scholarly journals DENSIDAD POBLACIONAL DE CUATRO ESPECIES DE ERIZO (ECHINODERMATA: ECHINOIDEA) EN EL ARRECIFE DE LA ENTREGA, OAXACA

2005 ◽  
Vol 20 (1-2) ◽  
pp. 65
Author(s):  
P. Zamorano ◽  
G. E. Leyte-Morales
Keyword(s):  
Population Density ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Depth Range ◽  
Deep Zone ◽  
Total Abundance ◽  
Subsequent Increase ◽  
Shallow Zone ◽  
Over Time ◽  
Shallow Part

De octubre de 2002 a agosto de 2003 se realizaron muestreos bimestrales de la abundancia de erizos en el arrecife de La Entrega. El arrecife fue dividido en dos profundidades (somero 0-6 m y profundo 6-12 m). En cada profundidad se realizaron seis transectos de 50 m de largo por 1 m de ancho. La mayor densidad anual correspondió a Diadema mexicanum (5.96±0.85 ind/m2), seguido de Eucidaris thouarsii (0.46±0.14 ind/m2); Echinometra vanbrunti y Toxopneustes roseus presentaron densidades bajas (0.03±0.01 ind/m2 y 0.02±0.01 ind/m2, respectivamente). Las cuatro poblaciones de erizos presentaron diferencias entre profundidades observándose mayor densidad en lo profundo; si consideramos la abundancia total de erizos en el arrecife, no se registraron diferencias temporales. Empero, al analizar por separado las profundidades, sólo E. thouarsii no presentó diferencias temporales en ambas profundidades. En diciembre, las densidades de D. mexicanum y E. thouarsii disminuyeron en lo profundo y aumentaron en lo somero, posiblemente porque sucedió una mortalidad coralina en lo somero del arrecife y el incremento de las algas motivó a estas especies a desplazarse a la parte dañada. Actualmente el arrecife de La Entrega se encuentra en avanzado estado de erosión lo que puede favorecer que la abundancia de erizos se incremente al igual que su actividad bioerosionadora. Population density of four species of sea urchin (Echinodermata: Echinoidea) at La Entrega Reef, Oaxaca Bimonthly samples of sea urchins fauna inhabiting the La Entrega Reef, Oaxaca, Mexico, were obtained from October 2002 to August 2003. The reef area was divided in two sampling zones, corresponding to shallow (0-6 m) and deep (6-12 m) water. Six transects of 50 m length by 1 m wide were sampled in each zone. Greatest annual density corresponded to Diadema mexicanum (5.96 ± 0.85 ind/m2),followed by Eucidaris thouarsii (0.46 ± 0.14 ind/m2); Echinometra vanbrunti and Toxopneustes roseus presented low densities (0.03 ± 0.01 indv/m2 and 0.02 ± 0.01 ind/m2, respectively). Density of the four populations varied considerably and higher densities were observed in the deep zone. Total abundance of sea urchins (shallow and deep samples) did not vary significantly over time. Abundance per depth range, however, was different over time for all species except for E. thouarsii. In December densities of D. mexicanum and E. thouarsii decreased in the deep zone and increased in the shallow zone, due to massive mortality of coral in the shallow part of the reef and to subsequent increase of algal coverage attracting these species to the shallowest part of the reef. The La Entrega reef is presently in an advanced state of erosion that could favor an increase of sea urchins abundance and of their bioerosion activity.

