Doses of darkness control latitudinal differences in breeding date in the barnacle Semibalanus balanoides

Abstract

This paper reports the first study of breeding in the boreo-arctic barnacle Semibalanus balanoides in which latitudinal variation in timing of egg mass hardening has been examined simultaneously over the geographical scale involved, thereby excluding temporal confounding of the data. The timing of autumn egg mass hardening on the middle shore was established in 2002 and 2003 at ten stations ranging latitudinally from Trondheim (63°24′N) to Plymouth (50°18′N). To assess variation at local scale (<10 km), breeding was studied on three shores at each of two Irish locations (Cork and Galway). At Oban (Scotland) and Cork, the effect of shore height on timing of breeding was investigated. A strong influence of latitude and day length on timing of breeding was found in both 2002 and 2003. In both years, barnacles bred much earlier (when day length was longer) at high rather than low latitudes. No significant effect of environmental temperature or insolation on timing of breeding was detected. Shores no more than 10 km apart showed minimal difference in middle shore breeding date (<4 days). However, upper shore barnacles bred significantly earlier (by 7–13 days) than middle shore animals. The data indicate that breeding is controlled by period of daily darkness, with high shore animals encountering longer effective ‘nights’ because of the opercular closure response to emersion (which will reduce light penetration to tissues). Predictions concerning the effects of global changes in climate and cloud cover on breeding and population distribution are made. It is suggested that increased cloud cover in the northern hemisphere is likely to induce earlier breeding, and possibly shift the present southern limit of Semibalanus southwards.

Responses of Marine Organisms to Climate Change across Oceans

“…Seasonal fluctuations in the intensity, duration, and spectral composition of light change with latitude, and act as important phenological cues for a range of marine species, sometimes in combination with temperature. Light regime thresholds likely trigger events such as reproduction and migration (Davenport et al, 2005), in addition to temperature thresholds. Thus, temperature-driven shifts in distribution and phenology of species can be constrained by the influence of the seasonality of light on photoperiod, particularly at high latitudes (Figure 4; Saikkonen et al, 2012;Sundby et al, 2016).…”

Ecological hindcasting of biogeographic responses to climate change in the European intertidal zone

“…The day-length hypothesis (Davenport et al, 2005) postulates that reproduction is dependent upon shortening day length, and that there is geographic variation in response. Extrapolation of the latitudeday of year regressions indicated that the southern limit of Semibalanus should be either in southern France or in Galicia (Davenport, 2005).…”

“…The warm winter hypothesis has support in that temperatures above 10°C have been shown in the laboratory to inhibit reproduction (Barnes, 1958;Crisp & Patel, 1969;Barnes & Stone, 1972). More recently Davenport et al (2005) proposed that day length might set the southern geographic limit of Semibalanus.…”

Larval ecology and synchronous reproduction of two crustacean species : Semibalanus balanoides in New England, USA and Gecarcinus quadratus in Veraguas, Panama

“…The timing of fertilization in the barnacle Semibalanus balanoides is linked mostly to photoperiod (Crisp 1959a;Davenport et al 2005), presumably so that the embryos will be developmentally ready to be released by the time the winter-spring phytoplankton bloom begins a few months later.…”

“…However, cloud cover is expected to increase as the climate changes, and this "global dimming" could alter the photoperiod that barnacles experience (Davenport et al 2005). Under these conditions, S. balanoides would be expected to undergo fertilization earlier in the year, since the perceived length of darkness would be longer.…”