Nutrient dynamics in the intertidal pools of the Mondego estuary: III - the importance of nutrient effluxes to macroalgal growth (Enteromorpho sp.)

Abstract

A navegação consulta e descarregamento dos títulos inseridos nas Bibliotecas Digitais UC Digitalis, UC Pombalina e UC Impactum, pressupõem a aceitação plena e sem reservas dos Termos e Condições de Uso destas Bibliotecas Digitais, disponíveis em https://digitalis.uc.pt/pt-pt/termos.Conforme exposto nos referidos Termos e Condições de Uso, o descarregamento de títulos de acesso restrito requer uma licença válida de autorização devendo o utilizador aceder ao(s) documento(s) a partir de um endereço de IP da instituição detentora da supramencionada licença.Ao utilizador é apenas permitido o descarregamento para uso pessoal, pelo que o emprego do(s) título(s) descarregado(s) para outro fim, designadamente comercial, carece de autorização do respetivo autor ou editor da obra.Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso. The aim of the present work was to evaluate the importance of nutrient f1uxes across the sediment-water interface to the growth of opportunistic macroalgae (Enteromorpha sp.) within tidal pools of an intertidal estuary. We hypothesised that different tidal pools. in relation with organic matier content in the sediment and the presence/absence of rooted-macrophytes. promote distinct growth responses of Enteromorpha sp. Nutrient dynamics (P04-P, NH4-N and N03-N) and Enteromorpha intestina/is growth were assessed during low-tide period in 4 different places: a sandy bare botiom pool. muddy pools (a bare botiom pool and a Spartina maritima covered pool) and the low-depth subtidal channel. Macroalgal growth in the subtidal area was estimated to compare with results from the tidal pools. Results showed that the growth rate of E. intestina/is was higher in the muddy bare botiom pool and statistically different from growth in the other places. No significant differences were found between macroalgal growth in the S. maritima covered pool. the sandy pool and the channel.The differences are partially explained by different nutrient dynamics between the muddy bare botiom pool and the other places. The availability of NH.-N was higher in the muddy bare botiom pool. followed by the S. maritima covered pool. the channel and the sandy bare botiom pool. N:P atomic ratios of the water suggested that. with the exception of the muddy bare botiom pool. ali the other places showed a potential N-limitation for primary production. Results also suggested that Spartina maritima affect the nutrient dynamics in tidal pools. However in this type of pools. the growth of E. intestina/is may also be affected by shading caused by the rootedmacrophyte presence. ln the channel. other factors (e.g. hydrodynamics) affect macroalgal growth. which determines differences in relation with tidal pools. At the system levei. these results suggest that in terms of nutrient availability. the occurrenc...

Phosphorus speciation and availability in intertidal sediments of a temperate estuary: relation to eutrophication and annual P-fluxes

“…Five different areas (Spartina maritima salt marshes and unvegetated mudflats) were selected along a welldocumented eutrophication gradient (e.g. Marques et al, 1997;Pardal et al, 2000;Cardoso et al, 2002;Martins et al, 2002;Dolbeth et al, 2003) to represent the outer part of the estuary (Mud A and Sp A), an intermediate part (Mud B and Sp B) and the most inner mudflats (Mud C) (Fig. 1B).…”

“…1) has Spartina maritima marshes and large areas of highly organic non-vegetated mudflats, with a net release of P by P-mineralisation and P-desorption. This system has a net release of 14 ton phosphate year ÿ1 to adjacent coastal waters (1 ton enters the system, while 15 tons are exported) (Flindt et al, 1997;Lillebø et al, 2002), and phosphate concentrations in spring/summer are suitable for macroalgal blooms to occur (Pardal et al, 2000;Martins et al, 2002). The main nutrient supply to the south arm of the Mondego is the Pranto river, which flows through highly fertilized agricultural fields.…”

Nutrient dynamics in the intertidal pools of the Mondego estuary: I - nutrient sources, sediment profiles, mineralisation and absorption dynamics

“…General information and more detailed description of the Mondego estuary can be found in Marques et aI. (2002) .…”

“…The current velocities peak with values of about 2 m S•I during spring tide periods (Martins et aI. 2002).…”

“…The next of this suite of papers conceming the nutrient dynamics in the Mondego estuary will I) compare the nutrient fluxes and dynamics in the different pools (Lilleb0 et aI. 2002b) , 2) demonstrate how macroalgae growt potential are affected by the nutrient fluxes in the different types of pools (Martins et aI. 2002) and 3) discuss and perspect the role of the nutrient dynamics in the different pool types on the system levei for the Mondego Estuary (Lilleb0 et aI.…”