The influence of river stage on endangered least terns and their fish prey in the Mississippi River (USA)

✍ Scribed by Tibbs, John E. ;Galat, David L.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 116 KB
• Volume: 14
• Category: Article
• ISSN: 0886-9375
• DOI: 10.1002/(sici)1099-1646(199805/06)14:3<257::aid-rrr500>3.0.co;2-9

✦ Synopsis

Spatial and temporal availability of small fishes, as forage for interior least terns (Sterna antillarum), was compared to the least tern reproductive period during 1993 and 1994 in the lower Mississippi River, Missouri. Timing of forage availability and least tern reproduction was also related to river stage and temperature regimes. Four deep-water habitats (main channel, secondary channel, side channel, and connected slough) and two shallow-water habitats (main-channel interface and side-channel interface) were sampled using a seine and neuston net, yielding 67245 fish510 cm. Catch-per-volume and richness were highest in shallow-water habitats in both years. Highest catches in deep-and shallow-water habitats occurred between 56 and 64 days after peak spring flows in both years. Water temperature was increasing rapidly during the spring flood peak each year. About 80% of total fish catch consisted of taxa known to spawn in floodplain habitats, supporting the connection between the spring flood and the timing and amount of forage available for nesting least terns. Timing of least tern reproduction was related to falling river stages in May and increased forage-fish availability in June. A conceptual model integrates the abiotic factors of hydrology and sand island area to least tern reproduction and small fish availability.