Field evidence of interpopulation variation in oocyte size of a marine invertebrate under contrasting temperature and food availability

Abstract

In marine invertebrates with planktotrophic larvae, modelling studies predict that water temperature and food availability are the primary factors influencing oocyte size, with large oocyte sizes being favoured by cold water and low food availability. We examined intraspecific variation in oocyte size in the polychaete Spirobranchus cariniferus in populations from the East and West Coasts of New Zealand's North Island, which differ in temperature and food availability during the reproductive season: the East Coast has consistently warmer seawater temperatures throughout the summer and higher phytoplankton abundance in late summer than the West Coast. A cross-fertilization experiment and DNA sequencing confirmed that Spirobranchus populations on both coasts belong to the same species. Then, analyses of S. cariniferus oocytes from 5 sites per coast revealed that the West Coast population produces oocytes that are on average 14% larger and contain up to 41% more triacylglycerols (TAGs) than the East Coast population. West Coast S. cariniferus oocytes also developed into larger larvae that reached competence 22% sooner than East Coast oocytes and larvae. These intraspecific comparisons of East and West Coast S. cariniferus populations reveal oocyte size to differ substantially even among populations that are probably not fully isolated, consistent with predictions of life history models. We estimate that genetic divergence may be responsible for up to 58% of the difference in oocyte size between East and West Coast populations, and that oocyte size may be subject to local adaptation to temperature and, to a lesser extent, food availability differences between coasts.

Elevated temperatures increase abnormalities in embryos and reduce larval survival in serpulid polychaetes

“…At 30°C, embryos of S. sinuspersicus (before as S. kraussii ) developed into larvae, but the larvae did not settle ( Crisp, 1977 ), while at 34°C the lowest success of fertilization occurred the embryonic stage did not develop and cells denatured ( Lavajoo and Amrollahi-Biuki, 2015 ). Gosselin et al (2019) found that the population of S. cariniferus (Gray) from the west coast of New Zealand produced larger eggs and larvae that developed faster than the population of this same species inhabiting the east coast (the east coast is up to 2°C warmer than the west coast). It was concluded that this species is adapting to living in places with colder waters, thus facing global warming scenarios.…”

“…Specifically, the effect of temperature on Spirobranchus has been investigated in a few species such as Spirobranchus sinuspersicus , Spirobranchus cariniferus and Spirobranchus bakau . Negative effects on embryonic and larval development have been described in these species, causing the death of larvae and poor settlement success ( Crisp, 1977 ; Castric-Fey, 1984 ; Lavajoo and Amrollahi-Biuki, 2015 ; Gosselin et al, 2019 ).…”

Differences in the Morphology and Reproduction of the Ascidian Boltenia Villosa Across a Latitudinal Gradient

“…Potential future research may examine the impacts of food availability and water temperature on oocyte diameter or the influence of water movement on a given habitat's morphotype (Koehl 1982;Gosselin et al 2019). A high priority for future work would be to collect and analyze animals from multiple depths at each of several latitudes to determine if the observed differences are latitudinal or bathymetric and to distinguish any new subspecies.…”

Role of depleted initial energy reserves in early benthic phase mortality of six marine invertebrate species

“…The minimum OM:ash weight ratio of 0.14 is likely determined by the amount of organic matter that is difficult to use as an energy source by the hatchlings. Almost all organic compounds that can readily be metabolized to release energy, mainly energetic lipids such as triacylglycerols (Gosselin et al, 2019;Lee et al, 2006;Sewell, 2005;Thiyagarajan et al, 2002;Whitehill & Moran, 2012), would thus be utilized within 40-50 days of the onset of the EBP if starved, leaving compounds such as structural lipids and proteins as the bulk of the remaining organic matter. Since energy content predictably decreases as a function of the duration of starvation, this finding confirmed that duration of starvation is a useful proxy for metabolizable energy content at the onset of the EBP.…”