Ecology of Euphausiids in the Gulf of St. Lawrence

1976 ◽  
Vol 33 (9) ◽  
pp. 1894-1905 ◽  
Author(s):  
F. Berkes
Keyword(s):  
Resource Partitioning ◽  
Phytoplankton Bloom ◽  
Distribution Patterns ◽  
Reproductive Season ◽  
The Other ◽  
Species Pairs ◽  
Vertical Distributions ◽  
Oceanic Species ◽  
Food And Feeding ◽  
Meganyctiphanes Norvegica

Geographical and vertical distributions, reproduction, growth and maturity, food and feeding of Meganyctiphanes norvegica, Thysanoessa raschii, T. inermis, and T. longicaudata in the Gulf of St. Lawrence were studied, based on plankton samples from 10 cruises, largely from 2 consecutive yr. Adults of the first three species occurred most abundantly in the western Gulf and their larvae in the Magdalen Shallows. By contrast, T. longicaudata, an oceanic species, occurred mainly in the eastern Gulf year-round. All four species reached reproductive maturity at 1 yr of age; all but T. longicaudata populations contained at least two breeding year-classes. The three Thysanoessa species started spawning in April at the time of the phytoplankton bloom; M. norvegica was a summer breeder. All four species were omnivorous, but M. norvegica and T. longicaudata stomachs contained relatively more animal matter than those of the other two. These findings were supported by studies on the morphology of feeding appendages.Thysanoessa longicaudata was differentiated from the other species mainly on the basis of distribution patterns, and M. norvegica from the remaining two mainly on the basis of differences in feeding and reproductive season. In contrast to relatively clear resource partitioning in five of the six species pairs, only relatively small differences in the stomach content composition in winter samples, the spacing of setules, and the length of the breeding season differentiated T. inermis from T. raschii.

scholarly journals Distribución altitudinal del género Pinus en el oeste de Estados Unidos de América y México

2017 ◽  
pp. 55
Author(s):  
Richard I. Yeaton
Keyword(s):  
United States ◽  
Resource Partitioning ◽  
Morphological Characteristics ◽  
The Other ◽  
Western United States ◽  
Mountain Ranges ◽  
Species Pairs ◽  
Associated Species ◽  
Species Being ◽  
Altitudinal Distributions

The altitudinal distributions of members of the genus Pinus were studied on mountain ranges in the western United States and Mexico. The community of pines on each mountainside consists of members of three major groupings - long-needled Diploxylon species, short-needled Diploxylon species and Haploxylon species. Long-needled Diploxylon species form a core sequence of altitudinally replacing species over whose distribution are superimposed sequences of members of one of the other two groups. In the northern mountains ranges Haploxylon species formed this second sequence while in the southern ranges short-neddled Diploxylon species assumed this role. Some morphological characteristics of these species were examined and random associations of species pairs generated using these characteristics. The results suggest that resource partitioning between altitudinally associated species does not occur but rather that a successional situatton exists with long-needled Diploxylon species being replaced by either Haploxylon in the norrhern ranges or short-needled Diploxylon species in the southern ranges.

scholarly journals Species-Specific Segregation of Gender-Associated Mitochondrial DNA Types in an Area Where Two Mussel Species (Mytilus edulis and M. trossulus) Hybridize

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1359-1367 ◽  
Author(s):  
Carlos Saavedra ◽  
Donald T Stewart ◽  
Rebecca R Stanwood ◽  
Eleftherios Zouros
Keyword(s):  
Mytilus Edulis ◽  
The Other ◽  
Allozyme Analysis ◽  
Mussel Species ◽  
Species Origin ◽  
Species Pairs ◽  
Nuclear Background ◽  
Species Specific ◽  
Dna Types ◽  
Fertile Hybrids

Abstract In each of the mussel species Mytilus edulis and M. trossulus there exist two types of mtDNA, the F type transmitted through females and the M type transmitted through males. Because the two species produce fertile hybrids in nature, F and M types of one may introgress into the other. We present the results from a survey of a population in which extensive hybridization occurs between these two species. Among specimens classified as “pure” M. edulis or “pure” M. trossulus on the basis of allozyme analysis, we observed no animal that carried the F or the M mitotype of the other species. In most animals of mixed nuclear background, an individual's mtDNA came from the species that contributed the majority of the individual's nuclear genes. Most importantly, the two mtDNA types in post-F1 male hybrids were of the same species origin. We interpret this to mean that there are intrinsic barriers to the exchange of mtDNA between these two species. Because such barriers were not noted in other hybridizing species pairs (many being even less interfertile than M. edulis and M. trossulus), their presence in Mytilus could be another feature of the unusual mtDNA system in this genus.

