Trophic ecology in the Sea Scheldt: unravelling food web cascades after hyper-eutrophication
The Sea Scheldt shifted from a heterotrophic to an autotrophic state in 2007, triggering pronounced faunal responses. To understand these changes, we integrated insights from spatio temporal monitoring data, trophic biomarker studies, and a field experiment in the oligohaline reach near the Rupel tributary, where state changes in oligochaetes, aquatic predators, and waterbirds were most profound.
Statistical modelling of historical monitoring data show that the recovery of shrimps and fish tracked the rise in oxygen concentrations, while European teal (Anas crecca) numbers were positively associated with oligochaete biomass, independent of spatial and temporal covariates. Wastewater loading was identified as the primary driver of long term oligochaete biomass declines, with fish biomass exerting an additional top down effect. In contrast to the modelling results, stable isotope analyses and a large exclosure experiment demonstrated that shrimps (Crangon crangon, Palaemon longirostris) and small gobies (Pomatoschistus microps) can impose strong top down control on oligochaetes, reducing biomass by ~30% over 15 weeks in summer. The exclosure experiment also revealed pronounced bottom-up effects: enhanced deposition of fine, organically enriched sediment increased oligochaete biomass by up to 75%.
Comparisons of intertidal oligochaete distribution between heterotrophic and autotrophic periods show that biomasses above the critical threshold at which European teal commence foraging, now occur only in high intertidal zones. This shift is likely explained by intensified aquatic predation suppressing oligochaete populations in lower intertidal habitats.
Together, these findings indicate that both bottom up and top down processes currently structure the trophic ecology of the oligohaline part of the Sea Scheldt. During the former heterotrophic state, high organic loading and the absence of aquatic predators allowed oligochaetes to flourish, providing an abundant foraging resource for European teal.
Statistical modelling of historical monitoring data show that the recovery of shrimps and fish tracked the rise in oxygen concentrations, while European teal (Anas crecca) numbers were positively associated with oligochaete biomass, independent of spatial and temporal covariates. Wastewater loading was identified as the primary driver of long term oligochaete biomass declines, with fish biomass exerting an additional top down effect. In contrast to the modelling results, stable isotope analyses and a large exclosure experiment demonstrated that shrimps (Crangon crangon, Palaemon longirostris) and small gobies (Pomatoschistus microps) can impose strong top down control on oligochaetes, reducing biomass by ~30% over 15 weeks in summer. The exclosure experiment also revealed pronounced bottom-up effects: enhanced deposition of fine, organically enriched sediment increased oligochaete biomass by up to 75%.
Comparisons of intertidal oligochaete distribution between heterotrophic and autotrophic periods show that biomasses above the critical threshold at which European teal commence foraging, now occur only in high intertidal zones. This shift is likely explained by intensified aquatic predation suppressing oligochaete populations in lower intertidal habitats.
Together, these findings indicate that both bottom up and top down processes currently structure the trophic ecology of the oligohaline part of the Sea Scheldt. During the former heterotrophic state, high organic loading and the absence of aquatic predators allowed oligochaetes to flourish, providing an abundant foraging resource for European teal.
Details
| Aantal pagina's | 20 |
|---|---|
| Type | Paper/Powerpoint/Abstract |
| Categorie | Onderzoek |
| Taal | Engels |
Bibtex
@inproceedings{70bd72b6-8b6f-4001-9b73-e4636c7731b7,
title = "Trophic ecology in the Sea Scheldt: unravelling food web cascades after hyper-eutrophication",
abstract = "The Sea Scheldt shifted from a heterotrophic to an autotrophic state in 2007, triggering pronounced faunal responses. To understand these changes, we integrated insights from spatio temporal monitoring data, trophic biomarker studies, and a field experiment in the oligohaline reach near the Rupel tributary, where state changes in oligochaetes, aquatic predators, and waterbirds were most profound.
Statistical modelling of historical monitoring data show that the recovery of shrimps and fish tracked the rise in oxygen concentrations, while European teal (Anas crecca) numbers were positively associated with oligochaete biomass, independent of spatial and temporal covariates. Wastewater loading was identified as the primary driver of long term oligochaete biomass declines, with fish biomass exerting an additional top down effect. In contrast to the modelling results, stable isotope analyses and a large exclosure experiment demonstrated that shrimps (Crangon crangon, Palaemon longirostris) and small gobies (Pomatoschistus microps) can impose strong top down control on oligochaetes, reducing biomass by ~30% over 15 weeks in summer. The exclosure experiment also revealed pronounced bottom-up effects: enhanced deposition of fine, organically enriched sediment increased oligochaete biomass by up to 75%.
Comparisons of intertidal oligochaete distribution between heterotrophic and autotrophic periods show that biomasses above the critical threshold at which European teal commence foraging, now occur only in high intertidal zones. This shift is likely explained by intensified aquatic predation suppressing oligochaete populations in lower intertidal habitats.
Together, these findings indicate that both bottom up and top down processes currently structure the trophic ecology of the oligohaline part of the Sea Scheldt. During the former heterotrophic state, high organic loading and the absence of aquatic predators allowed oligochaetes to flourish, providing an abundant foraging resource for European teal.
",
author = "Carl Van Colen and Frank Van de Meutter and Jeroen Speybroeck and Bart Vandevoorde and Alexander Van Braeckel and Joost Vanoverbeke and Gunther Van Ryckegem",
year = "2026",
month = sep,
day = "24",
doi = "",
language = "Nederlands",
publisher = "Instituut voor Natuur- en Bosonderzoek",
address = "België",
}