Juvenile Penaeid Shrimp Density, Spatial Distribution and Size Composition in four adjacent habitats within a Mangrove-Fringed Bay on Inhaca Island, Mozambique

Abstract

Abstract-The effects of habitat characteristics (mangrove creek, sandflat, mudflat and seagrass meadow) water salinity, temperature, and depth on the density, spatial distribution and size distribution of juveniles of five commercially important penaied shrimp species (Metapenaus monoceros, M. stebbingi, Fenneropenaeus indicus, Penaeus japonicus and P. semisulcatus) were investigated during a high shrimp recruitment peak lasting from January to June 2002, in four contiguous habitats within a non-estuarine mangrove bay at Saco da Inhaca, Inhaca Island, Southern Mozambique. A total of 14,976 specimens representing the five species were collected by means of a 1m beam-trawl fitted with a 2 mm mesh net with a cod-end. Every two weeks corresponding with spring tides on three consecutive nights, three trawls of 50 meters each were carried out each night in each habitat at 1.40-2.15 a.m. after the daily spring tide high water peak. Species distributions among the four habitats during the six months sampled showed significant differences in habitat preference (p>0.001). Fenneropenaeus indicus, M. stebbingi and P. japonicus dominated the catches in sand flats with densities of 27 ± 0.94, 18 ± 0.98 and 7 ± 0.76 shrimp /50 m 2 , respectively. Metapenaeus monoceros dominated catches in mudflats at a density of 21 ± 0.78 /50 m 2 followed by M. stebbingi with 13±1.2 /50 m 2 . Penaeus semisulcatus was almost exclusively captured in seagrass meadows at densities of 8± 0.57 /50 m 2 . Only the Metapeneaus species showed a wide range of habitat utilization. The differences in habitat preference emphasises spatial partitioning between shrimps, reducing competition. Multiple linear regressions of juvenile shrimp densities for each species with water depth, salinity and temperature showed some significant effects. Fenneropenaeus indicus density showed a significant negative relationship with salinity and water depth and a positive relationship with temperature and turbidity. Metapenaeus stebbingi numbers showed a significant positive correlation with increasing salinity and temperature, but a negative one with depth. Penaeus japonicus numbers were significantly related to decreasing salinity and depth. Penaeus semisulcatus abundance was significantly related to decreasing temperature, and increasing turbidity and depth. More than 50% of the total shrimps captured had carapace length of ≤ 3 mm, substantiating the nursery function of the different habitats sampled in the study.

Prawn community structure in the subtropical Mfolozi–Msunduzi estuarine system, KwaZulu-Natal, South Africa

“…The upper Mfolozi and the mouth supported a small community of M. lepidactylus, and the mouth alone supported a M. japonicus population (Table 2). De Freitas (1986) and Macia (2004) reported quite distinct habitat separation between penaeid prawn species in Inhaca Bay, with M. japonicus being found predominantly in sandy areas, F. indicus and P. monodon showing strong preference for muddy mangrovefringed channels, P. semisulcatus preferring submerged vegetation, while M. monoceros were equally abundant in different habitat types. Fenneropenaeus indicus has also been shown to prefer muddy areas associated with mangrove swamps in other estuarine systems (Forbes and Demetriades 2005).…”

Distribution related to temperature and salinity of the shrimps Acetes americanus and Peisos petrunkevitchi (Crustacea: Sergestoidea) in the south-eastern Brazilian littoral zone

“…Primavera (1998) observed that three shrimp of the genus Metapenaeus (Wood-Mason, 1891) presented spatial partitioning based on different salinities and types of sediments. Macia (2004) and Costa et al (2008) reported that juveniles of different Penaeidae species use different areas for nursery habitat to complete their life cycle. According to these authors, the spatial or temporal differentiation observed in closely related species can be due to avoidance of competition for food and territory.…”

Complexity affects habitat preference and predation mortality in postlarval Penaeus plebejus: implications for stock enhancement

“…Several studies have attempted to examine habitat preference in other penaeids (e.g. Hughes 1966, Macia 2004, Gribble et al 2007), but their methods tested for association with habitat rather than preference per se (see Underwood et al 2004 for distinction). Key exceptions include studies on juvenile Penaeus aztecus, P. esculentus and P. semisulcatus, which display similar affinities for complex habitats as reported here, studies on juvenile P. setiferus, which exhibit no preference for either vegetated or un-vegetated habitat (Minello & Zimmerman 1985, Hill & Wassenberg 1993, Kenyon et al 1997, and studies on juvenile Melicertus latisulcatus, which selected bare sand over vegetated habitat regardless of diel period (Tanner & Deakin 2001).…”

“…Despite abundant data supporting these theories in other species (e.g. Loneragan et al 1997, Primavera 1997, Macia 2004, it is still unclear whether the immediate cause of higher densities of P. plebejus within macrophyte beds is simply a result of lower post-settlement mortality (via predation or starvation) within this habitat or an innate preference for macrophyte beds during settlement. If P. plebejus postlarvae show a preference for structured habitats, then behavioral mechanisms could be influencing their distribution before post-settlement mortality through predation or starvation.…”