Drag coefficient parameter estimation for aquaculture systems

Environmental Fluid Mechanics - The flow conditions in and around a suspended canopy, resembling those formed by aquaculture structures such as rafts cages and longlines, were modeled using an...     

Temporal variation in total phosphorus concentrations revealed from a multidecadal monitoring program on Big Platte Lake,Michigan

Effective water quality management depends on enactment of appropriately designed monitoring programs to reveal current and forecasted conditions. Because water quality conditions are influenced by numerous factors, commonly measured attributes such as total phosphorus (TP) can be highly temporally varying. For highly varying processes, monitoring programs should be long-term and periodic quantitative analyses are needed so that temporal trends can be distinguished from stochastic variation, which can yield insights into potential modifications to the program. Using generalized additive mixed modeling, we assessed temporal (yearly and monthly) trends and quantified other sources of variation (daily and subsampling) in TP concentrations from a multidecadal depth-specific monitoring program on Big Platte Lake, Michigan. Yearly TP concentrations decreased from the late 1980s to late 1990s before rebounding through the early 2000s. At depths of 2.29 to 13.72 m, TP concentrations have cycled around stationary points since the early 2000s, while at the surface and depths ≥?18.29 concentrations have continued declining. Summer and fall peaks in TP concentrations were observed at most depths, with the fall peak at deeper depths occurring 1 month earlier than shallower depths. Daily sampling variation (i.e., variation within a given month and year) was greatest at shallowest and deepest depths. Variation in subsamples collected from depth-specific water samples constituted a small fraction of total variation. Based on model results, cost-saving measures to consider for the monitoring program include reducing subsampling of depth-specific concentrations and reducing the number of sampling depths given observed consistencies across the program period.     

Responses of Different Test Objects to Experimental Soil Contamination with Crude Oil

Russian Journal of Ecology - Responses to contamination of several soil types with crude oil were comparatively analyzed in organisms of different trophic groups. Samples of soddy podzolic, light...     

The use of nanovermiculite catalyst in the study of removal of the organic load and degradation of atrazine via ozone process in RPB reactor

Abstract

The main objective of this study is the degradation of a synthetic solution of atrazine by a modified vermiculite catalyzed ozonation, in a rotating packed bed (RPB) reactor. A 0.5?L RPB reactor was used to perform the experiments, using a Central Composite Design (CCD) response surface to construct the quadratic model based on the factors: pH, catalyst concentration and reactor rotation frequency. The response variable was the removal of the organic load measured in terms of Chemical Oxygen Demand (COD). After the complete quadratic model was constructed through the response surface, the COD degradation process had an optimal removal of 41% under the following conditions: pH 8.0, rotation of 1150?rpm and catalyst concentration 0.66?g L^?1.     

Improving ozonation to remove carbamazepine through ozone-assisted catalysis using different NiO concentrations

The carbamazepine (CBZ) abatement is herein evaluated using catalytic ozonation at different NiO concentrations as catalyst: 100, 300, and 500 mg      

Slowest of the slow: latitudinal insensitivity of burrowing capacity in the bivalve <Emphasis Type="Italic">Laternula</Emphasis>

Low temperature limits the rate of biochemical reactions and aerobic scopes of cold water ectotherms. To compensate for this limiting effect, animals living in cold environments often possess physiological or morphological adaptations to maintain vital functions. Cross-latitudinal comparison of aerobic capacities is one method to test which factors constrain activity in thermally distinct environments particularly when congeneric studies are carried out on related species with conservative ecology and habitat. Burrowing is a major aerobic activity of bivalve molluscs that is described here for the first time for the tropical mangrove species Laternula truncata and Laternula boschasina and then compared with their Antarctic congener Laternula elliptica. About 80% of L. truncata (16.3–46.1 mm shell length) and 63% of L. boschasina (11.3–27.7 mm shell length) buried within 24 h at 28°C. The burrowing rate index (BRI = [³√wet weight/time to bury]×10⁴) ranged between 1.1 and 20.2 for L. boschasina and 1.1–32.9 for L. truncata. These values are 2–3 orders of magnitude less than other tropical bivalve molluscs and are amongst the lowest recorded for any bivalve. Comparisons with the Antarctic L. elliptica showed little or no differences in BRI (Q ₁₀ of 1.0–1.2 for specimens of the same size). This is contrary to the general pattern over a wide range of bivalves, where BRI increases with a Q ₁₀ of between 2.9 and 6.4 between high latitudes and the equator. L. elliptica has 25–30% longer relative foot length than tropical congeners of the same size, which could be a morphological adaptation compensating for reduced burrowing speeds in a colder environment. Burrowing rates within the genus Laternula could, however, also be maintained by differing habitat, ecological and physiological constraints on burrowing capability.     

Gene flow via the dispersal of fertilizing sperm in a colonial ascidian (Botryllus schlosseri): the effect of male density

In marine invertebrate taxa with restricted larval dispersal, the movement of fertilizing sperm may contribute significantly to gene flow. Several recent studies have examined the ability of isolated males to fertilize eggs as a function of distance, but none has explicitly considered the effect of other males in the vicinity on the spatial distribution of fertilizations obtained by a male. I assayed the effect of additional males on the fertilization success of male Botryllus schlosseri (Pallas) colonies with respect to distance via an in situ mating experiment performed in Maine, USA during the summer of 1993. Allozyme markers were used to assay paternity. The presence of additional males reduced the ability of a focal male to fertilize eggs in all distance classes. This suggests that competition for fertilizations among males will reduce gene flow via sperm dispersal and that the fertilization success of isolated males may over-estimate gene flow via sperm dispersal in many natural populations.     

Effects of Forest Fragmentation on Understory Hummingbirds in Amazonian Brazil

We sampled understory hummingbirds in Amazonian forest fragments from before isolation through nine years after isolation. We recorded 377 captures of eight species in five 1-ha fragments and four 10-ha fragments. The three species netted before isolation, Phaethornis superciliosus, Phaethornis bourcieri , and Thalurania furcata , were nearly equally abundant at that time. After isolation abundance of P. bourcieri and T. furcata did not change, but P. superciliosus became nearly twice as common. Five additional species that were netted only after isolation represented about 10% of the post-isolation sample. The species recorded only after isolation were forest species usually found above the levels of nets; fragments were not colonized by nonforest species. Use of fragments did not differ between 1- and 10-ha fragments. The landscape surrounding the fragments included active cattle pasture, abandoned pasture, and Cecropia -dominated second growth, but this variation had little effect on use of fragments by hummingbirds. The results suggest that these understory hummingbirds can persist in a matrix of fragments, secondary growth, and large forest patches. This response is much different than that of the insectivorous birds that dominate the understory bird community at the site, which are much more vulnerable to fragmentation.