Annual dynamics of pelagic primary production and respiration in a shallow coastal basin

Loebl, Martina; Dolch, Tobias; Beusekom, Justus E. E. van

doi:10.1016/j.seares.2007.06.003

Cited by 40 publications

(32 citation statements)

References 32 publications

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“…Daily average wind speed ranged from 1.9 m s À1 to 16.5 m s À1 and was generally higher in winter compared with summer (data not shown). (Loebl et al, 2007). Chlorophyll a concentrations during the rest of the year were on an average 4.2 mg l À1 .…”

Section: Resultsmentioning

confidence: 94%

Time- and sediment depth-related variations in bacterial diversity and community structure in subtidal sands

et al. 2009

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Bacterial community structure and microbial activity were determined together with a large number of contextual environmental parameters over 2 years in subtidal sands of the German Wadden Sea in order to identify the main factors shaping microbial community structure and activity in this habitat. Seasonal changes in temperature were directly reflected in bacterial activities and total community respiration, but could not explain variations in the community structure. Strong sediment depthrelated patterns were observed for bacterial abundances, carbon production rates and extracellular enzymatic activities. Bacterial community structure also showed a clear vertical variation with higher operational taxonomic unit (OTU) numbers at 10-15 cm depth than in the top 10 cm, probably because of the decreasing disturbance by hydrodynamic forces with sediment depth. The depthrelated variations in bacterial community structure could be attributed to vertical changes in bacterial abundances, chlorophyll a and NO 3 À , indicating that spatial patterns of microbes are partially environmentally controlled. Time was the most important single factor affecting microbial community structure with an OTU replacement of up to 47% over 2 years and a contribution of 34% to the total variation. A large part of this variation was not related to any environmental parameters, suggesting that temporal variations in bacterial community structure are caused by yet unknown environmental drivers and/or by stochastic events in coastal sand habitats. Principal ecosystem functions such as benthic oxygen consumption and extracellular hydrolysis of organic matter were, however, at a high level at all times, indicating functional redundancy in the microbial communities.

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Section: Resultsmentioning

confidence: 94%

Time- and sediment depth-related variations in bacterial diversity and community structure in subtidal sands

et al. 2009

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“…The growth of 430 flagellates and Phaeocystis spp. was then favoured since they do not require Si, as shown by 431 Ly et al (2014) for the Marsdiep Basin in 2010 and for the List Tidal Basin (Loebl et al 2007). In 432 addition, Phaeocystis spp.…”

Section: Resuspension As An Enhancer Of Mineralization 392mentioning

confidence: 97%

Nutrients in the Western Wadden Sea: Freshwater Input Versus Internal Recycling

Leote

Mulder

Philippart

et al. 2015

Estuaries and Coasts

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10At present, phosphorus (P) is seen as the main limiting nutrient for phytoplankton growth in the 11 western Wadden Sea. Six cruises were performed for water sampling at selected stations 12 covering a full tidal cycle for later determination of dissolved and particulate nutrient 13 concentrations. The major P sources were identified on a seasonal basis, by comparing the 14 contribution of freshwater discharge and sediment release, calculated in a previous study, to the 15 concentrations in the water column. A close relationship was found between the pelagic 16 concentrations of dissolved inorganic nutrients and chlorophyll a, with a concomitant decrease 17 in nutrients and increase in chlorophyll. This was observed in early spring and was followed by a 18 later increase in the nutrient concentrations in spring-summer. The low concentrations found for 19 the freshwater and seawater end-members for this period ruled out their importance as nutrient 20 sources, suggesting that this increase resulted mainly from internal recycling in the Wadden 21Sea. Even though P limitation was observed during most the year, a potential seasonal change 22 in the limiting nutrient, from P to silica, was observed. The comparison between P supply to the 23 Wadden Sea by freshwater discharge and sediment release showed a much higher contribution 24 of the latter, especially in April-November. To our knowledge, this is the first study clearly 25 presenting internal recycling as the main nutrient source to the western Wadden Sea in spring-26 autumn, instead of freshwater discharge or the North Sea. 27 28

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“…Water volume at mean tidal level is about 845 9 10 6 m 3 . The mean water depth is 2.7 m (Loebl et al 2007) but reaches up to 40 m in the main tidal channel. The water column is mostly homogenously mixed.…”

Section: Study Sitementioning

confidence: 98%

Long-term variability of winter nitrate concentrations in the Northern Wadden Sea driven by freshwater discharge, decreasing riverine loads and denitrification

2007

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The hypothesis of a recent reversal in the eutrophication of the Wadden Sea and the potential of inshore waters in denitrification is explored. Salinity, temperature and nitrate concentrations in the List Tidal Basin (Northern Wadden Sea) have been measured about twice weekly since 1984. Salinity has a clear seasonal cycle with lowest salinities of about 27 in late winter and highest salinities of about 31 in summer. Mean annual deviations from the long-term mean salinity correlate significantly with riverine freshwater discharge. Winter nitrate concentrations are generally high (about 50 lM on average). The major part of the variability is related to salinity (*35%). Temperature had a minor impact (*1%). Superimposed on this, a long-term decrease of about 1 lM per year was found. Together, these processes account for about 45% of the nitrate variability. The long-term decrease of about 2% per year is similar to continental riverine trend in total nitrogen loads. In contrast to the List Tidal Basin, salinity explained more than 90% of nitrate variability in the off-shore German Bight. Salinity (30) normalised winter nitrate data of the German Bight also show a long-term decreasing trend. Most of the List Tidal Basin data are either on or below the nitrate-salinity relation found in the German Bight. This observation suggests that denitrification has a major impact on the winter nitrate concentrations in the Northern Wadden Sea compared to the German Bight. It is hypothesised that a large part of the unexplained variability is related to weather-dependent changes in residence time of tidal water masses in the Wadden Sea and circulation patterns within the German Bight.

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Annual dynamics of pelagic primary production and respiration in a shallow coastal basin

Cited by 40 publications

References 32 publications

Time- and sediment depth-related variations in bacterial diversity and community structure in subtidal sands

Time- and sediment depth-related variations in bacterial diversity and community structure in subtidal sands

Nutrients in the Western Wadden Sea: Freshwater Input Versus Internal Recycling

Long-term variability of winter nitrate concentrations in the Northern Wadden Sea driven by freshwater discharge, decreasing riverine loads and denitrification

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