Variation in abundances of herbivorous invertebrates in temperate subtidal rocky reef habitats

2004 ◽  
Vol 55 (1) ◽  
pp. 93 ◽  
Author(s):  
Mathew A. Vanderklift ◽  
Gary A. Kendrick
Keyword(s):  
Sea Urchin ◽  
Western Australia ◽  
Sea Urchins ◽  
Habitat Partitioning ◽  
Rocky Reef ◽  
Heliocidaris Erythrogramma ◽  
A Minor ◽  
Different Parts ◽  
Over Time ◽  
Rock Faces

The present study assessed variation in the abundances of large herbivorous invertebrates in south-western Australia. There was some habitat partitioning between different parts of the reef: of the most frequently recorded species, the sea urchins Phyllacanthus irregularis and Centrostephanus tenuispinus were found primarily at the base of steep rock faces, whereas the gastropods Turbo torquatus and Australium squamifera were found primarily on open sections of reef. The sea urchin Heliocidaris erythrogramma was evenly distributed between these two habitats. For C. tenuispinus and H. erythrogramma, differences among locations (separated by tens to hundreds of kilometers) were the main source of variation in abundances. Phyllacanthus irregularis was more evenly distributed among locations. Abundances of sea urchins at each reef varied little over 26 months, suggesting low mortality and low recruitment. Turbo torquatus and A. squamifera varied significantly in abundance among reefs separated by < 10 km, although these differences were influenced by fluctuations over time. Broad patterns in abundances were evident: overall, abundances of herbivorous invertebrates were low, but certain areas supported high abundances. This suggests that herbivory may be a minor process in this region; however, the importance of herbivory at reefs with and without high abundances of herbivores deserves further attention.

Canadian Exceptionalism: Explaining Differences over Time in Provincial and Federal Voter Turnout

2001 ◽  
Vol 34 (2) ◽  
pp. 299-319 ◽  
Author(s):  
Donley T. Studlar
Keyword(s):  
Regression Analysis ◽  
Population Density ◽  
Multiple Regression Analysis ◽  
Voter Turnout ◽  
The Political ◽  
Federal Level ◽  
Industrial Democracies ◽  
Different Types ◽  
Over Time ◽  
Cross National

Canada is unusual among advanced industrial democracies in having some provinces which regularly have greater voter turnouts for provincial than for federal elections. Provincial and federal turnouts by province in Canada are analyzed for the 1945-1998 period using multiple regression analysis, both for each set of elections and by comparing differences between the two. Federal turnout has declined over the years but provincial turnout appears to have increased slightly. Although the effects found here largely confirm previous findings about the relative effects of different types of variables found for the Canadian federal level only, several of the political explanations previously supported in cross-national research find less support. Instead, region, population density, months since the last federal or provincial election, and season of the year generally have greater and sometimes more consistent effects. This suggests the need for more studies of turnout in democracies at sub-central levels.

scholarly journals Biodiversity of echinoids and their epibionts around the Scotia Arc, Antarctica

2008 ◽  
Vol 20 (3) ◽  
pp. 227-244 ◽  
Author(s):  
Katrin Linse ◽  
Lisa J. Walker ◽  
David K.A. Barnes
Keyword(s):  
Southern Ocean ◽  
Current Knowledge ◽  
Sea Urchins ◽  
Marine Biodiversity ◽  
Current View ◽  
Depth Range ◽  
Tissue Mass ◽  
Scotia Arc ◽  
Biodiversity Changes ◽  
Study Species

