Browsing by Author "Sprung, Martin"
Now showing 1 - 10 of 13
Results Per Page
Sort Options
- Aplysia spp. in the Ria Formosa lagoon (S. Portugal): are they important herbivores?Publication . Sprung, Martin; Aníbal, J.; Santos, Rui; Vieira, V.The impact of the opistobranchs Aplysia fasciata and Aplysia depilans on green algae in the Ria Formosa lagoon has been assessed by a combination of field observations and laboratory experiments.
- Dinâmica das Ulvales (Chlorophyta) na Ria FormosaPublication . Aníbal, J.; Sprung, MartinEste trabalho teve como objectivo estudar a distribuição espacial e temporal da Ulvalves da Ria Formosa.
- Dinâmica das Ulvales (Chlorophyta) na Ria FormosaPublication . Aníbal, J.; Sprung, MartinEste trabalho teve como objectivo estudar a distribuição espacial e temporal da Ulvales na Ria Formosa, bem como determinar possíveis factores bióticos e abióticos que podessem influenciar essa distribuição.
- Dynamics of green algae and its associated fauna in the Ria Formosa: is herbivory important?Publication . Aníbal, J.; Sprung, MartinThe Ria Formosa is a system of salt marshes and tidal flats, separated from the Atlantic by a belt of sand dunes that extends for 55 Km along the southern coast of Portugal. A striking phenomenon, which has been registered every winter since 1988, is an intense bloom of green macroalgae, mainly Ulvales (Ulva spp. and Enteromorpha spp.) These blooms appear the first rain falls in autumn and disappear gradually during the following spring (Sprung, 1994). A distinct community of benthic fauna is associated with these green algae. The objective of this work was to study in the western part of Ria Formosa, if the Ulvales were controlled by herbivorous macroepifauna.
- Estimating macrobenthic secondary production from body weight and biomass: a field test in a non-boreal intertidal habitatPublication . Sprung, MartinProduction (P) and biomass (B) data of different species from 3 stations in the intertidal zone of the Ria Formosa (southern Portugal, 37-degrees-N) were analysed. They were compared with equations from the literature to estimate P/BBAR ratios from body weight. A clear distinction must be made between (1) an intraspecific and (2) an interspecific comparison. (1) Results from 3 species supported a body weight exponent of -0.25 for the P/BBAR ratio, as is to be expected from a linear relationship between growth and respiration. (2) In an interspecific comparison, the weight exponent depends on the contribution of age or growth rate to the presence of large specimens in a sample. It is concluded that production in the specific habitat examined cannot be calculated properly from body weight and biomass by 1 simple equation which mixes interspecific and intraspecific effects, rather that both aspects should be separated into 2 different calculation steps.
- Flagging greens: hydrobiid snails as substrata for the development of green algal mats (Enteromorpha spp.) on tidal flats of North Atlantic coastsPublication . Schories, D.; Aníbal, J.; Chapman, A. S.; Herre, E.; Isaksson, I.; Lillebo, A. I.; Pihl, L.; Reise, K.; Sprung, Martin; Thiel, M.During the past 3 decades, dense mats of green algae (especially Enteromorpha spp.) have been recorded regularly from tidal flats worldwide. The development of green algal mats on tidal flats may be initiated by overwintering and regrowth of adult plants or by the formation and release of small propagules, i.e. vegetative fragments, zoospores and zygotes. On soft sediments, macroinvertebrates may constitute prime substrata for germination of algal spores. Hydrobud (mud-) snails are widespread along North Atlantic soft sediment shores and were identified previously as important substrata for Enteromorpha spp. germlings in 1 of our study areas. To test the generality of this phenomenon, we investigated the presence of Enteromorpha spp. gerrnlings attached to hydrobud snails from November 1995 to December 1996 on 6 tidal flats of North Atlantic coasts (Tralebergslule, Sweden; Konigshafen Bay, Germany; Mondego Estuary, Portugal; Ria Formosa, Portugal; Cole Harbour, Nova Scotia, Canada; Lowes Cove, Maine, USA). With 1 exception, hydrobiid snails were present in all areas studied, and intensive growth of Enteromorpha spp. occurred during summer. Throughout winter 1995/96, hardly any Enteromorpha spp. gerrnlings were found on snail shells, but over the following months germlings developed on up to 60% of the hydrobiid snails present. In 2 areas (Konigshafen, Germany; Lowes Cove, USA), germhng abundance on hydrobuds began to rise before the peak of green algal mat development. In Tralebergskile, Sweden, high mat abundance occurred simultaneous to and after increased germling abundance on Hydrobia ulvae. Densities of snails were very low, however, and hydrobuds appeared to be unimportant as substratum. No clear temporal pattern between high germling abundance on snails followed by mat development was found in the other 3 study areas (Ria Formosa, Portugal; Mondego Estuary, Portugal; Cole Harbour, Canada). In Lowes Cove, USA, gerrnlings and juveniles of Enteromorpha spp. first grew at the site with high Hydrobia abundance and were subsequently drifted to another site where they developed into full mats. We conclude that initiation of green algal mats by germination on Hydrobia spp. may be a general phenomenon, but that other modes of development also occur frequently. Pelagic dnft of overwintering thalli to new sites, followed by prolific growth, might be of similar or greater importance.
