DIALNET OAI Articles
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Geociencias. Medio ambiente
Mostrando recursos 1 - 20 de 30.298
Nutrient limitation of phytoplankton growth and physiology in a subtropical estuary (Pensacola Bay, Florida) - Juhl, Andrew R.; Murrell, Michael C.
Phytoplankton nutrient limitation was studied in a sub-estuary of lower Pensacola Bay using multiple techniques in parallel. Nutrient-addition bioassays indicated year-round nutrient limitation, in contrast to seasonal patterns often described for higher-latitude estuaries. Although an earlier study found frequent P-limitation in Pensacola Bay, N-limitation dominated during this study, despite dissolved inorganic N:P ratios consistently above Redfield proportions. However, combined N and P additions enhanced phytoplankton growth more than single nutrients, indicating incipient co-limitation. In-situ alkaline phosphatase (Pase) activity was not clearly related to inorganic nutrient concentrations or ratios. however, changes in Pase activity after nutrient additions were consistent with the...
Short-term dispersal of an intentionally-released patch of larval Mercenaria Spp. in the Indian River Lagoon, Florida, USA - Hitchcock, Gary L.; Arnold, William S.; Frischer, Marc; Kelble, Christopher; Cowen, Robert K.
In July 1998 approximately 2.5 × 108 of recently-spawned Mercenaria spp. larvae were intentionally released in the northernmost basin of the Indian River Lagoon, Florida, to characterize the initial dispersion from a point source at time scales of hours to days. Larval densities measured with a quantitative molecular method indicated ambient concentrations were enhanced by 10 larvae L-1 near surface drifters released with the larvae. Surface distributions from samples collected near the drifters indicate that larval patches developed during the first day. diffusive processes evaluated from dye releases yield apparent diffusivity coefficients that suggest diffusive processes could spread larvae over...
Description of a new northeastern Atlantic aeolid of the genus Flabellina (Mollusca, Nudibranchia) - González-Duarte, Manuel M.; Cervera Currado, Juan Lucas; Poddubetskaia, Marina
A new species of aeolid nudibranch of the genus Flabellina Voigt, 1834 is described from the Bay of Arcachon (France), in the northeastern Atlantic. This species is cryptic of the aeolid Piseinotecus gaditanus Cervera, García and García, 1987. The external appearance is identical to P. gaditanus: body color is translucent white, ceratal surface transparent, digestive gland duct bright red and apex translucent white. The cerata arise from peduncles arranged in groups of five to seven, and opaque white spots are scattered all over the cerata surface. The radula is triseriate and the rachidian tooth has a triangular central cusp. The...
Genetic divergence among sympatric populations of three species of oyster drills (Urosalpinx) in Cedar Key, Florida - Robinson, John D.; Dillon, Robert T.
Three gastropod species of the genus Urosalpinx inhabit intertidal and subtidal regions of the southeastern United States. Urosalpinx cinerea (Say, 1822) is native to the Atlantic coast from Newfoundland to northeast Florida, while Urosalpinx perrugata (Conrad, 1846) and Urosalpinx tampaensis (Conrad, 1846) are largely restricted to the Gulf of Mexico. The morphological similarity of U. cinerea and U. perrugata is so striking that they have been suggested to be subspecies. We used a combination of molecular and morphological methods to examine divergence among populations of these three nominal species in a newly discovered area of sympatry: Cedar Key, Florida. Significant...
Sexual reproduction in the invasive octocoral Carijoa Riisei in Hawaii - Kahng, Samuel E.; Benayahu, Yehuda; Wagner, Daniel; Rothe, Nina
Since its initial discovery on Oahu in 1966, the azooxanthellate octocoral, Carijoa riisei (Duchassaing and Michelotti, 1860), has spread across the main Hawaiian Islands and proliferated in abundance. To help understand the substantial ecological success of C. riisei in Hawaii, its sexual reproduction was examined. Carijoa riisei is gonochoric with a male to female ratio of one. Gametogenesis is asynchronous, continuous, and does not exhibit seasonal or lunar periodicity. Carijoa riisei spawns negatively buoyant eggs which suggests external fertilization and possibly benthic larvae. Under favorable conditions, C. riisei exhibits high polyp fecundity. Asynchronous, continuous spawning of gametes is an unusual...