Morphometric Relationships, Gametogenic Development and Spawning of the Geoduck Clam Panopea Globosa (Bivalvia: Hiatellidae) in the Central Gulf of California

Genetic and Morphological Variation of Northeast PacificPanopeaClams: Evolutionary Implications

“…Panopea globosa from the northern Gulf of California (San Felipe and Puerto Pen˜asco) were significantly larger (SL, 155.9 mm vs. 147.7 mm; t ¼ 2.8, P ¼ 0.005) than those measured by Arago´n-Noriega et al (2007) in a comparable sample (n ¼ 77) collected in 2004/2005 from the Empalme Bay, on the eastern shore of the mid Gulf of California (Fig. 6).…”

“…In the case of P. globosa in the Gulf of California, the reproductive cycle may play a significant role in maintaining these phenotypic differences. Because Panopea clams are fundamentally temperate bivalves (Feldman et al 2004), reproduction of P. globosa in the Gulf of California is tightly coupled and triggered by a decrease in water temperature during winter, a few months before the peak in primary production (Arago´n-Noriega et al 2007;Caldero´n-Aguilera et al 2010). Compared with other geoduck populations of P. generosa and P. zelandica at higher latitudes, this environmental constraint entails a more protracted nonreproductive period (up to 7-8 mo) (Arago´n-Noriega et al 2007;Caldero´n-Aguilera et al 2010), during which energy can be directed to somatic growth.…”

“…Because Panopea clams are fundamentally temperate bivalves (Feldman et al 2004), reproduction of P. globosa in the Gulf of California is tightly coupled and triggered by a decrease in water temperature during winter, a few months before the peak in primary production (Arago´n-Noriega et al 2007;Caldero´n-Aguilera et al 2010). Compared with other geoduck populations of P. generosa and P. zelandica at higher latitudes, this environmental constraint entails a more protracted nonreproductive period (up to 7-8 mo) (Arago´n-Noriega et al 2007;Caldero´n-Aguilera et al 2010), during which energy can be directed to somatic growth. In contrast, samples of P. generosa from the Pacific coast of Baja California show a pattern of partial protracted spawning during the year (Calderon-Aguilera, unpublished results) comparable with those of conspecifics at higher latitudes (Andersen 1971, Sloan & Robinson 1984.…”

“…Notably, only three publications are available on the basic biology of P. globosa in Mexico: two from Bahı´a de Guaymas-Empalme, Sonora (Central Gulf of California), and one from the Upper Gulf of California (Caldero´n-Aguilera et al 2010). The first reports on the morphometric variation and reproductive biology of samples collected during 2004 and 2005, featuring a predominance of large clams and documenting peak spawning between January and February (winter), at the time of lowest sea surface temperature (18°C) (Arago´n-Noriega et al 2007). The second is a complementary report focusing on the reproductive aspects of the same sample collections, but elaborating on a comparative analysis with the reproductive cycles of P. generosa from Canada and P. zelandica from New Zealand (Arambula-Pujol et al 2008).…”

Morphological and Genetic Identification of the Validity of the SpeciesAtrina chinensis(Bivalvia: Pinnidae)

“…Studies of reproductive biology indicate that P. globosa is well adapted to warm temperatures; their reproductive cycle commences in late summer, when sea surface temperatures reach 28°C, and spawning occurs during winter months, when temperatures are close to 20°C (Arago´n-Noriega et al 2007). Conversely, P. generosa spawning peaks in late spring and early summer at temperatures closer to 12°C (Goodwin & Pease 1989, Arago´n-Noriega et al 2007, Ara´mbula-Pujol et al 2008). The maximum age recorded for P. globosa is 47 y (Gonza´lez-Pela´ez et al 2013) whereas P. generosa can live as long as 168 y (Bureau et al 2002).…”