Size divergence and dietary partitioning enhance coexistence of two herbivorous species of Diaptomus (Copepoda: Calanoida) in some shallow Quebec lakes

1992 ◽  
Vol 70 (5) ◽  
pp. 1016-1028 ◽  
Author(s):  
Patricia Chow-Fraser ◽  
Edward J. Maly
Keyword(s):  
Distribution Patterns ◽  
Significant Negative Correlation ◽  
Geographic Region ◽  
Horizontal Distribution ◽  
Sympatric Populations ◽  
Blue Green Algae ◽  
Diet Preference ◽  
Diaptomus Oregonensis ◽  
Vertical And Horizontal Distribution ◽  
Herbivorous Species

We examined the vertical and horizontal distribution patterns of Diaptomus minutus Lilljeborg and Diaptomus oregonensis Forbes in several shallow Quebec lakes where they occurred allopatrically and sympatrically within a small geographic region. Both species overlapped extensively in their vertical and temporal distributions and were found to be positively associated within and among lakes. Although size displacement could not be detected when body lengths of sympatric and allopatric populations were compared, in lakes where there was a reduction in size overlap between species, the two species coexisted at relatively high densities. This contrasted with situations where convergence in size between species was accompanied by a limited abundance of one or both diaptomids. We conducted stomach-content analyses on the sympatric populations of two of these lakes to determine if diet preference was related to copepod size divergence, and if algae were selected as a function of copepod size. We found that D. minutus, the smaller copepod, preferentially ingested a number of small algal particles (< 10 μm), whereas D. oregonensis, the larger copepod, tended to ingest a greater number of larger particles. Although preference for small algae (Selenastrum and small blue–green algae) was negatively correlated with prosome length, preference for larger algal taxa (Planktosphaerium, centric diatoms such as Melosira, and Achnanthes) was positively correlated with diaptomid size. There were, however, differences with respect to the degree of diet overlap between species in the two lakes, which was reflected in a significant negative correlation between dietary and size overlap. These observations are consistent with the hypothesis that reduction in size overlap has resulted in reduced exploitative competition, and that divergence in size and diet may be the mechanism that allows D. minutus and D. oregonensis to coexist when food becomes limiting.

Distribution of intertidal benthic algae in the vicinity of Townsville, tropical Australia

1980 ◽  
Vol 31 (2) ◽  
pp. 175 ◽  
Author(s):  
Y Ngan ◽  
IR Price
Keyword(s):  
Animal Species ◽  
Benthic Algae ◽  
Distribution Patterns ◽  
Horizontal Distribution ◽  
Vertical And Horizontal Distribution ◽  
Tropical Australia ◽  
Marine Algal

The vertical and horizontal distribution of 144 benthic marine algal taxa (25 of the Chlorophyta, 21 of the Phaeophyta, 92 of the Rhodophyta and 6 of the Cyanophyta) in the intertidal region in the vicinity of Townsville was investigated. The distribution patterns are discussed in relation to the zonation of animal species in the region and compared with information available for other tropical shores.

scholarly journals Spatial distribution by Canistropsis microps (E. Morren ex Mez) Leme (Bromeliaceae: Bromelioideae) in the Atlantic rain forest in Ilha Grande, Southeastern Brazil

2007 ◽  
Vol 67 (3) ◽  
pp. 467-474 ◽  
Author(s):  
AF. Nunes-Freitas ◽  
CFD. Rocha
Keyword(s):  
Rain Forest ◽  
Vegetative Reproduction ◽  
Inverse Correlation ◽  
Distribution Patterns ◽  
Horizontal Distribution ◽  
High Rate ◽  
Southeastern Brazil ◽  
Atlantic Rain Forest ◽  
Maximum Height ◽  
Vertical And Horizontal Distribution

