Shifting south-eastern North Sea macrofauna community structure since 1986: A response to de-eutrophication and regionally decreasing food supply?

Meyer, Julia; Nehmer, Petra; Moll, A.; Kröncke, Ingrid

doi:10.1016/j.ecss.2018.08.010

Cited by 17 publications

(24 citation statements)

References 62 publications

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“…This is in line with observations from the Helgoland road time series, even showing an overall decline in zooplankton densities (Boersma et al, 2015). Macrozoobenthos densities in the Wadden Sea have been relatively stable during the past decades (Drent et al, 2017) or even decreased in the adjacent coastal zone (Meyer et al, 2018). Philippart et al (2007) did not observe a clear decrease in macrobenthos biomass in the western Dutch Wadden Sea but did observe a decrease in filter capacity by the macrobenthos.…”

Section: Limiting Factors Of Phytoplankton Growth In the Wadden Seasupporting

confidence: 85%

Wadden Sea Eutrophication: Long-Term Trends and Regional Differences

Beusekom¹,

Carstensen

Dolch

et al. 2019

Front. Mar. Sci.

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The Wadden Sea is a shallow intertidal coastal sea, largely protected by barrier islands and fringing the North Sea coasts of Netherlands, Germany, and Denmark. It is subject to influences from both the North Sea and major European rivers. Nutrient enrichment from these rivers since the 1950s has impacted the Wadden Sea ecology including loss of seagrass, increased phytoplankton blooms, and increased green macroalgae blooms. Rivers are the major source of nutrients causing Wadden Sea eutrophication. The nutrient input of the major rivers impacting the Wadden Sea reached a maximum during the 1980s and decreased at an average pace of about 2.5% per year for total Nitrogen (TN) and about 5% per year for total Phosphorus (TP), leading to decreasing nutrient levels but also increasing N/P ratios. During the past decade, the lowest nutrient inputs since 1977 were observed but these declining trends are leveling out for TP. Phytoplankton biomass (measured as chlorophyll a) in the Wadden Sea has decreased since the 1980s and presently reached a comparatively low level. In tidal inlet stations with a long-term monitoring, summer phytoplankton levels correlate with riverine TN and TP loads but stations located closer to the coast behave in a more complex manner. Regional differences are observed, with highest chlorophyll a levels in the southern Wadden Sea and lowest levels in the northern Wadden Sea. Model data support the hypothesis that the higher eutrophication levels in the southern Wadden Sea are linked to a more intense coastward accumulation of organic matter produced in the North Sea.

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Section: Limiting Factors Of Phytoplankton Growth In the Wadden Seasupporting

confidence: 85%

Wadden Sea Eutrophication: Long-Term Trends and Regional Differences

Beusekom¹,

Carstensen

Dolch

et al. 2019

Front. Mar. Sci.

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“…At least two major trends are currently affecting phytoplankton dynamics in the North Sea: the warming trend that started between 1982 and 1987 (Beaugrand and Reid ; Edwards et al ; van Aken ; Høyer and Karagali ) and the de‐eutrophication trend, that is, the decreasing loads of nutrients and organic matter into coastal seas, that started in the 1980s (van Beusekom et al ; Burson et al ; Meyer et al ). In addition to potentially altering the stratification regime in the Central North Sea, increasing sea surface temperature (SST) may have strong effects on the physiology of marine phytoplankton, that is, temperature may enhance phytoplankton cell division rate (Hunter‐Cevera et al ) or, on the contrary, negatively affect net production when it exceeds temperature optima for photosynthesis while still enhancing cell respiration (Barton et al ).…”

mentioning

confidence: 99%

Changes in chlorophyll concentration and phenology in the North Sea in relation to de‐eutrophication and sea surface warming

