WBuffetJr I think is referring to a different scud Gammarus fasciatus than those that live in LA as noted by 'ryjohn'. Below I review the similar food habits of both G.fasciatus and PK shrimp (mississippi grass shrimp Palaemonetes kadiakensis). The feeding niches overlap and both can be closely associated with the bottom areas or in habitats above the bottom.
G.fasciatus prefers unpolluted, clear, cold waters, including springs, streams, pools, ponds, and lakes. They prefer highly oxygenated, shallow, still areas, with lots of vegetation or debris for coverage. Many scientists categorize them as cold water stenotherms, meaning that they require a narrow range of cold temperatures in order to survive
These amphipods prefer benthic regions of water bodies because they feed on the detritus, zooplankton and micro plantae (algae and diatoms) found there as well as the feces of Dreissena species (freshwater mussels). They are categorized as scavengers, and though they eat meat, they very rarely attack living animals to feed (though they will eat newly dead aquatic animals). Recent research has indicated that types of food consumed may shift throughout the life cycle, with smaller individuals feeding mainly on detritus and larger individuals having a more varied diet. ("Gammarus fasciatus", 2013; Bronmark and Hansson, 1998; Clemans, 1950; Limén, et al., 2005; Meglitsch and Schram, 1991; Pennak, 1989; Summers, et al., 1997).
Grass Shrimp
As epibenthic predators and benthic sediment disturbers, grass shrimp alter infaunal community structure (Bell and Coull 1978; Knieb and Stiven 1982).
The diet of eastern grass shrimp is dominated by algae (diatoms and green algae), but they also consume vascular plants, detritus, aquatic insects, and other benthic coarse particulate organic matter. Diatoms that glass shrimp eat include species in the genera Fragilaria, Nivicula, Stephanodiscus, Gomphonema, Synedra, and Cymbella. Examples of green algae consumed include species in the genera Cosmarium, Closterium, and Scenedesmus. In laboratory conditions, these shrimp were observed feeding on aquatic weeds. Insects they feed on include mayfly nymphs (Baetidae) and dipteran larvae in the families Chironomidae, Heleidae, Chaoboridae, and Culicidae. (Beck and Cowell, 1976).
These delicate crustaceans feed on a variety of very small invertebrates, plankton, and algae, and on various kinds of organic detritus. They often eat algae and other small organisms that grow upon the surfaces of submerged aquatic plants. The larger plants offer them shelter from predators.
As detritivores, grass shrimp aid in the mechanical breakdown of refractory organic material such as fibrous plant materials, as well as assimilate the associated m i c r o f l o r a , m i c r o - fauna, and fungi (Adams and Angelovic 1970). The assimilation of dissolved organic matter asorbed to finely divided particulate matter such as clay particles is important in grass shrimp nutrition (Odum and Heald 1972). Although grass shrimp often live among aquatic macrophytes (Adams and Angelovic 1970; Livingston et al. 1976; Heck and Orth 1980; Morgan 1980; Coen et al. 1981; Gore et al. 1981), there is little evidence that the macrophyte structure is actually consumed. More likely, grass shrimp eat and assimilate the epiphytic , microalgae that coat the plant structure (Morgan 1980). Grass shrimp also are predators of meiofauna and small 0ligochaetes, nematodes. As epibenthic predators and sediment disturbers, grass shrimp alter infaunal community structure (Bell and Coull 1978; Knieb and Stiven 1982).
Last edited by Bill Cody; 03/31/17 08:21 PM.
