Potential impact of climate warming on the recruitment of an economically and ecologically important species, the European lobster (Homarus gammarus) at Helgoland, North Sea

Abstract

A laboratory-based study was performed to assess the impact of climate warming on the recruitment of the endangered population of the European lobster (Homarus gammarus) at Helgoland (North Sea, German Bight). Egg-bearing females collected in situ just after spawning in late summer were subjected to various seasonal temperature regimes. Regimes with elevated temperatures (mild winters) resulted in a strong seasonal forward shift of larval hatching. Hatching took place at significantly lower temperatures than under regimes with normal winters. Experiments on larval development across a range of constant temperatures showed that no successful larval development occurred at temperatures below 14°C. Larval survival increased from 9% at 14°C to 80% at 22°C, while duration of larval development decreased correspondingly from 26 to 13 days. We hypothesize that an ongoing warming of the North Sea will strongly affect the recruitment success of the Helgoland lobster, mainly resulting from a decoupling of the seasonal peak appearance of larvae from optimal external conditions (temperature, food availability) for larval development.

Effects of temperature on the moulting and locomotory activity of hatchery-reared juvenile lobsters (Homarus gammarus) at Helgoland (North Sea)

“…However, the timing of moulting varied by few weeks only depending on different seasonal temperature regimes (Templeman 1940). In another study, no moulting occurred at or below 108C in lobster larvae (Schmalenbach & Franke 2010), and Aiken & Waddy (1976) reported that in lobsters held below 68C the moult induction was blocked.…”

“…Temperature thresholds appear to be associated with several stages of the lobster life cycle at Helgoland. The timing of embryogenesis and larval hatch was strongly dependent on late winter and spring temperatures (Schmalenbach & Franke 2010). In juvenile lobsters first moults and enhanced locomotory activity started when a threshold between 12 and 158C was passed independent of year class, which means also independent of size, underlining the importance of the temperature factor.…”

“…The temperature 20 I. Schmalenbach and F. Buchholz recorded reflected the sea surface temperature at Helgoland (Schmalenbach & Franke 2010), but as a result of the construction of the seawater supply system in the laboratory, water temperatures were on average 1Á28C higher than in the field.…”

Proteasomal activities in the claw muscle tissue of European lobster, Homarus gammarus, during larval development

“…This approach was used to determine the duration of the larval stages at the given experimental conditions (Table 1). Additional data about the duration of larval development were provided by Schmalenbach and Fanke (2010).…”

“…Within about 14 days, the larvae pass three zoea stages and molt into the first juvenile stage (Charmantier et al 1991;Schmalenbach and Fanke 2010). Similar to the adults, the larvae have to reduce and re-organize their muscles as well as the connective tissue.…”