Reproductive biology and energetics of the brooding sea star Anasterias antarctica (Echinodermata: Asteroidea) in the Beagle Channel, Tierra del Fuego, Argentina

Abstract

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.

Energetics and development modes of Asteroidea (Echinodermata) from the Southwestern Atlantic Ocean including Burdwood Bank/MPA Namuncurá

“…The lecithotrophic developmental strategy implies a trade-off between the quantity and quality of offspring as brooding involves a high energetic cost and the production of large, slow-developing, nutrient-rich eggs, which often comes at the cost of reduced fecundity (Thatje et al 2018). The low inorganic matter (IM) values in gonads and pyloric caeca (Table 1), (i.e., low content of ash) is in concordance with their suggested role as energy storage organs in echinoderms (McClintock and Pearse 1987;Pérez et al 2017). The difference obtained in the percentages of IM of ovaries and testes (Table 1) can be attributed to a larger amount of reserve compounds (organic matter) in females than in males.…”

“…For instance, McClintock and Pearse (1987) recorded high levels of lipids in the pyloric caeca of antarctic asteroids, which is an advantage over storing energy in the form of lower-energy protein or carbohydrate because more energy can be stored per unit mass. The pyloric caeca is considered an important source of nutrients and energy during gametogenesis (Lawrence and Lane 1982) and functions as a reserve organ in brooding females of species with direct development, especially in species where feeding is impossible during the incubation period (e.g., Anasterias antarctica Pérez et al 2017).…”

“…3b) could be the consequence of a higher transference of energy to the gonads for both sexes during gonadal maturation. Though gonadal cycles are well studied in several shallow water sea stars (Bosch and Pearse 1990;Pearse et al 1991;Cossi et al 2015;Pérez et al 2017), less is known about gonadal cycles of species inhabiting deeper depths, such as D. verrucosus, G. antarctica, and P. folliculatus.…”

“…Reproductive effort in sea stars can vary with the mode of development. For instance, in species with development modes that imply a planktotrophic stage, reproductive investment is usually equal between the sexes (Raymond et al 2007;Pérez et al 2010Pérez et al , 2017, while in species that brood, males may invest more energy in gamete production than females, whereas the latter may face costs associated with incubating embryos (Raymond et al 2004;Gillespie and McClintock 2007;Pérez et al 2015). As pyloric caeca serve as nutrient reserve organs (Lawrence 1987c), it is not surprising that many asteroids show an inverse relationship in seasonal gonadal and pyloric caeca indices due to the transference of energy and nutrients to developing gonads (Chia and Walker 1991).…”

Species composition of sea stars (Echinodermata: Asteroidea) in the Patagonian Argentinian deep sea, including seven new records: connectivity with sub-Antarctic and Antarctic fauna

“…Most studies on echinoderms from this area are restricted to the Argentinian shelf or near the slope, such as Bernasconi (1934Bernasconi ( , 1935Bernasconi ( , 1937Bernasconi ( , 1941aBernasconi ( , 1941bBernasconi ( , 1943Bernasconi ( , 1962aBernasconi ( , 1962bBernasconi ( , 1963Bernasconi ( , 1964aBernasconi ( , 1964bBernasconi ( , 1965Bernasconi ( , 1966aBernasconi ( , 1972Bernasconi ( , 1973aBernasconi ( , 1980, Tablado (1982), and Tablado and Maytia (1988), and more recent studies, such as Brogger et al (2010Brogger et al ( , 2013b, Martinez and Brogger (2012), Martinez et al (2015), Souto et al (2014), Brogger and O'Hara (2015), Di Giorgio et al (2015), Arribas et al (2016), Epherra et al (2015Epherra et al ( , 2017, Hunter et al (2016); Martinez (2016), Martinez and Penchaszadeh, (2017), Martinez et al (2018;, Wilkie and Brogger (2018), Carames et al (2019), Flores et al (2019), Martins and Tavares (2019), and Gil et al (2020). With regard to the class Asteroidea, few papers have been published recently: Romanelli and Tablado (2011), Pérez et al (2017),…”