Influence of environmental conditions on early development of the hydrothermal vent polychaete Alvinella pompejana

Abstract

Dispersal and colonisation processes at deep-sea vents are still not fully understood, essentially because early life stages of vent species remain unknown. The polychaete worm Alvinella pompejana forms colonies on chimney walls at East Pacific Rise vent sites where the temperature can frequently exceed 20°C. In vitro studies in pressure vessels showed that the early embryos tolerate temperatures in a lower range (10-14°C), suggesting that they would have to escape the colony to develop. Pressure vessels offer the advantage that each parameter can be independently controlled, but they do not simulate the more complex and dynamic conditions naturally encountered at vent sites. Accordingly, in addition to incubations in pressure vessels, we incubated embryos directly at a vent site, in different habitats along a gradient of hydrothermal influence. Embryos incubated on an adult A. pompejana colony where temperature and H 2 S concentrations were relatively high showed a very low survival rate and did not develop, whereas embryos incubated in a Riftia pachyptila clump environment with a lower hydrothermal signature, or at the base of the chimney where the influence of the hydrothermal activity was very weak, survived well and developed. Although the average temperature recorded in the A. pompejana colony was within the range tolerated by embryos (13°C), frequent peaks above 20°C were recorded. Estimated sulphide concentration at this site reached 200·µmol·l -1 . Punctuated exposure to both high temperature and elevated sulphide levels probably explain the low survival of embryos within the A. pompejana colony. The in situ experiments further support the idea that embryos require conditions with moderate hydrothermal influence not generally found within an adult colony. However, as much more benign physicochemical conditions can be found within a few tens of cm of adult colonies, embryos do not necessarily have to leave their vent of origin to develop. Further analyses are needed to pinpoint the specific factors that affect the survival and development of embryos at vents.

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

“…Energy availability is, in turn, determined by respiration rates, which can vary greatly with temperature. Larval duration for lecithotrophs can be prolonged, and thus dispersal potential enhanced, if development can proceed in the low temperature of ambient seawater as larvae disperse between vents (see Pradillon et al, 2005). Species such as mussels and crabs exhibit planktotrophic larval development, which is not limited by energy stores but can continue as long as the larvae can locate and consume food (e.g., Herring and Dixon, 1998;Trask and Van Dover, 1999).…”

Pressure and life: some biological strategies

“…In A. pompejana, 1-atm raised embryos exhibit abnormal distribution and relative size of the blastomeres (Fig. 2) (Pradillon et al 2005). Abnormal morphology was also demonstrated in developmental stages of 1-atm species exposed to high pressure (Young and Tyler 1993;Tyler and Young 1998).…”

“…Studies on the annelids Alvinella pompejana and Riftia pachyptila, both inhabiting hydrothermal vents from the East Pacific Rise (EPR) at 2500 m depth demonstrate the low thermal tolerance and the need for native pressures in early embryos of these species (Marsh et al 2001;Pradillon et al 2001Pradillon et al , 2005. The limited embryonic temperature tolerance was particularly significant in A. pompejana because adults of this species live closest to the vent fluid in the hydrothermal biotope, and are exposed to temperatures close Adult distributions inferred from collection depth are plotted together with potential distribution of embryos and larvae inferred from their pressure tolerance as found in in vitro studies (Young and Tyler 1993;Young et al 1996;Tyler and Young 1998; to 50°C (Cary et al 1998;Le Bris et al 2005).…”

“…The limited embryonic temperature tolerance was particularly significant in A. pompejana because adults of this species live closest to the vent fluid in the hydrothermal biotope, and are exposed to temperatures close Adult distributions inferred from collection depth are plotted together with potential distribution of embryos and larvae inferred from their pressure tolerance as found in in vitro studies (Young and Tyler 1993;Young et al 1996;Tyler and Young 1998; to 50°C (Cary et al 1998;Le Bris et al 2005). Embryos do not survive temperatures above 20°C, and develop well around 5-10°C at native pressure (Pradillon et al 2001(Pradillon et al , 2005. Embryos are then likely to leave hydrothermal vents and disperse through the water column.…”

Post-capture investigations of hydrothermal vent macro-invertebrates to study adaptations to extreme environments

“…However, these experiments were limited to a relatively short time span of exposure conditions (up to 1 month) due to high mortality and the problems associated with bio-corrosion on the surface of the pressure-chamber (discussed in Beech and Gaylarde 1999). Nonetheless in a recent developmental study of the early life stage of Alvinella pompejana in a pressure vessel (Pradillon et al 2005), the authors have recognized the limitations of the technique (pressure vessels do not simulate the complex and dynamic in situ thermal and chemical conditions typical of hydrothermal vents). Consequently, they have incubated embryos directly at the vent site along a fluid gradient with conditions similar to those re-created in the laboratory.…”