Diel and tidal periodicity in the responses of early life stages of marine fishes to an estuary opening event in temperate South Africa

Early life stages of fish were monitored in a breach channel during an opening event of the temporarily open/closed East Kleinemonde Estuary. For comparison, early life stages were also collected in the surf zone and estuary mouth region before, during and after the breaching event on a weekly basis...

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Bibliographic Details
Published in:African journal of aquatic science 2021-01, Vol.46 (1), p.22-32
Main Authors: Kisten, Y, Strydom, NA
Format: Article
Language:English
Subjects:
Associated species
Brackishwater environment
breach channel
Catch composition
Catch per unit effort
cueing
Estuaries
Estuarine dynamics
estuary dependence
Fish
ichthyoplankton
Juveniles
Larvae
Life history
Marine fish
Marine fishes
Periodicity
Rain
Rainfall
Recruitment
Recruitment (fisheries)
Seine nets
Species
Surf
Surf zone
Weekly
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Summary:Early life stages of fish were monitored in a breach channel during an opening event of the temporarily open/closed East Kleinemonde Estuary. For comparison, early life stages were also collected in the surf zone and estuary mouth region before, during and after the breaching event on a weekly basis. The breach channel was sampled day and night at each midtide state for five consecutive days using a larval fish seine net (mesh 500 µm). Catch per unit effort (CPUE) of mostly postflexion stage larvae increased in the surf zone during opening events with a concomitant peak in abundance in the breach channel. Catch composition included many estuarine associated species typically found in temporarily open/closed estuaries. Predominantly postflexion stage larvae and newly settled juveniles were caught. No overall patterns of diel and tidal use across species were found in the breach channel suggesting some degree of plasticity in recruitment that could be opportunistically driven for most species. However, for the abundant Rhabdosargus holubi (Sparidae), nocturnal flood tides were favoured for movement into the estuary. Natural estuary opening events, especially during peak rainfall in the recruitment season are critical to the early life history strategy of estuary-associated marine fish species.
ISSN:1608-5914
1727-9364
DOI:10.2989/16085914.2020.1796574