Evaluating Effects of Everglades Restoration on American Crocodile Populations in South Florida Using a Spatially-Explicit, Stage-Based Population Model

The distribution and abundance of the American crocodile (Crocodylus acutus) in the Florida Everglades is dependent on the timing, amount, and location of freshwater flow. One of the goals of the Comprehensive Everglades Restoration Plan (CERP) is to restore historic freshwater flows to American crocodile habitat throughout the Everglades. To predict the impacts on the crocodile population from planned restoration activities, we created a stage-based spatially explicit crocodile population model that incorporated regional hydrology models and American crocodile research and monitoring data. Growth and survival were influenced by salinity, water depth, and density-dependent interactions. A stage-structured spatial model was used with discrete spatial convolution to direct crocodiles toward attractive sources where conditions were favorable. The model predicted that CERP would have both positive and negative impacts on American crocodile growth, survival, and distribution. Overall, crocodile populations across south Florida were predicted to decrease approximately 3 % with the implementation of CERP compared to future conditions without restoration, but local increases up to 30 % occurred in the Joe Bay area near Taylor Slough, and local decreases up to 30 % occurred in the vicinity of Buttonwood Canal due to changes in salinity and freshwater flows.

Seasonal activity and road mortality of the snakes of the Pa-Hay-Okee wetlands of Everglades National Park

The current study describes the composition and activity of the snake community of the Pa-hay-okee wetlands of Everglades National Park. The study was conducted from January 1987 to January 1989. Sixteen species were observed, with Thamnophis sauritus, Thamnophis sirtalis, Nerodia fasciata pictiventris, and Agkistrodon piscivorus representing 90.2% of the total sample. The seasonal distribution and activity of the snakes were closely related to fluctuations in the water table. Most activity occurred in the winter months as snakes migrated west following the drying water edge of Shark River Slough. Seventy percent of all snakes observed during this study were either injured or dead on the road. Over 50% of annual mortality occurred during migration. The impact that road mortality is having on the local snake community cannot be ignored. Management options are provided to minimize loss. A comparison is made to the snake community of the Long Pine Key Region of Everglades National Park.

Surface characteristics and metazoa occurrence at ice station PS67/006-1 during POLARSTERN cruise ANT-XXII/2 (Nov 2004-Jan 2005)

The surface and sub-ice layer habitats and their metazoan fauna were studied on a drifting pack-ice floe in the western Weddell Sea from 29 November 2004 to 1 January 2005 during the "Ice Station POLarstern" (ISPOL). Flooding of the floe occurred at some places, and the establishment of surface layers with a brownish colour due to growing algae was observed at several sampling sites. The average surface-layer temperature, brine salinity and brine volume were -1.4 °C, 25.3 and 54%, respectively. The temperature-salinity relationship in the surface layer was seldom at equilibrium conditions. Chlorophyll a (Chl a) concentrations in the brine varied between 1.0 and 53.5 µg /L. Surface-layer thickness, salinity, Chl a concentration and copepod abundances were generally higher at the edge of the floe than in the inner part. The sympagic copepod species Drescheriella glacialis/racovitzai and Stephos longipes, with abundances ranging between 0 and 3830 ind/L (median: 2 ind/L) and 0 and 1293 ind/L (median: 4 ind/L), respectively, were the dominant members of the surface-layer meiofauna. Their populations consisted mainly of adults and early naupliar stages, which points to an active reproduction of these species within the surface layer. Other taxa found in the surface layer were undetermined turbellarians, the gastropod Tergipes antarcticus, and, for the first time, the ctenophore Callianira antarctica, and the amphipods Eusirus antarcticus and Eusirus tridentatus. During the course of our study, slight melting at the ice underside took place, releasing sympagic organisms to the water column. Chl a concentrations in the sub-ice water layer were very low (0.1-0.5 µg /L), except for 25 December when the Chl a concentration at 0 m depth increased to 2.3 µg /L. The most dominant sympagic copepod species found in the sub-ice layer was Ectinosoma sp., with abundances ranging between 1 and 599 ind/m**3 (median: 25 ind/m**3). Other sympagic copepod species occurring regularly in this habitat were D. glacialis/racovitzai, Diarthrodes cf. lilacinus, Idomene antarctica and S. longipes. All of these sympagic species were generally found in higher abundances at 0 m depth underneath the ice than at 5 m depth, in contrast to pelagic copepod species that occurred more frequently at 5 m depth. Niche separation and probable life-cycle strategies of dominant sympagic metazoans are discussed.

