Modelling of suspension-feeding and growth in the green-lipped mussel Perna canaliculus exposed to natural and experimental variations of seston availability in the Marlborough Sounds, New Zealand

Abstract

Responses In feeding behaviour to wide vanatlons in the amount and composition of natural seston were studled In the green-lipped (GreenshellT\'] mussel Perna canaliculus of standard 58 + 2 mm shell length Nutnent acquisition wds pnmanlv regulated by the rate that mussels cleared water of part~cles (I h ' I , which vaned In hyperbol~c relation with the abundance of chlorophyll-rich organics, lather than with the ren~alning organic 01 inorganic components of ava~lable 5eston Maximal clearance rates of about 15 1 h ' g ' consistently occurred when chlorophyll a was available at only 1 to 2 pg 1. ' Although clearance rates decreased exponentially, rates of filtrat~on and ~ngestion (mg h ') continued to grow as the total dry part~culczte mass (TPV) of available seston increased u p to about 1000 n~g l ' The proportlon of t~ltered matter ejected a s pseudofaeces before lngestlon remained at a constant fractlon xvh~ch averaged 0 87 at seston concentrations abovcl about 40 mg TP>l l Only above about 1000 m g TPM I-' dld a decline In f~ltration rate suggest any physical ovcrload~ng of feedlng mechanisms Within particles filtered on the cten~dla significant net ennchment of up to 0 23 * 0 10 (mean + 2 SE) tlmes the organic fractlon in available seston stemmed pnnlanly from the preferential retention of particles that were nch in chlorophyll a The efficiency of such retention vaned in quadratic relat~on with seston co~npos~tlon b e~n g maximal at an optimal concentrat~on of chlorophyll a per unit total organic matter Within ingested particles, f u r t h e~ net enrichment of up to as much as 1 47 + 0 26 times the organic iractlon within filtered matter stemmed from the differential pre-ingestive relectlon of particles w~t h i n pseudofaeces Efficlencies of both these selective mechanisms increased with filtrat~on rates The combined effect was that the organic content of ingested matter (OCI) was enhanced at faster filtration rates, to as much as 7 times the organic content of available seston (OCS). Associated benefits were a m p u l e d by a positlve hyperbolic relation that was confirmed between OCJ and the net absorption efficiency from Ingested organlcs Flndlngs showed that tissue wasting occurred in P canaliculus of l g dry soft tissue feedlng upon seston that contained less than 0.86 + 0.19 pg chlorophyll a l . Maximal net organic absorption rate indicated potcntial growth of 6 S":, d ' g ' dry soft tissue, assuciated with the peak in clearance rate. A high capacity for f~ltrat~on and the ability to adjust clear,ince ratr cnabled P canaliculus to optimise particle selection and absorption efficiencies at levels that maintained organic absorption rate independent of the reduction in OCS as TPM increased to at least 1000 mg I ' Collective findings help to explain why P canaliculus~s so well-suited for cultivation, establish that reduced mussel growth within the New Zealand GreenshellT\' industry from 1996 to 1998 was due at least in part to food limitation, and suggest a potential for significant expansion of ...

Dynamic filter-feeding responses in fouling organisms

“…It has been suggested that the filter pump is working to capacity in mussels, bryozoans and ascidians, stating that pumping rates are maximal at 'normal' food availabilities, and only decline in response to stress under unnaturally low or unnaturally high food conditions, thus, with no evidence of physiological regulation (Riisgard & Larsen 2000, Riisgard & Goldson 1997, Riisgard 2001). We do not agree that the variations in CR observed in various bivalves (Hawkins et al 1999(Hawkins et al , 2001, and here in Ciona intestinalis, Membranipora membranacea and possibly Ascidiella aspersa, are unnatural. The debate possibly hinges on the definition of 'normal' food availabilities.…”

Functional descriptions of feeding and energetics of the Pacific oyster Crassostrea gigas in New Zealand

“…FR has also been reported to decline at high S in other species. Navarro & Widdows (1997), for example, found a decline in FR above 300 mg l -1 for the cockle Cerastoderma edule, and Hawkins et al (1999) observed a decline in FR over 1000 mg l -1 in the mussel Perna canaliculus. We did not see this decline of FR for C. gigas within the range of S tested, which suggests that the S above which FR declines is likely to be above 600 mg l -1 for the population of C. gigas in New Zealand.…”

Open water integrated multi-trophic aquaculture: constraints on the effectiveness of mussels as an organic extractive component

“…Maximum ingestion rate and the initiation of biologically significant food rejection occurs in mussels at relatively high particle concentrations (>10 mg l −1 ; e.g. Hawkins et al 1998Hawkins et al , 1999) compared with levels observed at IMTA sites investigated in Canada, Norway, and the Mediterranean (Lander et al 2004, Sarà et al 2009, Reid et al 2010, MacDonald et al 2011, Handå et al 2012a). The following analysis is therefore meant to be applicable to similar environments.…”