Demersal fish biomass size spectra on the Scotian Shelf, Canada: species replacement at the shelfwide scale

1997 ◽  
Vol 54 (8) ◽  
pp. 1725-1735 ◽  
Author(s):  
D E Duplisea ◽  
S R Kerr ◽  
L M Dickie
Keyword(s):  
Time Series ◽  
Body Weight ◽  
Energy Input ◽  
Demersal Fish ◽  
Species Group ◽  
Total Biomass ◽  
Species Replacement ◽  
Scotian Shelf ◽  
Size Spectra ◽  
Species Groups

Three parameters were derived from annual biomass size spectra constructed for a 22-year time series of demersal fish data for the entire Scotian Shelf: (i) total sampled biomass density, (ii) modal body weight, and (iii) the shape of the various biomass size spectra. Temporal variability of these parameters was compared among six species groups and between the species groups and their total. Species-group biomass varied more over the time series than did the total biomass, indicating the presence of a system factor. Conversely, modal body weight was as variable, and sometimes more variable, for the total than it was within species groups, indicating variability mainly at the species level. The shape of the biomass size spectrum showed annual differences in variability owing mainly to contributions of species groups. This variability was higher than variability in the combined species totals. We conclude that total biomass is limited at the combined species (systemwide) level because it depends on energy input to the system. Variability is greater at the species group (subsystem) level because the multiage species-group biomasses do not equally reflect a given energy limitation. Neither modal body weight nor the shape of the biomass spectrum is sensitive to the degree of taxonomic aggregation, suggesting that both measures are independent of energy input (primary production). We found no evidence of consistent species replacement trends on the shelfwide scale and conclude that diffuse replacement best describes species succession on the Scotian Shelf as a whole.

Structure and functioning of the eastern Scotian Shelf ecosystem before and after the collapse of groundfish stocks in the early 1990s

2005 ◽  
Vol 62 (7) ◽  
pp. 1453-1473 ◽  
Author(s):  
Alida Bundy
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Trophic Levels ◽  
Total Biomass ◽  
Scotian Shelf ◽  
Mass Balance Models ◽  
Key Species ◽  
Before And After ◽  
Species Groups ◽  
System Properties

The fishery-induced collapse of the Atlantic cod (Gadus morhua) stock on the eastern Scotian Shelf has altered the species composition of this ecosystem. Ecopath mass-balance models of the ecosystem before and after the collapse were developed to explore how the structure, function, and key species of the ecosystem had changed. For the first time, an analysis of uncertainty was conducted to examine the effects of the uncertainty on model estimates. A comparison of the two Ecopath models indicated that although total productivity and total biomass of the ecosystem remained similar, there were changes in predator structure, trophic structure, and energy flow, many of which were robust to uncertainty. Biomass has significantly increased at trophic levels 3 and 4, and the composition of these trophic levels has changed as a result of the mean increase in trophic level of many species-groups. Piscivory has increased, presumably because of the high abundance of small pelagic fish, and the ratio of pelagic feeders to demersal feeders has increased from 0.3 to 3.0. Thus, the ecosystem has changed from a demersal-feeder-dominated system to a pelagic-feeder-dominated system. Although uncertainty remains concerning some model estimates, the ecosystem has been profoundly altered and exhibits classic symptoms of "fishing down the food web". However, overall system properties were generally conserved.

Demersal Fish Assemblages on the Scotian Shelf, Northwest Atlantic: Spatial Distribution and Persistence

1989 ◽  
Vol 46 (S1) ◽  
pp. s134-s152 ◽  
Author(s):  
Robin Mahon ◽  
Robert W. Smith
Keyword(s):  
Environmental Variables ◽  
Fishery Management ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Demersal Fish ◽  
Assemblage Structure ◽  
Bay Of Fundy ◽  
Scotian Shelf ◽  
Species Groups ◽  
Temporal And Spatial