Canistropsis microps (Bromeliaceae: Bromelioideae) is an endemic species of Atlantic rain forest areas in Rio de Janeiro State, which are very abundant in not very disturbed forests in Ilha Grande, on the southern coast of the State. In this study, we analyzed the vertical and horizontal distribution patterns of the species in an area of rain forest with little evidence of disturbance at Vila Dois Rios, Ilha Grande, relating the patterns to sunlight in the microhabitat. We also identified the types of substrate used by the species and the rate of asexual reproduction. Canistropsis microps had high densities (estimated at 84,425 rosettes/ha), and has an aggregated distribution (Id = 2.86). About 80% of the rosettes were generated by clonal growth, whereas less than 20% were produced from seedlings. Most of the rosettes were found on straight tree trunks (DBH > 50 cm). There was a significant inverse correlation between the incidence of sunlight in the habitat and the abundance of individuals. Rosettes were found up to a maximum height of 9.5 m, but most occured between 1.5 and 5.5 m, where light varied from 25 to 50 µmol.s-1.m-2. We conclude that vertical and horizontal distribution patterns in C. microps may be partially explained by the occurrence of appropriate substrate, an intensity of sunlight favorable to the development of the species and to a high rate of vegetative reproduction.

Mesoscale Aggregations of Euphausiid Sound Scattering Layers on the Continental Shelf of Vancouver Island

1989 ◽  
Vol 46 (7) ◽  
pp. 1238-1249 ◽  
Author(s):  
Yvan Simard ◽  
David L. Mackas
Keyword(s):  
Continental Shelf ◽  
High Frequency ◽  
Dry Weight ◽  
Distribution Patterns ◽  
Vancouver Island ◽  
Horizontal Distribution ◽  
Swimming Behavior ◽  
Shelf Break ◽  
Shelf Area ◽  
Vertical And Horizontal Distribution

High frequency acoustics (104 kHz) and stratified (BIONESS) net tows were used to map the vertical and horizontal distribution of macrozooplankton scattering layers on and seaward of the continental shelf off Vancouver Island, in June and August of 1986. The macrozooplankton scattering layers were dominated by euphausiids, primarily Euphausia pacifica and Thysanoessa spinifera. During both surveys, dense aggregations were found in the same two general regions. The first was along the shelf break, where highest biomass was observed (averages over a few kilometres of transect reaching to about 200 mg dry weight∙m−3 = about 40 individuals∙m−3 and > 4 g dry weight∙m−2). A second, broader and more diffuse aggregation occupied the deeper southeast end of the shelf (area about 200 km2, biomass 1–2 g∙m−2). The scattering layers showed a consistent diel vertical migration. Daytime depth was deeper at the shelf break (~ 150–200 m) than on the shelf (~ 100–150 m) and occasionally extended to the bottom. These day-depths corresponded to the California Undercurrent waters of 6–7 °C, a salinity of 33.75–34‰ and sigma-T > 26.5. Distribution patterns were coincident with those of upwelled regions, high phytoplankton biomass, and high hake and herring biomass. They were also associated with the shelf break jet and the recurrent Tully eddy. There is a strong possibility of aggregation in restricted areas through the coupling of advection and vertical swimming behavior of the animals.

scholarly journals Defining and Characterising Clusters in Palaeolithic Sites: a Review of Methods and Constraints

2021 ◽  
Author(s):  
Laura Sánchez-Romero ◽  
Alfonso Benito-Calvo ◽  
Joseba Rios-Garaizar
Keyword(s):  
Distribution Patterns ◽  
Horizontal Distribution ◽  
Spatial Studies ◽  
Innovative Methods ◽  
General Terms ◽  
Fabric Analysis ◽  
Gis Tools ◽  
Definition Of ◽  
Intentional Activities ◽  
Statistical Criteria

AbstractSpatial analysis studies in Palaeolithic archaeology arise as indispensable research tools for understanding archaeopalaeontological sites. In general terms, spatial studies have been specialised in the description of the distribution of materials and in the definition of accumulation areas, with the aim of distinguishing intentional activities or studying postdepositional processes. In recent decades, the development of GIS tools has enabled huge strides forward in the field of spatial archaeology research, such as spatial inferential statistics. These tools are particularly useful in the identification and location of clustering from statistical criteria, facilitating the subsequent analysis of accumulations through other archaeological, taphonomic and spatial techniques, such as fabric analysis or directional distribution. The cluster analysis, and its contextualisation considering all the archaeological and stratigraphical variables, allows the inference of some of the processes and factors that could have taken part in the accumulation of materials, as well as assessing how this affected the composition and preservation of the archaeological assemblage. The present article reviews the more traditional and innovative methods for studying horizontal distribution patterns and the objective definition of clusters, highlighting the parameters, uses and limitations of these techniques. We present an application of these methods to different Palaeolithic sites, going through different scenarios, such as location (open-air vs. cave), context, scale (large vs. small area), excavation methodology and spatial record methods.

