Enzymatic activity and organic substrates on a sandy beach of the Ligurian Sea (NW Mediterranean) influenced by anthropogenic pressure

Misic, Cristina; Harriague, Anabella Covazzi

doi:10.3354/ame047239

Cited by 17 publications

(8 citation statements)

References 24 publications

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“…Concentrations of DIN in the pore water were within the range of those previously found for similar sandy sediments (Sundbäck et al 2003, Engelsen et al 2008, and AMA was within the range found for shallow-water sandy sediments in an oligotrophic part of the Mediterranean (Misic & Harriague 2007). While levels of APA were low for the ultrasonicated 'algal' fraction (>1 μm), higher APA for the 'bacterial' fraction (<1 μm) indicated a limitation of phosphorus.…”

Section: Nutrient Limitationsupporting

confidence: 82%

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Dissolved organic nitrogen: an important source of nitrogen for the microphytobenthos in sandy sediment

Sundbäck¹,

Lindehoff²,

Granéli³

2011

Aquat. Microb. Ecol.

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To test the hypothesis that dissolved organic nitrogen (DON) is important for sustaining primary production by the microphytobenthos (MPB) in nitrogen-limited conditions, we measured the uptake of 15 N-labelled urea, the amino acids glycine (GLY) and glutamic acid (GLU), and nitrate and ammonium under simulated in situ light and temperature conditions. Microphytobenthic primary production and chlorophyll a (chl a) were also measured. The MPB was dominated by diatoms attached to sand grains, with cyanobacteria making up ~30% of the biomass. Activities of the hydrolytic ectoenzymes leucine aminopeptidase (AMA), alkaline phosphatase (APA) and β-glucosidase (GLA) in filter-fractionated sediment showed that the microbenthic community was strongly deficient in nitrogen (N), with the bacterial fraction (<1 μm) also limited in phosphorus. Uptake of DON (urea + GLU + GLY) accounted for ~50 to 65% of the uptake of 15 N-labelled substrates, with a higher proportion of DON uptake at low substrate concentrations (≤2 μM). Except for nitrate, the kinetics fitted a linear model. The calculated relative preference index (RPI), based on pore water concentrations, suggested that the order of preference of the microbenthic community was NH 4 + > urea > GLU > NO 3 -> GLY. Using a prokaryotic inhibitor (chloramphenicol), and theoretical calculations of algal uptake based on C:chl a ratios, it was estimated that the 'algal' uptake of nitrogen accounted for ~55 to 90% of DON uptake. Uptake rates were, however, estimated to cover only 26 to 50% of the nitrogen demand of the MPB, suggesting that pore water concentrations of nitrogen were not sufficient to meet the microalgal demand in early summer and that, in sandy sediments of microtidal waters, the MPB may often be severely limited in nitrogen. KEY WORDS: Microphytobenthos · Nitrogen · DON · Urea · Amino acids · EctoenzymesResale or republication not permitted without written consent of the publisher Aquat Microb Ecol 63: 89-100, 2011 As is the case for tropical sandy areas, which are extremely limited in nitrogen (Eyre et al. 2008), a strong influence of the MPB on benthic turnover of nitrogen also appears to apply to sandy sediments in cool nitrogen-poor microtidal areas , Engelsen et al. 2008. Although microalgae are apparently N-limited in such sediments, the MPB biomass and primary production are often as high -or even higher -than in relatively nutrient-rich silty sediments , Engelsen et al. 2008. This is also the case for sandy sediments on tidal coasts (Barranguet et al. 1998, Billerbeck et al. 2007). Explanations for a higher algal activity in sandy sediments include better light penetration and more effective transport of solute to the algae, particularly in permeable intertidal inundated sediments (Billerbeck et al. 2007). An additional explanation is that N is efficiently recycled within the microbial communities of the sediment surface (Lomstein et al. 1998, Cook et al. 2007, Gribsholt et al. 2009), sustaining productivity by using available 'old nitrogen'. ...

