The reproductive cycle of the Thecosomatous pteropod Limacina retroversa in the western South Atlantic

Life cycle and early development of the thecosomatous pteropod Limacina retroversa in the Gulf of Maine, including the effect of elevated CO2 levels

“…The authors also noted that reproductive development appeared to occur more rapidly in the summer, although it was also hypothesized that the two size cohorts observed in the region were a consequence of two unrelated populations of L. retroversa which were advected into the Gulf of Maine from offshore (Hsiao 1939;Redfield 1939). Studies of the South Atlantic population of L. retroversa similarly indicated that the major pulses of reproduction occurred in spring and at the end of summer (Dadon and Cidre 1992). In this case, however, the authors suggested that there were two generations per year, with individuals born in the spring maturing at a smaller size and growing faster during the warm season to produce eggs at the end of summer which then slowly developed during the fall and winter to produce offspring the following spring.…”

“…Thus, gender in Limacinidae varies with size, and three types can be identified: small individuals are typically sexually undifferentiated, somewhat larger individuals are solely males, and the largest are simultaneous hermaphrodites (Hsiao 1939). Previous work on the genus Limacina has suggested that some species spawn multiple times per year (Dadon and Cidre 1992), although these authors suggest that this is a consequence of asynchrony between two cohorts, with adult mortality after each reproductive event. It has been suggested that polar species may have a 1-2 year life span (Kobayashi 1974;Gannefors et al 2005;Hunt et al 2008;Wang 2014), but the life span of temperate and tropical species is unknown and likely shorter.…”

Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms

“…Yet only five species typically occur in such cold water regions and, of these, only one or two species are common at the highest latitudes 31 . High-latitude pteropods have one or two generations per year 12,15,32 , form integral components of food webs, and are typically found in the upper 300 m where they may reach densities of hundreds to thousands of individuals per m 3 (refs 11, 13-15). In the Ross Sea, for example, the prominent subpolar-polar pteropod Limacina helicina sometimes replaces krill as the dominant zooplankton, and is considered an overall indicator of ecosystem health 33 .…”

Seasonal pattern of zooplankton biomass in the Argentinian shelf off Southern Patagonia (45º - 55º S)

“…Hence, though the study focused mainly on the northern region down to 46°S, the production cycle was outlined for the first time (Carreto et al,1981b) and the pattern of zooplankton biomass was related to the abundance of fish eggs and larvae (Ciechomski and Sánchez, 1983). From the same collections, the extensive distribution -including southern Patagonia -of the dominant copepod species (Ramírez, 1981), hyperiid amphipods (Ramírez and Viñas, 1985), chaetognaths (Mazzoni, 1983(Mazzoni, , 1988 and pteropods (Dadon, 1986(Dadon, , 1990(Dadon, , 1992 were also reported on in detail, as well as the seasonal changes in the populations of the dominant species of euphausiids (Ramírez and Dato, 1983). Post 1970s information was limited to biomass estimates conducted during two cruises on the Patagonian shelf (Fernández Aráoz and Viñas, 1994;Santos, 1994) and to the macrozooplankton biomass and assemblages found around the Malvinas Islands (Rodhouse et al, 1992;Tarling et al, 1995).…”