Feeding ecology of Rhabdosargus holubi (family Sparidae) in multiple vegetated refugia of selected warm temperate estuaries in South Africa

Nel, L.; Strydom, Nadine A.; Perissinotto, Renzo; Adams, Janine B.; Lemley, Daniel A.

doi:10.1016/j.ecss.2017.08.026

Cited by 10 publications

(2 citation statements)

References 51 publications

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“…In an ecological context, the results of this study indicate that R. holubi juveniles are resilient to hypersaline conditions, enabling them to persist in a saline-tolerant food web. Juvenile R. holubi depend on vegetated refugia for food and protection from piscivores (Blaber 1974a, Edworthy and Strydom 2016, Nel et al 2017. This refuge is particularly important if mobility is reduced, due to the potential reduction in activity and fin erosion seen in this study.…”

Section: Discussionmentioning

confidence: 85%

The effects of hypersalinity on the growth and skeletal anomalies of juvenile Cape stumpnose, <em>Rhabdosargus holubi</em> (Sparidae)

2019

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Estuarine organisms are exposed to hypersaline conditions for prolonged periods during drought conditions and under severely restricted river flow resulting from freshwater abstraction and impoundments. Consequently, marine estuarine-dependent fish such as Rhabdosargus holubi may be subjected to extreme conditions, such as hypersalinity prevailing for long periods ( > 2 months). Hypersalinity may impact the energetic demands of fish due to osmoregulation leading to compromised growth. This study assessed the impact of high salinity on the growth and skeletal development of R. holubi juveniles. Skeletons of juveniles grown at different salinities in the wild and in aquaria were analysed for anomalies. The impact of hypersaline conditions on juvenile R. holubi growth was also determined in aquaria. Aquarium experiments indicated that hypersalinity of 50 did not significantly impact growth rates over two months. Overall, anomalies were rare and vertebral-related anomalies specifically did not differ significantly between salinities. However, fin rays were significantly impacted in fish growing at higher salinities in the wild. It was concluded that the strong osmoregulatory ability of R. holubi offers protection against hypersalinity affecting internal structures, but external structures may remain vulnerable. As such, from a locomotory standpoint, R. holubi may be vulnerable to long periods of exposure to hypersaline conditions.

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Section: Discussionmentioning

confidence: 85%

The effects of hypersalinity on the growth and skeletal anomalies of juvenile Cape stumpnose, <em>Rhabdosargus holubi</em> (Sparidae)

2019

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“…Although R. holubi juveniles (<140 mm standard length [LS]) occur throughout shallow estuarine habitats (Becker et al, 2010(Becker et al, , 2012, it is primarily regarded as a vegetation-associated species (Hanekom & Baird, 1984;James et al, 2019;Sheppard et al, 2012). Rhabdosargus holubi are omnivorous with plant matter consisting of filamentous algae and seagrass a dominant component of the diet of juveniles in estuaries (e.g., Blaber, 1974b;Carrasou et al, 2016;James et al, 2019;Nel et al, 2017;Whitfield, 1984).…”

Section: Introductionmentioning

confidence: 99%

Juvenile sparids (Rhabdosargus holubi) consistently select structurally dense vegetated habitat in nursery seascapes

Welch,

Childs,

Hempel

et al. 2023

Journal of Fish Biology

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Seagrass habitats provide structural complexity in coastal estuarine and marine environments, which offer fish optimal foraging grounds and refuge from predation. However, seagrasses are some of the most threatened ecosystems globally, with anthropogenic activities such as population growth and environmental degradation leading to the fragmentation, thinning, and loss of these habitats. Rhabdosargus holubi is one of only a few vegetation‐associated marine fish species in South African estuaries. Although field studies have shown a strong association with seagrass over other aquatic vegetation for the juveniles of this species, habitat choice has never been empirically tested. Here, we used artificial vegetation units to test habitat choice (different structural complexities) for this species. We also tested whether habitat choice is influenced by a predatory threat, with fish preferentially selecting dense habitat in the presence of a predator and whether this effect may be more apparent in smaller individuals. We found that R. holubi significantly prefer greater structural complexity over less complex habitats, in both the absence and presence of a predator and for both small and large juveniles, showing that R. holubi actively choose more complex structures and are attracted to the structure per se irrespective of the threat of predation. This study highlights the importance of dense seagrass as nursery areas for this species and demonstrates how the loss of these habitats could impact the nursery function of estuaries.

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Habitat Use and Connectivity

Able¹,

Simenstad²,

Strydom³

et al. 2022

Fish and Fisheries in Estuaries

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Feeding ecology of Rhabdosargus holubi (family Sparidae) in multiple vegetated refugia of selected warm temperate estuaries in South Africa

Cited by 10 publications

References 51 publications

The effects of hypersalinity on the growth and skeletal anomalies of juvenile Cape stumpnose, <em>Rhabdosargus holubi</em> (Sparidae)

The effects of hypersalinity on the growth and skeletal anomalies of juvenile Cape stumpnose, <em>Rhabdosargus holubi</em> (Sparidae)

Juvenile sparids (Rhabdosargus holubi) consistently select structurally dense vegetated habitat in nursery seascapes

Habitat Use and Connectivity

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