Evidence for eutrophication of the Irish Sea over four decades

Allen, John H.; Slinn, D. J.; Shummon, T. M.; Hurtnoll, R. G.; Hawkins, Stephen J.

doi:10.4319/lo.1998.43.8.1970

Cited by 54 publications

(27 citation statements)

References 27 publications

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“…5A-C), in contrast to the clear linking of nutrient load to primary production and chlorophyll biomass documented in various marine systems throughout Europe and North America (Jonge et al 1994, Solic et al 1997, Allen et al 1998). It should be stressed that the increase of the nitrate maximum in the open Black Sea (Fig.…”

Section: Long-term Trends Of Phytoplankton and Nutrientsmentioning

confidence: 91%

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Yunev¹,

Moncheva²,

Carstensen³

2005

Mar. Ecol. Prog. Ser.

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The objective of this study was to investigate long-term trends in the subsurface summer phytoplankton community and their underlying mechanisms in relation to nutrient enrichment of the open Black Sea. We analysed parameters describing the summer chlorophyll a (chl a) and annual mean nitrate depth distribution in terms of their maximum concentration and its depth, the mean nitrate gradient for the layer between the 2 maxima, and Secchi depth. Investigating the entire period from 1964 to 1996 did not reveal any direct relationship between the nitrate and phytoplankton levels. The nitrate level in the open Black Sea increased until 1984/85, corresponding with general increases in anthropogenic riverine nutrient inputs to the sea. Thus, the average maximum nitrate concentration and the nitrate gradient for all depth profiles increased between 1969 and 1984 and then remained constant. Despite the early increase in nitrate characteristics, the maximum in the chl a profile remained unaltered from 1964 to 1984. After the mid-1980s, the magnitude of the chl a profile gradually increased to 1991 and peaked with an exceptionally high concentration in 1992. In this same period there were only moderate fluctuations in the nitrate profile characteristics. The change of the summer phytoplankton biomass levels since 1984/85 coincided with an intensification of the Rim Current and the associated transport of nitrate to the euphotic zone. Prior to 1984/85 strong stratification and a deep halocline resulted in nitrate accumulation only, whereas uplifting of the halocline, combined with intensified advective currents, increased the transport of nitrate to the euphotic zone during the summer. This resulted in an associated increase in phytoplankton production and biomass in the following period. While this study shows that the open Black Sea, like the coastal regions, has been impacted by eutrophication, the response is different from the coastal region due to the different physical characteristics of the open waters.

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Section: Long-term Trends Of Phytoplankton and Nutrientsmentioning

confidence: 91%

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Yunev¹,

Moncheva²,

Carstensen³

2005

Mar. Ecol. Prog. Ser.

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“…In these systems, phytoplankton production is often light limited year-round, and growth is low despite the high levels of nutrient input (Heip et al 1995). Consequently, effects of high nutrient concentrations are often exported downstream to more quiescent nearshore coastal waters, where they may be manifest (e.g., by more intense and longer lasting spring blooms in the plume of large estuaries) (Allen et al 1998).…”

Section: Acknowledgmentsmentioning

confidence: 99%

Long‐term change in dissolved inorganic nutrients in the heterotrophic Scheldt estuary (Belgium, The Netherlands)

Soetaert

Middelburg

Heip

et al. 2006

Limnology & Oceanography

183

192

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We investigated long-term trends in dissolved inorganic nutrients in the tidal part of the Scheldt estuary (Belgium, The Netherlands). Annually averaged concentrations of dissolved silicate (DSi), dissolved inorganic nitrogen (DIN), and phosphate (DIP) increased significantly until the mid-1970s, after which they declined linearly at rates of 0.6, 2.9, and 0.3 mol L Ϫ1 yr Ϫ1 , respectively. This co-occurred with a deterioration followed by a restoration of water column oxic conditions. Because of the differences in the reduction rate of DSi (1.2% yr Ϫ1 ), DIN (1.7% yr Ϫ1 ), and DIP (5.4% yr Ϫ1 ), the N : P and Si : P ratios more than doubled from 1980 to 2002. The Si : N ratio varied from 0.2 to 0.4 and was positively correlated with river discharge. The part downstream from the confluence of the main rivers was a net sink for DSi during the entire period but evolved from a net sink to a net source for DIP, while the reverse was true for DIN. This differential behavior of the estuary with respect to DIN and DIP strongly buffered the altered loadings to the upper estuary. The input of oxygen-consuming substances at the head of the estuary triggered a sequence of oxidation reactions. In the early 1970s, high loadings of ammonium and organic matter caused oxygen depletion and intense water-column denitrification in the upstream part and intense nitrification downstream, with a nitrate maximum succeeding a nitrite peak. With oxic conditions improving and the input of ammonium decreasing, water-column denitrification declined, the nitrification front migrated upstream, and the estuary evolved from a net producer of nitrite to a net consumer. Now, at the beginning of the 21st century, nitrate behaves almost conservatively over the entire estuary.

