Diurnal activity patterns of the temporary fish ectoparasite, Gnathia africana Barnard, 1914 (Isopoda, Gnathiidae), from the southern coast of South Africa
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Date
2018Author
Welicky, Rachel L.
Sikkel, Paul
Smit, Nico J.
Ferreira, Maryke L.
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Gnathiid isopods are one of the most common fish ectoparasites, and are found in both temperate and tropical oceans. On
coral reefs, gnathiids are most active at dusk and dawn, and contribute significantly to trophic dynamics, as they are a prey
resource for cleaner fish and parasitize numerous fishes. Gnathiids also inhabit temperate intertidal waters, but their activity
patterns and contribution to intertidal trophic dynamics remain unstudied. To provide the first ecological data on temperate
intertidal gnathiid activity patterns, 172 gnathiid-free Clinus superciliosus were set in an intertidal system in Tsitsikamma
National Park, South Africa, during early morning, morning, afternoon, early evening, and evening, high and low tide, and
within the inter- and infra-tidal zone to examine gnathiid infestation levels. After exposure, gnathiids from each fish were
identified to the species level, counted, and their developmental stage was recorded. All gnathiids were identified as
Gnathiia africana. On average, 1+ 5SD gnathiids were collected from each fish, and the majority of gnathiids collected
were stage 1. Significantly more gnathiids were collected during morning and afternoon compared with all other time
periods. The number of gnathiids collected was not influenced by the fish’s exposure to high or low tide, or placement
within the tide zone. Although G. africana is free from cleaner fish predation because cleaner fish do not reside in temperate
intertidal habitat, G. africana abundance is surprisingly small. Future studies should examine what regulates G. africana
population size and the role they play in temperate intertidal food webs
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http://hdl.handle.net/10394/31668https://www.cambridge.org/core/services/aop-cambridge-core/content/view/B32B5193CD0FDAAFB23D605201A76DEC/S0025315417001369a.pdf/diurnal_activity_patterns_of_the_temporary_fish_ectoparasite_gnathia_africana_barnard_1914_isopoda_gnathiidae_from_the_southern_coast_of_south_africa.pdf
https://doi.org/10.1017/S0025315417001369