Reproductive biology of female blue swimmer crabs in the temperate estuaries of south-eastern Australia

Abstract

The blue swimmer crab (BSC, Portunus armatus) is an economically and culturally important species distributed throughout the coastal waters of the Indo-Pacific region. Reproduction of BSC is poorly understood in southeastern Australia, a region that is experiencing substantial tropicalisation from global warming. We examined gonadal development, egg-mass relationships, and the influence of temperature on gonadal development and egg production within five different estuaries spanning ,2.58 of latitude. A negative correlation between the gonadosomatic index (GSI, an index of gonadal development and reproductive investment) and hepatosomatic index (HSI, an index of energy storage) was observed in only the final stages of ovarian development. The weight of the egg mass increased logarithmically with body mass, accounting for up to 55% of total body mass, which was significantly larger than observed in other studies. Thermal performance curves showed a peak in individual reproductive output at a mean monthly temperature of ,248C, at which the individual egg mass weight reached a maximum and the HSI reached a minimum. Environmentally driven variation in BSC reproduction has implications for population productivity and inter-annual variation in recruitment.

Crabs Go With the Flow: Declining Conductivity and Cooler Temperatures Trigger Spawning Migrations for Female Giant Mud Crabs (Scylla serrata) in Subtropical Estuaries

“…Ovigerous Giant Mud Crabs typically suppress feeding (Heasman 1980), suggesting a 'capital breeding' strategy, whereby females rely on stored energy reserves during ovarian development (Griffen 2018;Nolan et al 2021). If this is the case, behaviours that are energetically conservative or efficient are likely to be favoured.…”

Cross-jurisdictional larval supply essential for eastern Australian spanner crabs (

“…This would also allow for the collection of data to monitor spatial and temporal variations in the distribution and abundance of the spawning population, possibly even with reference to optimal sea-surface temperatures for spawning. This is particularly important, with rapid ocean warming occurring within the EAC region (Wu et al 2012), and temperature clearly affecting fecundity in other decapods (Johnston and Yeoh 2021;Nolan et al 2022). However, the cost-benefit of increased fishery-independent monitoring and the relative value of data on spawning populations (e.g.…”

Mesoscale oceanographic features drive divergent patterns in connectivity for co‐occurring estuarine portunid crabs

“…They are fast-growing and highly fecund species (Johnson et al, 2010;Nolan et al, 2021;Quinitio et al, 2001) with an oceanic larval phase and an estuarine juvenile-adult phase (similar to Blue Crab, Callinectes sapidus [Rathbun]; Epifanio, 2019). Off eastern Australia (Figure 1), Giant Mud Crab undertake a downstream migration to spawn in oceanic waters (Hewitt et al, 2022;Hill, 1994), with evidence that mature F I G U R E 1 Map of eastern Australia showing the release locations for backwards-in-time particle tracking simulations, and range of east coast populations of (a) Giant Mud Crab (dark green), (b) Blue Swimmer Crab (blue) and (c) an example of the structure of the EAC (as simulated by ozROMS; Wijeratne et al, 2018), including sea surface temperature (SST, C) and the approximate locations of key oceanographic features, including the EAC jet ($24-28 S); the EAC separation (28-31 S); and mesoscale eddy field (south of 31 S; dashed box).…”

“…Giant Mud Crab ( Scylla serrata [Forskål]; Keenan et al, 1998) and Blue Swimmer Crab ( Portunus armatus [Milne‐Edwards], formerly Portunus pelagicus ; Lai et al, 2010) are estuarine portunid crabs (Family: Portunidae) widely distributed across the Indo‐West Pacific (Gopurenko et al, 1999; Kailola et al, 1993; Keenan et al, 1998). They are fast‐growing and highly fecund species (Johnson et al, 2010; Nolan et al, 2021; Quinitio et al, 2001) with an oceanic larval phase and an estuarine juvenile–adult phase (similar to Blue Crab, Callinectes sapidus [Rathbun]; Epifanio, 2019). Off eastern Australia (Figure 1), Giant Mud Crab undertake a downstream migration to spawn in oceanic waters (Hewitt et al, 2022; Hill, 1994), with evidence that mature females continue to migrate northwards once in the ocean (Hewitt et al, 2022).…”

“…Off eastern Australia (Figure 1), Giant Mud Crab undertake a downstream migration to spawn in oceanic waters (Hewitt et al, 2022; Hill, 1994), with evidence that mature females continue to migrate northwards once in the ocean (Hewitt et al, 2022). Blue Swimmer Crab are thought to spawn primarily within estuaries (Johnson et al, 2010, Nolan et al, 2021), but may also spawn in coastal waters during wetter years (Gillson et al, 2012). For both species, spawning is followed by a dispersive larval phase (~13–28 days; Bryars & Havenhand, 2006; Nurdiani & Zeng, 2007), before settlement in the inshore region (Webley & Connolly, 2007) and subsequent recruitment into estuaries (Potter et al, 1983; Webley et al, 2009).…”