Significant Difference In Mean Abundance Research Articles

Meta-Analysis of the Relative Abundance of Nuisance and Vector Mosquitoes in Urban and Blue-Green Spaces.

Simple SummaryThe increase in global urbanization has highlighted the need for sustainable infrastructure and integration of the urban and natural environment. However, there is concern that an increase in urban blue-green space may create habitats for vector species and potentially increase the risk for transmission of mosquito-borne disease. We conducted a meta-analysis to investigate the effect of urban blue-green spaces on mean mosquito abundance compared to traditional urban cities. We report that the abundance of Aedes aegypti is significantly higher in urban areas void of blue-green space. However, an analysis of three genera (Aedes, Culex, Anopheles), larval habitat guild, and specific taxa (Aedes albopictus and Culex pipiens complex) did not suggest any preference for either habitat considered. Given the lack of available studies and data focusing on contrasting mosquito abundance in blue-green spaces, we recommend that future surveillance studies quantifying mosquito abundance in urban landscapes report the quantitative data necessary to conduct meta-analyses such as this one.Blue-green spaces (BGSs), urban areas characterized by the presence of vegetation and or water, and infrastructure form a potential solution for public health threats from increasing urbanization. We conducted a meta-analysis to test the hypothesis that blue-green spaces increase the abundance of nuisance and vector mosquito species compared to non-greened urban areas. After screening 7306 studies published since 1992, we identified 18 studies containing sufficient data from both traditional urban areas and BGSs. We found no significant difference in mean abundance of all mosquito taxa in three genera (Aedes, Culex, Anopheles) when comparing blue-green spaces and non-greened urban spaces. Similarly, a separate analysis of each individual genera found no significant differences. An analysis of the taxa by larval habitat guilds found no differences for container-breeding mosquitoes. Flood-water species tended to be more abundant in blue-green spaces, but the differences were not significant. The individual taxa of Aedes albopictus and the Culex pipiens complex showed no differences between blue-green and urban spaces, while the abundance of Aedes aegypti was significantly higher in traditional urban spaces. Due to the variety existing between and among the several types of blue-green spaces, further studies comparing each unique type of blue-green space or infrastructure will be necessary to draw conclusions regarding the influence of each structure on for urban mosquito communities.

Relative abundance and temporal distribution of adult Frankliniella occidentalis (Pergande) and Frankliniella schultzei (Trybom) on French bean, lettuce, tomato and zucchini crops in relation to crop age

Field studies assessed the differences in temporal distribution and abundance of Frankliniella occidentalis and F. schultzei on French bean, tomato, lettuce and zucchini from one week after planting to senescence or harvest. Ten samples each of three plant parts leaf and stem, flower and growing tip samples were collected at weekly intervals, in eleven field plantings in the Lockyer Valley (south-east Queensland, Australia) over a three-year period from December 2011 to June 2014. There were significantly more F. schultzei than F. occidentalis in lettuce and tomato, and significantly more F. occidentalis than F. schultzei in French beans. Zucchini supported the highest abundance of both species, with no significant difference in mean abundance. Both species displayed similar preferences for different plant parts, with significantly more in flowers compared to leaf and stem and growing tip samples. There were significantly more thrips in female zucchini flowers compared to male flowers. Thrips were present in small numbers one week after planting in all crops, with peak abundance at flowering. F. occidentalis were temporally segregated by crop age (weeks since planting), with significantly higher levels present in zucchini compared to French bean, lettuce and tomato between weeks three and six, followed by significantly higher levels in French bean between weeks eight and ten. F. schultzei were temporally separated by crop age between zucchini and lettuce, with significantly higher levels present in zucchini between weeks four and six, and in lettuce between weeks eight and ten. Implications for crop monitoring are that sampling should be concentrated at pre-flowering for F. occidentalis in French bean and zucchini and for F. schultzei in tomato and zucchini. For lettuce, the seedling stage is most vulnerable to infestation by both species. Growers should be aware of the potential for both Frankliniella species to disperse from senescing zucchini flowers from week seven and aim to implement control strategies around this period.

