ALBERT

Description: Symptoms characteristic of wasting disease, thought to result from infection by protozoan pathogens (i.e. Labyrinthula spp.), are a common phenomenon affecting seagrass species worldwide. However relatively little is known about factors that control the survival and success of Labyrinthula in part due to the difficulty associated with quantifying the growth of this organism. Here we describe a simple and inexpensive method for measuring growth of Labyrinthula in liquid culture that takes into consideration both cell density and areal spread. The technique allows for examination of the effects of both abiotic and biotic factors on the growth of Labyrinthula apart from its seagrass host, separating the effects of environmental condition on the host from their effects on the pathogen.

Description: Based upon the molecular and isotopic composition of hydrocarbons it has been proposed that the source of CH4 in Gulf of Cadiz mud volcanoes (MV) is a mixture of deep sourced thermogenic CH4 and shallow biogenic CH4. We directly investigated this possibility by comparing porewater CH4 concentrations and their δ13Cvalues with the potential for Archaeal methanogenesis in Gulf of Cadiz mud volcano (MV) sediments (Captain Arutyunov, Bonjardim, Ginsburg and Porto) using 14C-rate measurements. The CH4 has a deep sourced thermogenic origin (δ13C ∼ −49‰) but becomes 13C-depleted in and beneath the zone of anaerobic oxidation of methane (AOM) where the rates of hydrogenotrophic methanogenesis increase. Thus we infer that a portion of AOMproduced CO2 is being recycled to CH4 by methanogens yielding further 13C-depleted CH4, which might be misinterpreted as indicative of a fully shallow biogenic origin for this gas. Production of H2 is related to compositional changes in sedimentary organic matter, or to upward flux of substrate-enriched fluids. In contrast to otherMVsin the Gulf of Cadiz, GinsburgMVfluids are enriched in SO2−4 and contain very high concentrations of acetate (2478 μM below 150 cmbsf); however, the high levels of acetate did not stimulate methanogenesis but instead were oxidized to CO2 coupled to sulphate reduction. Both anaerobic oxidation of thermogenic CH4 linked to shallow methanogenesis and fluid geochemistry control the recycling of deep-sourced carbon at Gulf of Cadiz MVs, impacting near-surface δ13C-CH4 values.

Description: We examined the effect of increased copper concentrations (0-10 mu M) on hydrothermal vent microorganisms and the production of copper (Cu)-binding ligands as a response. Hydrothermal vent microbes originated from diffuse fluids at the Lilliput mussel field and the Irina II site in the Logatchev hydrothermal vent field, both on the Mid-Atlantic Ridge. Parallel studies were also conducted with amino acids supplemented to the incubations in order to verify whether dissolved amino acids, present in hydrothermal fluids, can buffer the bioavailable copper and reduce the active production of Cu-binding ligands. In all incubations, ligand concentrations increased with rising copper concentrations, but microbial cell numbers remained constant. This study shows that microbes were able to cope with as much as 10 mu M dissolved copper by buffering the free copper concentration. The presence of amino acids had no significant influence on the active ligand production. Our results imply that mediation of chemical speciation by vent microbes may have an important impact on hydrothermal trace metal fluxes into the ocean.

Description: Reproductive features of the poorly known oceanic squid Octopoteuthis sicula are described and quantified to gain insight into the reproductive biology of the species. The data are based on 39 complete and partial specimens from southern African waters, collected between 1975 and 2005. The specimens ranged in mantle length from 38 mm to 290 mm and included juveniles and mature females and males. The species shows female-biased sexual size dimorphism. Ovulation is asynchronous, indicating a repeated spawning strategy. Males transfer spermatophores presumably by using their long terminal organ. Spermatangia (discharged spermatophores) were found implanted in several parts of the body in both females and males, including in the anterior dorsal and ventral rugose, semi-gelatinous mantle tissue of maturing and mature females. This modified mantle tissue was only well developed in females. The morphologies of the spermatophore and the spermatangium of O. sicula are described. The spermatophoric reaction is reconstructed, using various stages of discharge, to provide insight into the process of intradermal implantation of spermatangia of this species.

Description: The functional response of Sepia officinalis early stages, preying on mysids of the species Mesopodopsis slabberi was investigated. The effects of five prey densities (12.5, 25, 37.5, 50 and 125 mysids l−1) and two hatchling ages (1-day-old and 7-day-old) on consumption rate and the frequency of non-feeding animals were tested. Older animals were approximately 50% heavier than newly hatched ones. Hatchlings were individually assayed under 0.25 W m−2 natural light, 37.8 psu in salinity and 19°C. The effect of prey density on consumption rate was highly significant and no effect of age was detected within the age range tested. Maximal values recorded for consumption rate were about 0.45 mysids h−1. The frequency of non-feeding individuals was strongly reduced at saturating prey densities. The functional response curve showed an interval of prey densities for which density-dependent prey mortality is probable.

Description: A visible pathological condition located in the arms and mantle of the Hubb octopus Octopus hubbsorum from the Northeast Pacific waters is described for the first time. Histological sections confirmed later stages (fibrosis) of a chronic inflammatory condition of unknown aetiology.

