Thank you very much for downloading modern applied statistics with s. As you may know, people have search hundreds times for their favorite readings like this modern applied statistics with s, but end up in harmful downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some harmful virus inside their laptop. modern applied statistics with s is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the modern applied statistics with s is universally compatible with any devices to read.

Modern Applied Statistics With S

Antarctic krill (Euphausia superba) and salps (mainly Salpa thompsoni) are major grazers in the Southern Ocean, and krill support commercial fisheries. Their density distributions have been described in the period 1926-51, while recent localized studies suggest short-term changes. To examine spatial and temporal changes over larger scales, we have combined all available scientific net sampling data from 1926 to 2003. This database shows that the productive southwest Atlantic sector contains >50% of Southern Ocean krill stocks, but here their density has declined since the 1970s. Spatially, within their habitat, summer krill density correlates positively with chlorophyll concentrations. Temporally, within the southwest Atlantic, summer krill densities correlate positively with sea-ice extent the previous winter. Summer food and the extent of winter sea ice are thus key factors in the high krill densities observed in the southwest Atlantic Ocean. Krill need the summer phytoplankton blooms of this sector, where winters of extensive sea ice mean plentiful winter food from ice algae, promoting larval recruitment and replenishing the stock. Salps, by contrast, occupy the extensive lower-productivity regions of the Southern Ocean and tolerate warmer water than krill. As krill densities decreased last century, salps appear to have increased in the southern part of their range. These changes have had profound effects within the Southern Ocean food web.

Long-term decline in krill stock and increase in salps within the Southern Ocean.

Many free-ranging predators have to make foraging decisions with little, if any, knowledge of present resource distribution and availability. The optimal search strategy they should use to maximize encounter rates with prey in heterogeneous natural environments remains a largely unresolved issue in ecology. Levy walks are specialized random walks giving rise to fractal movement trajectories that may represent an optimal solution for searching complex landscapes. However, the adaptive significance of this putative strategy in response to natural prey distributions remains untested. Here we analyse over a million movement displacements recorded from animal-attached electronic tags to show that diverse marine predators-sharks, bony fishes, sea turtles and penguins-exhibit Levy-walk-like behaviour close to a theoretical optimum. Prey density distributions also display Levy-like fractal patterns, suggesting response movements by predators to prey distributions. Simulations show that predators have higher encounter rates when adopting Levy-type foraging in natural-like prey fields compared with purely random landscapes. This is consistent with the hypothesis that observed search patterns are adapted to observed statistical patterns of the landscape. This may explain why Levy-like behaviour seems to be widespread among diverse organisms, from microbes to humans, as a 'rule' that evolved in response to patchy resource distributions.

Scaling laws of marine predator search behaviour

Autonomous Underwater Vehicles (AUVs): Their past, present and future contributions to the advancement of marine geoscience

Robotic systems are increasingly being utilized as fundamental data-gathering tools by scientists, allowing new perspectives and a greater understanding of the planet and its environmental processes. Today's robots are already exploring our deep oceans, tracking harmful algal blooms and pollution spread, monitoring climate variables, and even studying remote volcanoes. This article collates and discusses the significant advancements and applications of marine, terrestrial, and airborne robotic systems developed for environmental monitoring during the last two decades. Emerging research trends for achieving large-scale environmental monitoring are also reviewed, including cooperative robotic teams, robot and wireless sensor network (WSN) interaction, adaptive sampling and model-aided path planning. These trends offer efficient and precise measurement of environmental processes at unprecedented scales that will push the frontiers of robotic and natural sciences.

Robots for Environmental Monitoring: Significant Advancements and Applications

We surveyed Antarctic krill (Euphausia superba) under sea ice using the autonomous underwater vehicle Autosub-2. Krill were concentrated within a band under ice between 1 and 13 kilometers south of the ice edge. Within this band, krill densities were fivefold greater than that of open water. The under-ice environment has long been considered an important habitat for krill, but sampling difficulties have previously prevented direct observations under ice over the scale necessary for robust krill density estimation. Autosub-2 enabled us to make continuous high-resolution measurements of krill density under ice reaching 27 kilometers beyond the ice edge.

