Invertebrate re-colonisation in Mariager Fjord (Denmark) after severe hypoxia. I. Zooplankton and settlement

Hansen, Benni Winding; Stenalt, Ea; Petersen, Jens Kjerulf; Ellegaard, Christina

doi:10.1080/00785236.2002.10409499

Cited by 23 publications

(14 citation statements)

References 46 publications

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“…However, because of high grazing rates, PP is funnelled very effectively through the food chain during summer, especially from May to August, confirming earlier studies carried out for shorter time periods in the region (see, e.g. Kiørboe 1993;Markager et al 1999a;Hansen et al 2002;Zervoudaki et al 2009). …”

Section: Impact Of Zooplankton Grazing On Phytoplankton Standing Stocksupporting

confidence: 75%

How Well Does Chlorophyll Explain the Seasonal Variation in Phytoplankton Activity?

Lyngsgaard

Markager

Richardson

et al. 2017

Estuaries and Coasts

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The seasonal variation in phytoplankton activity is determined by analysing 1385 primary production (PP) profiles, chlorophyll a (Chl) concentration profiles and phytoplankton carbon biomass concentrations (C) from the period 1998-2012. The data was collected at six different stations in the Baltic Sea transition zone (BSTZ) which is a location with strong seasonal production patterns with light as the key parameter controlling this productivity. We show that the use of Chl as a proxy for phytoplankton activity strongly overestimates the contribution from the spring production to annual pelagic carbon flow. Spring (February and March) Chl comprised 16-30% of the total annual Chl produced, whereas spring C was much lower (8-23%) compared to the annual C. Spring PP accounted for 10-18% of the total annual PP, while the July-August production contributed 26-33%, i.e. within the time frame when zooplankton biomass and grazing pressure are highest. That is, Chl failed in this study to reflect the importance of the high summer PP. A better proxy for biomass may be C, which correlated well with the seasonal pattern of PP (Pearson correlation, p < 0.05). Thus, this study suggests to account for the strong seasonal pattern in C/Chl ratios when considering carbon flow in coastal systems. Seasonal data for PP were fitted to a simple sinusoidal wave model describing the seasonal distribution of PP in the BSTZ and were proposed to present a better parameterizaton of PP in shallow stratified temperate regions than more commonly applied proxies.

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Section: Impact Of Zooplankton Grazing On Phytoplankton Standing Stocksupporting

confidence: 75%

How Well Does Chlorophyll Explain the Seasonal Variation in Phytoplankton Activity?

Lyngsgaard

Markager

Richardson

et al. 2017

Estuaries and Coasts

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“…The direct effects of hypoxic-anoxic events on benthic macrofauna are well-document (Kristensen 2000;Nordberg et al 2001;Hansen et al 2002) whereas little is known for meiofauna (Josefson and Widbom 1988;Murell and Fleeger 1989;Hendelberg and Jensen 1993;Steyaert et al 2007). Meiofauna due to their relatively short life cycles, high turnover rates and lack of larval dispersion, are expected to respond rapidly to environmental changes and food availability (Modig and Olafsson 1998;Danovaro and Fabiano 1997;Danovaro et al 1995aDanovaro et al , 2000aDanovaro et al , b, 2004La Rosa et al 2001;Danovaro and Gambi 2002;Austen and Widdicombe 2006;De Troch et al 2006) whereas macrofauna respond more slowly (Somerfield et al 1995;Albertelli et al 1999;Widdicombe and Austen 2001;Austen and Widdicombe 2006).…”

