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- Title
BIOMASS AND DYNAMICS OF GROWTH OF <em>ULVA</em> SPECIES IN PALMONES RIVER ESTUARY.
- Authors
Hernández, Ignacio; Peralta, Gloria; Páns, J. Lucas; Vergara, Juan J.; Niell, F. Xavier
- Abstract
During the last decade, the Polmones River estuary has undergone severe eutrophication followed by a green tide episode; two species of Ulva, rotundata Blid, and Ulva curvata (Kütz.) De Toni, were the main macroalgae responsible for this bloom. From November 1993 to December 1994, we followed the biomass, the growth dynamics, and tissue elemented composition (C:N:P) of Ulva species, as well as some physicohemical variables in the estuary. Maximum biomass (up to 375 g dry wt-m[sup2] in some spots, corresponding to a thallus ara index of nearly 17 m[sup2] Ulva-m[sup2] sediment were observed in June and December However, the biomass varied among the sampling stations. Water nitrate, ammania, and phosphate showed high concentrations throughout the year, with extremely high transient pulses, sustaining the high growth rates observed. Growth rates were estimated directly in the field. The rates were generally higher in Ulva discs maintained in net cages than those estimated by changes in biomass standing stock between two consecutive samplings. The difference between both estimates was used to quantify the importance of the processes causing loss of biomass, which were attributable to grazing, exported biomass, and thallus decomposition under annaerobic conditions resulting from extreme self-shading Maximum chlomphyll content was found in winter, wehreas the minimum was in spring. Atomic N:P ratios were generaly higher in the algae than in the water. However, the absolute concentrations of tissue N and Power always higher than the critical levels for maximum growth, which suggests that growth was not limited by inorganic N or P availability. The results suggested that the increase in nutrient loading in the river may have triggered the massive development of green algae and that light himitation and temperatures stress in summer seem to be the main factors controlling the abundance of Ulva in the estuary. In addition to light availability and the thermal stress, the different loss processes may have a decisive role in the dynamic of Ulva biomass.
- Subjects
PALMONES River (Spain); SPAIN; BIOMASS; ULVA; SPECIES; EUTROPHICATION; GROWTH; PRIMARY productivity (Biology)
- Publication
Journal of Phycology, 1997, Vol 33, Issue 5, p764
- ISSN
0022-3646
- Publication type
Article
- DOI
10.1111/j.0022-3646.1997.00764.x