Bay-scale spatial growth variation of mussels Mytilus edulis in suspended culture, Prince Edward Island, Canada

Abstract

Spatial growth variation of experimentally cultured blue mussels Mytilus edulis in Tracadie Bay, Prince Edward Island, Canada, was consistent in both years of a 2 yr study. The spatial pattern displayed reduced tissue growth along a gradient of decreasing tidal exchange from the inlet mouth to the inner estuary. There was no indication of persistent spatial differences in seston concentration among stations. The data imply that the flux of food (expressed as the product of concentration and current speed) controls the spatial variation in growth, with decreasing flux from the outer to inner bay. Growth trajectories analysed by polynomial regression differed between years despite spatial similarities within each year. Results of multiple regression analyses explaining mussel growth suggested that temporal variability in seston characteristics was more important in explaining growth than annual mean seston levels. Chlorophyll a and meat weight showed similar patterns of increase during 1998. In 1999, higher summer temperatures were more important in determining upper limits of growth, with later growth stimulation apparently in response to an autumn phytoplankton bloom. The pattern of spatial variability in mussel growth, representing decreased growth rates in the inner relative to the outer bay, provided evidence that the density of mussels in Tracadie Bay was exceeding the food supply.KEY WORDS: Mussels · Mussel growth · Food availability · Phytoplankton · Aquaculture · Carrying capacity Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 297: [157][158][159][160][161][162][163][164][165][166][167] 2005 There are many scales at which food limitation can affect the growth of cultured bivalves. High density at a local scale (e.g. within socking sleeves) may lead to reduced growth of interior bivalves (Parsons & Dadswell 1992, Côté et al. 1994. Seston depletion resulting from the distribution of bivalves on longlines may also affect their growth in the centre of a farm (Pilditch et al. 2001). A large-scale gradient in mussel growth can occur as a result of the interaction between the distribution of phytoplankton, the filtration capacity of local populations, and water circulation patterns in heavily cultured embayments (Dolmer 2000). Seston depletion might be expected to be most severe in the innermost part of a bay if the majority of the food supply is from incoming tides (Dowd 2000). There are surprisingly few studies of spatial variation in growth of cultured bivalves despite the potential importance of this factor to shellfish growth.This study investigated the relationship between blue mussel growth and food supply within an intensely cultured embayment in PEI. Mussel growth was measured coincident with monitoring seston concentrations and temperature at 5 geographically distinct locations within the embayment. Growth trajectories were described statistically and the interaction between mussel growth, environmental variables, and location examined. In a...

Physiological and biochemical indicators of mussel seed quality in relation to temperatures

“…• C during the summer (Waite et al 2005;Pernet et al 2006;Smith 2009). The productivity of the mussel industry may benefit from the use of stocks best able to support high temperatures, particularly in periods of increasing water temperatures.…”

Influence of mussel aquaculture on nitrogen dynamics in a nutrient enriched coastal embayment

“…We used a linear growth model to estimate the average monthly size of Tracadie Bay mussels over a 24 mo grow-out period to 0.7 g dry weight at harvest. Meat weight trajectories in Tracadie Bay vary each year (Waite et al 2005) and the linear function represents average conditions. The clearance rate (C) for each mussel was calculated for each month using the allometric equation of , which is based on similar natural dietary conditions as found in Tracadie Bay.…”

Influence of filtering and biodeposition by the cultured scallop Chlamys farreri on benthic-pelagic coupling in a eutrophic bay in China

“…Although a shift toward anaerobic metabolism at bivalve culture sites may exist, the impact of the build-up of discarded cultured organisms, and fouling algae or ascidians beneath longline culture sites, is more noticeable than any impacts from bivalve biodeposition (Grant et al 1995, Zhou 2000, Stenton-Dozey et al 2001. In some cases, however, the accumulation of biodeposits in suspended cultures may result in a locally anoxic environment and faunal impoverishment (Haven & MoralesAlamo 1966, Dahlbäck & Gunnarsson 1981, StentonDozey et al 2001, Waite et al 2005. In Sishili Bay, surface sediments at 2 scallop culture sites were also anoxic in August, with AVS-S as high as 590 µg g -1 (Zhou 2000).…”