Section: Introductionmentioning

confidence: 97%

Biodiversity response to experimental induced hypoxic-anoxic conditions in seagrass sediments

et al. 2008

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The effects of induced hypoxic-anoxic conditions on the metazoan meiofaunal assemblages and nematode diversity were investigated with an in situ experiment in a Posidonia oceanica meadow. The experiment, of the duration of five months, was performed in three experimental sets of plots. Two of them were enriched with organic matter to induce anoxic conditions (1 set with sucrose and 1 set with sugar plus nutrients, i.e. nitrogen and phosphorus) whereas the last set of plots was kept undisturbed and used as Control. Metazoan meiofauna displayed a fast response to the induced anoxic conditions with an immediate reduction of the richness of taxa (only nematodes and copepods tolerated the hypoxic-anoxic conditions). Nematodes were the most tolerant organisms as their species richness did not change in hypoxic-anoxic conditions, but their species composition and trophic structure displayed significant changes. Some genera (Desmoscolex and Bolbolaimus) were replaced by other (Chromadorella, Sabatiera and Polysigma) more tolerant to the extreme conditions. No significant differences were observed in the Control plots, whereas in treated plots, selective deposit feeders and predators decreased significantly, being replaced by non-selective deposit feeders and epistrate feeders. These results indicate that, events causing a reduction in oxygen availability, can have an impact on the nematode beta-diversity and functional diversity with potential important implications on the benthic food web and functioning of the seagrass systems.

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“…Eutrophication is a variable of particular importance in Danish estuaries and a variable causing a wide spectrum of local effects in estuaries, including modification of nutrient availability or light penetration, and occasionally severe hypoxia. Effects range from changes in species composition and diversity of macroalgae (Middelboe et al ., 1998), increased biomass of benthic macrofauna, which reflects secondary production (Josefson & Rasmussen, 2000), and, in some estuaries, complete defaunation due to anoxia (Fallesen et al ., 2000; Hansen et al ., 2002a; Petersen et al ., 2002). It is not known, however, whether there are general long‐term effects of eutrophication on macrofauna species richness in the area.…”

Section: Introductionmentioning

confidence: 99%

Species richness of benthic macrofauna in Danish estuaries and coastal areas

Josefson¹,

Hansen²

2004

Global Ecology and Biogeography

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Aim Cross-system comparisons of species richness of benthic macrofauna and environmental factors were made of estuaries and adjacent sea areas in order to reveal possible regulating factors of estuarine biodiversity.Location Denmark.Methods Annual species abundance and biomass data from four years, from unvegetated soft sea/estuary floors were used from 26 grids, of which 15 were situated in estuaries. Bottom water data for oxygen concentration, salinity, and temperature were obtained from stations in or close to, the grids. Data on nutrient loading, water residence time and morphology were obtained for whole estuaries. Species richness from the grids, standardized to the same sample size, were related to environmental variables using linear regression.Results Species richness was unrelated to oxygen deficiency and productivity, but positively related to salinity. However, an equally high degree of explanation ( R 2 ∼ 0.70) was obtained using a model where richness was positively related to saltwater flux, which was computed from estuary volume and residence time and corrected for freshwater flux. The relationship was present for the dominating groups with pelagic dispersal, Annelida and Mollusca, but not for Crustacea, where recruitment is mainly by benthic pathways. Saltwater flux was strongly positively correlated with salinity, illustrating the high importance of flux from adjacent sea areas for water renewal in Danish estuaries. Similarity of species composition was greater for sites within than between saltwater current pathways, and the increases of richness with saltwater flux and salinity in the estuaries was largely due to marine species occurring in the open sea areas.Conclusion Danish estuaries are largely open systems where a part of estuarine species richness is sustained by dispersal from a species pool in adjacent seas. Results are consistent with the barrier prediction of island biogeography theory, but not the island size prediction.

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Invertebrate re-colonisation in Mariager Fjord (Denmark) after severe hypoxia. I. Zooplankton and settlement

Cited by 23 publications

References 46 publications

How Well Does Chlorophyll Explain the Seasonal Variation in Phytoplankton Activity?

How Well Does Chlorophyll Explain the Seasonal Variation in Phytoplankton Activity?

Biodiversity response to experimental induced hypoxic-anoxic conditions in seagrass sediments

Species richness of benthic macrofauna in Danish estuaries and coastal areas

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