scholarly journals Microcrustacean assemblages composition and environmental variables in lakes and ponds of the Andean region - South of Chile (37-39° S)

2011 ◽  
Vol 71 (2) ◽  
pp. 353-358 ◽  
Author(s):  
P. De los Ríos-Escalante ◽  
E. Hauenstein ◽  
M. Romero-Mieres
Keyword(s):  
Random Process ◽  
Chlorophyll Concentration ◽  
Null Model ◽  
Principal Component ◽  
Model Analysis ◽  
Species Number ◽  
Coastal Zones ◽  
Main Determinant ◽  
Chilean Patagonia ◽  
Main Regulator

The zooplankton assemblages in Chilean Patagonian lakes are characterised mainly by their low biodiversity and high predominance of calanoids copepods, a pattern that has been studied for large and deep lakes between 38-51° S, and shallow ponds at 51° S. The aim of the present study was analyse the zooplankton assemblages in different water bodies located in coastal zones, middle valleys and mountain zones between 37-39° S. For this purpose, the following variables were considered: maximum depth, latitude, altitude, chlorophyll-a and species number, and to these variables, a Principal Component Analysis (PCA) was applied. A co-occurrence null model analysis was also applied for determining the existence of a random process in crustacean species associations. The results denoted low species richness, and different species associations for studied sites, and the null model analysis revealed the absence of a random process as regulator of species associations. Furthermore, a low species/genera ratio was identified, which denotes low productivity of the studied sites. These results were supported by a PCA analysis which denoted that the main determinant factors are chlorophyll concentration and species number that are directly associated. The obtained results are in agreement with descriptions in the literature for species diversity for lakes of Chilean Patagonia that describes oligotrophy as the main regulator of zooplankton assemblages. Other ecological and limnological topics are discussed in the present study.

A null model to study community structure of microcrustacean assemblages in north Patagonian urban wetlands (39-41°S, Chile)

Crustaceana ◽  
2014 ◽  
Vol 87 (11-12) ◽  
pp. 1377-1385
Author(s):  
Patricio De los Ríos-Escalante ◽  
Andrés Muñoz-Pedreros ◽  
Patricia Möller
Keyword(s):  
Community Structure ◽  
Trophic Status ◽  
Null Model ◽  
Model Analysis ◽  
Jaccard Index ◽  
Field Observations ◽  
Urban Wetlands ◽  
Community Similarity ◽  
Chilean Patagonia ◽  
Inland Water Bodies

The inland water bodies of northern Chilean Patagonia (38-41°S) have many lakes, wetlands and ponds with different littoral and zooplanktonic crustacean assemblages. This study presents field observations of species associations sampled from shallow wetlands located in the urban zones of Valdivia (39°S) and Puerto Montt (41°S). A species presence-absence matrix was created for calculating the Jaccard Index of community similarity and for testing null models of species associations, with the aim of determining whether species associations are random or not. The results of the Jaccard Index calculations indicated the existence of non-defined groups. The results of the null model analysis denoted the presence of regulating factors for Valdivia wetlands, whereas for Puerto Montt wetlands no such factors could be demonstrated. The outcomes of both the Jaccard Index and the significant null model analysis agree with previous ecological descriptions of changes in trophic status as a consequence of changes in the surrounding basin as a determinant of species associations. The ecology of these communities is also discussed.

scholarly journals Inland water microcrustacean assemblages in an altitudinal gradient in Aysen region (46° S, Patagonia Chile)

2014 ◽  
Vol 74 (1) ◽  
pp. 8-15 ◽  
Author(s):  
Patricio De los Ríos-Escalante ◽  
Esteban Quinán ◽  
Patricio Acevedo
Keyword(s):  
National Park ◽  
Altitudinal Gradient ◽  
Null Model ◽  
Tierra Del Fuego ◽  
Species Number ◽  
Regional Studies ◽  
Inland Water ◽  
Chilean Patagonia ◽  
Water Ecosystems ◽  
Torres Del Paine

The Chilean Patagonia has numerous kinds of inland water ecosystems such as lakes, ponds, wetlands and rivers that have been poorly studied due to access difficulties. This study was carried out in Aysen region, in southern Chile, and it included different kinds of water bodies such as rivers, streams, ponds, lagoons and lakes distributed along an altitudinal gradient at 46° S. It was found a low species number, essentially cladocerans, copepods and amphipods. A null model was applied in order to determine the existence of regulator factors of species associations, and the results revealed that they are not random. The patterns would be influenced by geographical and limnological characteristics of the studied sites. Our results would agree with regional studies on habitat heterogeneity such as in Torres del Paine National Park and other zones in Tierra del Fuego island.

