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Habitat Selection And Predation Risk In Larval Lampreys, Dustin M. Smith
Habitat Selection And Predation Risk In Larval Lampreys, Dustin M. Smith
Graduate Theses, Dissertations, and Problem Reports
This thesis examines habitat preference and the influence of habitat on predation of larvae (ammocoetes) of the least brook lamprey (Lampetra aepyptera). The thesis comprises three chapters: (1) an introduction and literature review on the general life history of lampreys and on studies related to ammocoetes and their habitat, (2) an experimental study of habitat preference in ammocoetes of the least brook lamprey, and (3) an experimental study of the relationship between habitat availability and predation risk in ammocoetes. For the first study, we quantified substrate selection in small (< 50 mm) and large (100-150 mm) ammocoetes of the least brook lamprey. In aquaria, ammocoetes were given a choice to burrow into six equally-available substrate types: small gravel (2.36-4.75 mm), coarse sand (0.5-1.4 mm), fine sand (0.125-0.5 mm), organic debris (approximately 70% decomposing leaves and stems, 15% silt, and 15% sand), an even mixture of silt, clay, and fine sand, and silt/clay (< 0.063 mm). Fine sand was selected with a significantly higher probability than any other substrate. In the second study, we experimentally examined the influence of habitat availability on predation risk of ammocoetes. Ammocoetes were placed in aquaria containing a predator species (yellow bullhead, Ameiurus natalis) and one of 3 substrates: fine sand (0.125-0.5 mm), coarse sand (0.5-1.4 mm), or silt/clay (<0.063 mm). Use of the three substrate types was based on a previous experiment where fine sand was determined to be the preferred benthic habitat of least brook lamprey. Based on 10 trials with each habitat type, survival of ammocoetes was highest in aquaria with fine sand (mean = 80%), and lower in those with coarse sand (mean = 58%) and silt/clay (mean = 4%). The results of both studies conducted indicate that populations of least brook lamprey ammocoetes may be limited by the availability of fine sand habitat. The first study indicated that least brook lamprey ammocoetes are habitat specialists, preferring substrates composed primarily of fine sand. The second study showed that the availability of fine sand habitat may influence the predation risk of ammocoetes, as ammocoete survival from predation was highest in fine sand, and lower in other substrates.
Food Habits Of The Allegheny Woodrat (Neotoma Magister ), Nikole Lee Castleberry
Food Habits Of The Allegheny Woodrat (Neotoma Magister ), Nikole Lee Castleberry
Graduate Theses, Dissertations, and Problem Reports
Regional declines in Allegheny woodrat (Neotoma magister ) populations suggest a better understanding of the ecology of this species is needed for proper management. I described seasonal food habits of the Allegheny woodrat in the Ridge and Valley and Allegheny Plateau physiographic provinces of West Virginia and Virginia using microhistological techniques. In the Allegheny Plateau, the top 5 food items were fungi, blueberries ( Vaccinium spp.), acorns (Quercus spp.), ferns ( Dryopteris spp.), and lichens. In the Ridge and Valley woodrats ate primarily blackberry (Rubus spp.) leaves, fungi, greenbrier (Smilax spp.) leaves, acorns, and oak leaves. Additionally, we examined the …