Seasonality, spatial dispersion patterns and migration of benthic invertebrates in an intertidal marsh-sandflat system of puget sound, washington, and their relation to waterfowl foraging and the feeding ecology of staghorn sculpin, leptocottus armatus
Seattle, Wash., Univ. of Washington, Diss., 1980
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| Sprache: | eng |
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Tag hinzufügen | Zusammenfassung: | Seattle, Wash., Univ. of Washington, Diss., 1980 The effect of waterfowl foraging on the spatial dispersion patterns of the benthic invertebrates of Skagit Bay, Puget Sound, was investigated using sampling and experimental techniques. Sampling within and outside depressions dug in bare sandflats by foraging dabbling ducks showed that this activity reduced abundances of most benthic species. Experiments using artifically disturbed substrate indicated that recolonization occurred slowly for some taxa; in one experiment four taxa required at least 31 days to re-invade the disturbed area and one species, Pygospio elegans, a spionid polychaete, required over three months. Monitoring studies showed that, annually, about one percent of the substratum per day was disturbed by dabbling ducks. It was concluded that some of the patchiness observed in the benthos could be attributed to this disturbance; at any one time, 18 to 31 percent of the substratum could be in some stage of recovery from disturbance by ducks. Similar efforts to determine whether foraging of snow geese within emergent marsh affected benthic dispersion patterns were inconclusive. However, some circumstantial evidence suggested that foraging of geese in areas of older bulrush marsh could create unvegetated pools in which some invertebrate species could survive above their normal tidal range. The feeding habits of staghorn sculpins, Leptocottus armatus, and the populations of two of their four major prey species, Corophim salmonis and Tanais sp., were investigated to determine the extent to which the sculpin diet depended on the invertebrate populations on the sandflats. It was found that prey populations within a study tidal stream were very low in the late spring prior to the immigration of juvenile sculpins, but that the populations grew rapidly in early summer. Since reproduction and growth of the invertebrate populations within the tidal stream appeared to be insufficient to account for this increase, it was concluded that the sculpins (which a 24-hour sample showed were continuously feeding) relied heavily upon immigration of prey from the flats into the tidal stream. |
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| Beschreibung: | 189 S. |