/pdf/antarctic-krill-under-sea-ice-elevated-abundance-in-a-narrow-22rt2d3y8l.pdf

Antarctic Krill Under Sea Ice: Elevated Abundance in a Narrow Band Just South of Ice Edge

Oceanographic data collected to the north of South Georgia were examined for three consecutive summers (1996/97, 1997/98, 1998/99). The results show the existence of a shelf break front during each period. The most reliable means of defining the front was the potential density anomaly at the near-surface potential temperature minimum. In each year, off-shelf waters were separated from on-shelf waters by water with a potential density anomaly between 27.22 and 27.29 kg m )3 . During 1997/98, the near-surface potential temperature minimum was much colder and much shallower than in other years and was consistent with waters originating from much further south than South Georgia; these differences were further evident at a single deep off-shelf station. The oceanographic changes during 1997/98 were consistent with a mesoscale or large-scale movement of the southern Antarctic Circumpolar Current front. Acoustically determined densities of Antarctic krill, Euphausia superba, at South Georgia showed consistent patterns between years. Densities were substantially higher over the shelf compared with off-shelf, with the highest densities at the shelf edge; densities were also higher to the east of the island. During 1997/98, acoustic densities of krill were substantially higher than in other years. The coincidence of the elevated acoustic density and the cooler oceanographic conditions was explored. When data from all years were combined and analysed by Generalized Additive Model, an inverse relationship between acoustic density and temperature was apparent. Historical data were also examined and it was noted that the only other occurrence of such a high estimate of krill density at South Georgia, was when oceanographic conditions were also colder.

/pdf/oceanographic-variability-and-changes-in-antarctic-krill-25hnvn44fo.pdf

Oceanographic variability and changes in Antarctic krill (Euphausia superba) abundance at South Georgia

Encaged aggregations of live krill in good to pristine condition have been ensonified at 38 and 120 kHz. Concurrent underwater television observations of behavior resemble those made by underwater divers in naturally occurring swarms, with comparably high densities of the order of 104 animals/m3 . Mean, single‐animal target strengths have been inferred from measurements of echo energy. For aggregations with mean lengths in the range [30,39] mm, the mean single‐krill target strengths are in the range [−88,−83] dB at 38 kHz and [−81,−74] dB at 120 kHz. Collateral measurements on some of the same encaged specimens determined a density contrast of 1.0357±0.0067 and sound‐speed contrast of 1.0279±0.0024, relative to seawater. These numbers have been used with the fluid‐sphere model as stated by Greenlaw [Limnol. Oceanogr. 24, 226–242 (1979)] . Computed backscattering cross sections have been averaged over the length distributions of each measured aggregation, resulting in target strength predictions in the ran...

/pdf/target-strengths-of-antarctic-krill-euphausia-superba-at-38-gcqqmc8u9f.pdf

Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz

Predator data and exploratory fishing in the Scotia Sea have revealed the presence of cephalopod stocks in the Antarctic Polar Frontal Zone (PFZ) This is a vast, remote region where large epipelagic cephalopods aggregate into highly mobile schools making them difficult to locate and sample We used satellite tagged predators and shipboard acoustics for coarse and fine scale location of cephalopod concentrations, and sampled them with commercial and scientific nets to determine the relationship between cephalopod distribution and mesoscale oceanographic features at the PFZ Satellite tags were attached to 9 grey-headed albatrosses Diomedea chrysostoma, breeding at Bird Island, South Georgia, to monitor foraging at sea in January-March 1994 A foraging area at the PFZ, north of South Georgia, was located, an acoustic survey undertaken and a fixed station established where acoustic targets were found A net survey was carried out with a commercial pelagic trawl, a rectangular midwater trawl 25 m2 (RMT25), a horizontal multiple plankton sampler and a neuston net Acoustic layers were targeted and the RMT25 sampled 200 m layers to 1000 m in daylight and darkness Cephalopods were simultaneously recovered from food samples fed to D chrysostoma chicks at Bird Island Two CTD transects, approximately normal to the major current flow, were undertaken across the PFZ and remote-sensed sea-surface temperature images from NOAA polar orbiting satellites were obtained aboard ship The pelagic trawl sampled a cephalopod community that closely resembled that exploited by D chrysostoma The largest and most conspicuous species was the ommastrephid squid Martialia hyadesi which is the most important cephalopod prey species Net-sampled M hyadesi had been feeding on crustaceans and mesopelagic fish The cephalopod community was sampled in a feature, interpreted as a warm core ring, in an area characterised by mesoscale features associated with the bathymetry of the northern end of the Northeast Georgia Rise and near a gap in the Falkland Ridge The association of these mesoscale features with the bathymetry suggests that they may be predictable foraging locations for the cephalopods and their predators

