollutional episodes, are the chlorinated hydrocarbon insecticides. These compounds, generally speaking, have almost no solubility in water, are subject to very slow microbial degradation if any at all, and are so resistent to natural degradation forces they can persist almost indefinitely in aqueous environments; characteristics that are all detrimental from a stream pollution standpoint. In addition, studies have shown that, as a group, the chlorinated hydrocarbons are more toxic to higher forms of aquatic life than other chemicals widely used for pest control. Because of these undesirable characteristics, present trends are to discontinue using these highly toxic, persistent compounds for pest control in outdoor areas. Legislation banning the sale of DDT has been introduced. Similar legislation controlling the use of several of the chlorinated hydrocarbon pesticides is probably the most effective way to reduce pollution.     

Welfare and Environmental Implications of Farmed Sea Turtles

Various captivity-related health problems have been described as arising in the farming of sea turtles at the Cayman Turtle Farm (CTF). Our study included a desktop review of turtle farming, direct onsite inspection at the CTF, assessment of visual materials and reports provided by investigators from the World Society for the Protection of Animals (WSPA), and a limited analysis of water quality for potential pathogens. In particular, we assessed physical and behavioural condition of animals for signs of stress, injury and disease. During the onsite inspection we identified three distinct signs of physical injury and disease, six distinct signs of abnormal and problematic arousal- and discomfort-related behaviour; and three distinct signs of normal quiescence- and comfort-related behaviour. On evaluation of evidence provided by the WSPA we identified ten distinct signs of physical injury and disease, and management- or genetic-related conditions; six distinct signs of abnormal and problematic arousal- and discomfort-related behaviour; and three distinct signs of normal quiescence- and comfort-related behaviour. We conclude that sea turtles at the CTF manifested important physical and behavioural signs that are indicative of problematic management and captivity-related stress, and the limitations of sea turtle adaptive plasticity in captivity. The problematic physical and behavioural signs, in our view, related to the inherent nature of intensive turtle propagation which in particular involves overt- and crypto-overcrowding and understimulating environments, and an associated failure to meet all the physical, biological and innate behavioural needs of sea turtles.     

Self-reported job burnout among female human service professionals

A sample of 135 female human service professionals completed the Maslach Burnout Inventory (MBI) and the Staff Burnout Scale for Health Professionals (SBS), along with measures of job satisfaction, role stress, self-esteem, alienation, and locus of control. Principal components factor analysis of this battery indicates considerable covariation of self-reported burnout with job dissatisfaction and perceived role stress, and moderate overlap with more general feelings of alienation and low self-esteem. Item factor analysis of the 22 MBI items resulted in two independent factors, one defined by the Emotional Exhaustion and Depersonalization items, the other by the Personal Accomplishment items. Item factoring of the SBS produced one large factor which was highly correlated with the MBI exhaustion-depersonalization factor. Implications of these findings for the construct validity of the MBI and SBS are discussed.     

Mature and old-growth riparian forests: structure, dynamics, and effects on Adirondack stream habitats.

Riparian forests regulate linkages between terrestrial and aquatic ecosystems, yet relationships among riparian forest development, stand structure, and stream habitats are poorly understood in many temperate deciduous forest systems. Our research has (1) described structural attributes associated with old-growth riparian forests and (2) assessed linkages between these characteristics and in-stream habitat structure. The 19 study sites were located along predominantly first- and second-order streams in northern hardwood-conifer forests in the Adirondack Mountains of New York (U.S.A.). Sites were classified as mature forest (6 sites), mature with remnant old-growth trees (3 sites), and old-growth (10 sites). Forest-structure attributes were measured over stream channels and at varying distances from each bank. In-stream habitat features such as large woody debris (LWD), pools, and boulders were measured in each stream reach. Forest structure was examined in relation to stand age using multivariate techniques, ANOVA, and linear regression. We investigated linkages between forest structure and stream characteristics using similar methods, preceded by information-theoretic modeling (AIC). Old-growth riparian forest structure is more complex than that found in mature forests and exhibits significantly greater accumulations of aboveground tree biomass, both living and dead. In-stream LWD volumes were significantly (alpha = 0.05) greater at old-growth sites (200 m3/ha) compared to mature sites (34 m3/ha) and were strongly related to the basal area of adjacent forests. In-stream large-log densities correlated strongly with debris-dam densities. AIC models that included large-log density, debris-dam density, boulder density, and bankfull width had the most support for predicting pool density. There were higher proportions of LWD-formed pools relative to boulder-formed pools at old-growth sites as compared to mature sites. Old-growth riparian forests provide in-stream habitat features that have not been widely recognized in eastern North America, representing a potential benefit from late-successional riparian forest management and conservation. Riparian management practices (including buffer delineation and restorative silvicultural approaches) that emphasize development and maintenance of late-successional characteristics are recommended where the associated in-stream effects are desired.     

