Effect of salinity on the embryonic development ofMacrobrachium acanthurus(Decapoda: Palaemonidae)

Abstract

Palaemonid shrimps occur in the tropical and temperate regions of South America and the Indo-Pacific, in brack-ish/freshwater habitats, and marine coastal areas. They form a clade that recently (i.e., ~30 mya) invaded freshwater, and one included genus, Macrobrachium Bate, 1868, is especially successful in limnic habitats. Adult Macrobrachium acanthurus (Wiegmann, 1836) dwell in coastal freshwaters, have diadromous habit, and need brackish water to develop. Thus, they are widely recognized as euryhaline. Here we test how this species responds to a short-term exposure to increased salinity. We hypothesized that abrupt exposure to high salinity would result in reduced gill ventilation/perfusion and decreased oxygen consumption. Shrimps were subjected to control (0 psu) and experimental salinities (10, 20, 30 psu), for four and eight hours (n = 8 in each group). The water in the experimental containers was saturated with oxygen before the beginning of the experiment; aeration was interrupted before placing the shrimp in the experimental container. Dissolved oxygen (DO), ammonia concentration, and pH were measured from the aquaria water, at the start and end of each experiment. After exposure, the shrimp's hemolymph was sampled for lactate and osmolality assays. Muscle tissue was sampled for hydration content (Muscle Water Content, MWC). Oxygen consumption was not reduced and hemolymph lactate did not increase

Reproductive performance of Macrobrachium acanthurus (Crustacea, Palaemonidae) females subjected to unilateral eyestalk ablation

“…Fukuda et al. (2017), using females captured in the same region as this study and after reproduction in captivity, found a similar incubation time (approximately 12 days) at the same temperature (29°C). However, in the south of Brazil this species exhibited more prolonged development (16 days at 25°C) (Müller et al., 2007).…”

“…This statistical difference is biologically insignificant (since smaller than one day) and hence does not have implications for the farming of the species. Fukuda et al (2017), using females captured in the same region as this study and after reproduction in captivity, found a similar incubation time (approximately 12 days) at the same temperature (29°C). However, in the south of Brazil this species exhibited more prolonged development (16 days at 25°C) (Müller et al, 2007).…”

“…The results of the analyses suggest that M. acanthurus has a mean embryo loss of 38% in intact females and 46% in ablated ones. The increase in egg volume that occurred throughout the embryonic development of M. acanthurus (Fukuda et al., 2017; Tamburus et al., 2012) intensifies the competition for space among the eggs, decreasing their fixation, which may favour their loss during the ventilation movements of the pleopods (Balasundaram & Pandian, 1982).…”

“…However, in the south of Brazil this species exhibited more prolonged development (16 days at 25°C) (Müller et al., 2007). Such difference may be related to the water temperature during the incubation period, since higher temperatures increase the speed of metabolic processes and, consequently, reduce the time of embryonic development (Fukuda et al., 2017).…”

Embryonic development of marine ornamental shrimp, Lysmata amboinensis (De Man, 1888)

“…Egg volume increased significantly during egg (Nazari et al, 2003;Zhao et al, 2007). The volume increase in the developing egg may be due to water osmotic uptake (Fukuda et al, 2016). Changes in the egg size throughout the development is important as osmotic swelling facilitates the outer membrane rupture for hatching process (Soundarapandian, 2008).…”