Behavior and Distribution of Nonylphenol Ethoxylates and their Metabolites in Sediments of Nansi Lake, China

2011 ◽  
Vol 356-360 ◽  
pp. 1733-1738
Author(s):  
Fang He ◽  
Aya Obara ◽  
Shi Long Wang ◽  
Li Guo Wang
Keyword(s):  
Water Flow ◽  
Flow Direction ◽  
Sediment Cores ◽  
Sewage Treatment ◽  
Vertical Direction ◽  
Total Content ◽  
Horizontal Distribution ◽  
Nansi Lake ◽  
Increasing Trend ◽  
Vertical And Horizontal Distribution

The vertical and horizontal distribution of NPEOn and their metabolites of NP and NPEnC in the Upper Nansi Lake, North China were investigated using LC-MS and LC-MS/MS methods, sampling at three sites (St.1, St.2 and St.3) along the water flow direction. The total content of NPEOn (n=1–15) bound onto the sediment of this lake changed in the range of 60.7–631.5 μg/kg-dry with the horizontal flow direction and the vertical direction of the sediment cores with sediment thickness up to 35 cm. Compared to the presence levels of all detected NPEOn species, the content of NP was much higher, falling in 26.5–1,998.4 μg/kg-dry. A general increasing trend of the NP content along the water flow direction of this lake was revealed. NPEnC showed a roughly increasing trend from the upstream to the downstream, with the total concentrations being obviously lower than NPEOn and NP and falling in 2.13–23.1 μg/kg-dry. The short chain NPEOn dominant in NPEO mixtures in these sedimentary cores indicated that this lake received some effluents from STPs, and the sewage treatment ratio is relatively low in this area. Furthermore, the computed magnitudes of NPEO 1-2/NPEO1-15, NP/NPEO 1-15 and NPEC 1-10/NPEO 1-15 suggested that the non-oxidative hydrolytic transformation seemed to be a major process occurring within the sediment phase of Nansi Lake, while the oxidative hydrolytic transformation pathway was probably less involved.

scholarly journals Wątrobowce (Hepaticae) Beskidu Żywiecko-Orawskiego (Karpaty Zachodnie) [Liverworts (Hepaticae) of the Beskid Żywiecko-Orawski Range (Polish Western Carpathians)]

2014 ◽  
Vol 79 ◽  
pp. 1-144 ◽  
Author(s):  
Henryk Klama
Keyword(s):  
Endangered Species ◽  
Habitat Preferences ◽  
Horizontal Distribution ◽  
Western Carpathians ◽  
Vulnerable Species ◽  
Floristic Analysis ◽  
Vertical And Horizontal Distribution

The study area comprises two mountain groups – Wielka Racza and Pilsko – situated in western part of the Beskid Żywiecko-Orawski Range in Polish Western Carpathians. The flora of this area includes 111 species of liverworts and 2 species of hornworts. 81 species of liverworts and 2 species of hornworts were found in the area of the Wielka Racza group, 108 species of liverworts and 2 species of hornworts – in the area of the Pilsko group. The species new for the Polish part of the Beskid Żywiecki Range were found (27), as well as for the whole Range including the Slovakian part (22) and for the Western Beskids (2). Moreover, 20 species rare in the Western Beskids as well as 11 species rare in the whole area of the Western Carpathians were recorded. 6 species regarded as threatened in the Polish flora occur in the study area. Four of them belong to the category of endangered species (E):<em> Fossombronia wondraczekii, Frullania tamarisci, Porella baueri</em> and <em>P. platyphylla</em>, the remaining two belong to the category of vulnerable species (V): <em>Geocalyx graveolens</em> and <em>Metzgeria conjugata</em>. A particular attention should be payed to the species threatened on European scale: <em>Lophozia ascendens</em> (R category), <em>Porella baueri</em> (T) and <em>Scapania parvifolia</em> (T). The floristic analysis of habitats covered by liverworts as well as habitat groups of liverworts and habitat preferences of particular species arę presented in the paper. The phytogeographic characteristics of the flora is also given, including vertical and horizontal distribution of liverworts in the study area.

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