https://www.int-res.com/articles/meps/136/m136p037.pdf

Cephalopods and mesoscale oceanography at the Antarctic Polar Front:satellite tracked predators locate pelagic trophic interactions

The nekton community was sampled by a Rectangular Midwater Trawl (RMT 25) over the upper 1000 m of the Scotia Sea during January 1991. A total of 81 nekton and micronekton species were collected from 2 sites, one in the oceanic western Scotia Sea (Stn 1) and the other on the northwestern slope of the South Georgia shelf (Stn 2). Species composition, abundance, biomass and day/night vertical distribution were investigated. Crustaceans were the most important group in terms of species numbers (28 species) followed by mesopelagic fish (24), molluscs (15) and coelenterates (11). Species diversity increased with depth and was higher at Stn 2 (76 species) than at Stn 1 (62 species). Biomass in the upper 1000 m was considerably higher at Stn 1 (94.6 g wet wt m(-2) during daytime, 87 g wet wt m(-2) during night) than at Stn 2 (10.2 and 23.7 g wet wt m(-2), respectively), mostly due to dense concentrations of the tunicate Salpa thompsoni (41.6 g wet Mrt m(-2) during night). The other main contributors to the high biomass at Stn 1 were coelenterates (28.3 g wet wt m(-2) during night) and mesopelagic fish (4.9 g wet wt m(-2) during night). Euphausiids (Euphausia triacantha and E. superba) accounted for 1.5 g wet wt m(-2) at Stn 2 during night, with E. triacantha the more important of the two (1.4 g wet wt m(-2)). Except for Bathylagus antarcticus all common mesopelagic fishes showed a marked diurnal vertical migration (i.e. Electrona antarctica, Gymnoscopelus braueri, Krefftichthys anderssoni, Protomyctophum bolini). During daylight they stayed in the core of the Circumpolar Deep Water (CDW; 400 to 800 m) and at night they were mainly distributed in the Antarctic Surface Water (ASW; 0 to 400 m). Other species with pronounced vertical migration were the hydromedusa Calycopsis borchgrevinki, the squid Brachioteuthis ?picta, and the euphausiid Euphausia triacantha. The scyphomedusae Atolla wyvillei and Periphylla periphylla and the crustaceans Cyphocaris richardi, Gignato-cypris mulleri and Pasiphaea scotiae did not appear to migrate and remained concentrated in the CDW. Spatial variability was analysed by multivariate data analyses (clustering techniques) and related to hydrography. Four main groups, characterised by different nekton communities, were derived: (1) a lower mesopelagic nekton community from the deeper layers of the CDW, apparent at both stations, (2) an upper mesopelagic nekton community from the core of the CDW, apparent at both stations, (3) an epipelagic nekton community from the ASW over the South Georgia slope (Stn 2) and finally (4) an epipelagic nekton community from the ASW of the oceanic Scotia Sea (Stn 1). The performance of the midwater trawl is discussed as it has a substantial impact on the catchability of the nekton. The presented data provide new information on the structure and spatial variability of Antarctic nekton communities and emphasise the geographical and vertical discontinuities between communities.

/pdf/nekton-community-of-the-scotia-sea-as-sampled-by-the-rmt-25-16hdqrz48r.pdf

Douglas G. Bone

Papers

Antarctic Krill Under Sea Ice: Elevated Abundance in a Narrow Band Just South of Ice Edge

Oceanographic variability and changes in Antarctic krill (Euphausia superba) abundance at South Georgia

Target strengths of Antarctic krill (Euphausia superba) at 38 and 120 kHz

Cephalopods and mesoscale oceanography at the Antarctic Polar Front:satellite tracked predators locate pelagic trophic interactions

Nekton community of the Scotia Sea as sampled by the RMT 25 during austral summer