Author : Emily Anne Miller
Publisher :
ISBN 13 : 9780355462142
Total Pages : pages
Book Rating : 4.4/5 (621 download)
Book Synopsis Niche Partitioning by Green Sturgeon (Acipenser Medirostris) and White Sturgeon (A. Transmontanus) in the San Francisco Estuary and Sacramento River by : Emily Anne Miller
Download or read book Niche Partitioning by Green Sturgeon (Acipenser Medirostris) and White Sturgeon (A. Transmontanus) in the San Francisco Estuary and Sacramento River written by Emily Anne Miller and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Niche partitioning allows two similar species to coexist through differential use of resources. Green Sturgeon (Acipenser medirostris) and White Sturgeon (A. transmontanus) are two closely related species that inhabit the San Francisco Estuary and Sacramento River. To examine evidence of niche partitioning, I used acoustic telemetry to describe their movements in the watershed and stable isotope analysis to compare their dietary sources. The effect of acoustic tagging had been studied in White Sturgeon, but it had not been studied in Green Sturgeon. Despite some similarities in morphology and life history the two species have distinct differences. For this reason, one species cannot serve as a proxy for the other. For my dissertation, first I studied the effect of acoustic tagging on Green Sturgeon growth, incision healing, and swimming performance in the laboratory. The results demonstrated no detrimental effect of tagging on the Green Sturgeon so critical telemetry studies are justified when using recommended tagging practices. There were cases of inflammation around undissolved sutures so practices that reduce the number of sutures and the use of suture material that dissolves rapidly is advisable. Using these results, I could interpret my telemetry data as representative of untagged individuals. I tagged 41 Green Sturgeon and 160 White Sturgeon ranging from large juveniles to adults. I found that Green and White Sturgeon adults differed the timing of their migratory movements at every reach of the watershed. They also differed in their route selection through the Sacramento-San Joaquin Delta. White Sturgeon were more likely to use northern sloughs and Green Sturgeon were more likely to use the mainstem of the Sacramento River. White Sturgeon also spent more time in the Delta prior to entering the Sacramento River and appears to be over-wintering behavior. Green Sturgeon spent significantly longer time in the spawning reaches than White Sturgeon, with some individuals staying nearly a year. Green Sturgeon juveniles and subadults were distributed lower in the system (more marine) relative to White Sturgeon juveniles and subadults. Juveniles and subadults of both species moved between the San Francisco Bay and Delta throughout the year. Finally, to compare differences in dietary sources, I collected whole blood and plasma samples from 26 Green Sturgeon and 35 White Sturgeon of various body sizes. Green Sturgeon had more marine d13C signatures than White Sturgeon. Larger sturgeon of each species had more marine d13C signatures than smaller sturgeon. Green and White Sturgeon did not have different d15N signatures for whole blood indicating that they fed at the same trophic level, but d15N values were lower for White Sturgeon than Green Sturgeon in plasma samples. This difference suggests White Sturgeon were feeding at a lower trophic level more recently, though not over a longer time scale. Length did not affect d15N signatures of either species. There is evidence of niche partitioning by Green and White Sturgeon spatially, temporally, and in the dietary sources.