AbstractThe Scotia Arc, linking the Magellan region with the Antarctic Peninsula, comprises young and old islands both near continents and isolated, and is the only semi-continuous link between cool temperate and Antarctic environments. It is an ideal region for studies on how marine biodiversity changes across an extended transition zone. Echinoids (sea urchins) and their associated epibionts were found across depths from 91–1045 m, with 19 species from shelf and four from slope depths. The 23 species from 38 trawls represent 31% of all echinoid species known from the Southern Ocean and 38% of the shelf/upper slope echinoids. The specimens collected comprise representatives of the five families Cidaridae, Echinidae, Temnopleuridae, Schizasteridae and Pourtalesiidae. Echinoids are probably a good model for how well we know Antarctic shelf and slope megabenthos; none of the species we report are new to science but we found nine (39%) of our study species present at new localities, some thousands of kilometres from previous findings. New biogeographic ranges are illustrated forCtenocidaris gigantea,C. nutrix,C. spinosa,Abatus curvidens,A. ingens,A. shackletoni,Amphineustes rostratus,Tripylaster philippiandPourtalesia aurorae. Southern Ocean echinoids show eurybathy as the mean depth range of our study species was 1241 m and only one was at less than 500 m. The current view of echinoid dominance of super-abundance in the shallows seems to be not transferable to shelf and slope depths as only one of 38 trawls was dominated by echinoids. Current knowledge on maximum sizes in Antarctic echinoids seems to be good as our morphometric measurements were mainly within known size ranges. Regular echinoids increased predictably in mass with increasing test length, apart fromCtenocidaris spinosa. Tissue mass of cidaroid species was ~17%, but across irregular species varied from 17.7–8.9%. No epibionts were found on irregular echinoids or Echinidae but 70 cidaroids examined carried 51 species representing ten classes. Many of these species are reported as cidaroid epibionts for the first time. Cidaroids and their epibionts constituted > 38% of the total macrofaunal richness in the trawls they were present in. Echinoids and their epibionts clearly contribute significantly to Southern Ocean biodiversity but are minor components of biomass except in the shallows.

Evidence for Association of Vibrio Echinoideorum with Tissue Necrosis on Body Shell of the Green Sea Urchin Strongylocentrotus Droebachiensis

2021 ◽  
Author(s):  
Jonathan Hira ◽  
Klara Stensvåg
Keyword(s):  
Sea Urchin ◽  
Virulence Genes ◽  
Vibrio Vulnificus ◽  
Sea Urchins ◽  
Opportunistic Pathogen ◽  
Significant Degree ◽  
Strongylocentrotus Droebachiensis ◽  
Host Immune System ◽  
Progressive Development ◽  
Green Sea Urchin

Abstract “Sea urchin lesion syndrome” is known as sea urchins disease with the progressive development of necrotic epidermal tissue and loss of external organs, including appendages on the outer body surface. Recently, a novel strain, Vibrio echinoideorum has been isolated from the lesions of green sea urchin (Strongylocentrotus droebachiensis), an economically important mariculture species in Norway. V. echinoideorum has not been reported elsewhere in association of with green sea urchin lesion syndrome. Therefore, in this study, an immersion based bacterial challenge experiment was performed to expose sea urchins (wounded and non-wounded) to V. echinoideorum, thereby mimicking a nearly natural host-pathogen interaction under controlled conditions. This infection experiment demonstrated that only the injured sea urchins developed the lesion to a significant degree when exposed to V. echinoideorum. Pure cultures of the employed bacterial strain was recovered from the infected animals and its identity was confirmed by the MALDI-TOF MS spectra profiling. Additionally, the hemolytic phenotype of V. echinoideorum substantiated its virulence potential towards the host, and this was also supported by the cytolytic effect on red spherule cells of sea urchins. Furthermore, the genome sequence of V. echinoideorum was assumed to encode potential virulence genes and were subjected for in silico comparison with the established virulence factors of Vibrio vulnificus and Vibrio tasmaniensis. This comparative virulence profile provided novel insights about virulence genes and their putative functions related to chemotaxis, adherence, invasion, evasion of the host immune system, and damage of host tissue and cells. Thus, it supports the pathogenicity of V. echinoideorum. In conclusion, the interaction of V. echinoideorum with injured sea urchins appears to be essential for the development of lesion syndrome and therefore, revealing its potentiality as an opportunistic pathogen.

