Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
It is well established that benthivorous fish in shallow lakes can create turbid conditions that influence phytoplankton growth both positively, as a result of elevated nutrient concentration in the water column, and negatively, due to increased attenuation of light. The net effect depends upon the degree of turbidity induced by the benthivores. Stocked Carassius carassius dominate the benthivorous fish fauna in many nutrient-rich Chinese subtropical and tropical shallow lakes, but the role of the species as a potential limiting factor in phytoplankton growth is ambiguous. Clarification of this relationship will help determine the management strategy and cost of restoring eutrophic lakes in China and elsewhere. Our outdoor mesocosm experiment simulating the effect of high density of crucian carp on phytoplankton growth and community structure in eutrophic shallow lakes suggests that stocking with this species causes resuspension of sediment, thereby increasing light attenuation and elevating nutrient concentrations. However, the effect of light attenuation was insufficient to offset the impact of nutrient enhancement on phytoplankton growth, and significant increases in both phytoplankton biomass and chlorophyll a concentrations were recorded. Crucian carp stocking favored the dominance of diatoms and led to lower percentages (but not biomass) of buoyant cyanobacteria. The dominance of diatoms may be attributed to a competitive advantage of algal cells with high sedimentation velocity in an environment subjected to frequent crucian carp-induced resuspension and entrainment of benthic algae caused by the fish foraging activities. Our study demonstrates that turbidity induced by stocked crucian carp does not limit phytoplankton growth in eutrophic waters. Thus, removal of this species (and presumably other similar taxa) from subtropical or tropical shallow lakes, or suspension of aquaculture, is unlikely to boost phytoplankton growth, despite the resulting improvements in light availability.
It is well established that benthivorous fish in shallow lakes can create turbid conditions that influence phytoplankton growth both positively, as a result of elevated nutrient concentration in the water column, and negatively, due to increased attenuation of light. The net effect depends upon the degree of turbidity induced by the benthivores. Stocked Carassius carassius dominate the benthivorous fish fauna in many nutrient-rich Chinese subtropical and tropical shallow lakes, but the role of the species as a potential limiting factor in phytoplankton growth is ambiguous. Clarification of this relationship will help determine the management strategy and cost of restoring eutrophic lakes in China and elsewhere. Our outdoor mesocosm experiment simulating the effect of high density of crucian carp on phytoplankton growth and community structure in eutrophic shallow lakes suggests that stocking with this species causes resuspension of sediment, thereby increasing light attenuation and elevating nutrient concentrations. However, the effect of light attenuation was insufficient to offset the impact of nutrient enhancement on phytoplankton growth, and significant increases in both phytoplankton biomass and chlorophyll a concentrations were recorded. Crucian carp stocking favored the dominance of diatoms and led to lower percentages (but not biomass) of buoyant cyanobacteria. The dominance of diatoms may be attributed to a competitive advantage of algal cells with high sedimentation velocity in an environment subjected to frequent crucian carp-induced resuspension and entrainment of benthic algae caused by the fish foraging activities. Our study demonstrates that turbidity induced by stocked crucian carp does not limit phytoplankton growth in eutrophic waters. Thus, removal of this species (and presumably other similar taxa) from subtropical or tropical shallow lakes, or suspension of aquaculture, is unlikely to boost phytoplankton growth, despite the resulting improvements in light availability.
Benthivorous fish disturbance and nitrogen loading are two important factors that influence the community structure of submersed macrophytes, but their interactive effect is not well elucidated. We conducted an outdoor mesocosm experiment to examine the individual and combined effects of these two factors on the growth of two submersed macrophytes of different growth forms, i.e., the rosette-forming Vallisneria natans and the canopy-forming Myriophyllum spicatum. The treatments involved two levels of fish (Carassius auratus) disturbance crossed with two levels (0 and 12 g NH4Cl per month) of ammonium (NH4+-N) loading. For M. spicatum, we found that maximum height (MH) was reduced by 30.7%, 26.4%, and 51.0% in fish addition alone (F) and nitrogen addition treatments (N, F + N), respectively, compared with the control (C) treatment. The density of M. spicatum declined by 20%, 62% and 68.8% in the F, N and F + N treatment. The above-ground biomass (AGB) of M. spicatum respectively reduced by 56.7%, 94%, and 96.5% in the F, N and F + N treatments, and the roots/shoots ratio (R/S) increased by 114%, and 176% in N and N + F treatments, respectively. Regarding V. natans, only the MH in the N treatment was reduced (71.9%), and the density exhibited a reduction of 59.1% and 64.5% in the N and F + N treatments, respectively. The AGB of V. natans was significantly lower in the N (90.3%) and N + F (78.4%) treatments compared with the C treatment, while increased by 60.3% in F treatment. The R/S of V. natans increased by 227%, and 74.4% in the N and F + N treatments compared with the C treatment. The interactive effect of fish disturbance and high N on MH and AGB of V. natans and density of M. spicatum were antagonistic. However, the interactive effect on density and BGB of V. natans and AGB of M. spicatum were negatively synergistic. Moreover, fish activity significantly increased the concentration of total suspended solids (TSS) in the water, while total nitrogen (TN), ammonium, total phosphorus (TP), light, pH and salinity were unaffected. When fish and nitrogen were combined, TN, TP, TSS and salinity increased significantly, while pH decreased. Our study reveals that the interactive effects of fish disturbance and high N are synergistic and/or antagonistic, suggesting that the same stressor interaction may vary from synergistic to antagonistic depending on the response variables and growth forms of the macrophytes examined. Our study contributes to the understanding of how different factors can interact with each other and affect submersed macrophytes in aquatic ecosystems. This is timely and relevant knowledge, considering the range of multiple stressors involved in the decline of aquatic ecosystems worldwide at present.
Crucian carp (Carassius carassius) is a key fish species in most Chinese subtropical and tropical shallow lakes. Through sediment feeding, crucian carp could greatly change water turbidity and nutrient levels, as well as the abundance of herbivorous consumers, which may have important influences on seston element stoichiometry. However, so far, experimental studies on this topic are lacking. We conducted a 36-day mesocosm experiment to explore the effects of crucian carp on water physicochemical and biological properties, and C/N/P ratios in suspended particulate matter (SPM) under eutrophic conditions. Our results provided three major findings: (1) Crucian carp resuspended sediments and along with them, reduced light penetration and lower light/total phosphorus (TP) ratios. (2) Crucian carp reduced biomasses of both zooplankton and macrozoobenthos, whereas their effect on phytoplankton was weak, potentially because of resuspension-induced light limitation. (3) Both C/P and N/P ratios in SPM were significant lower in mesocosms with crucian carp than in fish-free controls, which may be attributed to the high contribution of P-rich sediments and low light to nutrient supply caused by fish-induced resuspension. Our results suggest that besides planktivorous fish, benthivore (e.g., crucian carp) in warm shallow waters could also affect pelagic C/N/P stoichiometry via sediment feeding, which may further influence energy transfer efficiency in lake food chain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.