On the geographic distribution of Boeckella brevicaudata (Brady, 1875) (Copepoda, Calanoida) and its species associations in seasonal ephemeral pools in the Magallanes region (53°S, Chile)

Crustaceana ◽  
2014 ◽  
Vol 87 (5) ◽  
pp. 540-550 ◽  
Author(s):  
Patricio De los Ríos-Escalante ◽  
Andrés Mansilla
Keyword(s):  
Calanoid Copepod ◽  
Null Model ◽  
Niche Overlap ◽  
Model Analysis ◽  
South American ◽  
South American Species ◽  
Mineral Contents ◽  
Ephemeral Pools ◽  
Chilean Patagonia ◽  
Southern Patagonia

The distribution of crustaceans of inland waters in southern Patagonia is characterized by the presence of sub-Antarctic and southern South American species. The aims of the present study were to study the geographical distribution of the calanoid copepod Boeckella brevicaudata (Brady, 1875) and the community structure of the zooplankton assemblages in which this species occurs. This last purpose was approached by applying null-models analyses based on species co-occurrence and niche-sharing. The species itself inhabits sub-Antarctic islands as well as southern South America. The results of the co-occurrence null model analysis revealed that the communities with this species have no regulating factors, whereas the niche overlap null model analysis revealed that these species share the same ecological niche. We thus found low abundances for all species, with specifically low B. brevicaudata abundance, at low mineral contents of the water. The results obtained were similar among sites in southern Argentinean and southern Chilean Patagonia, and on sub-Antarctic islands of which data were available.

scholarly journals Species co-occurrences based on a presence/absence null model for Copepoda and cladocerans in Patagonia and Tierra del Fuego lakes and ponds

Biologia ◽  
2010 ◽  
Vol 65 (6) ◽  
Author(s):  
Patricio Ríos ◽  
Andrés Mancilla ◽  
Marcela Vega
Keyword(s):  
Saline Lake ◽  
Null Model ◽  
Study Data ◽  
Tierra Del Fuego ◽  
Species Number ◽  
Random Pattern ◽  
Ecological Features ◽  
Chilean Patagonia ◽  
Halophilic Species ◽  
Artemia Persimilis

AbstractThe zooplankton assemblages in southern Chilean Patagonia are characterized by calanoid dominance and low species number that is observable under oligotrophic status and wide conductivity values, whereas at mesotrophic status the daphnids are dominant with high species number, and finally at hyper-saline environments halophilic species such as Artemia persimilis and/or the calanoid Boeckella poopensis predominate. In the present study data of different lakes and ponds between 45-53° S were analyzed, with the aim to determine potential structures at different sites. For this purpose a null model based in guild structure was applied, considering each guild a different kind of water body (lake, small lake, permanent pond, ephemeral pond, and saline lake). The results revealed in two simulations that guild are structured. These results are similar with other descriptions on the basis of null models that revealed a random pattern of species associations for similar ecosystems due to many species repeated in all or practically all studied sites or similarities of ecological features. Ecological and biogeographical topics were discussed.

First report of Branchinecta (Anostraca) in seasonal coastal pools in the Araucania region (Puaucho, 39°S, Chile)

Crustaceana ◽  
2018 ◽  
Vol 91 (10) ◽  
pp. 1219-1230
Author(s):  
Patricio De los Ríos ◽  
Eriko Carreño
Keyword(s):  
Principal Component Analysis ◽  
Low Temperature ◽  
Null Model ◽  
Principal Component ◽  
Niche Overlap ◽  
Total Dissolved Solids ◽  
Inland Waters ◽  
Dissolved Solids ◽  
Chilean Patagonia ◽  
Fairy Shrimps

Abstract To date, he fairy shrimps (Anostraca) of Chilean inland waters have been poorly described. Those that were described mainly belong to the genus Branchinecta, and the reports are primarily restricted to shallow seasonal pools at the northern and southern extremes of Chile. The aim of the present study was to give a first description of Branchinecta rocaensis, reported from ephemeral coastal pools in the Puaucho dunes, situated in the Araucania region. The results of null model analysis revealed first, that species associations are random and that there is niche overlap, while according to the principal component analysis, B. rocaensis was present at sites with low conductivity, low total dissolved solids and low temperature values, but with a high abundance of ostracods. The results obtained would agree with similar observations for Branchinecta habitats in southern Chilean Patagonia.

scholarly journals Null models for study Rotifers and Crustaceans Zooplankton species richness in Chilean Patagonian lakes

2016 ◽  
Vol 28 (0) ◽  
Author(s):  
Patricio de los Ríos Escalante
Keyword(s):  
Latitudinal Gradient ◽  
Chlorophyll Concentration ◽  
Null Model ◽  
Species Number ◽  
Inverse Association ◽  
Zooplankton Species ◽  
Crustacean Species ◽  
Number Pattern ◽  
Patagonian Lakes ◽  
Total Species

Abstract Aims The Patagonian lakes are characterized by their oligotrophy that is the cause of low species number in their zooplankton assemblage. The aim of the present study is to analyze the crustacean and rotifers species number pattern in Patagonian lakes among a latitudinal gradient (40-51 °S). Results The results revealed that there are direct significant correlations between total species with rotifer species, and chlorophyll concentration with crustacean species number, and an inverse association between latitude with total species. Conclusion The results of co-occurrence species null model revealed presence of regulator factors in one of three simulations, that would be due to the presence of many species repeated in studied sites. Similar patterns were observed in Argentinean Patagonian lakes.

