TY - JOUR

T1 - Stable isotope analysis of archived roach (Rutilus rutilus) scales for retrospective study of shallow lake responses to nutrient reduction

AU - Grey, Jonathan

AU - Graham, Conor T.

AU - Britton, J. Robert

AU - Harrod, Christopher

PY - 2009/8

Y1 - 2009/8

N2 - 1. There is increasing interest in the use of stable isotope analysis of archived materials to study the long-term impacts of lake perturbations, including nutrient manipulation or species invasion. We tested the utility of this approach in a shallow productive lake using the zooplanktivorous early life stages of roach (Rutilus rutilus), a fish species that is widespread throughout Eurasian lakes.2. Barton Broad is a shallow lake with a well-documented history of earlier eutrophication followed by nutrient reduction, including sediment removal from 1997 to 2000. Using scale samples collected pre- and post-sediment removal, we demonstrated a strong, positive relationship between roach scale δ13C and total phosphorus. We argue that this reflects a decrease in the phytoplankton production which had dominated dissolved inorganic carbon dynamics, and a relative increase in the contribution of respired carbon in the food web.3. We also derived a scale : muscle isotope relationship for roach which allowed us to model changes in fish muscle against putative prey. Concomitant isotopic shifts in preserved zooplankton samples indicated that the phosphorus reduction measures had an ecosystem-wide impact and that changes in roach scale isotope values were not a result of fish switching diet.4. Roach scale δ15N increased after sediment removal. Since this was not due to a switch in fish diet, we suggest that it probably reflects the loss of nitrogen-fixing, heterocystous cyanobacteria from the plankton.

AB - 1. There is increasing interest in the use of stable isotope analysis of archived materials to study the long-term impacts of lake perturbations, including nutrient manipulation or species invasion. We tested the utility of this approach in a shallow productive lake using the zooplanktivorous early life stages of roach (Rutilus rutilus), a fish species that is widespread throughout Eurasian lakes.2. Barton Broad is a shallow lake with a well-documented history of earlier eutrophication followed by nutrient reduction, including sediment removal from 1997 to 2000. Using scale samples collected pre- and post-sediment removal, we demonstrated a strong, positive relationship between roach scale δ13C and total phosphorus. We argue that this reflects a decrease in the phytoplankton production which had dominated dissolved inorganic carbon dynamics, and a relative increase in the contribution of respired carbon in the food web.3. We also derived a scale : muscle isotope relationship for roach which allowed us to model changes in fish muscle against putative prey. Concomitant isotopic shifts in preserved zooplankton samples indicated that the phosphorus reduction measures had an ecosystem-wide impact and that changes in roach scale isotope values were not a result of fish switching diet.4. Roach scale δ15N increased after sediment removal. Since this was not due to a switch in fish diet, we suggest that it probably reflects the loss of nitrogen-fixing, heterocystous cyanobacteria from the plankton.

KW - carbon

KW - ecosystem perturbation

KW - fish

KW - nitrogen

KW - zooplankton

U2 - 10.1111/j.1365-2427.2009.02215.x

DO - 10.1111/j.1365-2427.2009.02215.x

M3 - Journal article

VL - 54

SP - 1663

EP - 1670

JO - Freshwater Biology

JF - Freshwater Biology

SN - 0046-5070

IS - 8

ER -