TY - JOUR
T1 - Predicting the effects of freshwater diversions on juvenile brown shrimp growth and production
T2 - a Bayesian-based approach
AU - Adamack, Aaron
AU - Stow, Craig
AU - Mason, Doran
AU - Rozas, Lawrence
AU - Minello, Thomas
PY - 2012
Y1 - 2012
N2 - Freshwater diversions from the Mississippi River may help restore coastal wetlands in Louisiana, but their implementation will alter temperature and salinity regimes, potentially affecting juvenile shrimp growth and production. We developed a bioenergetics model for brown
shrimp Farfantepenaeus aztecus to investigate water temperature and salinity effects on brown shrimp growth. The model used a Bayesian framework that provided estimates of parameter and model uncertainty. Temperature affected shrimp metabolism, whereas salinity modified food
availability. Mortality was modeled using a size-dependent function. We examined the effects of diversion timing (February, March, April and May), length (2ÿ 14, as well as 30 and 60 d), temperature change (+1, 0, ⿿1, ⿿5 and ⿿10°C), initial salinity (5, 15, 25), salinity during the diversion (2, 5, 10, 15, 20 and 25) and prey biomass response time (7, 14 and 28 d) on juvenile brown shrimp production. Diversions during February and March had little effect on shrimp, but 30 and 60 d diversions starting in April and May often had large, negative effects on production. April and May diversions that dropped water temperature by 5°C or more could decrease juvenile brown shrimp production by 40 to 60% compared with the baseline, no diversion scenarios. Whether
changes in salinity had a positive or negative effect on brown shrimp production depended on the initial salinity of the scenario. Longer diversions and slower prey response times extended the duration brown shrimp were exposed to either the positive or negative effects of diversions, and this magnified the overall (positive or negative) effect on shrimp production. Limiting diversions to February and March when brown shrimp populations are not abundant would minimize negative
effects on shrimp production, though managers will be constrained by the needs of other species such as oysters, as well as ecosystem considerations.
AB - Freshwater diversions from the Mississippi River may help restore coastal wetlands in Louisiana, but their implementation will alter temperature and salinity regimes, potentially affecting juvenile shrimp growth and production. We developed a bioenergetics model for brown
shrimp Farfantepenaeus aztecus to investigate water temperature and salinity effects on brown shrimp growth. The model used a Bayesian framework that provided estimates of parameter and model uncertainty. Temperature affected shrimp metabolism, whereas salinity modified food
availability. Mortality was modeled using a size-dependent function. We examined the effects of diversion timing (February, March, April and May), length (2ÿ 14, as well as 30 and 60 d), temperature change (+1, 0, ⿿1, ⿿5 and ⿿10°C), initial salinity (5, 15, 25), salinity during the diversion (2, 5, 10, 15, 20 and 25) and prey biomass response time (7, 14 and 28 d) on juvenile brown shrimp production. Diversions during February and March had little effect on shrimp, but 30 and 60 d diversions starting in April and May often had large, negative effects on production. April and May diversions that dropped water temperature by 5°C or more could decrease juvenile brown shrimp production by 40 to 60% compared with the baseline, no diversion scenarios. Whether
changes in salinity had a positive or negative effect on brown shrimp production depended on the initial salinity of the scenario. Longer diversions and slower prey response times extended the duration brown shrimp were exposed to either the positive or negative effects of diversions, and this magnified the overall (positive or negative) effect on shrimp production. Limiting diversions to February and March when brown shrimp populations are not abundant would minimize negative
effects on shrimp production, though managers will be constrained by the needs of other species such as oysters, as well as ecosystem considerations.
KW - Farfantepenaeus aztecus
KW - Restoration
KW - Salt marsh
KW - Freshwater diversion
KW - Mississippi River
KW - Louisiana
U2 - 10.3354/meps09431
DO - 10.3354/meps09431
M3 - Article
SN - 0171-8630
VL - 444
SP - 155
EP - 173
JO - Marine Ecology Progress Series
JF - Marine Ecology Progress Series
ER -