Benthic invertebrate community in Khur-e-Mussa creeks in northwest of Persian Gulf and the application of the AMBI (AZTI's Marine Biotic Index)

Benthic invertebrates are a well-established target in environmental quality status evaluations. The AMBI (AZTI's Marine Biotic Index) was developed to determine the impacts and the quality status of soft-bottom marine benthic communities. The aim of this study was investigating multivariate pattern of benthic invertebrate community and application of AMBI (AZTI's Marine Biotic Index) for determining quality of health status in Khuzestan coastal waters. Seasonal samplings were collected from eight creeks over one year study by Peterson grab sampler, beginning from October 2005. All creeks are characterized by muddy bottom. According to sensitivity to environmental stress, macrobenthic animals classified into 5 ecological groups. Among 28 identified faunal groups the most abundant groups were polychaets, molluscs, crustaceans and nematodes, respectively. Two way ANOVAs showed only seasonal significant differences in mean abundance (P<0.05) and Margalef richness index values (P<0.05), while all of studied creeks shows similar biological characters based on benthic communities. According to annual mean of AMBI value all creeks were in ecological group III with slightly polluted condition, except for Darvish that was in unpolluted category. In the present study, although the number of species initially increased, but due to appearance of dominant species such as Capitella sp. and nematods (as opportunist species), diversity values reduced. In general, according to AMBI and Biotic index values, the most creeks are classified into unpolluted and slightly polluted categories except for Zangy, Doragh and Patil in summer and also Zangy and Bihad in winter which was in moderate to heavily polluted category. Different types of exploitation, industrial and shipping activities in this area could result in unbalanced to polluted status in benthic animals (as the best indicators in sediment quality assessment) so these results can be acceptable.

Small-mammal response to group-selection silvicultural systems in Engelmann spruce – subalpine fir forests 14 years postharvest

Concerns about the impacts of clear-cut harvesting on ecosystem components in subalpine forests have generated a variety of alternative silvicultural systems in high-elevation forests in western North America. We examined responses of forest-floor small mammals, 14 years posttreatment, in four replicate units, uncut forest, a 1.0 ha group-selection cut, a large (&gt;30 ha) clearcut, and the edge between the group-selection cut and uncut forest, in the Engelmann Spruce ( Picea engelmannii Parry ex Engelm.) – Subalpine Fir ( Abies lasiocarpa (Hook.) Nutt.) biogeoclimatic zone in south-central British Columbia, Canada. Populations of small mammals were livetrapped during five sessions from June to September 2006. The mean abundance of southern red-backed voles ( Myodes gapperi Vigors) was significantly lower on large clearcuts than in uncut old-growth forests, with intermediate numbers in 1 ha cuts. The opposite trend was found for dusky shrews ( Sorex monticolus Merriam), while there was no significant difference in mean abundance of deer mice ( Peromyscus maniculatus Wagner) among treatments. Trappability, proportion of adult females breeding, and rate of survival of red-backed voles and deer mice were similar among treatments. Our results suggest that group-selection silviculture conducted in subalpine forests may have fewer negative impacts on the small-mammal community than large clearcuts.

Population biology and habitat of the stauromedusa Haliclystus auricula in southern Chile

The population biology and habitat of Haliclystus auricula was studied from samples taken every two months in southern Chile between November 2001 and November 2002. A total of 3790 medusae were collected and examined. The abundance of H. auricula varied seasonally. Maximum densities occurred in summer (1405/m2) and minimum densities during the winter, when the population gradually disappeared. Gonads were observed in medusae starting from a size of 2·0 mm. Stauromedusae were found most often on the red filamentous alga Ceramium rubrum (69%), followed by Gymnogongrus furcellatus (12%) and Ulva sp. (10%). There were highly significant differences in mean abundance of medusae on these three algae (P&lt;0·05). The remaining 9% of medusae were found on other seaweeds. The smallest medusae (0·08–0·9 mm umbrella height) were found exclusively on C. rubrum. The highest densities were recorded in the midlittoral zone.

