Material exchange and food web of seagrass beds in the Sylt-Rømø Bight: how significant are community changes at the ecosystem level?

Asmus, Harald; Asmus, Ragnhild

doi:10.1007/s101520050012

Cited by 53 publications

(33 citation statements)

References 112 publications

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“…For example, Gätje & Reise (1998) provided detailed information and summaries of ecological data on virtually the entire ecological spectrum from nutrient fluxes to the abundance of fish and bird communities. The flow of energy in a seagrass community in the Bight has been described by Asmus & Asmus (2000), as well as for the food web of the tidal flats (Asmus & Asmus 1985, Asmus 1994. Sprung et al (2001) reported on energy flow in the benthic assemblages of the intertidal area of the basin.…”

Section: Introductionmentioning

confidence: 99%

Energy flow of a boreal intertidal ecosystem, the Sylt-Rømø Bight

Baird¹,

Asmus

Asmus³

2004

Mar. Ecol. Prog. Ser.

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A detailed energy flow model consisting of 56 living and 3 non-living compartments was assembled for the intertidal area of the Sylt-Rømø Bight. The model depicts the biomass of each compartment, carbon flow between the components, imports and exports, as well as an energy budget for each. The food web was analysed by means of network analysis which showed that about 17% of the total daily flow through the system is recycled through a complex cycling structure consisting of 1197 cycles. The cycling network indicated that about 99% of the recycling involves 2 to 3 compartments, with sediment bacteria and particulate organic carbon (POC) participating in most instances. Input/output analyses indicated that phytoplankton production in the Bight does not satisfy the demands of filter-feeders on an annual average basis so that about 160 mg C m -2 d -1 of phytoplankton have to be imported. We compared several dimensionless system level indices, such as internalised and normalised A/DC (ascendancy/development capacity) ratios, calculated for the Bight with those of other marine and estuarine ecosystems on a global basis. These comparisons showed that energy is rather inefficiently transferred within the Bight at a mean trophic efficiency index of 2.61%, and that most of the system level indices are lower than those of other coastal ecosystems. However, higher values were obtained for flow diversity and food web connectance compared to other systems. This study has revealed the Bight to be a highly complex system whose energy pathways appear to be sensitive to external perturbations.

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Section: Introductionmentioning

confidence: 99%

Energy flow of a boreal intertidal ecosystem, the Sylt-Rømø Bight

Baird¹,

Asmus

Asmus³

2004

Mar. Ecol. Prog. Ser.

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“…nutrient cycling, productivity, can be closely related to species abundance. To give an example, the particle and nutrient sink in two Zostera meadows in Sylt, North Sea, was positively correlated with their density (ASMUS & ASMUS, 2000). A positive relation between shoot density of seagrasses and fish and shrimp density was also documented (FONSECA et al, 1996a, b).…”

Section: Discussionmentioning

confidence: 96%

“…These communities not only form the basis of natural, pristine marine environments (PANAYOTIDIS et al, 2001) but also support many ecosystem services, e.g. sustain biodiversity (DEN HARTOG, 1970;PHILLIPS & MEŇEZ, 1988;NIENHUIS, 1992), maintain fish habitat (HARMELIN-VIVIEN et al, 1995;POLLARD, 1984;BELL et al, 1992;FRANCOUR, 1997;EDGAR, 1999b;BLADER et al, 2000), offer detritus to the trophic chain (EDGAR, 1999a), maintain water quality (BULTHUIS et al, 1984;DAUBY et al, 1995;GACIA et al, 1999;ASMUS & ASMUS, 2000), stabilize sediment and control erosion (FONSECA, 1996;ASMUS & ASMUS, 2000).…”

Section: Discussionmentioning

confidence: 99%

Ecological evaluation of transitional and coastal waters: A marine benthic macrophytes-based model

2001

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A model to estimate the ecological status and identify restoration targets of transitional and coastal waters was developed. Marine benthic macrophytic species (seaweeds, seagrasses) were used to indicate shifts in the aquatic ecosystem from the pristine state with late-successional species (Ecological State Group I) to the degraded state with opportunistic (ESG II) species. The first group comprises species with a thick or calcareous thallus, low growth rates and long life cycles (perennials), whereas the second group includes sheet-like and filamentous species with high growth rates and short life cycles (annuals). Seagrasses were included in the first group, whereas Cyanophyceae and species with a coarsely branched thallus were included in the second group.The evaluation of ecological status into five categories from high to bad includes a cross comparison in a matrix of the ESGs and a numerical scoring system (Ecological Evaluation Index). The model could allow comparisons, ranking and setting of priorities at regional and national levels fulfilling the requirements of the EU Water Frame Directive. A successful application of the model was realized in selected lagoons of the Macedonian and Thrace region (North Greece) and in the Saronic Gulf coastal ecosystems (Central Greece).

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“…Whether this bioturbation is a cause of the Zostera decline remains to be seen. High numbers of invertebrates are typically associated with Zostera beds (Heck et al 1995;Asmus and Asmus 2000). Thus the integrity of wildfowl populations that feed on these invertebrates is indirectly associated with the health of the Zostera meadows.…”

Section: Discussionmentioning

confidence: 99%

Decline of Canada geese ( Branta canadensis ) and common goldeneye ( Bucephala clangula ) associated with a collapse of eelgrass ( Zostera marina ) in a Nova Scotia estuary

Seymour

Miller

Garbary

2002

Helgoland Marine Research

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Mean numbers of migrant Canada geese (Branta canadensis) in Antigonish Harbour in the southern Gulf of St. Lawrence (Canada) during October to December were similar (approx. 450-500 birds) for the period 1998-2000. Similarly, during this period, geese used two foraging sites. However, in 2001, the average number of birds decreased by half and the primary foraging sites were used only rarely. This coincided with a decline of about 95% in the biomass of roots and rhizomes of eelgrass (Zostera marina) that occurred between October 2000 and 2001. Eelgrass is the principal food of geese in this estuary. In addition, there was a reduction of around 50% in the numbers of common goldeneye (Bucephala clangula), which feed on invertebrates associated with eelgrass. Lower than usual weekly abundances of geese and goldeneye are probably the result of an unusually short residence time in the estuary, rather than a decline in the total number of visiting migrants. We attribute these changes in the distribution and abundance of geese and goldeneyes to the dramatic decline in eelgrass.

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Material exchange and food web of seagrass beds in the Sylt-Rømø Bight: how significant are community changes at the ecosystem level?

Cited by 53 publications

References 112 publications

Energy flow of a boreal intertidal ecosystem, the Sylt-Rømø Bight

Energy flow of a boreal intertidal ecosystem, the Sylt-Rømø Bight

Ecological evaluation of transitional and coastal waters: A marine benthic macrophytes-based model

Decline of Canada geese ( Branta canadensis ) and common goldeneye ( Bucephala clangula ) associated with a collapse of eelgrass ( Zostera marina ) in a Nova Scotia estuary

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