Association of brook trout and Oncorhynchus spp. with large wood jams in a Lake Superior tributary in a northern old‐growth watershed

Wood in streams functions as fish habitat, but relationships between fish abundance (or size) and large wood in streams are not consistent. One possible reason for variable relationships between fish and wood in streams is that the association of fish with wood habitat may depend on ecological context such as large‐scale geomorphology. We studied the relationship between salmonid assemblages and large wood jams (LWJ) in four settings that differed geomorphically at the scale of the stream corridor along a tributary to Lake Superior in old‐growth conifer–hardwood forest in northern Michigan. The focal fish species of this study were brook trout (Salvelinus fontinalis), which were wild in the stream. Relocation efforts for coaster brook trout (an adfluvial life history variant of brook trout) were ongoing in the study stream. We measured fish abundance and length in pairs of pools of similar size and substrate, but varying in the presence of LWJ; this allowed us to evaluate associations of fish simply with the presence of LWJ rather than with other channel or flow‐shaping functions of LWJ. The length of Oncorhynchus spp. and young introduced brook trout was not strongly correlated with LWJ presence; however, the presence of LWJ in pools was positively correlated with larger wild brook trout. We also found that the correspondence of LWJ with the abundance of salmonids appears to be moderated by the presence of alternative habitat in this relatively natural, old‐growth forest stream.     

Economics of Sustainable Intensification of Aquaculture: Evidence from Shrimp Farms in Vietnam and Thailand

There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm‐level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm‐level natural resource use efficiency. Additional research that incorporates economic analysis into on‐farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.     

Survival and behavioural responses of cool and warm water fish sedated with AQUI‐S®20E (10% eugenol) at high loading densities

This study evaluated the effects of AQUI‐S^®20E (10% eugenol) sedation on the survival and behaviour of yellow perch Perca flavescens (Mitchill) and Nile tilapia Oreochromis niloticus L. held in high loading densities. Fish were held in 0–300 mg L^?1 AQUI‐S^®20E (0–30 mg L^?1 eugenol) for up to 10 h in static tanks. At 17°C, yellow perch held in 200 and 300 mg L^?1 AQUI‐S^®20E were lightly sedated for up to 7 h. Yellow perch at 200 and 300 mg L^?1 AQUI‐S^®20E also had >95% mean survival 7‐days post exposure using loading densities up to 360 g L^?1. Nile tilapia were only sedated for ≤3 h in concentrations up to 300 mg L^?1 at 22°C and had >90% mean survival at loading densities ≤480 g L^?1. Ammonia in tanks increased significantly as loading density increased, but treatment with AQUI–S^®20E did not reduce ammonia accumulation. Results suggest that AQUI–S^®20E was effective to sedate yellow perch and Nile tilapia at high loading densities, but sedation varied with loading density and species.     

Burgess shale faunas and the cambrian explosion

Soft-bodied marine faunas from the Lower and Middle Cambrian, exemplified by the Burgess Shale of British Columbia, are a key component in understanding the major adaptive radiations at the beginning of the Phanerozoic ("Cambrian explosion"). These faunas have a widespread distribution, and many taxa have pronounced longevity. Among the components appear to be survivors of the preceding Ediacaran assemblages and a suite of bizarre forms that give unexpected insights into morphological diversification. Microevolutionary processes, however, seem adequate to account for this radiation, and the macroevolutionary patterns that set the seal on Phanerozoic life are contingent on random extinctions. They weeded out the morphological spectrum and permitted rediversification among surviving clades. Although the predictability of which clades will play in successive acts of the Phanerozoic theater is low, at least the outlines of the underlying ecological plot are already clear from the opening of the drama.     

Circadian periodicity in susceptibility to lidocaine hydrochloride

Separate groups of mice standardized in an alternating 12-hour-light,12-hour-dark regimen were treated with lidocaine hydrochloride every 3 hours over a 24-hour period. The results indicate a quantitative circadian periodicity with maximal convulsant activity at 2100 hours which was approximately a fourteen fold increase over the values observed at 1500 hours.     

Identification of interleukin-1 in equine osteoarthritic joint effusions

Interleukin-1 (IL-1) is a protein secreted by stimulated cells of the monocyte-macrophage line, which has a number of important biologic activities. Interleukin-1 has been implicated in the induction and augmentation of the pathologic processes involved in arthritis and articular cartilage destruction. Horses develop osteoarthritis with a frequency and degree of severity similar to human beings. To further document the similarity of the osteoarthritic process in people and horses, the synovial fluid from 5 horses with clinical osteoarthritis was tested for IL-1 bioactivity. Interleukin-1 activity was found in all tested synovial fluids. Upon column chromatography, the synovial fluid-derived factor had a molecular weight consistent with that of IL-1 in other mammalian species. Ion exchange chromatography of osteoarthritic synovial fluid revealed the principal peaks of bioactivity to be in the fractions with isoelectric points of 7.2, 5.4, and 4.7, which are characteristic of IL-1. A considerable degree of homology between human and equine IL-1 was demonstrated by the cross hybridization of human IL-1 beta cDNA probe with RNA derived from IL-1-producing equine adherent monocytes. These results indicate that equine IL-1 is in all of the osteoarthritic equine joints tested and that equine IL-1 has many of the characteristics of IL-1 isolated from other species.     

Management and environmental factors associated with annual sow culling rate: A path analysis

The relationships between management and environmental factors and annual sow culling rate were investigated in 152 Minnesota swine breeding herds. Data were obtained through a postal survey. A general path model was hypothesized to describe relationships among variables. Multiple least-squares and logistic regressions were used to test the statistical significance of pathways. The associations between the indepen variables and the annual culling rate (ACR) were decomposed into direct, indirect, and common cause associations.

The mean ACR of the 152 farms was 39% ± 2% rm(SE). Using path-analysis techniques, only the type of flooring during gestation, the size of the herd and the lactation length had a direct relationship with ACR. The type of housing during gestation and farrowing were related indirectly to the ACR. Their association was mediated by the type of flooring during gestation and the weaning age. Herds housing their sows in total confinement during gestation were most likely to keep them on partially or totally slatted floors which were associated with a higher ACR. Sows kept in crates during the farrowing period were more likely to have a short lactation length which was associated with a higher ACR.

Most associations between the use of preventive veterinary services and the ACR were due to association with other variables. Herds using veterinary preventive medicine were most likely to have a short lactation length, a large number of females, and sows housed in total confinement during gestation and in crates during the farrowing period. All of the aforementioned variables were associated with a high ACR.

The relationships of other management and environmental factors with the ACR were due to common cause associations. These factors included having the sows individually identified, using a more comprehensive recording system, mainly a hand-mating system, testing regularly for pregnancy and housing sows in total confinement during the breeding period. The strongest associations with the ACR were the type of flooring during gestation and the size of the herd.     

Eosinophilic dermatitis with edema in nine dogs, compared with eosinophilic cellulitis in humans.

A unique eosinophilic dermatitis with edema in dogs is characterized by extremely erythematous coalescing macules and plaques with associated edema, and is similar to eosinophilic cellulitis (Wells' syndrome) in humans. Histopathologic features include a profound eosinophilic dermal infiltrate, focal areas of collagen fiber degeneration surrounded by eosinophils (flame figures), dilated vessels, and dermal edema. Etiopathogenesis is unknown, but a hypersensitivity reaction to medications, arthropod bites, or other foreign antigens is suspected.