This study is based on 18 surveys, 12 in summer, and three each in spring and fall, with bottom trawls over the Scotian Shelf and Bay of Fundy. The data analysis sequence was: temporal and spatial aggregation of trawl sets; estimation of interspecies and intersite distance indices; clustering and ordination of sites and species, and discrimination of site groups using environmental variables. Nine species-groups, and 10 site-groups were defined, and displayed in a two-way table. Depth and temperature were the environmental variables most strongly associated with differences in assemblage structure among site-groups. Changes in assemblage structure from one area to another were distinct but apparently gradual, with no sharp assemblage boundaries. This pattern is expected if species are distributed independently on environmental gradients, rather than if assemblages consist of highly co-evolved, interdependent species. The observed spatial patterns were highly persistent through time. There are regions which are relatively homogeneous with regard to species composition and which can therefore be useful in dealing with bycatch problems. However, this study does not indicate the existence of discrete assemblages which might be appropriate as ecologically based fishery management units.

Review of species of the genus Cercyon of Russia and adjacent regions. VI. Subgenus Cercyon, the C.shinanensis group (Coleoptera: Hydrophilidae)

2019 ◽  
Vol 28 (2) ◽  
pp. 258-266 ◽  
Author(s):  
S.K. Ryndevich ◽  
H. Hoshina ◽  
A.A. Prokin
Keyword(s):  
Russian Far East ◽  
Far East ◽  
Species Group ◽  
Palaearctic Species ◽  
Diagnostic Features ◽  
Kunashir Island ◽  
Species Groups ◽  
The Russian Far East

The Cercyon shinanensis species group with two included species is erected within the nominotypical subgenus of Cercyon Leach, 1817. This group is compared with other Palaearctic species groups of Cercyon s. str. The little-known C. shinanensis Nakane, 1965 from Japan (Honshu) is redescribed and its diagnostic features are given. Cercyon sundukovi sp. nov. is described from the Russian Far East (Kunashir Island).

Algae Migration Characteristics in Fresh Water Red Tide

1993 ◽  
Vol 28 (7) ◽  
pp. 197-201 ◽  
Author(s):  
Dunchun Wang ◽  
Isao Somiya ◽  
Shigeo Fujii
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Fresh Water ◽  
Field Data ◽  
Field Survey ◽  
Red Tide ◽  
Bottom Layer ◽  
Total Biomass ◽  
Quality Indices ◽  
Vertical Distributions

To understand the algae migration characteristics in the fresh water red tide, we performed a field survey in the Shorenji Reservoir located in Nabari City, Japan. From the analysis of the field data, it is found that the patterns of vertical distributions of the indices representing biomass are very different in the morning and the afternoon. Since some water quality indices have reverse fluctuations between the surface and the bottom layer in respect of the time series changes and the total biomass of the vertical water column is relatively constant, it is concluded that vertical and daily biomass variation of red tide alga is caused by its daily migration, that is the movement from the bottom layer to the surface in the morning and the reverse movement in the afternoon.

Discovery of New Genera Challenges the Subtribal Classification of Tok-Tok Beetles (Coleoptera: Tenebrionidae: Sepidiini)

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Olivia M Gearner ◽  
Marcin J Kamiński ◽  
Kojun Kanda ◽  
Kali Swichtenberg ◽  
Aaron D Smith
Keyword(s):  
Dna Sequences ◽  
Species Group ◽  
Phylogenetic Placement ◽  
Darkling Beetles ◽  
Species Groups ◽  
Taxonomic Groups ◽  
Inference Methods ◽  
A New Species ◽  
Coleoptera Tenebrionidae

