Ecología y modelación de la dinámica de grupos morfo-funcionales de macroalgas en pastos marinos al Norte de Ciego de Ávila, Cuba
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Fecha
2011-07-08
Autores
Avila Alonso, Dailé
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Universidad Central "Marta Abreu" de Las Villas
Resumen
Los pastos marinos constituyen uno de los ecosistemas de mayor valor en la biosfera
y de los más amenazados globalmente. Entre los organismos asociados a los pastos
marinos se encuentran las macroalgas, junto a las cuales integran el macrofitobentos.
Con el objetivo de caracterizar el macrofitobentos asociado a los pastos marinos y
modelar la evolución del mismo en dos localidades al Norte de Ciego de Ávila se
determinaron las variaciones de biomasa de los grupos morfo-funcionales de
macroalgas, su correlación con las variables ambientales (temperatura, salinidad,
oxígeno disuelto y precipitaciones) y se determinó por modelo matemático la
estabilidad del pasto marino. Los muestreos se realizaron mensualmente (marzo de
2010-febrero de 2011), utilizando marco cuadrado de 25 cm de lado y se tomaron 15
unidades de muestreo en cada sitio. Para la modelación, a partir de las ecuaciones de
Biber et al. 2004, se determinó un nuevo procedimiento para la estabilidad del
ecosistema. La laguna tuvo menor diversidad algal (13 géneros) y mayor biomasa total
(2706,05 g/m²), determinado por el aporte de las calcáreas articuladas, mientras que
la playa fue un poco más diversa (26 géneros) y menos productiva (1859,13 g/m²). Se
determinaron cinco grupos morfo-funcionales: macrófitas corticadas, coriáceas,
calcáreas articuladas, filamentosas y foliosas y globosas. Los grupos corticadas,
filamentosas y calcáreas articuladas presentaron variaciones espacio-temporales. Los
picos máximos estuvieron en verano debido al enriquecimiento producto del arrastre
por las lluvias y los mínimos en primavera. Las variaciones espaciales estuvieron
dadas fundamentalmente por las diferencias entre las localidades en cuanto a régimen
hidrodinámico y nutrientes. La biomasa de las corticadas y filamentosas mostró
correlación con valores elevados de salinidad y oxígeno disuelto y las calcáreas
articuladas y coriáceas lo fueron para valores elevados de temperatura y
precipitaciones. Se determinaron dos puntos de equilibrio del pasto marino: uno
inestable, donde la biomasa se iguala a cero y otro estable, donde se igualan las tasas
de crecimiento y mortalidad. Se obtuvieron las fracciones ff y fr que constituyen pesos
estadísticos en las ecuaciones de transformación de grupos funcionales a grupos
morfo–funcionales. Las biomasas más cercanas al equilibrio se encontraron en los
meses con valores ambientales favorables para cada grupo en particular.
Seagrass are recognized as one of the most valuable and threatened ecosystems worldwide. In order to characterize and model the evolution of the macrophytobenthos associated to the seagrass in two localities of the northern coast of Ciego de Avila, the biomass variations of different macroalgae morpho-functional groups were determined as well as its correlation with environmental variables such as: salinity, temperature, oxygen dissolved, and precipitation. Ecosystem stability was determined by using a mathematical model. Surveys were conducted on a monthly basis from March 2010 to February 2011 by using a 25-cm-square and 15 sampling units were placed per site. For modeling purpose, a new procedure was performed taking into account Biber et al. 2004 equations. The lagoon showed a comparatively low diversity (13 macroalgae genera), but high biomass values (2706, 05 g/m²) owing to the calcareous articulate contributions. On the contrary, the sandy beach exhibited a higher diverse (26 genera) but lower productivity (1859, 13 g/m²). Up to five morpho-functional groups were identified: coarsely-branched, thick-leathery, jointed-calcareous, sheet and filamentous. Groups including the coarsely-branched, filamentous and jointed-calcareous showed spatiotemporal variations; with highest biomass values recorded in summer because of an increased nutrient level from precipitations and lowest figures during spring. Spatial variations were best explained by the differences of nutrients and hydrodynamic regimes between sampling sites. The coarsely-branched and filamentous biomasses were correlated with high salinity and dissolved oxygen, meanwhile jointed-calcareous and thick-leathery group’s biomasses were correlated with high temperature and precipitation. Two equilibrium points were determined for the seagrass ecosystem; a stable point defined as when mortality and growth rates evened out, and an unstable where biomass equaled to zero. Fractions ff and fr were obtained as statistics in the transformation equations from functional groups to morpho-functional groups. Biomass values near the equilibrium point were recorded during months when the environmental variables reached optimal levels for each morpho-functional group.
Seagrass are recognized as one of the most valuable and threatened ecosystems worldwide. In order to characterize and model the evolution of the macrophytobenthos associated to the seagrass in two localities of the northern coast of Ciego de Avila, the biomass variations of different macroalgae morpho-functional groups were determined as well as its correlation with environmental variables such as: salinity, temperature, oxygen dissolved, and precipitation. Ecosystem stability was determined by using a mathematical model. Surveys were conducted on a monthly basis from March 2010 to February 2011 by using a 25-cm-square and 15 sampling units were placed per site. For modeling purpose, a new procedure was performed taking into account Biber et al. 2004 equations. The lagoon showed a comparatively low diversity (13 macroalgae genera), but high biomass values (2706, 05 g/m²) owing to the calcareous articulate contributions. On the contrary, the sandy beach exhibited a higher diverse (26 genera) but lower productivity (1859, 13 g/m²). Up to five morpho-functional groups were identified: coarsely-branched, thick-leathery, jointed-calcareous, sheet and filamentous. Groups including the coarsely-branched, filamentous and jointed-calcareous showed spatiotemporal variations; with highest biomass values recorded in summer because of an increased nutrient level from precipitations and lowest figures during spring. Spatial variations were best explained by the differences of nutrients and hydrodynamic regimes between sampling sites. The coarsely-branched and filamentous biomasses were correlated with high salinity and dissolved oxygen, meanwhile jointed-calcareous and thick-leathery group’s biomasses were correlated with high temperature and precipitation. Two equilibrium points were determined for the seagrass ecosystem; a stable point defined as when mortality and growth rates evened out, and an unstable where biomass equaled to zero. Fractions ff and fr were obtained as statistics in the transformation equations from functional groups to morpho-functional groups. Biomass values near the equilibrium point were recorded during months when the environmental variables reached optimal levels for each morpho-functional group.
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Palabras clave
Algas marinas, Ciego de Avila