Pollen and macrofossil profiles from six cores in Illinois, U.S.A

Pollen analysis of Wisconsinan sediments from eleven localities in northern and central Illinois, combined with the results of older studies, allows a first general survey of the vegetational changes in Illinois during the last glaciation. In the late Altonian (after 40,000 B.P.), pine was already the most prevalent tree type in northern Illinois. Probably because of the influence of the last Altonian ice advance to northern Illinois, pine migrated to the south and reached south-central Illinois, which was at that time a region of prairie, with oak and hickory trees in favorable sites. Likewise in the late Altonian, spruce appeared in northern Illinois. Spruce also expanded its area to the south during the Wisconsinan, reaching south-central Illinois only after 21,000 B.P., in the early Woodfordian. Deciduous trees (predominantly oak) were present in south-central Illinois throughout the Wisconsinan. Their prevalence decreased to the north. The vegetation during the different subdivisions of the last glacial period in Illinois was approximately as follows: Late Altonian: Pine/spruce forest with some deciduous trees in northern and central Illinois; prairie and oak/hickory stands in south-central Illinois; immigration of pine. Farmdalian: Pine/spruce forest in central Illinois; deciduous trees and pine in south-central Illinois, with areas of open vegetation, perhaps similar to the present-day transition of prairie to forest in the northern Great Plains. Woodfordian: Northern and central Illinois ice covered; in south central Illinois, spruce and oak as dominant tree types, but also pine and grassland. During the Woodfordian, pine and spruce disappeared again from south-central Illinois, and oak/hickory forest and prairie again prevailed. The ice-free areas of northern Illinois become populated temporarily with spruce, but later there is proof of deciduous forest in this region. Pollen investigations in south-central Illinois have shown convincingly that deciduous trees could survive relatively close (less than 60 km) to the ice margin. Therefore the frequently presented view that arctic climatic conditions prevailed in North America during the last glaciation far south of the ice margin can be refuted for the Illinois area, confirming the opinion of other authors resulting from investigations of fossil mollusks and frost-soil features. The small number of localities investigated still permits no complete reconstruction of the vegetation zones and their possible movements in Illinois. During the Altonian and Farmdalian in Illinois, a vegetational zonation probably existed similar to that of today in North America. As the ice pushed southward as far as 39° 20' N. lat in the early Woodfordian, this zonation was apparently broken up under the influence of a relatively moderate climate. In any case, the Vandalia area, which was only about 60 km south of the ice, was at that time neither in a tundra zone nor in a zone of boreal coniferous forest.

Stock assessment of whaler and hammerhead sharks (Carcharhinidae and Sphyrnidae) in Queensland

This stock assessment provides detailed results for the most common sharks encountered by Queensland commercial fishers. These sharks come from the whaler (Carcharhinidae) and hammerhead (Sphyrnidae) families and comprise sharpnose sharks (Rhizoprionodon taylori and R. oligolinx), the milk shark (R. acutus), the creek whaler (Carcharhinus fitzroyensis), the hardnose shark (C. macloti), the spot-tail shark (C. sorrah), the Australian blacktip shark (C. tilstoni), the common blacktip shark (C. limbatus), the spinner shark (C. brevipinna), bull and pigeye sharks (C. leucas and C. amboinensis), the winghead shark (Eusphyra blochii), the scalloped hammerhead (Sphyrna lewini) and the great hammerhead (S. mokarran). Reef sharks were excluded because fishery observer data indicated that they were largely spatially segregated from sharks caught in the inshore net fisheries. The three common species of reef sharks in Queensland, which are all whaler sharks, are the grey reef shark Carcharhinus amblyrhynchos, the blacktip reef shark C. melanopterus and the whitetip reef shark Triaenodon obesus.

Nesting biology of the fungus growing ants Mycetarotes Emery (Attini, Formicidae)

Fungus-growing ants of the genus Mycetarotes are among the least studied in the tribe Attini. This report documents nest architecture and worker population numbers for 19 nests of M. parallelus and 5 nests of M. acutus, including the first such report for M. acutus. This new information is integrated with the scant biological information reported on Mycetarotes to date. The resulting picture of Mycetarotes life history, as well as the relative ease with which large numbers of nests can be collected and observed in the field, suggest that Mycetarotes (particularly M. parallelus) is an ideal model system for the study of coevolution of lower-attine ants and their cultivated fungi.