Another new, diminutive Rock Gecko (Cnemaspis Strauch) from Peninsular Malaysia and a discussion of resource partitioning in sympatric species pairs

Zootaxa ◽  
2010 ◽  
Vol 2569 (1) ◽  
pp. 55 ◽  
Author(s):  
L. LEE GRISMER ◽  
CHAN KIN ONN ◽  
EVAN QUAH ◽  
MOHD ABDUL MUIN ◽  
ANNA E. SAVAGE ◽  
...  
Keyword(s):  
New Species ◽  
Body Size ◽  
Endemic Species ◽  
Resource Partitioning ◽  
Sympatric Species ◽  
Southeast Asian ◽  
Peninsular Malaysia ◽  
Activity Period ◽  
Species Pairs

A new, diminutive species of Rock Gecko, Cnemaspis shahruli sp. nov. from Penang Island, Penang; Pulau Jerejak, Penang; Pulau Pangkor, Perak; and the adjacent mainland at Sungai Sedim, Kedah was previously confused with juveniles of the sympatric, endemic species C. affinis (Stoliczka) on Penang Island. Cnemaspis shahruli sp. nov. is diagnosed from all other Southeast Asian Cnemaspis on the basis of several unique aspects of squamation, coloration, and body size. It is proposed that this new species has a more extensive mainland distribution than is presented here based on its southernmost record on Pulau Pangkor, Perak. A pattern of resource partitioning on the basis of body size, habitat, and activity period among sympatric species pairs of Cnemaspis is discussed.

scholarly journals Daily Activity Patterns and Co-Occurrence of Duikers Revealed by an Intensive Camera Trap Survey across Central African Rainforests

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2200
Author(s):  
Fructueux G. A. Houngbégnon ◽  
Daniel Cornelis ◽  
Cédric Vermeulen ◽  
Bonaventure Sonké ◽  
Stephan Ntie ◽  
...  
Keyword(s):  
Daily Activity ◽  
Activity Patterns ◽  
Camera Trap ◽  
Camera Traps ◽  
The Other ◽  
Species Pairs ◽  
Free Ranging ◽  
First Time ◽  
Daily Activity Patterns ◽  
Temporal Overlap

The duiker community in Central African rainforests includes a diversity of species that can coexist in the same area. The study of their activity patterns is needed to better understand habitat use or association between the species. Using camera traps, we studied the temporal activity patterns, and quantified for the first time the temporal overlap and spatial co-occurrence between species. Our results show that: (i) Two species are strongly diurnal: Cephalophus leucogaster, and Philantomba congica, (ii) two species are mostly diurnal: C.callipygus and C. nigrifrons, (iii) one species is strongly nocturnal: C.castaneus, (iv) and one species is mostly nocturnal: C.silvicultor. Analyses of temporal activities (for five species) identified four species pairs that highly overlapped (Δ^≥ 0.80), and six pairs that weakly overlapped (Δ^ between 0.06 and 0.35). Finally, co-occurrence tests reveal a truly random co-occurrence (plt > 0.05 and pgt > 0.05) for six species pairs, and a positive co-occurrence (pgt < 0.05) for four pairs. Positive co-occurrences are particularly noted for pairs formed by C.callipygus with the other species (except C. nigrifrons). These results are essential for a better understanding of the coexistence of duikers and the ecology of poorly known species (C. leucogaster and C. nigrifrons), and provide clarification on the activity patterns of C. silvicultor which was subject to controversy. Camera traps proved then to be a powerful tool for studying the activity patterns of free-ranging duiker populations.