Spatial and temporal definition of Ochlerotatus camptorhynchus (Thomson) (Diptera: Culicidae) in the Gippsland Lakes system of eastern Victoria

Abstract The confirmed vector of Ross River virus, Ochlerotatus camptorhynchus (Thomson), is the dominant mosquito species inhabiting saline marshes in coastal Victoria. This paper re‐examines previously published data on Oc. camptorhynchus, plus additional data collected since that time, and provides greater spatial and temporal definition of Oc. camptorhynchus numbers at seven sites across the Gippsland Lakes system of eastern Victoria. A total of 357 672 Oc. camptorhynchus was captured from 1188 trap‐nights across the seven trap sites during trapping seasons from 1990 to 2001. The dominance of Oc. camptorhynchus across the seven sites averaged 75%, with significant differences in mean abundance of Oc. camptorhynchus found between all trap sites. Significant differences in monthly abundance of Oc. camptorhynchus were observed for Wellington Shire. Increase in populations of Oc. camptorhynchus was associated with increases in rainfall at all trap sites, higher minimum temperatures at two of the seven trap sites, and wind speed at one trap site. Prioritisation of mosquito control may be applied based on spatial and temporal factors according to the findings of this study.

Physicochemical Effects of the Flood Pulse on Fishes in the Atchafalaya River Basin, Louisiana

We examined the relationships between physicochemistry and the distribution and abundance of fishes at 36 sites in the lower Atchafalaya River basin (ARB), Louisiana, a bottomland hardwood swamp fed by waters (distributaries) of the Mississippi and Red rivers. We used principal components analysis (PCA) of the 29 most common ARB fishes to examine fish assemblage structure and then related the first two components to physical habitat (e.g., standing timber, submerged macrophytes, and brushy cover) and water quality (e.g., dissolved oxygen (DO), pH, and specific conductance) variables. To further examine the relationship between physicochemistry and species abundance and distribution, we regressed the habitat and water quality variables on the abundance of common ARB fishes. Regression analysis indicated that DO concentration, DO differential (surface less bottom), specific conductance, and current velocity were most strongly associated with fish distribution and abundance. A PCA of these four variables separated sample sites into green-water (lakes, lentic bayous, and canals), brown-water (lotic distributaries of the Atchafalaya River and Intracoastal Waterway), and black-water (hypoxic (DO < 2.0 mg/L) interior bayous and canals) habitats. Analyses of variance of rank fish abundance showed that 15 of the 29 most common fish species had significant differences in mean abundance (P < 0.05) among black-, brown-, and green-water habitats. Bluegill Lepomis macrochirus, gizzard shad Dorosoma cepedianum, threadfin shad D. petenense, white bass Morone chrysops, largemouth bass Micropterus salmoides, redear sunfish L. microlophus, and black crappie Pomoxis nigromaculatus had higher abundances in green-water than in black-water or brown-water habitats. The bullhead minnow Pimephales vigilax was significantly more abundant in brown-water than in black-water or green-water areas, and warmouth L. gulosus had higher abundance in black water than in other water types. Four species (smallmouth buffalo Ictiobus bubalus, longear sunfish L. megalotis, freshwater drum Aplodinotus grunniens, and spotted bass Micropterus punctulatus) showed similar abundance patterns in both green and brown water and were collected at higher abundances there than in black-water habitats. The results of this study indicate that water quality (particularly DO) is more important than physical habitat characteristics in determining fish distribution and abundance in the lower ARB during the flood pulse. The ARB has historically been managed for flood control and navigation, and flow management has resulted in substantial sedimentation and widespread water quality problems. Thus, improved water circulation in the ARB would probably increase production of commercially valuable and sport fish species.

An assessment of the use of stabilized coal and oil ash for construction of artificial fishing reefs: Comparison of fishes observed on small ash and concrete reefs

Fishes present on small artificial reefs located 2 km off the central east coast of Florida (USA) were surveyed to determine the acceptability of using stabilized oil and coal ash residue as a component material in construction of artificial fishing reefs. Species richness was not significantly different over 2.5 yr on stabilized oil and coal ash reefs compared to concrete control reefs. Of 19 species tested for significant differences in mean abundance, lane snapper was observed at significantly higher mean abundances on fossil-fuel ash reefs (stabilized oil ash/coal fly ash), while three reef species (hairy blenny, porkfish and gray snapper) were significantly more common on concrete control reefs. Further study is needed to determine whether contaminants (Cu, V, Ni and Zn) from stabilized ash blocks can cause abundance differences for some fishes. Plausible alternate explanations for the differences in mean abundance include both interspecific interactions (competition and predation) and differences in the attraction or retention of fish among reef replicates due to slight variations in reef dimensions.