Abstract Sepidiini is a speciose tribe of desert-inhabiting darkling beetles, which contains a number of poorly defined taxonomic groups and is in need of revision at all taxonomic levels. In this study, two previously unrecognized lineages were discovered, based on morphological traits, among the extremely speciose genera Psammodes Kirby, 1819 (164 species and subspecies) and Ocnodes Fåhraeus, 1870 (144 species and subspecies), namely the Psammodes spinosus species-group and Ocnodes humeralis species-group. In order to test their phylogenetic placement, a phylogeny of the tribe was reconstructed based on analyses of DNA sequences from six nonoverlapping genetic loci (CAD, wg, COI JP, COI BC, COII, and 28S) using Bayesian and maximum likelihood inference methods. The aforementioned, morphologically defined, species-groups were recovered as distinct and well-supported lineages within Molurina + Phanerotomeina and are interpreted as independent genera, respectively, Tibiocnodes Gearner & Kamiński gen. nov. and Tuberocnodes Gearner & Kamiński gen. nov. A new species, Tuberocnodes synhimboides Gearner & Kamiński sp. nov., is also described. Furthermore, as the recovered phylogenetic placement of Tibiocnodes and Tuberocnodes undermines the monophyly of Molurina and Phanerotomeina, an analysis of the available diagnostic characters for those subtribes is also performed. As a consequence, Phanerotomeina is considered as a synonym of the newly redefined Molurina sens. nov. Finally, spectrograms of vibrations produced by substrate tapping of two Molurina species, Toktokkus vialis (Burchell, 1822) and T. synhimboides, are presented.

Beyond Wallace: a new lineage of Chrysorthenches (Lepidoptera: Yponomeutoidea: Glyphipterigidae) reveals a journey tracking its host-plants, Podocarpus (Pinopsida: Podocarpaceae)

2020 ◽  
Vol 190 (2) ◽  
pp. 709-736
Author(s):  
Jae-Cheon Sohn ◽  
Shigeki Kobayashi ◽  
Yutaka Yoshiyasu
Keyword(s):  
Maximum Likelihood ◽  
East Asia ◽  
Host Plants ◽  
Morphological Characters ◽  
Species Group ◽  
Geological History ◽  
Dna Barcodes ◽  
History Of ◽  
Species Groups ◽  
Maximum Likelihood Phylogeny

Abstract A northward trans-Wallacean radiation is demonstrated for Chrysorthenches, a member of the Orthenches group. Here we review Chrysorthenches and allied genera resulting in a generic transfer of Diathryptica callibrya to Chrysorthenches and two new congeners: C. muraseaeSohn & Kobayashisp. nov. from Japan and C. smaragdinaSohnsp. nov. from Thailand. We review morphological characters of Chrysorthenches and allied genera, and find polyphyly of Diathryptica and the association of the Orthenches-group with Glyphipterigidae. These findings were supported in a maximum likelihood phylogeny of DNA barcodes from ten yponomeutoids. We analysed 30 morphological characters for 12 species of Chrysorthenches, plus one outgroup, via a cladistic approach. The resulting cladogram redefined two pre-existing Chrysorthenches species-groups and identified one novel lineage: the C. callibrya species-group. We review the host associations between Chrysorthenches and Podocarpaceae, based on mapping the working phylogenies. Our review suggests that ancestral Chrysorthenches colonized Podocarpus and later shifted to other podocarp genera. Biogeographical patterns of Chrysorthenches show that they evolved long after the Podocarpaceae radiation. Disjunctive trans-Wallacean distribution of the C. callibrya species-group is possibly related to the tracking of their host-plants and the complicated geological history of the island-arc system connecting Australia and East Asia.

Revision of the Metallactus kollari species-group with a new diagnosis of the genus (Coleoptera: Chrysomelidae: Cryptocephalinae)

Zootaxa ◽  
2018 ◽  
Vol 4413 (1) ◽  
pp. 57
Author(s):  
DAVIDE SASSI
Keyword(s):  
Type Species ◽  
Species Group ◽  
Identification Key ◽  
Original Diagnosis ◽  
Taxonomic Treatment ◽  
Species Groups ◽  
New Diagnosis ◽  
Good Resource