scholarly journals Directionally Correlated Movement Can Drive Qualitative Changes in Emergent Population Distribution Patterns

Mathematics ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 640
Author(s):  
Jonathan R. Potts
Keyword(s):  
Spatial Distribution ◽  
Pattern Formation ◽  
Characteristic Time ◽  
Population Distribution ◽  
Distribution Patterns ◽  
The Other ◽  
Linear Pattern ◽  
Fundamental Goal ◽  
Spatial Pattern Formation ◽  
Qualitative Changes

A fundamental goal of ecology is to understand the spatial distribution of species. For moving animals, their location is crucially dependent on the movement mechanisms they employ to navigate the landscape. Animals across many taxa are known to exhibit directional correlation in their movement. This work explores the effect of such directional correlation on spatial pattern formation in a model of between-population taxis (i.e., movement of each population in response to the presence of the others). A telegrapher-taxis formalism is used, which generalises a previously studied diffusion-taxis system by incorporating a parameter T, measuring the characteristic time for directional persistence. The results give general criteria for determining when changes in T will drive qualitative changes in the predictions of linear pattern formation analysis for N ≥ 2 populations. As a specific example, the N = 2 case is explored in detail, showing that directional correlation can cause one population to ‘chase’ the other across the landscape while maintaining a non-constant spatial distribution. Overall, this study demonstrates the importance of accounting for directional correlation in movement for understanding both quantitative and qualitative aspects of species distributions.

scholarly journals Vertical distribution of pre-settled sandeel (Ammodytes marinus) in the North Sea in relation to size and environmental variables

2003 ◽  
Vol 60 (6) ◽  
pp. 1342-1351 ◽  
Author(s):  
Henrik Jensen ◽  
Peter J Wright ◽  
Peter Munk
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
North Sea ◽  
Distribution Patterns ◽  
Food Concentration ◽  
The North ◽  
Vertical Distributions ◽  
The North Sea ◽  
Drift Trajectory ◽  
Vertical Positioning

Abstract Vertical distribution patterns of larval and juvenile sandeels were investigated at four locations in the North Sea. Sandeels between 6 and 65 mm were found to depths of 80 m, with vertical distributions dependent on both length and environmental factors. At one location with a stratified water column, the highest densities were found during the day in midwater where food concentration was also highest. In areas without marked vertical hydrographic gradients, larvae were relatively more abundant in surface waters during the day. At all locations, larvae of all sizes were generally more homogeneously distributed in the water column during night than during day. The extent of vertical migration, as measured by the standard deviation of the mean depth, increased generally with length. Gear avoidance was evident for larvae ≥20 mm. Catch efficiency generally depended on both length class and surface light intensity. A simulated drift pattern of larvae, based on ADCP current measurements from two locations, predicts that the horizontal drift trajectory would only be affected slightly by the vertical positioning of the larvae in the water column during the time of sampling. The implication of vertical migrations for dispersal of larvae away from the spawning grounds is discussed.

scholarly journals Entomostraca

1879 ◽  
Vol 168 ◽  
pp. 215-218 ◽  
Keyword(s):  
Brackish Water ◽  
High Water ◽  
Freshwater Lake ◽  
The Other ◽  
Calanus Finmarchicus ◽  
Freshwater Species ◽  
Kerguelen Island ◽  
High Water Mark ◽  
Oceanic Species

[Ostracoda. All of the Ostracoda collected by me in Kerguelen Island were lost by a breakage.—A. E. E.] Copepoda. The Entomostraca submitted to me were taken in the following localities:—One surface-net gathering, in lat. 35° 9' S., long. 45° 30' E.; another gathering from a freshwater lake, and a third from a pool above high-water mark, both in Kerguelen Island. The oceanic species were Calanus Finmarchicus and a Sapphirina , either identical with or very closely allied to S. danœ , Lubbock; those from Kerguelen Island were a freshwater species, apparently new, described by me briefly in Ann. and Mag. Nat. Hist., Sept. 1875, under the name Centropages brevicaudatus ; and a species from brackish water, Harpacticus fulvus . No species have yet been recorded by the other Expeditions.