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Section: Nutrient Limitationsupporting

confidence: 82%

“…Interestingly, the highest activity of GLA, which is considered to reflect mainly bacterial activity (e.g. Misic & Harriague 2007), was found in the sonicated >1 μm 'algal' fraction, suggesting that algae may have been mainly responsible for GLA, although this fraction may also have included some bacteria.…”

Section: Share Of Algal Uptakementioning

confidence: 99%

Dissolved organic nitrogen: an important source of nitrogen for the microphytobenthos in sandy sediment

Sundbäck¹,

Lindehoff²,

Granéli³

2011

Aquat. Microb. Ecol.

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“…The results of the present study indicated different activity level of tested enzymes along the horizontal profile of the studied water–sediment interface. The horizontal zonation of the enzymatic activity is a well‐known global phenomenon in different water basins (Kalwasińska & Brzezińska, ; Misic & Harriague, ; Perliński, ). In the SWI of the studied estuary, the activity level of extracellular enzymes along the horizontal profile was probably strongly affected by environmental conditions (freshwater, mixed, and seawater zone).…”

Section: Discussionmentioning

confidence: 99%

Enzymatic biodegradation of high molecular weight polymers in the sediment–water interface in the coastal river estuary

Perliński

Mudryk

2018

River Research & Apps

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The level of activity of eight extracellular hydrolytic enzymes responsible for biodegradation of high molecular weight polymers in the water-sediment interface in the coastal river estuary was determined. The ranking order of the mean enzyme activity rates in the sediment-water interface was as follows: lipase > aminopeptidase > phosphatase > β-glucosidase > α-glucosidase > xylanase > chitinase > cellulase. The activity of the studied enzymes differed between various parts of the estuary. Each enzyme had its characteristic horizontal activity profile. Extracellular enzymatic activities were strongly influenced by the season. As a rule, tested enzymes showed their maximum hydrolytic activity during the vegetation period.

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“…According to UrbanMalinga and Opaliński (1999), as much as 1.1 kg of organic C m -2 could be introduced daily into the interstitial system of a marine beach. Such accumulation of organic matter generates optimal conditions for the growth of numerous heterotrophic microorganisms, mainly bacteria, which play a key role in the processes of decomposition and transformation of organic matter accumulated in sandy beach ecosystems (Mudryk et al 2001, Malm et al 2004, Misic and Harriague 2007. According to , about 70% of organic matter reaching the ecosystems of marine beaches is mineralised by bacteria transforming it into their own biomass or utilizing it for respiratory purposes as a source of energy.…”

Section: Introductionmentioning

confidence: 99%

Studies concerning heterotrophic bacteria decomposing macromolecular compounds at two marine beaches

Mudryk

Skórczewski

Perliński

et al. 2011

Oceanological and Hydrobiological Studies

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The potential capability to decompose macromolecular compounds was confirmed in heterotrophic bacteria isolated from two sandy beaches located on the southern Baltic coast. Proteolytic bacteria were the most numerous group, whereas lipolytic organisms were rare among bacteria inhabiting the studied beaches. All studied physiological groups of bacteria were considerably more numerous in the sand of the beach subject to stronger anthropopressure. The differences in bacteriological parameters across the horizontal profile of the beaches were noted. In both studied beaches a higher number of bacteria able to decompose macromolecular compounds were recorded in the surface as compared to the subsurface sand layer.

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Enzymatic activity and organic substrates on a sandy beach of the Ligurian Sea (NW Mediterranean) influenced by anthropogenic pressure

Cited by 17 publications

References 24 publications

Dissolved organic nitrogen: an important source of nitrogen for the microphytobenthos in sandy sediment

Dissolved organic nitrogen: an important source of nitrogen for the microphytobenthos in sandy sediment

Enzymatic biodegradation of high molecular weight polymers in the sediment–water interface in the coastal river estuary

Studies concerning heterotrophic bacteria decomposing macromolecular compounds at two marine beaches

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