Host use pattern and life history of Liopetrolisthes mitra, a crab associate of the black sea urchin Tetrapygus niger

2000 ◽  
Vol 80 (4) ◽  
pp. 639-645 ◽  
Author(s):  
J.A. Baeza ◽  
M. Thiel
Keyword(s):  
Sea Urchin ◽  
Black Sea ◽  
Sea Urchins ◽  
Austral Summer ◽  
Average Density ◽  
The Black Sea ◽  
Reproductive Pattern ◽  
Host Use ◽  
Austral Spring ◽  
Use Pattern

The porcellanid crab Liopetrolisthes mitra is a common associate of the black sea urchin, Tetrapygus niger in north central Chile. The host-use pattern, population dynamics and reproductive pattern of L. mitra on sea urchins were examined between January 1996 and February 1997. Each month, between 60 and 95 per cent of all collected urchins hosted crabs, with the highest frequency of cohabitation occurring during the austral summer (January to March). Group sizes of crabs on individual urchins ranged from 1 to 25 crabs per host. The average density of crabs on the urchins ranged from 2 to 5.5 crabs per host. Large urchins were inhabited by crabs more frequently than small urchins but urchin size had no effect on the number or size of crabs. The sex ratio of adult crabs was ˜1:1 during most months. Reproduction occurred throughout the year but was most intense during the austral spring and summer (October to March), when the highest percentage of ovigerous females were found. Similarly, recruitment of L. mitra occurred throughout the year but reached a peak during austral summer and early autumn (January to May). All life stages of L. mitra including recently settled megalopae and reproductive adults were found on urchins. Size–frequency analysis indicated that many crabs live >1.5 years. The results of this study confirm that the association between L. mitra and T. niger is strong and persists throughout the benthic life of the commensal crab.

scholarly journals Effects of five southern California macroalgal diets on consumption, growth, and gonad weight, in the purple sea urchin Strongylocentrotus purpuratus

2014 ◽  
Author(s):  
Matthew C Foster ◽  
Jarrett E Byrnes ◽  
Daniel C Reed
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Strongylocentrotus Purpuratus ◽  
Macrocystis Pyrifera ◽  
Reproductive Capacity ◽  
Giant Kelp ◽  
Mixed Diet ◽  
Gonad Weight ◽  
Consumption Growth ◽  
Purple Sea Urchin

Consumer growth and reproductive capacity are direct functions of diet. Strongylocentrotid sea urchins, the dominant herbivores in California kelp forests, strongly prefer giant kelp (Macrocystis pyrifera), but are highly catholic in their ability to consume other species. The biomass of Macrocystis fluctuates greatly in space and time and the extent to which urchins can use alternate species of algae or a mixed diet of multiple algal species to maintain fitness when giant kelp is unavailable is unknown. We experimentally examined the effects of single and mixed species diets on consumption, growth and gonad weight in the purple sea urchin Strongylocentrotus purpuratus. Urchins were fed single species diets consisting of one of four common species of macroalgae (the kelps Macrocystis pyrifera and Pterygophora californica, and the red algae Chondracanthus corymbiferus and Rhodymenia californica (hereafter referred to by genus) or a mixed diet containing all four species ad libitum over a 13-week period in a controlled laboratory setting. Urchins fed Chondracanthus, Macrocystis and a mixed diet showed the highest growth (in terms of test diameter, wet weight and jaw length) and gonad weight while urchins fed Pterygophora and Rhodymenia showed the lowest. Urchins consumed their preferred food, Macrocystis at the highest rate when offered a mixture, but consumed Chondracanthus or Macrocystis at similar rates when the two algae were offered alone. The differences in urchin feeding behavior and growth observed between these diet types suggest the relative availability of the algae tested here could affect urchin populations and their interactions with the algal assemblage. The fact that the performance of urchins fed Chondracanthus was similar or higher than those fed the preferred Macrocystis suggests purple sea urchins could sustain growth and reproduction during times of low Macrocystis abundance as is common following large wave events.

scholarly journals Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic)

2014 ◽  
Vol 15 (3) ◽  
pp. 475 ◽  
Author(s):  
S. GARCIA-SANZ ◽  
P. G. NAVARRO ◽  
F. TUYA
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Late Summer ◽  
Paracentrotus Lividus ◽  
Abundant Species ◽  
Late Winter ◽  
Gran Canaria ◽  
Arbacia Lixula

Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula) at Gran Canaria Island (eastern Atlantic) via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds) within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula) with the most conspicuous species (D. africanum) in the study area.

