Improvements in water quality following biomanipulation of gizzard shad (Dorosoma cepedianum) in Lake Denham, Florida

We quantified the effects of planktivore biomass and planktivore type in an experimental mesocosm study of factorial design in which five levels of fish biomass (0–75 g/m3) were cross-classified with two plantivore types: filter-feeding gizzard shad (Dorosoma cepedianum) and visual-feeding bluegill (Lepomis macrochims). As fish biomass increased, cladocerans, cyclopoids, particulate phosphorus (PP) > 200 μm, and chironomids declined; conversely, rotifers, primary productivity, chlorophyll a, turbidity, unicellular flagellates, colonial and unicellular green algae, pennate diatoms, total phosphorus, and 20–200 and 12–20 μm PP were enhanced. In the presence of gizzard shad, as compared with bluegill, cyclopoids, turbidity, unicellular green algae, pennate diatoms, > 200 μm PP, and chironomid tubes were higher whereas colonial green algae and < 0.2 μm PP were lower. Fish biomass operated independently of planktivore type for most variables, except copepods, colonial green algae, turbidity, and 20–200 μm PP. Although gizzard shad and bluegill have different trophic cascade pathways, fish biomass was more important than planktivore type as a regulator of plankton communities and water quality.

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Reflecting materials in the eyes of three teleosts, Orthopristes chrysopterus, Dorosoma cepedianum and Anchoa mitchilli

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1973.0028 ◽

1973 ◽

Vol 184 (1074) ◽

pp. 15-27 ◽

Cited By ~ 19

Keyword(s):

Body Length ◽

Pigment Epithelium ◽

Total Body Length ◽

Gizzard Shad ◽

Dorosoma Cepedianum ◽

Anchoa Mitchilli ◽

First Report ◽

Total Body ◽

Bay Anchovy

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.

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Digestive enzyme and gut surfactant activity of detritivorous gizzard shad (Dorosoma cepedianum)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-036 ◽

2000 ◽

Vol 57 (6) ◽

pp. 1113-1119 ◽

Cited By ~ 15

Author(s):

James C Smoot ◽

Robert H Findlay

Keyword(s):

Enzyme Activity ◽

Protease Activity ◽

Feeding Strategy ◽

Digestive Enzyme ◽

Artificial Substrates ◽

Gizzard Shad ◽

Dorosoma Cepedianum ◽

Digestive Physiology ◽

Protease Enzyme ◽

Surfactant Activity

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.

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