Chemical composition and tissue energy density of the cuttlefish (Sepia apama) and its assimilation efficiency by Diomedea albatrosses

Abstract

The cuttlefish Sepia apama Gray (Mollusca: Cephalopoda) is a seasonally abundant food resource exploited annually by moulting albatrosses throughout winter and early spring in the coastal waters of New South Wales, Australia. To assess its nutritional value as albatross forage, we analysed S. apama for water, lipid protein, ash contents, energy density and amino acid composition. Because albatrosses consistently consume S. apama parts preferentially in the order of head, viscera and mantle, we analysed these sections separately, but did not identify any nutritional basis for this selective feeding behaviour. The gross energy value of S. apama bodies was 20.9 kJ/g dry mass, but their high water content (>83%; cf <70% for fish) results in a relatively low energy density of 3.53 kJ/g. This may contribute to a need to take large meals, which subsequently degrade flight performance. Protein content was typically >75% dry mass, whereas fat content was only about 1%. Albatrosses feed on many species of cephalopods and teleost fish, and we found the amino acid composition of S. apama to be comparable to a range of species within these taxa. We used S. apama exclusively in feeding trials to estimate the energy assimilation efficiency for Diomedea albatrosses. We estimated their nitrogen-corrected apparent energy assimilation efficiency for consuming this prey to be 81.82 ± 0.72% and nitrogen retention as 2.90 ± 0.11 g N kg(-1) d(-1). Although S. apama has a high water content and relatively low energy density, its protein composition is otherwise comparable to other albatross prey species. Consequently, the large size and seasonal abundance of this prey should ensure that albatrosses remain replete and adequately nourished on this forage while undergoing moult.

Combination of At-Sea Activity, Geolocation and Feather Stable Isotopes Documents Where and When Seabirds Molt

“…When compared to primaries, body feathers revealed higher variance in their isotopic values, thus indicating that some of them grew in habitats different from the core molting areas depicted by the GLS locations. This is in agreement with the little available information indicating that body feathers of Procellariiformes are replaced gradually over several months, mainly during the non-breeding period (Warham, 1996;Battam et al, 2010;Bugoni et al, 2015). A protracted body molt minimizes temporal overlap with active wing molt and thus lowers the associated nutrient and energetic costs of renewing all feather types simultaneously (but see Bugoni et al, 2015).…”

Feeding biology and biochemical composition of the lessepsian migrant Octopus aegina (Cephalopoda: Octopodidae)

“…Generally, Cephalopods' bodies contain low level of lipid (Battam et al, 2010). In the present results, analysis of total lipid content of Octopus aegina muscles revealed that in both males and females there was a trend of decreasing lipid content in the muscles with maturation.…”

A comprehensive isotopic investigation of habitat preferences in nonbreeding albatrosses from the Southern Ocean

“…Body feathers were used because their isotopic composition was not signifi cantly diff erent from that of primaries in breeding albatrosses (Jaeger et al 2009), being thus a safe alternative to fl ight feathers whose collection impairs the birds ' fl ying ability. Instead, albatross feathers are gradually replaced over the long internesting period (about 7% of body feathers at any time, Battam et al 2010), and their isotope values were therefore assumed to represent diet during that period (Phillips et al 2009). Instead, albatross feathers are gradually replaced over the long internesting period (about 7% of body feathers at any time, Battam et al 2010), and their isotope values were therefore assumed to represent diet during that period (Phillips et al 2009).…”

“…In albatrosses, moult (including body moult) of active breeding adults does not take place during the reproductive period (Prince et al 1993). Instead, albatross feathers are gradually replaced over the long internesting period (about 7% of body feathers at any time, Battam et al 2010), and their isotope values were therefore assumed to represent diet during that period (Phillips et al 2009). Depending on breeding frequency and on the duration of the breeding cycle, the inter-nesting period spans one winter ( ~ four months) in annual breeders (ten taxa), a full year ( ~ 12 months) in large biennal breeders of the genus Diomedea (7 taxa), and a full year plus a winter ( ~ 16 months) in small biennal breeders (three species, including the grey-headed albatross Th alassarche chrysostoma and the two Phoebetria species).…”