Reproductive traits of the intertidal sea star Anasterias antarctica (Echinodermata: Asteroidea) from the Beagle Channel, Argentina

2021 ◽  
Vol 168 (12) ◽  
Author(s):  
Cintia P. Fraysse ◽  
Claudia C. Boy ◽  
Analía F. Pérez
Crustaceana ◽  
2021 ◽  
Vol 94 (9) ◽  
pp. 1071-1084
Author(s):  
C. Nahxieli Reyes-González ◽  
Eduardo Suárez-Morales

Abstract A new species of the diverse and widely distributed symbiotic copepod genus Asterocheres is described from the sea star Nidorellia armata (Gray, 1840) in Mexican waters of the Eastern Tropical Pacific. The new species resembles various other congeners by sharing several characters including: (1) a siphon extending to the intersection of the maxilliped, (2) a 21-segmented antennule, and (3) a 2-segmented mandible palp. It can be distinguished by the unique structure and ornamentation of the maxilla, the armature and proportions of the fifth leg, and its body shape. This is the first documented record of Asterocheres from the Mexican Pacific and the first finding of a symbiotic copepod on this sea star host. Males, ovigerous females and copepodites were recorded from the host, thus suggesting a well-established symbiotic association. It is likely that copepods feed on the host’s tegument. Further studies will be needed to assess the reproductive traits and seasonality of this copepod as a symbiont.


2017 ◽  
Vol 65 (1-1) ◽  
pp. 221 ◽  
Author(s):  
Analía F. Pérez ◽  
Cintia Fraysse ◽  
Claudia C. Boy ◽  
Lucia Epherra ◽  
Calcagno Javier

The brooding sea star Anasterias antarctica is distributed from the coast of Patagonia to the northern Peninsula of Antarctica. In the Beagle Channel, the females of A. antarctica brood their eggs for seven months and do not feed during this period. The endoparasite Dendrogaster argentinensis (Crustacea: Ascothoracica) causes castration in several species of Anasterias. We randomly collected four samplings of adults in May, August and October (brooding period) and January (non-brooding period). The gonad (GI) and pyloric caeca index (PCI) were calculated as organ wet weight (g) x 100/total wet weight (g). Each individual was sexed by microscopic examination of the gonads. Sex ratio, brooding females/non-brooding females and mature females/non-mature females ratios was 1:1. The male GI reached maximum values in January, when most individuals were sexually mature. The GI of non-brooding females reached its maximum during October when it was significantly higher than those from brooding females. The PCI was minimum in October, being lower in brooding females (August and October). During the non-brooding period, mature females had a significantly higher GI than non-mature females. The PCI did not vary neither between males, nor between mature and non mature females. By the end of the brooding period, non-brooding females showed a higher GI than the brooding females. This is explained by proliferation and increase of the oocytes size of non-brooding females. Mature females showed an incremented GI with presence of mature oocytes, while non-mature females exhibited more abundance of previtelogenic oocytes. Males showed synchronicity in reproductive condition. The females that have not brooded presented a process of active gametogenesis, reaching the summer with a high GI, therefore becoming mature females. Females that had brooded were probably lacking energy for new gonadal maturation. The pyloric caeca would be performing the role of a reserve organ in the brooding females, decreasing its size during the brooding period. Prevalence of D. argentinensis in A. antarctica was 11.06%. As this parasite was recorded in sea stars lacking gonads, these infected hosts could have been castrated. Rev. Biol. Trop. 65(Suppl. 1): S221-S232. Epub 2017 November 01. 


Fruits ◽  
2005 ◽  
Vol 60 (6) ◽  
pp. 395-403 ◽  
Author(s):  
Rajbir Singh ◽  
Ram Roshan Sharma ◽  
Rajiv Kumar Jain

2020 ◽  
Vol 637 ◽  
pp. 59-69 ◽  
Author(s):  
J Sullivan-Stack ◽  
BA Menge

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.


Author(s):  
L. Ovchinnikova ◽  
E. Babich

In the Republic of Kazakhstan over the past decade positive changes have been observed in increasing the number of farm animals, increasing their productivity, and increasing the gross production of milk, meat and other products. At the same time the development of dairy cattle breeding is mainly due to the breeding of Black-and-White, Red Steppe, Simmental breeds and their intra-breed types as well as imported from abroad Holstein breed. The purpose of the research was to analyze ways to improve the intra-breed type Karatomar of Black-and-White breed in Northern Kazakhstan. Research work has been carried out on breeding animals such as Karatomar type cattle of Black-and-White breed in LLP “Experimental farm Zarechnoe” in the Kostanay district in the Kostanay region. The dynamics of growth and development indicators, reproductive traits of heifers of a new intra-breed type Karatomar of Black-and-White cattle have been studied. A comprehensive assessment of their economically useful traits in the first lactation, determined by the resistance of animals to climatic and forage conditions, the efficiency of breeding of animals of different genotypes has been conducted. It has been found that the replacement heifers – daughters of American breeding sires inherited precocity and showed higher growth energy after 6 months of age and continued to grow rapidly until 18 months. The advantage in metabolism was in the daughters of Holstein sires of the American selection Orbit 4078, and the increased immune status of the organism in the daughters of the sire of the domestic selection Yamal 975 as the most adapted to the conditions of Northern Kazakhstan. The best ability to increasing the milk yield, stable lactation activity, high milk productivity, gross content of dry matter and nonfat milk solids have been characterized by the daughters of sires of the American selection Orbit 4078 and Lowrider 4129. Analysis of economic indicators of milk production has been shown that from cows – daughters of sires Orbit 4078 and Lowrider 4129 for 305 days of lactation received 15,8 and 15,2 % more milk of base fat, the expenditures of EFU per 1 kg of production was lower by 10,2 and 5,9 %. A higher level of profitability has been observed in the group of daughters of the sires Orbit 4078 – 35,5 % and Lowrider 4129 – 33,1 %, which was 8,5 and 10,8 % higher than in the group of daughters of the sire Yamal 975.


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