Bc. Anderson et al., Differential grazing effects by isopods on Gracilaria gracilis and epiphytic Ceramium diaphanum in suspended raft culture, AQUACULTURE, 169(1-2), 1998, pp. 99-109
Large populations of epiphytic Ceramium diaphanum and the isopod Paridotea
reticulata are found in association with commercially farmed Gracilaria gra
cilis. When given a choice, P. reticulata consumed C. diaphanum rather than
G. gracilis. Feeding rate experiments indicate that small isopods could co
nsume 0.060 +/- 0.040 mg((dry)) C. diaphanum per gram((dry)) of isopod per
day and that large isopods consumed 0.043 +/- 0.007 mg((dry)) C. diaphanum
per gram((dry)) of isopod per day. In contrast, the amount of G. gracilis c
onsumed was negligible. One year's population data indicated that P. reticu
lata populations increased as C. diaphanum populations increased. However,
P. reticulata's influence on C. diaphanum was only significant when C. diap
hanum populations were low. Using the consumption rate of 0.060 +/- 0 040 g
((dry)) C. diaphanum consumed per gram((dry)) of isopod per day and biomass
values obtained in the field, it was calculated that during some months P.
reticulata is capable of consuming 7.8% of the total C. diaphanum populati
on per day. (C) 1998 Elsevier Science B.V. All rights reserved.