The genus Metallactus has been controversial since its introduction due to the ambiguous nature of the original diagnosis. This has caused some confusion in the taxonomy of Neotropical Pachybrachina. In this work the morphology of endophallus, which is useful for the characterization of species groups in several groups of Coleoptera, including Cryptocephalinae, has been analyzed. This has proven to be a good resource also in the taxonomic treatment of the species belonging to the genus Metallactus. After a careful survey on most of the species described so far, the endophallus shape in Metallactus turned out to be remarkably distinctive and very promising in the delimitation of species groups. The present work includes: a) a new diagnosis of the genus Metallactus on the basis of the aedeagal anatomy; b) the designation of the type species of the nominal genus; c) the revision of a first species-group of the genus, including the type species, hereinafter called Metallactus kollari species-group. Before this revision, catalogues had been reporting 13 species attributable to this group, in the present work three species have been synonymized and seven have been described as new to science. Therefore, the group includes 17 species. The species described as new are: Metallactus rileyi n. sp., M. bellatrix n. sp., M. longicornis n. sp.; M. londonpridei n. sp., M. regalini n. sp., M. bezoar n. sp., M. guarani n. sp. The new synonymies are as follows: Metallactus albipes Suffrian, 1866 (= M. nigrofasciatus Suffrian, 1866 n. syn.), M. albifrons Suffrian, 1866 (= M. flavofrontalis Jacoby, 1907 n. syn.), M. dodecastictus Suffrian, 1866 (= Griburius nigritarsis Jacoby, 1907 n. syn.). The lectotypes of all previously described species have been designated. The new synonymies, the name-bearing type fixations and designations and the nomenclatural acts have been critically discussed. An identification key for the species-group is also provided. 

scholarly journals Individuals from different-looking animal species may group together to confuse shared predators: simulations with artificial neural networks

2006 ◽  
Vol 274 (1611) ◽  
pp. 827-832 ◽  
Author(s):  
Colin R Tosh ◽  
Andrew L Jackson ◽  
Graeme D Ruxton
Keyword(s):  
Animal Species ◽  
Empirical Work ◽  
Species Group ◽  
Mixed Species ◽  
Retinotopic Maps ◽  
Species Groups ◽  
Artificial Neural ◽  
Mixed Species Groups ◽  
Species Grouping ◽  
Prey Items

Individuals of many quite distantly related animal species find each other attractive and stay together for long periods in groups. We present a mechanism for mixed-species grouping in which individuals from different-looking prey species come together because the appearance of the mixed-species group is visually confusing to shared predators. Using an artificial neural network model of retinotopic mapping in predators, we train networks on random projections of single- and mixed-species prey groups and then test the ability of networks to reconstruct individual prey items from mixed-species groups in a retinotopic map. Over the majority of parameter space, cryptic prey items benefit from association with conspicuous prey because this particular visual combination worsens predator targeting of cryptic individuals. However, this benefit is not mutual as conspicuous prey tends to be targeted most poorly when in same-species groups. Many real mixed-species groups show the asymmetry in willingness to initiate and maintain the relationship predicted by our study. The agreement of model predictions with published empirical work, the efficacy of our modelling approach in previous studies, and the taxonomic ubiquity of retinotopic maps indicate that we may have uncovered an important, generic selective agent in the evolution of mixed-species grouping.

Three new Anaulacomera species (Orthoptera: Tettigoniidae: Phaneropterinae) from the Iguaçu National Park and nearby areas, southern Brazil

Zootaxa ◽  
2021 ◽  
Vol 5061 (2) ◽  
pp. 340-352
Author(s):  
MARCOS FIANCO ◽  
OSCAR J. CADENA-CASTAÑEDA ◽  
NEUCIR SZINWELSKI ◽  
LUIZ R. R. FARIA
Keyword(s):  
New Species ◽  
Atlantic Forest ◽  
National Park ◽  
Species Group ◽  
Southern Brazil ◽  
Distribution Maps ◽  
Incertae Sedis ◽  
Present Distribution ◽  
Species Groups ◽  
Three New Species

Three new species of Anaulacomera are described, Anaulacomera (Anaulacomera) mariellae sp. n. and Anaulacomera (Anallomes) arlindoi sp. n., belonging respectively to the Inermis and Lanceolata species group, and Anaulacomera angelinae sp. n., placed as incertae sedis. The individuals were collected at the Iguaçu National Park and adjacent small fragments of Atlantic Forest, in southwestern Paraná state, Brazil. The description was based on external morphology of males. We also present distribution maps for the species of the Inermis and the Lanceolata species groups.  

Sign in / Sign up

Export Citation Format

Share Document