Are carrion resources as scarce as we think?

As humans, we tend to focus on the greener, living aspects of the environment and often forget the other side filled with death and decay. Carrion, the decaying flesh of dead animals, is a nutrient-rich, spatially patchy ephemeral resource, relied upon as a food by a variety of organisms. As a patchy and finite resource, carrion\u27s availability and distribution are unpredictable. Some factors that can influence the availability and production of carrion include predation, old age, and anthropogenic causes. Feeding on these resources are many scavengers, both facultative and obligate, vertebrate and arthropod. A primary consumer of carrion are blow flies (Diptera: Calliphoridae); often the first organisms to arrive at a decaying carcass. There are at least 11 blow fly species in SW Ontario, all requiring carrion resources for immature larval development yet manage to co-exist on what has been stated to be a rare, patchy ephemeral resource. My thesis will be testing the hypothesis that carrion resources are not as rare as previously considered and may be predicted using land-use attributes. Specifically, I will be using geospatial technology to model land-use attributes in the urban and rural areas of Essex County, Ontario. Some distinct elements of land-use being examined include farm, residential, commercial, and conservation. Following this, sites will be randomly chosen to trap blow flies across the gradient of land-use predicted to influence carrion availability, measuring blow fly species diversity along this gradient. This knowledge furthers our understanding of blow fly co-existence across a spatial and temporal landscape

Thermocline management of stratified tanks for heat storage

Stratified tanks are useful for maximising the thermal energy efficiency of non-continuous and semi-continuous processes. Liquid at two or more dissimilar temperatures is stored within the same tank to provide a buffer for variations in heating and cooling loads. Control of the thermocline between the hot and cold fluid regions is needed to minimise thermocline growth and maximise operation of the storage tank. An experimental programme using a scale model of an industrial stratified tank (aspect ratio 3.5) and Perspex tank (aspect ratio 8.2) is reported. The behaviour and growth of the hot-cold thermocline under various operating conditions is presented. A siphoning method to re-establish the thermocline without interrupting the use of the tank is tested. Siphoning of the thermocline region from either 20%, 50% or 80% of the tank height is an effective strategy for uninterrupted interface re-establishment. However, the rate and position of siphoning and the load balance of the exit streams are critical variables for minimising the time for effective re-establishment of the two temperature zones

Bacteria Mediate Oviposition by the Black Soldier Fly, \u3ci\u3eHermetia illucens\u3c/i\u3e (L.), (Diptera: Stratiomyidae)

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Bacteria Mediate Oviposition by the Black Soldier Fly, Hermetia illucens (L.), (Diptera: Stratiomyidae)

There can be substantial negative consequences for insects colonizing a resource in the presence of competitors. We hypothesized that bacteria, associated with an oviposition resource and the insect eggs deposited on that resource, serve as a mechanism regulating subsequent insect attraction, colonization, and potentially succession of insect species. We isolated and identified bacterial species associated with insects associated with vertebrate carrion and used these bacteria to measure their influence on the oviposition preference of adult black soldier flies which utilizes animal carcasses and is an important species in waste management and forensics. We also ascertained that utilizing a mixture of bacteria, rather than a single species, differentially influenced behavioral responses of the flies, as did bacterial concentration and the species of fly from which the bacteria originated. These studies provide insight into interkingdom interactions commonly occurring during decomposition, but not commonly studied

Density, Temperature, and Comingled Species Affect Fitness within Carrion Communities: Coexistence in Phormia regina and Lucilia sericata (Diptera: Calliphoridae)

Blow fly (Diptera: Calliphoridae) interactions vary between competition and facilitation. Female blow flies engage in aggregated egg-laying, resulting in larval feeding masses differing in density and species composition. Numerous species are abundant within the same season, and some oviposit near or directly on eggs of other species, modifying their oviposition location choice depending on the presence or absence of other species. The ability to coexist on carrion, a temporary resource, was successfully attributed to resource, spatial, and temporal heterogeneity. Despite these broad categorizations, the specific mechanisms of coexistence within blow fly communities require further investigation. This study investigates variation in temperature and larval density as potential mechanisms of coexistence between two forensically important blow fly species: Lucilia sericata Meigen and Phormia regina Meigen (Diptera: Calliphoridae). Larval density, species ratio mix, and ambient temperature during development were manipulated in the presence of conspecifics and heterospecifics in the laboratory, and the fitness of each species was measured. In heterospecific treatments, the survival and body size of P. regina increased even at high ambient temperatures. In contrast, the survival of L. sericata remained unaffected by density or presence of heterospecifics, whereas body size increased in L. sericata-dominated heterospecific treatments depending on temperature and density. The negative effects of density were observed at high ambient temperatures, suggesting that density impacts are a function of ambient temperature. Overall, species coexistence was dependent on temperature, which mediated the outcome of species interactions

Density, Temperature, and Comingled Species Affect Fitness within Carrion Communities: Coexistence in <i>Phormia regina</i> and <i>Lucilia sericata</i> (Diptera: Calliphoridae)

Blow fly (Diptera: Calliphoridae) interactions vary between competition and facilitation. Female blow flies engage in aggregated egg-laying, resulting in larval feeding masses differing in density and species composition. Numerous species are abundant within the same season, and some oviposit near or directly on eggs of other species, modifying their oviposition location choice depending on the presence or absence of other species. The ability to coexist on carrion, a temporary resource, was successfully attributed to resource, spatial, and temporal heterogeneity. Despite these broad categorizations, the specific mechanisms of coexistence within blow fly communities require further investigation. This study investigates variation in temperature and larval density as potential mechanisms of coexistence between two forensically important blow fly species: Lucilia sericata Meigen and Phormia regina Meigen (Diptera: Calliphoridae). Larval density, species ratio mix, and ambient temperature during development were manipulated in the presence of conspecifics and heterospecifics in the laboratory, and the fitness of each species was measured. In heterospecific treatments, the survival and body size of P. regina increased even at high ambient temperatures. In contrast, the survival of L. sericata remained unaffected by density or presence of heterospecifics, whereas body size increased in L. sericata-dominated heterospecific treatments depending on temperature and density. The negative effects of density were observed at high ambient temperatures, suggesting that density impacts are a function of ambient temperature. Overall, species coexistence was dependent on temperature, which mediated the outcome of species interactions

Testing Different Search Methods for Recovering Scattered and Scavenged Remains

Vertebrate scavengers are primary mechanisms for scatter and disarticulation of human remains in rural habitats. Because recovery of the body can be hampered by the degree of scatter due to scavengers, the methods used to search for body parts will influence how much is found and the length of time taken to recover the body. We compared the frequency of scavenging by vertebrates in two different habitats, a deciduous forest and a tall grass meadow, and measured the time taken to search for scattered remains within a designated search area using four methods. Freshly killed 23 kg pigs were placed in either a forest or tall grass meadow habitat, and scavenging by vertebrates was observed over a 5–6 day period. Subsequently, the link, line, zone, and spiral methods were used to search for remains within a 21 m2 search area. Three of 5 pigs in the forest and 4 of 5 pigs in the meadow habitat were scavenged by a variety of vertebrates. Mean time to search the designated area around each pig differed between the forest and the meadow, but not by search method. Mobility within each habitat likely explains the difference in search times, and also accounts for some of the variability between search methods