Secondary production by tail regeneration in a tidal flat population of lugworms (Arenicola marina), cropped by flatfish

Sediment cores were collected inside and outside of a bed of a bromophenol-producing marine polychaete, Notomastus lobatus, and examined for impact of the bromophenols on sediment microflora and meiofauna around N. lobatus burrows. No significant differences were found between microbial parameters measured inside and outside of the N. lobatus bed. Integrated 6 cm cores taken adjacent to N. lobatus burrows contained 1.2 x 10' bacteria ml-l. Cell numbers were similar at control sites within the bed, but away from burrows, and not significantly different from cell numbers (1.0 X log cells ml-l) at a nearby site. 13H]-acetate net assimilation rates were 12.7 + 5.0 pm01 ml-l h-' adjacent to burrows and 11.9 * 1.4 pm01 ml-' h-' in non-burrow control cores. Microalgal biomass was 20.1 2 1.2 mg chl a m-2 adjacent to burrows and 24.3 + 1.0 mg chl a m-2 in non-burrow control cores. Microalgal production was 4.17 L 0.31 mm01 O2 m-2 h-' near burrows and 5.84 + 0.97 mm01 O 2 m-' h-' in nonburrow controls. Distribution of bacteria, microalgae, and meiofauna showed no consistent effects of proximity to the worm burrows. These data indicate that the concentrations of bromophenols found inside of the N. lobatus worm bed are not inhibitory to sediment microflora and that the microbial populations found there are adapted to exposure to these toxic compounds.

Section: Discussionmentioning

confidence: 99%

Bacterial numbers and activity, microalgal biomass and productivity, and meiofaunal distribution in sediments naturally contaminated with biogenic bromophenols

Steward¹,

Pinckney²,

Piceno³

et al. 1992

“…Diet composition for each component was derived from synthesis of published literature and local expert knowledge (Plagmann 1939, Ehlert 1964, Jacobsen 1967, Höfmann & Hörschelmann 1969, Fenchel & Koefoed 1976, de Vlas 1979, Fauchald & Jumars 1979, Jensen & Siegismund 1980, Heip et al 1984, Pihl & Rosenberg 1984, Pihl 1985, Zwarts & Blomert 1992 and sources in Gätje & Reise (1998). Excess production and egestion by water column organisms (bacteria, zooplankton) were assumed to remain in suspension as particulate POC.…”

Section: Methodsmentioning

confidence: 99%

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

Baird¹,

Asmus

Asmus³

2004

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.

“…The cropping of tail tips of the lugworm Arenicola marina results in a loss of posterior segments and hence a reduction of the overall life span (De Vlas 1979b). At a frequency of amputation of once a week, growth and reproductive output also decreased (Bergman et al 1988).…”

Section: Top-down Effects Of Flatfish Predationmentioning

confidence: 99%

Long-term trends in juvenile flatfish indicate a dramatic reduction in nursery function of the Balgzand intertidal, Dutch Wadden Sea

Veer¹,

Koot²,

Aarts³

et al. 2011

Since 1975, juvenile flatfish (plaice and flounder) populations have been monitored at the Balgzand intertidal and, based on this data series , the interannual patterns in predation pressure were quantified. Temporal patterns in abundance have changed greatly, especially for plaice. Up to the early 1980s, 3 year classes (0-, I-and II-group) were present and growing up in the area, but from the late 1980s onwards, densities of the I-and II-group plaice dropped from a few hundred individuals per 1000 m 2 to levels close to zero. It appears that the Balgzand intertidal has lost its nursery function for I-and II-group plaice, although feeding conditions have remained the same or even slightly increased since the late 1970s. The absence of I-and II-group flatfish in the intertidal cannot be explained at present; however, processes operating offshore are most likely involved. As a consequence, the annual predation pressure by juvenile flatfish upon the intertidal macrozoobenthos dropped by 94%, declining from an average of approximately 5 to 0.25 g ash free dry mass m -2. Such a decline in top-down predation may not only have directly influenced the macrozoobenthic community, but may also have indirectly affected food availability and accessibility for other top predators (e.g. shorebirds).