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“…Long-term data are essential to understand both regional and localscale eutrophication, particularly in separating broader oceanographic drivers from processes internal to the catchment of enclosed seas [32,44]. Often a combination of particular hydrographic conditions such as warm sunny weather enhancing stratification and higher nutrients due to eutrophication lead to blooms of harmful algal species [45,46].…”

Section: Policy Relevancementioning

confidence: 99%

“…The Dove time-series collected by the University of Newcastle (NE England), owed much to Buchanan, Evans and latterly Frid [27][28][29][30][31]. The Port Erin Marine Laboratory hydrography and nutrient timeseries was built by Slinn [27,32]. Wulf was the stalwart and steward of the Helgoland time-series [30] now taken on by Wiltshire [33].…”

Section: Challenges With Long Term Data Collectionmentioning

confidence: 99%

Sustained Observation of Marine Biodiversity and Ecosystems

M¹

2013

Oceanography

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At a time of unprecedented global change it is essential to distinguish short-term and local scale variability ("noise") from the low-amplitude longer wavelength signal of climate-driven change. Moreover, global responses to climate need to be separated from regional and local scale impacts and their interactions better understood to enable effective management of marine ecosystems. In this short editorial, we make the case for sustaining long-term and broad-scale observations of the oceans and coastal waters. First we consider the value of longterm observations drawing on work in the Western English Channel [1,2]; before considering the challenges of sustaining time series and cautioning that such observations are at risk in any period of financial constraints for public sector research funding. We conclude by discussing their relevance to policy and marine management. This editorial is written primarily from an ecological and inshore perspective reflecting the experience of the lead author but the general issues discussed apply equally to work in the open ocean. Value of Long-Term and Broadside ObservationsEmpirical observations of the physics, chemistry and biology of the oceans and coastal seas have been made since the last quarter of the 19 th Century, given impetus by the major oceanographic expeditions (e.g. Porcupine -1868-1869, Challenger -1872-1876, Hirondelle I and II -1886-1922, Princesse Alice I and II -1886-1922, National -1889 and Valdivia -1898-1899 was an early and important attempt to integrate and network the efforts of multiple nations. In the UK the Marine Biological Association of the United Kingdom (MBA) led the work from its Laboratories at Lowestoft and Plymouth. The work in the English Channel initiated a long-running, but much interrupted time-series. Wars, funding cuts, institutional re-organisation and changes in research priorities all took their toll at various times over the last century.The Plymouth time-series (initially led by the MBA until 1987, with additional parameters measured by Plymouth Marine Laboratory (PML) , consolidated as the Western Channel Observatory www.westernchannelobservatory.org.uk in 2007, has made some major contributions to marine science over the last 100 years. One of the strengths of the Western English Channel time-series is its comprehensive nature covering physical, chemical measurements and observations of various biological compartments (phytoplankton, zooplankton, fish, benthos, intertidal assemblages) [1-6] of the ecosystem and its grid nature with two to three main stations E1, L5, L4 [2] on an inshore-offshore axis with both stratified and mixed water bodies. Observations in the Western English Channel have shown how climate fluctuations can drive whole nearshore and coastal ecosystems [3,4,[7][8][9][10]. These were apparent long before the recent spell of rapid warming since the late 1980s [1,2] and were coined "the Russell Cycle" by Cushing and Dickson [11]. Thus they provide a true fluctuating baseline of colder (early part of 20 th Cen...

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Evidence for eutrophication of the Irish Sea over four decades

Cited by 54 publications

References 27 publications

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: eutrophication and climate change

Long‐term change in dissolved inorganic nutrients in the heterotrophic Scheldt estuary (Belgium, The Netherlands)

Sustained Observation of Marine Biodiversity and Ecosystems

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