Effect of continuous nutrient enrichment on microalgae colonizing hard substrates

Abstract

In order to understand the effect of changing nutrient conditions on benthic microalgae on hard substrates, insitu experiments with artificial substrates were conducted in Kiel Fjord, Western Baltic Sea. As an extension of previous investigations, we used artificial substrates without silicate and thus were able to supply nutrient media with different Si:N ratios to porous substrates, from where they trickled out continuously. The biofilm developing on these substrates showed a significant increase in biovolume due to N + P enrichment, while Si alone had only minor effects. The stoichiometric composition of the biomass indicated nitrogen limitation during most of the year. The C:N ratios were lowered by the N + P addition. The algae were dominated by diatoms in most cases, but rhodophytes and chlorophytes also became important. The nutrient treatment affected the taxonomic composition mostly at the species level. The significance of the results with regard to coastal eutrophication is discussed.

Diversity and biomass accumulation in cultured phototrophic biofilms

“…Similar community changes, in combination with diversity reduction in ageing biofilms and cyanobacterial dominance, were also found in natural freshwater biofilms (Sekar et al, 2002). The decrease in diversity probably indicated a greater contribution to the community of the growth of species already present on the substrata compared with the settlement of new species, especially under nutrient replete conditions and reduced availability of bare substrata (Hillebrand & Sommer, 2000).…”

Effect of nitrogen and phosphorus additions on a benthic microbial mat from a hypersaline lake

“…Silicate can thus be provided to microbiota by superficial dissolution of these particles, and sediments are therefore an important source of silicates, as was clearly suggested by earlier experimental observations in marine benthic systems (Nilson et al 1991, Sundbäck & Snoeijs 1991. Another study has shown that even for diatom-dominated benthic communities on hard substrates, silica additions had only a minor effect compared to N or P additions (Hillebrand & Sommer 2000). The artificial lake water we used contained less silicate (i.e.…”

The first report on periphytic diatoms on artificial and natural substrate in the karstic spring Bunica, Bosnia and Herzegovina

“…Total surface area is known and the problems associated with the measurement of irregular natural substrates are eliminated (LAMBERTI and RESH 1985). In the early days of fouling, increased diversity can be related to the colonization of new taxa (HILLEBRAND and SOMMER 2000). Through development of fouling on artifi cial substrate, stages of growth and loss take turns.…”

“…Summer minimum riverine water discharge and higher temperature conditions provide favorable and stable conditions for the development of periphytic diatoms (HILLEBRAND and SOMMER 2000).…”