scholarly journals Single cell RNA sequencing of the Strongylocentrotus purpuratus larva reveals the blueprint of major cell types and nervous system of a non-chordate deuterostome

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Periklis Paganos ◽  
Danila Voronov ◽  
Jacob M Musser ◽  
Detlev Arendt ◽  
Maria Ina Arnone
Keyword(s):  
Single Cell ◽  
Rna Sequencing ◽  
Sea Urchin ◽  
Regulatory Networks ◽  
Sea Urchins ◽  
Neuronal Cell ◽  
Cell Types ◽  
Molecular Fingerprint ◽  
Larval Body ◽  
Single Cell Rna Sequencing

Identifying the molecular fingerprint of organismal cell types is key for understanding their function and evolution. Here, we use single cell RNA sequencing (scRNA-seq) to survey the cell types of the sea urchin early pluteus larva, representing an important developmental transition from non-feeding to feeding larva. We identify 21 distinct cell clusters, representing cells of the digestive, skeletal, immune, and nervous systems. Further subclustering of these reveal a highly detailed portrait of cell diversity across the larva, including the identification of neuronal cell types. We then validate important gene regulatory networks driving sea urchin development and reveal new domains of activity within the larval body. Focusing on neurons that co-express Pdx-1 and Brn1/2/4, we identify an unprecedented number of genes shared by this population of neurons in sea urchin and vertebrate endocrine pancreatic cells. Using differential expression results from Pdx-1 knockdown experiments, we show that Pdx1 is necessary for the acquisition of the neuronal identity of these cells. We hypothesize that a network similar to the one orchestrated by Pdx1 in the sea urchin neurons was active in an ancestral cell type and then inherited by neuronal and pancreatic developmental lineages in sea urchins and vertebrates.

scholarly journals Haplotype distribution and connectivity of the white sea urchin Tripneustes ventricosus across the Brazilian biogeographic province

2016 ◽  
Author(s):  
Wander O Godinho ◽  
Rodrigo Maggioni ◽  
Ana L Lacerda ◽  
Tito M C Lotufo
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Sea Urchin ◽  
White Sea ◽  
Sea Urchins ◽  
Marine Ecosystems ◽  
Brazilian Coast ◽  
The White Sea ◽  
Biogeographic Province ◽  
Fernando De Noronha

Sea urchins play important roles in marine ecosystems as key herbivores and some species have wide geographic range. The Atlantic white sea urchin Tripneustes ventricosus is abundant in many rock reefs of the eastern and western Atlantic, and may be found in high densities in Atolls and Archipelagos. Despite the importance of sea urchins in insular ecosystems, there is no study evaluating the genetic structure and the origin of the white sea urchin in isolated ecosystems. Such information is crucial to understand the connectivity and genetic diversity of these populations from the tropical Atlantic provinces. To evaluate the origin of the white sea urchin in Fernando de Noronha Archipelago and the genetic features of this population, we conducted studies on the population structure of the white sea urchin using mitochondrial DNA (COI), in two regions within the Brazilian biogeographic province and compared with other regions in the Atlantic. The white sea urchin from Fernando de Noronha was found to be genetically distinct, with FST ranging from 0.3 to 0.9 from other populations in Atlantic. The sharing of haplotypes between the Brazilian coast and the archipelago suggests that insular species derived from the Brazilian coast, rather than the East Atlantic. Moreover, all other Atlantic populations were genetically isolated, with low genetic diversity being a common characteristic among them (ranging from 0.0011 to 0.0022). The low connectivity found within populations might be related to the presence of soft barriers among the Brazilian biogeographic province. The low nucleotide diversity may also suggest that T. ventricosus may have undergone bottleneck processes at some stage of their evolution. This study has important implications on the geographic distribution, population structure and gene flow of the white sea urchin among the Atlantic regions. Further studies should evaluate the biological and ecological aspects of the species in both insular and continental marine ecosystems.

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