After the 2-wk acclimation at 22[degrees]C, 315 ark shells were selected randomly and transferred in equal numbers into tanks with water temperatures of 17[degrees]C, 27[degrees]C, and 32[degrees]C for 72 h.
Three hemolymph pools were collected from three ark shells held at each experimental temperature (17[degrees]C, 27[degrees]C, and 32[degrees]C) and each sampling time point (0, 1, 6, 12, 24, 48, and 72 h during stress and 1 and 6 h during recovery).
05) decreases in SOD activity were found in CFH of ark shells after 48 h exposure to 27[degrees]C and 32[degrees]C.
ABSTRACT Ark shell Scapharca broughtonii is one of the most commercially important bivalve resources and is widely distributed in northeastern Asia.
KEY WORDS: ark shell, genetic characterization, mitochondrial DNA, COI gene, Scapharca broughtonii
Ark shell Scapharca broughtonii belongs to the family Arcidae inhabiting the muddy sediments of shallow coastal waters.
Third, the growth patterns of ark shells were compared between the northern and southern areas of Sendai Bay, and among Sendai, Nanao, and Mutsu bays.
The first ventral growth rings of the ark shells from Mutsu Bay were observed clearly in the cross-sections, thus we cut a thin cross-section only of their umbonal region.
Despite the larger maximum size of the ark shells from Nanao Bay compared with those from Sendai Bay, the maximum age of the ark shells from Nanao Bay was far younger than that from Sendai Bay.
A total of 149 subcrenated ark shells ranging from 17-50 mm in shell length were examined histologically to determine the profile of gametogenesis and reproductive cycle.
Analysis of the glycogen contents of the organs (mantle, gill, adductor muscle, digestive gland, and foot) of the subcrenated ark shells in April 2004 is shown in Figure 11.
In the present study, histological observations of the gonads of subcrenated ark shells in Ariake Bay revealed that gametogenetic development of the male and female commenced in April, when the water temperature had reached 17[degrees]C.
The gonad mass of the two largest groups of ark shells, measuring 50-70 mm and 70-90 mm in shell length, respectively, increased rapidly during the first months of the study to a peak in late September 2002, and then a major decrease occurred during October 2002 through January 2003 (Fig.
Although gonad mass was consistently low in ark shells up to a shell length of about 50 mm, the gonad index increased at 18-20 mm in shell length (up to 32%), indicating the onset of gonad production.
The observations of seasonal changes in gonad indices for the four different size groups of ark shells further showed that 10-30 mm individuals had negligible reproductive output, and that 30-50 mm individuals had substantially less output than larger individuals.