Species and epilimnion/hypolimnion‐related differences in size at larval settlement and metamorphosis in Dreissena (Bivalvia)

Abstract

Abstract-Recently settled postlarval quagga mussels (Dreissena bugensis) and zebra mussels (D. polymorpha) were examined using optic microscopy to determine planktonic shell growth and size at settlement and metamorphosis from two habitats in Eastern Lake Erie: nearshore epilimnion and offshore hypolimnion. Postlarvae (shell length ϳ400-2000 m) were collected from various substrates between 1992 and 1995. Planktonic shell growth and size at settlement and metamorphosis were determined by measuring height of the prodissoconch I (PI) and prodissoconch II (PII) on right valves. Mean PI height was 79.07 (SD ϭ 4.64) and 79.62 m (SD ϭ 4.28) for the quagga and zebra mussel, respectively, and did not differ between species or across habitats. There was, however, a distinct between-species difference in size at settlement and metamorphosis (PII size), with larvae of the quagga mussel settling at significantly larger sizes than those of the zebra mussel (nearshore/epilimnion data: quagga PII means, 256-284 m; zebra PII means, 236-249 m). In addition, quagga mussel larvae settled at a greater size in the offshore hypolimnion habitat (PII mean ϭ 313.64 m, SD ϭ 24.69, n ϭ 320) compared to nearshore epilimnion habitat (mean ϭ 261.89 m, SD ϭ 19.41, n ϭ 207). The additional 28% of larval shell (PII) secreted by offshore hypolimnion quagga mussels may be linked to several factors, including a prolonged planktonic period. This study is the first to document the relationship between offshore distance and size at settlement in a bivalve.

Flexible diet and trophic position of dreissenid mussels as inferred from stable isotopes of carbon and nitrogen

“…However, in many shallow-water habitats of Lakes Erie and Ontario, D. bugensis are much more numerous than D. polymorpha (Department of Fisheries and Oceans Canada 2000). Larvae of D. bugensis have been shown to mature and settle at a larger size than larvae of D. polymorpha (Martel et al 2001), which may provide a competitive edge, and the range of D. bugensis has been expanding at the expense of D. polymorpha in the Ukraine and western Lake Erie (Stoeckmann 2003). The results of this study confirm that these two species have nearly identical diets, and hence in areas of sympatry will experience strong, direct competition for resources.…”

Invasion history, distribution, and relative abundances of Dreissena bugensis in the old world: a synthesis of data

“…These attributes give D. bugensis a strong competitive advantage during periods of low food and high temperatures. Also, because of higher growth rates, D. bugensis larvae settle at a larger size than D. polymorpha larvae, giving them a competitive advantage (Martel et al 2001). While some laboratory studies found D. bugensis to be less tolerant of higher temperatures than D. polymorpha (Domm et al 1993), controlled studies under more natural conditions showed that growth and survival of D. bugensis was similar to, or greater than, D. polymorpha at typical summer-warm temperatures (MacIsaac 1994; Thorp et al 2002).…”

Veliger Size at Metamorphosis and Temporal Variability in Prodissoconch II Morphometry in the Blue Mussel (Mytilus edulis): Potential Impact on Recruitment

“…Factors such as water depth where planktotrophic veligers spend at least part of their developmental period have been linked to variability in PII size at settlement (Robertson 1994, Martel et al 2001. However, water depth is likely not a significant factor in the shallow environment at BHA and in the usual habitat of Mytilus edulis inhabiting the intertidal and the shallow subtidal environment.…”

“…A clear demarcation formed by a comarginal growth line occurs at the boundary between PII and dissoconch, indicating the end of larval life. Postlarval mussels were placed in holding glass Petri dishes and oriented using a modified version of the method described in Martel et al (1995Martel et al ( , 2001. A small ridge of dark Plasticine (ca.…”

“…In the case of bivalves with planktotrophic larval development, the information preserved in the shell includes the size of the first larval shell secreted (prodissoconch I [PI]), representing the early veliger, or D-shape stage (which also correlates with egg size) (Chanley & Andrews 1971, Casse et al 1998, Martel et al 2000, Zardus & Martel 2002, and the maximum size the veliger larva reached before metamorphosis (prodissoconch II [PII]). The PII shell thus represents the size of the bivalve at metamorphosis at the onset of its benthic life (Martel et al 1995, Martel et al 2001, thus providing valuable post facto information on the larval ecology and early benthic ecology of the animal.…”