Metal and Trace Element Burdens in Two Shorebird Species at Two Sympatric Wintering Sites in Southern California

In January and November, 1994, ten willets (Catoptrophorus semipalmatus) and ten black-bellied plovers (Pluvialis squatarola) were collected at a south-facing sandy beach at the North Island Naval Air Station (NASNI) and ten willets and three plovers were collected at the Tijuana Slough National Wildlife Refuge (TSNWR), 16 km to the southeast. Concentrations of 19 inorganic analytes were determined in the livers. Differences between sexes in diet or abilities to retain some analytes are indicated because male willets tend to have greater levels of Cd than females and male plovers tend to have greater levels of Fe, Hg, and Mn than females. Concentrations of Hg and Mg in willets decreased from January to November. If this decrease is a part of an annual cycle, then the birds may be acquiring those elements while at NASNI. The differences between sites shows higher levels of As and Se but lower levels of Mn in willets at NASNI while plovers have lower levels of Cu, Mg and Zn at NASNI. There were no correlations between Hg and Se concentrations in the livers of any sample group of birds.     

The political ecology of Yukon forestry: managing the forest as if people mattered

Over the past several decades a growing interest has emerged in the relationship between forest dependent communities and their use of non-timber forest resources (NTFR—i.e. berries, roots, barks). Motivated in large part by international concerns over the loss of biological and cultural diversity, efforts are now being made to conserve the world's remaining forests by repositioning NTFR to the forefront of the forest management process. Together with the Little Salmon Carmacks First Nation, we have undertaken an assessment that: 1) addresses the role of NTFR in fulfilling basic human necessities and well-being of community members, and 2) identifies the perceptual differences that exist among First Nation and non-First Nation community members regarding the security and future availability of forest resources. Based on our findings, we argue that if the true value of the forest is to be understood, and thus sustained, those involved in management must consider the full array of products and services the forest provides. Thus the conventional and over-simplified view that the forest is to provide primarily for commercial timber must be challenged in light of the multiplicity of values community members gain from forest use.     

Geographic shifts in the highland cooking banana (Musa spp., group AAA-EA) production in Uganda

Summary

Between 1970 and 1990 Uganda witnessed the decline of the highland cooking banana from traditional growing areas in the central region, coupled with crop expansion in the country's southwest. Apprehension that the factors leading to loss of sustainability in the central region may be replayed in extant production areas has raised concern about the future of the cooking banana in Uganda. Consequently, a multi-disciplinary study was conducted at nine central and six southwestern sites to document shifts in cooking banana production and to elucidate the causes behind these shifts.

Cooking banana production in central Uganda sites fell from 18% of total food crop and 7% of total cash crop production in the 1970s to 4% and 2%, respectively, in the 1990s. Farmers identified reduced labour availability and management, increasing pest pressure and declining soil nutrient status as the major causes of decline. On-farm verification confirmed farmers' observations: weevil levels were the highest yet found in Uganda, while foliar samples indicated deficiencies in magnesium, nitrogen, and potassium. Soil nutrient deficiencies, however, appear to be a direct outcome ofreduced management rather than ‘soil exhaustion’ as postulated by farmers.

In southwestern Uganda, the importance of the cooking banana as a cash crop has quadrupled since 1970. Banana first penetrated the region because of its ease of production and stability of yield. High yields attracted traders and urban market demand drove further crop expansion. With current market incentives, banana management standards have been high. Under current levels of management, it is unlikely that farmers in southwestern Uganda will experience a similar process of decline as that which occurred in the central region. However, concern remains aboqt lack of replenishment of nutrients leaving the farm in the form of fruits sold for market, a nutrient loss which may eventually lead to non-sustainability of the cropping system.     

Influences of divergent behavioral strategies upon risk allocation in juvenile flatfishes

Animals balance feeding and anti-predator behaviors at various temporal scales. When risk is infrequent or brief, prey can postpone feeding in the short term and temporally allocate feeding behavior to less risky periods. If risk is frequent or lengthy, however, prey must eventually resume feeding to avoid fitness consequences. Species may exhibit different behavioral strategies, depending on the fitness tradeoffs that exist in their environment or across their life histories. North Pacific flatfishes that share juvenile rearing habitat exhibit a variety of responses to predation risk, but their response to risk frequency has not been examined. We observed the feeding and anti-predator behaviors of young-of-the-year English sole (Parophrys vetulus), northern rock sole (Lepidopsetta polyxystra), and Pacific halibut (Hippoglossus stenolepis)—three species that exhibit divergent anti-predator strategies—following exposure to three levels of predation risk: no risk, infrequent (two exposures/day), and frequent (five exposures/day). The English sole responded to the frequent risk treatment with higher feeding rates than during infrequent risk, following a pattern of behavioral response that is predicted by the risk allocation hypothesis; rock sole and halibut did not follow the predicted pattern, but this may be due to the limited range of treatments. Our observations of unique anti-predator strategies, along with differences in foraging and species-specific ecologies, suggest divergent trajectories of risk allocation for the three species.