- Hydroiid snails conditioning green algae mats (Enteromorpha spp.) in the Northern HemispherePublication . Schories, D.; Albrecht, A.; Aníbal, J.; Fletcher, R.; Isaksson, I.; Lillebo, A. I.; Pihl, L.; Pye, K.; Reise, K.; Sprung, Martin; Thiel, M.For the last decades dense mats of filamentous green algae Enteromorpha spp. have regularly occurred worldwide on tidal Àats. The development of green algal rnats on intertidal Àats is commonly achieved by overwintering and regrowth of adult plants or by the formation and detachment of propagules. Up to now the study of germlings as initiators of algal mats have received relatively little attention. It was known from one of our study sites (Konigshafen Bay, Germany) that shells of living mudsnails (Hydrobia ulvae) serve as the main substrate of overwintering Enteromorpha spores and initiate in this way extensive growth of Enteromorplza mats in spring. We investigated the presence of Enteromorpha germlings attached on hydrobiid snails in different places of Canada, England, Germany, Portugal, Sweden and the United States between November 1995 and November 1996. At all investigation sites huge amounts of hydrobiid snails were present during the last years and and intensive growth of Enteromorplm occurred during the course of the season. - During winter 1995 /96 hardly any Enteromorpha germlings were found on the snail houses, but depending on the site, germlings developed on up to 60 % of hydrobiid snails during spring. It is obvious, that at least in some areas the germling development was related to overwintering of spores on snails, due to poor biomass of adult Enteromorpha plants during winter. In our study we could demonstrate that hydrobiid snails can play an important role in soft sediments for the successfull development of green algal mats in soft sediments.
- Influence of the mudflat surface shape on the green macroalgae and its associated macroepifaunaPublication . Aníbal, J.; Sprung, MartinAlthough the mudflats are relatively plain, a closer observation will show that they are a succession of mud ripples, composed by consecutive convex and concave sections. The aim of this study was to determine the influence of those sections on the dynamics of the macroalgae ulvales (Chlorophyta) and its associated macroepifauna in the Ria Formosa (a tidal lagoon on the southern coast of Portugal).
- Influência da superfície sedimentar na dinâmica das macroalgas verdes e da sua macroepifauna associada na Ria FormosaPublication . Aníbal, J.; Sprung, MartinO sistema lagunar, conhecido vulgarmente por Ria Formosa, desenvolve-se na costa meridional Portuguesa, desde o Ancão a ocidente até Cacela a oriente. Com extensão, de aproximadamente 55 km, apresenta a sua maior largura, de 6 km, no sector Norte-Sul entre Faro e o Cabo de Santa Maria. Este sistema é um conjunto de ilhas-barreira que proteje a zona lagunar adjacente à plataforma litoral algarvia, da invasão marinha. A área total do Parque Natural da Ria Formosa é aproximadamente de 163 km2, sendo 48 km2 cobertos por sapal e 32 km2 ocupados por canais, esteiros e baixios (Teixeira & Alvim, 1978). Durante as marés vivas, as áreas intertidais expostas são de aproximadamente 50 km2. Estas áreas são predominantemente cobertas por plantas de sapal (Spartina maritima), angiospérmicas marinhas (Zostera e Cymodocea) e mantos de macroalgas (Entermorpha, Ulva e Fucus). 20 km2 do sistema são ocupados por salinas e aquaculturas (CCRA, 1984).
- Influência do relevo superficial nas comunidades presentes em zonas vasosasPublication . Aníbal, J.; Sprung, MartinEmbora as zonas interditais vasosas pareçam relativamente planas, são constituídas por uma sucessão de ondulações compostas por zonas convexas e côncovas.