scholarly journals Microphytoplankton structure from the neritic and oceanic regions of Pernambuco State - Brazil

2009 ◽  
Vol 69 (4) ◽  
pp. 1037-1046 ◽  
Author(s):  
ML. Koening ◽  
BE. Wanderley ◽  
SJ. Macedo
Keyword(s):  
Principal Component ◽  
Mesh Size ◽  
Species Number ◽  
Phytoplankton Diversity ◽  
Trichodesmium Erythraeum ◽  
Species Association ◽  
Tropical Water ◽  
Key Species ◽  
Distribution And Ecology ◽  
Planktonic Species

This research was carried out to assess phytoplankton diversity, distribution and ecology on the Pernambuco Continental Shelf and Oceanic region (lat. 7º 33' 00" S to 8º 41' 50" S and long. 34º 04' 47" W to 35º 01' 20" W). Samples were collected during the Joint Oceanographics Projects (JOPS II-Leg 5) by double oblique hauls with a baby bongo net 64 µm mesh size at depth between 14 and 150 m in inshore and offshore waters respectively, in seven transects, totaling 34 stations. The temperature and salinity characterised the tropical water masses. The dissolved oxygen was oversaturated in all stations. The nutrient-low concentrations showed an oligothrophic pattern in the whole area. 173 specific and infraspecific taxa were identified: Dinophyta (103 taxa), Bacillariophyta (61 taxa), Cyanobacteria (7 taxa), Chlorophyta and Chrysophyta (1 taxon). The family Ceratiaceae presented the highest species number (47 taxa). The cyanobacteria Trichodesmium erythraeum Ehrenberg, Oscillatoria spp. and the diatom Leptocylindrus danicus Cleve had higher frequence of occurrence and abundance. Species diversity varied from 0.71 to 3.46 bits.cell-1 and this low index was due to Trichodesmium erythraeum bloom and evenness from 0.14 to 0.65, showing an unstable pattern. The oceanic planktonic species were responsible for the higher richness with 78 taxa, corresponding to 58.39% of the total microphytoplankton. The species association presented two groups. The first one divided in two subgroups: one associated to the neritic/oceanic and oceanic planktonic species and the other to the oligotrophic indicator species. The second group was composed of some key species which were the most abundant and frequent in the area. The first three Principal Component Analyses (PCAs) explained 50.91% of the data variance showing that the area is structured by two groups: one offshore composed by oligotrophic indicators, and another nearshore influenced by continental fluxes.

scholarly journals Statistical challenges in null model analysis

Oikos ◽  
2011 ◽  
Vol 121 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Nicholas J. Gotelli ◽  
Werner Ulrich
Keyword(s):  
Null Model ◽  
Model Analysis

Decapods Associated with the Southern King Crab (Lithodes santolla) Fishery in Central Patagonia (44° S, Chile)

2021 ◽  
Vol 9 (12) ◽  
pp. 1353
Author(s):  
Guillermo Figueroa-Muñoz ◽  
Carlos Molinet ◽  
Manuel Díaz ◽  
Patricio De los Ríos-Escalante
Keyword(s):  
Generalized Linear Model ◽  
Species Abundance ◽  
Null Model ◽  
The Body ◽  
Fishery Resource ◽  
King Crab ◽  
Body Of Knowledge ◽  
Chilean Patagonia ◽  
Different Depths ◽  
Total Species

The southern king crab, Lithodes santolla, is an important fishery resource in the inner seas of Chilean Patagonia. The fishing gear used to catch southern king crab (bait trap) and its operation at different depths over several months provide the opportunity to gather information about relative abundance. The aim of the present study was to analyze the information collected from the catches of southern king crab and its associated fauna in the Magdalena Fjord to study the biodiversity and ecology of scavenging decapod crustaceans. Specifically, the study aimed to determine the bathymetric patterns of abundance by species, to model the abundance by season (winter and spring) and to determine the structuring pattern of scavenging decapods assemblage. Samples were collected between June and November 2019 by deploying traps in four bathymetric strata: 1 = 0–50 m; 2 = 51–100 m; 3 =101–150 m; 4 = 151–200 m. We registered a total of 673 decapod specimens associated with the southern king crab fishery, representing five species: Lithodes santolla (n = 96), Libidoclaea smithii (n = 10), Metacarcinus edwardsii (n = 58), Munida gregaria (n = 507) and Peltarion spinulosum (n = 2). The abundance of decapod species varied by month and bathymetric strata. We found bathymetric patterns for L. santolla abundance, M. gregaria, M. edwardsii, and total species abundance. The most informative model to explain scavenging decapod abundance by generalized linear model (GLM) included species and season. The null model of species co-occurrence analysis revealed that all species associations during the sampled months were random. Our study is the first that provides evidence about patterns of bathymetrical and temporal variation of scavenging decapod abundance and expands the body of knowledge regarding the biodiversity of scavenger decapods in the Magdalena Sound.

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