Feeding by fish visiting inundated subtropical saltmarsh
Author(s)
Hollingsworth, Anna
Connolly, Rod M
Griffith University Author(s)
Year published
2006
Metadata
Show full item recordAbstract
Australian saltmarshes are inundated less frequently and for shorter periods than most northern hemisphere marshes, and when inundated provide transient fish a diverse prey assemblage. We determined the extent of feeding on saltmarsh by examining stomach contents of a common marsh transient, glassfish (Ambassis jacksoniensis), in the Coombabah estuary in subtropical Queensland. We tested the hypotheses that fish caught after visiting the marsh (after (M)) would have similar quantities of food (stomach fullness index, SFI) but different prey composition (abundance, weight) both to fish collected before (Before) saltmarsh ...
View more >Australian saltmarshes are inundated less frequently and for shorter periods than most northern hemisphere marshes, and when inundated provide transient fish a diverse prey assemblage. We determined the extent of feeding on saltmarsh by examining stomach contents of a common marsh transient, glassfish (Ambassis jacksoniensis), in the Coombabah estuary in subtropical Queensland. We tested the hypotheses that fish caught after visiting the marsh (after (M)) would have similar quantities of food (stomach fullness index, SFI) but different prey composition (abundance, weight) both to fish collected before (Before) saltmarsh inundation and to fish that had not visited the marsh but were caught after marsh inundation (After (NM)). Sampling was done on multiple nights over 3 months in winter, when the marsh is inundated on spring tides at night only. SFI values of After (M) fish were significantly higher (SFI 蠱2%) than those of Before and After (NM) fish (SFI 蠰-1%). After (M) fish also had very different prey composition, eating more crab zoea (> 100 zoea fish- 1) than Before fish (10) and After (NM) fish (0). After (M) fish showed a consistent pattern in zoea abundances among sampling nights, in all months, with lower zoea abundances on the first night that the marsh was inundated than on subsequent nights. This is attributed to the synchronized spawning of crabs resident on the marsh, releasing their zoea on the ebb of the second inundating tide of the month. Fish stomach contents did not differ before and after smaller high tides not inundating the marsh (SFI 蠰-1%). Experimental evidence showed that glassfish evacuate their stomach contents in about an hour under starvation conditions, further strengthening our contention that the stomach contents of After (M) fish represent prey ingested on the marsh. The demonstration of intensive feeding by fish visiting this marsh points to a potentially important role of saltmarsh in the trophodynamics of subtropical Australian estuaries.
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View more >Australian saltmarshes are inundated less frequently and for shorter periods than most northern hemisphere marshes, and when inundated provide transient fish a diverse prey assemblage. We determined the extent of feeding on saltmarsh by examining stomach contents of a common marsh transient, glassfish (Ambassis jacksoniensis), in the Coombabah estuary in subtropical Queensland. We tested the hypotheses that fish caught after visiting the marsh (after (M)) would have similar quantities of food (stomach fullness index, SFI) but different prey composition (abundance, weight) both to fish collected before (Before) saltmarsh inundation and to fish that had not visited the marsh but were caught after marsh inundation (After (NM)). Sampling was done on multiple nights over 3 months in winter, when the marsh is inundated on spring tides at night only. SFI values of After (M) fish were significantly higher (SFI 蠱2%) than those of Before and After (NM) fish (SFI 蠰-1%). After (M) fish also had very different prey composition, eating more crab zoea (> 100 zoea fish- 1) than Before fish (10) and After (NM) fish (0). After (M) fish showed a consistent pattern in zoea abundances among sampling nights, in all months, with lower zoea abundances on the first night that the marsh was inundated than on subsequent nights. This is attributed to the synchronized spawning of crabs resident on the marsh, releasing their zoea on the ebb of the second inundating tide of the month. Fish stomach contents did not differ before and after smaller high tides not inundating the marsh (SFI 蠰-1%). Experimental evidence showed that glassfish evacuate their stomach contents in about an hour under starvation conditions, further strengthening our contention that the stomach contents of After (M) fish represent prey ingested on the marsh. The demonstration of intensive feeding by fish visiting this marsh points to a potentially important role of saltmarsh in the trophodynamics of subtropical Australian estuaries.
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Journal Title
Journal of Experimental Marine Biology and Ecology
Volume
336
Publisher URI
Subject
Environmental sciences
Biological sciences
Agricultural, veterinary and food sciences