Validation of annulus formation in sagittal otoliths of three tropical cichlids Oreochromis andersonii
 (Castelnau, 1861), Oreochromis macrochir
 (Boulenger, 1912), and Coptodon rendalli
 (Boulenger, 1896)

Peel, Richard A.; Taylor, Geraldine C.; Weyl, Olaf L. F.

doi:10.1111/jai.13110

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Water temperature was recorded in each system using HOBO Pro v2 data loggers (Onset, Bourne), programmed to log temperature at 6 hr intervals between August 2013 and August 2014. Temperature varied little between the three river systems, ranging from 30°C in summer to 17°C in winter and, depending on sampling locality, averaged between 23.7 and 25.4°C (see Peel, Taylor, & Weyl, ).…”

Section: Methodsmentioning

confidence: 99%

“…The Upper Zambezi River also has the largest flood magnitude of about 6.1 m at Katima Water temperature was recorded in each system using HOBO Pro v2 data loggers (Onset, Bourne), programmed to log temperature at 6 hr intervals between August 2013 and August 2014. Temperature varied little between the three river systems, ranging from 30°C in summer to 17°C in winter and, depending on sampling locality, averaged between 23.7 and 25.4°C (see Peel, Taylor, & Weyl, 2016). , 16, 22, 28, 35, 45, 57, 73, 93, 118 and 150 mm stretched diamond mesh approximately 2.5 m deep were set overnight.…”

Section: Introductionmentioning

confidence: 99%

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Comparing the fish assemblages and food‐web structures of large floodplain rivers

et al. 2017

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The Upper Zambezi, Kavango and Kwando are large floodplain rivers with substantial biodiversity, providing water and ecosystem services to a large tract of southern Africa. These rivers differ in hydrological regime. The Upper Zambezi and Kavango rivers are in flood for 4 months (March, April, May, June) while, in the Kwando River, floods are later and last for 1–2 months in July and August. The Upper Zambezi River has the largest annual flood pulse, followed by the Kavango River, while the Kwando River experiences small and unreliable floods. During years of exceptional flooding of the Upper Zambezi and Kavango rivers, the rivers are interconnected at peak flows and therefore share a common ichthyofauna. This provided a natural experiment to investigate the responses of fish communities comprised of the same species to differing flood regimes by comparing the fish assemblages and food‐web structures between rivers. Fish assemblage structure was characterised by analysing biomass catch per unit effort data collected using gillnets in all water‐level seasons for all three rivers. Whole ecosystem‐stable isotope data collected once from each river were used to examine differences in food‐web structure and fish feeding ecology between rivers. Due to temporal differences in hydrology, the Upper Zambezi and Kavango river food webs were characterised during the low and falling water seasons, while the Kwando River food web was sampled during the rising water season. In the Upper Zambezi and Kavango rivers, fish assemblages varied with hydrological season due to the homogenising influence of the flood pulse, while in the Kwando River fish assemblages did not change seasonally. The Upper Zambezi River food web had a restricted nitrogen range (NR = 0.90), with a reduced food chain length and predators did not occupy elevated trophic positions compared to those in the Kavango and Kwando river food webs (NR = 1.05 and 0.97 respectively). The Kwando and Kavango rivers are less exploited than the heavily fished Upper Zambezi River, where fishing has reduced the abundance of primary and tertiary consumers, potentially resulting in the observed reduction in food chain length. The Upper Zambezi and Kavango river food webs were based on differing basal resources compared to the Kwando River food web. The Upper Zambezi and Kavango river food webs were likely supported by 13C‐enriched resources such as C4 riparian vegetation from the floodplain, while the Kwando River food web was likely based on 13C‐depleted resources such as filamentous algae and aquatic macrophytes. The influence of the varying flood pulses on the fish communities of these three rivers supports the flood pulse concept. There is also evidence that food‐web structures differ between rivers but, due to differing hydrological regimes in the rivers, further study is required to understand causal factors. These ecosystems are increasingly impacted by human population growth and development, as well as climate change, and improved predictions in fish communit...

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparing the fish assemblages and food‐web structures of large floodplain rivers

et al. 2017

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“…Recently, individual data have been used for direct validation. The seasonal and annual formation of opaque zones has been investigated using the mark and recapture method (Szedlmayer and Beyer 2011;Cavole and Haimovici 2016;Peel et al 2016) coupled with daily growth increments (Cavole and Haimovici 2016;Aldanondo et al 2016). These studies determined that opaque zones were formed following the spawning period.…”

Section: Type Amentioning

confidence: 99%

A description of four types of otolith opaque zone

Katayama

2018

Fish Sci

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Analysis of the alternating opaque and translucent zones in fish otoliths is a widely used method to determine age in fish. The mechanisms underlying the annual periodicities in the formation of these zones remain unknown, although various interpretations and explanations have been presented to explain the appearance of the opaque zones. Here I review the biological and structural characteristics of the opaque zones in otoliths from a number of fish species. The results of this review suggest that the opaque zones can be classified into four different types. Type A is a dark opaque zone, displaying minute, dense crystals, and is typically formed at a young life-history stage. Type B comprises an aggregation of grooves and discontinuous crystals that are formed during growth-stagnant periods. Type C can be described as a washy black zone that has the appearance of an object that is smeared with ink; it is formed during seasons of active growth. Type D has deep grooves, appears luminous in transmitted light in etched otolith sections, and is formed during the spawning season. Types A and C otolith opaque zones are typical of younger fish and are formed during growing periods. They are complementary to Types B and D otolith opaque zones which are formed during periods of stagnant growth and/or during the spawning seasons and which are typical of older fish, which generally lack Type A zones. To ensure precise age determination in fish, it is therefore necessary to understand the structural and biological characteristics that produce these four distinct types of opaque zones.

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Validation of the periodicity of growth zone formation in the otoliths of four fish species from the Upper Zambezi ecoregion, southern Africa

et al. 2016

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Validation of annulus formation in sagittal otoliths of three tropical cichlids Oreochromis andersonii (Castelnau, 1861), Oreochromis macrochir (Boulenger, 1912), and Coptodon rendalli (Boulenger, 1896)

Cited by 5 publications

References 24 publications

Comparing the fish assemblages and food‐web structures of large floodplain rivers

Comparing the fish assemblages and food‐web structures of large floodplain rivers

A description of four types of otolith opaque zone

Validation of the periodicity of growth zone formation in the otoliths of four fish species from the Upper Zambezi ecoregion, southern Africa

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