Energy Flow in a Tidal Flat Ecosystem

Abstract

This review considers the energy flow through a tidal flat ecosystem in the western Wadden Sea. Based on available estimates of primary production, input of allochthonous organic matter, a s well as on consumption and production a t different trophic levels, a modified concept of energy flow is advanced. In the traditional concept the secondary level has mainly been quantified in terms of herbivorous macrobenthos with a n apparently excessive primary food supply, and with the higher trophic levels being food-limited. In our opinion, the importance of small a n d very small zoobenthos with a negligible biomass, but with a relatively high production, has hitherto been underestimated. This complex -in this review referred to a s 'small food web' -consists, in addition to bacteria, of microfauna, meiofauna, temporary meiofauna and small macrofauna. In our opinion these groups contr~bute far more to the consumption of primary food and to the production of food for small carnivores than is generally assumed i n food-chain studies conducted in the western Wadden Sea.

The importance of grazing food chain for energy flow and production in three intertidal sand bottom communities of the northern Wadden Sea

“…Based upon these findings, it was postulated that autochthonous primary production is relatively low and that it only insufficiently explains the richness and high production of the fauna (Van den Hoek et al, 1979;Kuipers et al, 1981). These authors suppose that the input of phytoplankton and detritus from the North Sea builds the main source of food in the Wadden Sea ecosystem.…”

“…During this period, the mean value of respiration is 109 ml 02 m -2 h -1 and corresponds to values from other phytal regions (Jansson & Wulff, 1977;Asmus et al, 1980). In the Dutch Wadden Sea, first measurements of community metabolism suggest that oxygen is mainly taken up by the small food web (bacteria, microfauna, small macrofauna), while maximum macrofauna respiration should only be 20-30 % (Kuipers et al, 1981). Van Es (1982) points out the important role of bacteria in community metabolism.…”

“…Kuipers et al (1981) have shown that food supply consisting of 100 g C m -2 a -1 primary production and 250 g C m -2 a -1 detritus input (de Jonge & Postma, 1974) is used up by secondary production (18 g C m -2 a -1) to only a low degree. The small food web which includes microfauna and small macrofauna like H. ulvae fills this gap representing a link between primary and secondary producers.…”

“…One of the first measurements of community metabolism was conducted at the American Pacific coast (Pamatmat, 1968). Energy flow, carbon and nutrient cycles have been studied in various marine ecosystems (Odum, 1961;Odum & Smalley, 1959;Odum & Heald, 1972Nixon et al, 1976Nixon et al, , 1980Pilson et al, 1979;Pomeroy et al, 1983}. Questions about energy flow and community metabolism in the Wadden Sea have been raised by de Wilde (1980) and Kuipers et al (1981}. These authors focussed their attention on comparing the significance of macrofauna with that of microbenthos (bacteria, microfauna, meiofauna}. They postulated the dominance of microbenthos in processes of metabolic turnover.…”

Predictive ecosystem research in the Wadden Sea

“…Primary production is accomplished primarily by benthic and pelagic microalgae in about equal proportions (Cadee & Hegemann, 1977). In addition to imported seston, this primary production is consumed by microorganisms and the macrobentic fauna, roughly in a 4 to 1 ratio (Kuipers et al, 1981;Wilde & Beukema, 1984;Witte & Zijlstra, 1984). About 10% of the carbon consumed by the macrobenthic fauna is eventually passed on to shrimp, fish and birds in approximately equal proportions.…”