COMPUTED TOMOGRAPHY OF THE LUNG OF HEALTHY SNAKES OF THE SPECIES PYTHON REGIUS, BOA CONSTRICTOR, PYTHON RETICULATUS, MORELIA VIRIDIS, EPICRATES CENCHRIA, AND MORELIA SPILOTA

Thirty-nine healthy boid snakes representing six different species ( Python regius, Boa constrictor, Python reticulatus, Morelia viridis, Epicrates cenchria , and Morelia spilota ) were examined using computed tomography (CT) to characterize the normal appearance of the respiratory tissue. Assessment was done subjectively and densitometry was performed using a defined protocol. The length of the right lung was calculated to be 11.1% of the body length, without a significant difference between species. The length of the left lung in proportion to the right was dependent on the species examined. The most developed left lung was in P. regius (81.2%), whereas in B. constrictor , the left lung was vestigial or absent (24.7%). A median attenuation of −814.6 HU and a variability of 45.9 HU were calculated for all species with no significant difference between species. Within the species, a significantly higher attenuation was found for P. regius in the dorsal and cranial aspect of the lung compared with the ventral and caudal part. In B. constrictor , the reduced left lung was significantly hyperattenuating compared with the right lung. Results of this study emphasize the value of CT and provide basic reference data for assessment of the snake lung in these species.     

Do Development Impact Fees Reduce the Rate of Residential Development?

ABSTRACT Over the last twenty-five years local governments in the United States and Canada have increasingly used impact fees and other development exactions as methods of financing capital and infrastructure requirements mandated by residential growth. While several studies have examined the effects of impact fees on housing and land prices, rigorous empirical analysis of their effects on residential development is lacking. In this paper a sample of all municipalities in DuPage County, Illinois from 1977 through 1992 is used to examine the effects of impact fees on the rate of residential development. The empirical results show that impact fees reduce rates of residential development by more than 25 percent.     

Basin-scale advection and population persistence of Calanus finmarchicus

Advection of Calanus finmarchicus in the eastern North Atlantic was analysed using a particle-tracking model based on the Hamburg Shelf Ocean Model (HAMSOM). Quasi-static seasonal mean flowfields were simulated, archived and interpolated to represent a climatological-mean annual cycle. Particles had a simple prescribed depth profile comprising deep overwintering, spring ascent, a shallow-water phase followed by descent to overwintering depth. Export routes for C. finmarchicus from the model area were identified to the south of Greenland and to the north of the Lofoten Basin. Self-sustaining overwintering areas were identified by observing how closely particles returned to their origins after one calendar year. Several such areas were found, notably in the Norway and Lofoten Basins, and in the Færoe–Shetland Channel. The particle tracking was run for up to 10 years to demonstrate persistence of these cycles. Known features of the winter and summer distributions of C. finmarchicus were reproduced by the model. The success of the HAMSOM in simulating both the shallow and deep circulation of the eastern North Atlantic and Norwegian Sea was critical to the identification of these spatio-temporal cycles of C. finmarchicus.     

Ocean scale hypoxia‐based habitat compression of Atlantic istiophorid billfishes

Oxygen minimum zones (OMZs) below near‐surface optimums in the eastern tropical seas are among the largest contiguous areas of naturally occurring hypoxia in the world oceans, and are predicted to expand and shoal with global warming. In the eastern tropical Pacific (ETP), the surface mixed layer is defined by a shallow thermocline above a barrier of cold hypoxic water, where dissolved oxygen levels are ≤3.5 mL L^?1. This thermocline (～25–50 m) constitutes a lower hypoxic habitat boundary for high oxygen demand tropical pelagic billfish and tunas (i.e., habitat compression). To evaluate similar oceanographic conditions found in the eastern tropical Atlantic (ETA), we compared vertical habitat use of 32 sailfish (Istiophorus platypterus) and 47 blue marlin (Makaira nigricans) monitored with pop‐up satellite archival tags in the ETA and western North Atlantic (WNA). Both species spent significantly greater proportions of their time in near‐surface waters when inside the ETA than when in the WNA. We contend that the near‐surface density of billfish and tunas increases as a consequence of the ETA OMZ, therefore increasing their vulnerability to overexploitation by surface gears. Because the ETA OMZ encompasses nearly all Atlantic equatorial waters, the potential impacts of overexploitation are a concern. Considering the obvious differences in catchability inside and outside the compression zones, it seems essential to standardize these catch rates separately to minimize inaccuracies in stock assessments for these species. This is especially true in light of global warming, which will likely exacerbate future compression impacts.     

Thermal habitat of striped bass (Morone saxatilis) in coastal waters of northern Massachusetts,USA, during summer

Striped bass, Morone saxatilis, were captured and released with temperature‐measuring data storage tags in Salem Sound, Massachusetts, to collect data on their thermal preferences in coastal and marine waters and to identify environmental factors that may influence temperatures experienced during their summer residence. Striped bass recaptured during summer of 2006 (21 of 151 releases) experienced a wide range of temperatures (6.5–28.0°C) while at‐large for 1–53 days. Overall mean temperature and standard deviation selected by striped bass recaptured in Salem Sound during the longest commonly‐shared duration of time (3–12 July) were 17.8 and 3.57°C, respectively. Comparison of temperature data between fish and 13 vertical arrays in Salem Sound revealed that striped bass experienced higher and more variable temperatures, and that daily changes in temperature actually experienced were unrelated to daily changes in surrounding ambient temperature. Regular cyclical changes in temperature of all striped bass and vertical arrays were identified as influences of the local tide, which contributed about a 2°C change in temperature, on average, over the complete cycle. Most striped bass appeared to limit their activities to depths shallower than the lower limit of the thermocline, above which temperatures generally exceed 9.0°C in Salem Sound. Therefore, it is likely that the vertical distribution of striped bass is restricted by the low temperatures below this depth. An implication of this finding is that the spatial distribution of striped bass may be defined coarsely by knowledge of the distribution of temperature in coastal areas.