Predicting the invasion success of an introduced omnivore in a large, heterogeneous reservoir

2007 ◽  
Vol 64 (10) ◽  
pp. 1329-1345 ◽  
Author(s):  
Shane Vatland ◽  
Phaedra Budy

We demonstrate that invasion success, through the introduction and establishment stages, can generally be predicted based on biological characteristics of the organisms and physical aspects of the environment; however, predicting subsequent effects during integration is more challenging, especially for omnivorous fish species in large, heterogeneous systems. When gizzard shad (Dorosoma cepedianum) were incidentally introduced into Lake Powell, Utah–Arizona (2000), we predicted they would be successful invaders and would have food-web effects ranging from neutral to negative. As predicted, gizzard shad successfully established and dispersed throughout this large reservoir (300 km) within just 4 years, and their density was positively correlated with productivity. Also as predicted, gizzard shad exhibited fast growth rates, and striped bass (Morone saxatilis) predators were thus gape-limited, obtaining little gizzard shad forage. Contrary to our predictions, however, competition over zooplankton resources between gizzard shad and both threadfin shad (Dorosoma petenense) and juvenile striped bass appeared limited because of spatial segregation and diet preference. In sum, gizzard shad will continue to be successful invaders, but with limited effects on the established predator–prey cycle.

2011 ◽  
Vol 27 (4) ◽  
pp. 287-297 ◽  
Author(s):  
Walt Godwin ◽  
Michael Coveney ◽  
Edgar Lowe ◽  
Lawrence Battoe

The tapeta lucida of three species of teleosts were examined to determine the composition of the reflecting material. The fishes were bay anchovy Anchoa mitchilli (Engraulidae), gizzard shad Dorosoma cepedianum (Clupeidae) and pigfish Orthopristes chrysopterus (Haemulidae). The tapetum of each species was situated in the pigment epithelium of the eye. That of the pigfish contained triglycerides identified as chiefly glyceryl tridocosahexaenoate. A reduced pteridine, 7, 8-dihydroxanthopterin, occurred in the tapetum of the gizzard shad. Guanine occurred in the tapetum of the bay anchovy. The tapetum of the shad contained brightly reflecting particles about 0.5 μm in diameter There were 10.8 mg of dihydroxanthopterin in the tapetum of a shad (total body length 23 cm) and 0.46 mg of guanine in the tapetum of an anchovy (total body length 9 cm). This is the first report of a pteridine acting as a retinal reflector in vertebrates. Various aspects of retinal reflectors of teleosts are discussed and their variety and common characteristics commented upon.


2000 ◽  
Vol 57 (6) ◽  
pp. 1113-1119 ◽  
Author(s):  
James C Smoot ◽  
Robert H Findlay

Measuring digestive enzyme and surfactant activities tested specialization of gizzard shad (Dorosoma cepedianum) digestive physiology to a detritivorous feeding strategy. Digestive enzyme activity was measured in adult and larval gizzard shad using fluorescently labeled artificial substrates. Surfactant activity in gizzard shad was measured by comparing gut juice drop diameters over a range of dilutions. Enzyme activity in the ceca region of adult gizzard shad was high for esterase, beta-glucosidase, lipase, and protease. Enzyme activity was lower in posterior intestine sections than in anterior intestine sections, although protease activity remained high for the greatest distance in the intestine. Micelles were detected in adult gizzard shad gut juice, and surfactant activity was greatest in the ceca region. Larval gizzard shad protease activity was similar to that of adult fish, and surfactants were below their critical micelle concentration. Gizzard shad coupled digestive physiology with gut anatomy to obtain nutrients from detritus, and these adaptations may explain elevated growth rates observed in these fish when they are planktivorous.


1996 ◽  
Vol 15 (10) ◽  
pp. 1752-1759 ◽  
Author(s):  
Alan S. Kolok ◽  
James N. Huckins ◽  
Jimmie D. Petty ◽  
James T. Oris

Fishes ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 50
Author(s):  
Andrews ◽  
Hirtle ◽  
Linnansaari ◽  
Curry

The native striped bass (Morone saxatilis) population of the Miramichi River, New Brunswick is undergoing an unprecedented recovery while Atlantic salmon (Salmo salar) numbers within that system continue to decline. Atlantic salmon smolt depart from the Miramichi system during the striped bass spawning period and it is hypothesized that elevated striped bass abundances will increase encounter rates and predation on smolts. We summarize all available striped bass diet studies occurring within the native range of Atlantic salmon and present a review of the feeding behavior and diet preferences of striped bass before, during, and after their spawning period. The key studies vary in methodologies and interpretability. We present a standardized approach for assessing striped bass predation threats and smolt vulnerability and thus an improved understanding of the species interactions to guide future management in the Miramichi River.


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