Distribution and abundance of some Hyperiidea (Crustacea : Amphipoda) in Northern Queensland Waters

1984 ◽  
Vol 35 (3) ◽  
pp. 285 ◽  
Author(s):  
W Zeidler
Keyword(s):  
High Salinity ◽  
Abundant Species ◽  
The Other ◽  
Barrier Reef ◽  
Short Period ◽  
Regular Sampling ◽  
Salinity Data ◽  
Oceanic Species ◽  
Quantitative Results ◽  
Inshore Waters

Hyperiid amphipods (35 species) were collected at eight regular sampling stations, spaced evenly between Townsville and the Great Barrier Reef, over 1 year (October 1972 to October 1973). The distribution and abundance of the Hyperiidea in northern Queensland, where hyperiids were generally most abundant during October-December and April-July, are discussed and quantitatively analysed and related to temperature and salinity data collected at the same time. The quantitative results indicate that hyperiids can be relatively abundant and may be a more important component of the inshore plankton than was thought previously. Only 13 species were sufficiently abundant to permit a more detailed discussion of their ecology. The two most abundant species, Lestrigonus bengalensis and Hyperioides sibaginis, were found most often in inshore waters and may form permanent local populations. Most of the other species were epipelagic oceanic species preferring warm waters (> 25�C) of relatively high salinity (>35 × 10-3) and were rarely found close inshore. Some species, Simorhynchotus antennarius, Tullbergella cuspidata and species of Phronimidae, only occurred in the plankton for a short period.

scholarly journals A diagnostic analysis of MONEX-1979 onset vortex over the Arabian Sea

MAUSAM ◽  
2022 ◽  
Vol 44 (4) ◽  
pp. 321-328
Author(s):  
KSHUDIRAM SAHA ◽  
R SURANJANA SAHA
Keyword(s):  
Arabian Sea ◽  
Diabatic Heating ◽  
Heat Budget ◽  
The Other ◽  
Diagnostic Analysis ◽  
Structure Development ◽  
Cyclonic Storm ◽  
Vertical Distributions ◽  
Differential Behaviour ◽  
Temperature Tendency

Based on MONEX-,1979 data over the Arabian Sea, the paper analyses observationally the structure, development and movement of a vortex which formed during onset of the monsoon around mid-June near the coast of Kerala developed into a cyclonic storm at mid-sea and moved towards the coast of Oman to die out there Heat budget computations bring out the differential behaviour of the different quadrants of the disturbance and appear to highlight the contrasting features between the northwestern and the other quadrants in regard to vertical. distributions of diabatic heating, local temperature tendency thermal advection and adiabatic heating or cooling. The study reveals an interaction of the vortex with two eastward-propagating subtropical westerly troughs which might have contributed significantly to its explosive development (decay) through warm (cold) advection. Both barotropic and baroclinic energy conversions appear to supply energy to the storm; though there appears to be a dominance of one over the other at different stages of development and at different heights. It seems likely that condensation heating also contributed to development of the storm.

Tracing the Distribution of Chinese and World Bank-Funded Projects and Public Demonstrations in Cameroon and Uganda

2020 ◽  
pp. 002190962093911
Author(s):  
Afa’anwi Ma’abo Che
Keyword(s):  
Foreign Aid ◽  
World Bank ◽  
Distribution Patterns ◽  
Armed Conflicts ◽  
The Other ◽  
State Repression ◽  
Management Standards ◽  
Chinese Official ◽  
The One ◽  
Public Demonstrations

Extant literature has explored the effects of foreign aid on armed conflicts and state repression, but not on public demonstrations. This article compares distribution patterns of Chinese and World Bank-funded projects and public demonstrations in Cameroon, receiving predominantly Chinese official finance, and Uganda, receiving predominantly traditional, Western aid. Distributive patterns suggest negative and positive associations between Chinese and traditional official finance on the one hand and public demonstrations on the other. However, with respect to anti-project demonstrations specifically, I find through fieldwork interviews in Cameroon that Chinese-funded projects are more prone to anti-project demonstrations owing to less stringent risk management standards.

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