Long-term changes in nutrients, weed mats and shorebirds in an estuarine system
Raffaelli, D.; Hull, S.; Milne, H. (1989). Long-term changes in nutrients, weed mats and shorebirds in an estuarine system. Cah. Biol. Mar. 30(2): 259-270
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, more
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| Authors | | Top |
- Raffaelli, D.
- Hull, S.
- Milne, H.
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| Abstract |
Long-term data sets on agricultural practice, river nutrients, biomass of macro-algal mats and numbers of shorebirds are analysed for the Ythan Estuary, Aberdeenshire, Scotland. The results suggest a 2-3 fold increase of nitrogen in river water over a 25-year period, associated with an increase in the proportion of land under cereal crop production. Biomass of the green seaweed Enteromorpha has also increased over this period which now forms dense mats in much of the estuary. The abundance of the amphipod Corophium volutator is reduced under weed mats but there are at present sufficient unweeded refuge areas between the mats to maintain an overall highly productive invertebrate community. A general increase in mudflat invertebrate productivity may account for increases in the numbers of several species of shorebirds on the Ythan over the study period. However, if weed mats become too extensive, these highly productive refuges may disappear altogether with dramatic consequent effects on the general ecology of the estuary. |
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