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Tracking Diet And Movement Of Atlantic Bluefin Tuna (Thunnus Thynnus) Using Carbon And Nitrogen Stable Isotopes, John Logan
Doctoral Dissertations
Atlantic bluefin tuna (ABFT; Thunnus thynnus) are important top predators in pelagic ecosystems. Understanding their diet and movements is necessary for proper management, but existing methods are costly and logistically challenging. Naturally occurring stable isotopes have been used to study diet and movement in many aquatic ecosystems and offer a novel approach for studying these large pelagic fishes.
Lipids, which have lower carbon isotope values than protein, can affect isotope analyses of bulk tissue. Both chemical and mathematical corrections were used to address lipid effects on ABFT and the prey. All chemical extraction methods altered nitrogen isotope values. Mathematical corrections …
Factors Affecting Plant Community Composition And Dynamics In The Ossipee Pine Barrens, New Hampshire, Lauren Fredrick Howard
Factors Affecting Plant Community Composition And Dynamics In The Ossipee Pine Barrens, New Hampshire, Lauren Fredrick Howard
Doctoral Dissertations
Forty-one 0.25 ha sites were sampled in the Ossipee Pine Barrens to identify and describe tree community types and investigate factors controlling forest composition and dynamics. Every site had three site-time assemblages (STA's) representing past, present, and future trees. Past (1952) vegetation was calculated based on reverse growth estimates of current stems and stumps. Future (2052) vegetation was predicted by current sapling (<10 cm dbh and ≥1 m tall) relative densities.
Cluster analysis produced three community types from 121 STA's: pitch pine, mixed pine-hardwoods, and red maple. Pitch pine communities comprised 63% of sites in 1952, but declined since. Mixed pine-hardwoods peaked at 58% in 2002, but were …