Description: A study of Rossia macrosoma in Portuguese waters with emphasis on its biogeographical, biological and biochemical characteristics is presented. Approximately 1000 specimens collected in 32 cruises between 1990 and 2003 were used to determine the distribution and abundance of the species and some population biology parameters (weight, length, sex and maturation). The first biochemical characterization of the species at different stages of gonad development was made. The species was found at depths up to 860 m along the whole Portuguese coast. The sex ratio was approximately 1:1 and did not vary with depth or position along the coast (P≫0.05). Females grew larger (84:67 mm mantle length) and heavier (161:100 g total body weight) than males. Mature specimens of both sexes constituted 〈1% of all records. Immature and maturing specimens were found year round, without significant differences between female monthly distributions (P 〉 0.05). No significant difference between sexes in the distribution of maturity stages with depth or position along the coast was noted (P≫0.05). During sexual maturation there was a significant increase (P 〈 0.05) in total amino acid, protein, lipid and fatty acid contents in the gonad, but the allocation of these organic compounds from digestive gland and muscle was not evident. In the three tissues analysed, the major fatty acids were 16:0, 18:0, 18:1, 20:1, 20:4n-6, 20:5n-3 and 22:6n-3, the major essential amino acids were lysine, leucine and arginine and the major non-essential amino acids were glutamic acid, aspartic acid and serine.

Description: This paper introduces new data on Todaropsis eblanae morphology, morphometry and functional aspects of the male reproductive system and hectocotylus. Spermatophores differ in specimens from the Atlantic Ocean (average length, 18.28 ± 1.45 mm, 15.63 ± 0.8% of mantle length; weight, 2.0–12.0 mg) and the Indian Ocean (average length, 24.8 ± 2.85 mm, 16.9 ± 2.1% of mantle length; weight, 35.0–39.6 mg) (t = 3.14; p 〈 0.01 for absolute sizes and t = 0.711; p 〉 001 for relative sizes). An additional important distinctive trait is the form of connection of the cement body with the ejaculatory tube. In recent years, T. eblanae has been regularly caught in the Barents Sea, meaning its range has extended to subarctic waters. The morphology and morphometry of the spermatophoric complex of organs did not vary in investigated parts of its range. Hectocotylus patterns and some important spermatophore traits distinguish Todaropsis from other Ommastrephidae.

Description: Octopuses of the family Octopodidae adopt two major life-history strategies. The first is the production of relatively few, large eggs resulting in well-developed hatchlings that resemble the adults and rapidly adopt the benthic habit of their parents. The second strategy is production of numerous small eggs that hatch into planktonic, free-swimming hatchlings with few suckers, simple chromatophores and transparent musculature. These distinctive planktonic stages are termed paralarvae and differ from conspecific adults in their morphology, physiology, ecology and behaviour. This study aims to review available knowledge on this subject. In benthic octopuses with planktonic stages, spawning characteristics and duration of planktonic life seem to play an important role in their dispersal capacities. Duration of the hatching period of a single egg mass can range from 2 days to 11 wk, while duration of the planktonic stage can range from 3 wk to half a year, depending on the species and temperature. Thus these paralarvae possess considerable potential for dispersal. In some species, individuals reach relatively large sizes while living as part of the micronekton of oceanic, epipelagic waters. Such forms appear to delay settlement for an unknown period that is suspected to be longer than for paralarvae in more coastal, neritic waters. During the planktonic period, paralarval octopuses feed on crustaceans as their primary prey. In addition to the protein, critical to the protein-based metabolism of octopuses (and all cephalopods), the lipid and copper contents of the prey also appear important in maintaining normal growth. Littoral and oceanic fishes are their main predators and defence behaviours may involve fast swimming speeds, use of ink decoys, dive responses and camouflage. Sensory systems of planktonic stages include photo-, mechano- and chemoreceptors controlled by a highly evolved nervous system that follows the general pattern described for adult cephalopods. On settlement, a major metamorphosis occurs in morphology, physiology and behaviour. Morphological changes associated with the settlement process include positive allometric arm growth; chromatophore, iridophore and leucophore genesis; development of skin sculptural components and a horizontal pupillary response. At the same time, animals lose the Kölliker organs that cover the body surface, the ‘lateral line system’ and the oral denticles of the beaks. Strong positive phototaxis is a common response for hatchlings and some later paralarval stages but this response reduces, disappears or reverses after settlement. There are many gaps in our knowledge of the planktonic phases of benthic octopuses. Most of our understanding of octopus paralarvae comes from studies of just two species (Octopus vulgaris and Enteroctopus dofleini) and knowledge of the vast majority of benthic octopus species with planktonic stages is considered rudimentary or non-existent. Research is needed in a variety of fields, from taxonomy to ecology. Studies of feeding and nutrition are critical in order to develop the nascent aquaculture of key species and ageing studies are necessary to understand planktonic population dynamics,particularly in commercially valuable species targeted by fisheries. Current and potential anthropogenic impacts on these early life stages of octopuses, such as pollution, overfishing and global warming, are also identified.

Description: A two-leg cruise of R/V G. O. Sars in summer of 2004 along the Mid-Atlantic Ridge explored the diversity and distribution patterns of pelagic and non-hydrothermal bottom communities in the vicinity of the northern Mid-Atlantic Ridge. In total, 1295 cephalopods were caught, representing 56 species. Differences in species composition and size were apparent among the various types of trawls used. The Aakra trawl and bottom trawl caught the largest numbers of species (38 and 34, respectively); size of cephalopods was directly related to the size of the net. Many more species were caught in the southern part of the study area than farther north. The most abundant species was Gonatus steenstrupi, found mostly in the northern part of the study area. A few abundant species, such as Mastigoteuthis agassizii, were found throughout the region, with no clear indication that their northern or southern distributional limits occur within the area sampled. Several benthic and one pelagic species, all taken in small numbers, were captured only in the region of the Charlie Gibbs Fracture Zone. We found many species at very low numbers (i.e. 37 species with 〈10 specimens in all gear types combined).