Aspects of the biology of the little cuttlefish, Sepiola atlantica and the common European cuttlefish, Sepia officinalis (Mollusca: Cephalopoda)

Abstract

Aspects of the biology of the little cuttlefish Sepiola atlantica and the common
European cuttlefish, Sepia officinalis were examined in order to further the
understanding of the culture, ecology, husbandry and reproductive biology of both species. The distribution of Sepiola atlantica around Anglesey, North Wales during the summer months (April to October) was assessed. These data together with a detailed investigation of the reproductive condition and the population biology of Sepiola atlantica in the shallow subtidal from two sites with contrasting wave exposure were undertaken over consecutive years (2006, 2007 and 2008). Sepiola atlantica of a wide size range and of all maturity stages were found to make an annual seasonal inshore migration in July into shallow coastal waters. The inshore migration began when seawater temperatures started increasing in the spring with numbers of migrants peaking in July and August and then falling between September and October as seawater temperatures decljned in the autumn. These data indicate that S. atlantica of all sizes and maturity stages congregate in the shallow waters around Anglesey to
mate when environmental conditions are favourable for enhanced growth and
maturation and where the concentrations of large numbers of individuals increases the opportunity and the chance of a successful mating.
Experiments were undertaken to culture Sepiola atlantica from eggs held in
the laboratory. Wild-caught S. atlantica transferred to laboratory aquaria and held
under controlled conditions of seawater flow, food supply and lighting laid egg
masses in June, August and September. These eggs were observed throughout
development and the resultant hatchling paralarvae reared on a diet of zooplankton collected from the Menai Strait. The small numbers of juveniles that developed into adulthood were fed on shrimp, Crangon crangon, however none of these individuals went on to spawn in the laboratory. The life cycle of S. atlantica is similar to those of other frequently cultured sepioids, although there is a need for further experimentation to establish that S. atlantica can be reared through consecutive generations in the laboratory.
The survival of eggs and the hatching frequency, hatching success and
subsequent growth of hatchlings from samples of Sepia officinalis eggs transported under a range of environmental conditions have been investigated. Eggs were transported for 8.5h under the following conditions: 1) Wet: in sea water, 2) Wet & aerated: eggs in sea water with continuous aeration, 3) Damp: eggs wrapped loosely in damp paper towel and 4) Dry: eggs gently blotted dry in air. Hatchlings from eggs transported "Dry" were significantly smaller in length than those transported using other treatments. The finding that there were no significant differences in hatching success, hatching frequency, growth and survival between treatments, indicates that it is feasible to transport cuttlefish eggs for periods of ~8hours using simple and cost-effective methodologies.

Date of Award	Dec 2009
Original language	English
Awarding Institution	Bangor University
Sponsors	European Social Fund & Anglesey Sea Zoo
Supervisor	Christopher Richardson (Supervisor)