Desmit

Nohe

Borges

et al. 2019

Limnology & Oceanography

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At least two major drivers of phytoplankton production have changed in recent decades in the North Sea: sea surface temperature (SST) has increased by~1.6 C between 1988 and 2014, and the nitrogen and phosphorus loads from surrounding rivers have decreased from the mid-1980s onward, following reduction policies. Long time series spanning four decades of nutrients, chlorophyll (Chl), and pH measurements in the Southern and Central North Sea were analyzed to assess the impact of both the warming and the deeutrophication trends on Chl. The de-eutrophication process, detectable in the reduction of nutrient river loads to the sea, caused a decrease of nutrient concentrations in coastal waters under riverine influence. A decline in annual mean Chl was observed at 11 out of 18 sampling sites (coastal and offshore) in the period 1988-2016. Also, a shift in Chl phenology was observed around 2000, with spring bloom formation occurring earlier in the year. A long time series of pH in the Southern North Sea showed an increase until the mid-1980s followed by a rapid decrease, suggesting changes in phytoplankton production that would support the observed changes in Chl. Linear correlations, however, did not reveal significant relationships between Chl variability and winter nutrients or SST at the sampling sites. We propose that the observed changes in Chl (annual or seasonal) around 2000 are a response of phytoplankton dynamics to multiple stressors, directly or indirectly influenced by deeutrophication and climate warming.

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“…The spatial distribution of macrofauna communities in the southeastern North Sea reveales five macrofauna communities, namely the Tellina (Fabulina) fabula community, the Amphiura filiformis community, the Nucula nitidosa community, the Goniadella spisula community and the Bathyporeia spp. community (Meyer et al, 2018). Spatial distribution of macrofauna communities are in particular structured by environmental parameters such as water depth, sediment structure, tidal forcing and water temperature (Reiss et al, 2009;Meyer et al, 2018).…”

Section: Benthic Communitiesmentioning

confidence: 99%

“…community (Meyer et al, 2018). Spatial distribution of macrofauna communities are in particular structured by environmental parameters such as water depth, sediment structure, tidal forcing and water temperature (Reiss et al, 2009;Meyer et al, 2018).…”

Section: Benthic Communitiesmentioning

confidence: 99%

“…7-10 allow an approximation of biogenic reworking rates from readily available oceanographic parameters. The correlations with water depth and median grain size most likely differentiate different benthic communities (Reiss et al, 2009;Meyer et al, 2018) with different reworking effort. For the correlations between biogenic reworking and the physical quantities temperature and flow velocity, the following causal relations are plausible.…”

Section: Physical Boundary Conditions For Biogenic Reworking Activitymentioning

confidence: 99%

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Relations of physical and biogenic reworking of sandy sediments in the southeastern North Sea

Krämer

Ahmerkamp

Schückel

et al. 2019

Preprint

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Abstract. The reworking of sandy sediments in shallow coastal and shelf seas is mainly driven by physical forcing in the form of wave- and current-induced shear stress. As an important habitat for benthic species seeking shelter and food, the upper seafloor is also marked by intense bioturbation. Although this reworking activity is recognized as an important mechanism for the exchange of particular matter and solutes between sediment and water column, quantifications and assessments of the relative importance of physical and biogenic reworking of subtidal shelf sediments are rare. This work presents in situ measurements of volumetric reworking rates from six different locations in the southeastern North Sea. The investigated sites cover a range of water depths between 23 and 41 m, different magnitudes of physical (wave and current) forcing and sedimentological conditions as well as different habitats and benthic communities. The measured biogenic reworking rates reach up to 14 % of physically driven reworking via bedform migration. Comparisons with physical quantities water depth, median grain size, bottom water temperature and flow velocity reveal good correlations and allow for an approximation of the biogenic reworking rate from a combination of these readily available oceanographic parameters. The diffusive relocation of sediment by benthic fauna also influences the topography of small scale bedforms and may reduce their height by up to 10 % in a few hours during hydrodynamically inactive conditions. The observations show that even in an energetic environment such as the southeastern North Sea, the benthic fauna contributes an important regulating ecosystem service by overturning upper seafloor sediments. This reworking mechanism becomes particularly important in areas and during periods of sub-threshold conditions for physically driven sediment reworking.

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Shifting south-eastern North Sea macrofauna community structure since 1986: A response to de-eutrophication and regionally decreasing food supply?

Cited by 17 publications

References 62 publications

Wadden Sea Eutrophication: Long-Term Trends and Regional Differences

Wadden Sea Eutrophication: Long-Term Trends and Regional Differences

Changes in chlorophyll concentration and phenology in the North Sea in relation to de‐eutrophication and sea surface warming

Relations of physical and biogenic reworking of sandy sediments in the southeastern North Sea

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