Relative growth and morphological sexual maturity of the caridean shrimpNematopalaemon schmitti(Decapoda: Caridea: Palaemonidae) in an upwelling region in the Western Atlantic

Abstract

In crustaceans, successful reproductive processes, such as the transition from juvenile to adult, exhibit important morphological changes that can be detected by analyzing relative growth. This study describes the relative growth of body structures in Nematopalaemon schmitti and its secondary sexual characteristics, and also estimates the morphological sexual maturity of this species in a region influenced by upwelling. The carapace length (CL), second pleuron length (PlL), cheliped carpus length (CaL), cheliped propodus length (PrL) and the length of appendix masculina (AML) of the shrimp were measured. The relationships that best demonstrated the changes in allometric coefficient between demographic categories were AML vs. CL for males, and PlL vs. CL for females. The estimated CL for morphological sexual maturity in males was 8.51 mm and 9.30 in females. Our results showed the appendix masculine and the second pleuron were secondary sexual characteristics that play roles in reaching the morphological sexual maturity necessary for reproductive success and to assure the life cycle of this species.

Relative growth and morphological sexual maturity of the caridean prawn Macrobrachium villosimanus (Tiwari, 1949) (Decapoda: Palaemonidae)

“…An increased slope of the adult stage, compared to the juvenile stage, for the CL versus AML relationship indicates the appendix masculina grows faster in the adult stage relative to the juvenile stage. Several studies (Ahamed & Ohtomi, 2014;Bauer, 2004;Herrera et al, 2017) also observed the transition or inflexion point in relative growth of the appendix masculine, proposing it could be used as an indicator of morphological sexual maturity.…”

“…Crustacean growth is characterized by ontogenetic changes during their development, being widely used to observe and detect the transition point between the juvenile and adult stages (Dalabona et al, 2005;Hartnoll, 1978Hartnoll, , 1982Herrera et al, 2017;Vaninni & Gherardi, 1988;Wenner et al, 1974). Such studies of certain organs or body structures can be used to estimate morphological sexual maturity by differentiating between the juvenile and adult stages and the energy cost directed towards reproduction (Collins, 2001;Hartnoll, 1982;Taylor & Gabriel, 1992), along with the possible dimorphism between the sexes and between the juveniles and adults (Hartnoll, 1974).…”

“…The onset of sexual maturity in many crustacean species is characterized by crucial morphological changes (Hartnoll, 1982;Lovett & Felder, 1989;Petriella & Boschi, 1997;Sampedro et al, 1999), some of which can be detected by analysing the relative growth (Ahamed & Ohtomi, 2014;Haley, 1969;Herrera et al, 2013). A number of studies have used this methodology as an important tool to characterize morphological sexual maturity of decapod crustaceans (Ahamed & Ohtomi, 2014;Castiglioni & Negreiros-Fransozo, 2003;Davanso et al, 2016;Hartnoll, 1982Hartnoll, , 1985Herrera et al, 2013Herrera et al, , 2017Hirose et al, 2012;Pantaleão et al, 2012;Pescinelli et al, 2014Pescinelli et al, , 2015Teodoro et al, 2014). None of these studies, however, have addressed the morphological changes related to the sexual maturity of M. villosimanus.…”

Effects of the upwelling system on the assessment of reproductive parameters of the caridean shrimp Nematopalaemonschmitti (Holthuis, 1950) in the Western Atlantic

“…Ovigerous condition (OF) was identified by the presence of eggs attached to pleopods. Shrimps with CL size equal to or greater than those estimated by Herrera et al (2018) for morphological sexual maturity were considered adults. According to this study, the established size for morphological sexual maturity was 8.5 mm for males and 9.3 mm for females.…”

“…Shrimps are an important link between primary production and higher trophic levels (Kikuchi, 1966;Unsworth et al, 2007), and such information can assist in responsible planning for the conservation of species. Studies involving N. schmitti have been conducted in Brazil, including its ecological distribution (Almeida et al, 2012;Fransozo et al, 2009;Herrera et al, 2017), population structure (Almeida et al, 2011), fecundity and reproductive investment (Pereira et al, 2017) and relative growth and morphological sexual maturity (Herrera et al, 2018). Despite these studies, there is still a knowledge gap about assessing the reproductive parameters of species in a region with unusual features such as upwelling.…”