Biology of the cirrate octopod grimpoteuthis glacialis (cephalopoda; opisthoteuthididae) in the south Shetland Islands, Antarctica

The capture of 52 specimens of the cirrate octopod Grimpoteuthis glacialis (Robson, 1930), of dorsal mantle length 20–165 mm during a 1996 trawling survey near the Antarctic Peninsula allowed the basic biology ofthe species to be examined. Their presence in bottom trawls at depths of 333–879 m, but their absence from benthopelagic and pelagic trawls, is consistent with a primarily benthic habitat. The largest single sample, 40animals, came from a soft mud bottom and highlights the patchy nature of the distribution. Males tended to be bigger in total length and mass than females of similar mantle length. The males, however, were mature ata smaller size. Mature males have tiny sperm packets, rather than typical cephalopod spermatophores, in their distal reproductive tract. Mature females have large, smooth eggs in the proximal oviduct, in the huge oviducal gland and in the distal oviduct. Eggs in the distal oviduct have a thick, sticky coating that hardens in seawater into a secondary egg case. Ovarian eggs vary greatly in size, possibly indicating protracted egg laying.Observations on live animals indicate that the species swims primarily by fin action, rather than by jetting or medusoid pulses with the arm/web complex. It may be capable of limited changes in colour pattern,especially on the oral surface of the web. Three pairs of surface structures that appear superficially to be white spots anterior to the eyes and near the bases of the fins are actually transparent patches in the skin. Whenconsidered in association with the transparent subdermal layer and the anatomy of the eyes, optic nerves and optic lobes, these clear patches seem to function in detecting unfocused light on the horizontal plane of the benthic animal

On the biology of the European flying squid Todarodes Sagittatus (Lamarck, 1798) (cephalopoda, ommastrephidae) in the Central Eastern Atlantic

A total of 206 specimens of the ommastrephid squid Todarodes sagittatus, obtained from three areas of the central eastern Atlantic (Canary Islands/African coast, Madeira, and the Gettysburg Bank area south of Portugal) were examined. New information on size, mass, length-mass relationships, reproductive biology, and diet of the squid from a hitherto not very well studied area is supplied. Females dominated the samples (78%) and attained larger size and mass than males. Dorsal mantle lengths of T. sagittatus in the Canary Islands/African coast samples and in the Madeira region were similar, 167 – 348 mm for females and 175 – 269 mm for males. From the Gettysburg Bank all specimens were immature, females ranging between 71 and 276 mm and males from 98 to 233 mm. Mature females were found mainly during winter and mature males nearly year-round,indicating that they mature earlier than females and at a smaller size. Prey consisted mainly of fish (54.9%), decapods (18.8%) and cephalopods (12.1%). Otoliths and fish bones identified from stomach contents suggestthat myctophids were the most common and diverse prey

Age and growth estimation of Southern Ocean squid Moroteuthopsis longimana: can we use beaks collected from predators’ stomachs?

Squid play a major role in the Southern Ocean food web. However, their age and growth remain poorly studied. Here, using upper and lower beaks of Moroteuthopsis longimana collected from the diet of Dissostichus mawsoni from Pacific and Atlantic sectors of the Southern Ocean, we studied: (1) Feasibility of using beaks collected from predators’ stomachs to study the age of Southern Ocean oceanic squid; and (2) Age estimation and growth patterns of M. longimana. The rostrum sagittal section (RSS) of both beaks had micro-increments, with the lower beak being the best to observe and count a readable sequence of increments to estimate the age. Assuming a daily deposition of increments, our results suggest that M. longimana can live up to 820 days and may hatch throughout the year. Studied individuals presented a consistent growth rate from hatching to death but with, at least, one period of faster growth. A novel pattern of regular cycles, composed of 7–10 lighter increments followed by a darker one, was found in the medium-anterior region of the RSS. Differences were found in the growth rate and size reached at the same age between individuals from the Pacific and Atlantic sectors, which might be related with different environmental conditions between both capture sites. This study shows that lower beaks from predators’ stomachs can be used to study the age of Southern Ocean squids and that M. longimana hatches in all seasons, being available year round to predators that feed of this species

Analysis of Heat Effects on Marine Corps AM2 Mat Mechanical Properties

Navy AM2 mats are used as portable aircraft landing platforms for the Short Take-off/Vertical Landing (STOVL) aircraft operations. This investigation presents the study performed to determine whether the surface discoloration is a precursor to degradation in the mechanical property of the AM2 mat material. The red discoloration on the mat surfaces had a clear correlation with the decrease in yield strength, ultimate strength, and hardness properties

The effect of the North Atlantic Subpolar Front as a boundary in pelagic biogeography decreases with increasing depth and organism size

Broad-scale patterns in the distribution of deep-sea pelagic species and communities are poorly known. An important question is whether biogeographic boundaries identified from surface features are important in the deep mesopelagic and bathypelagic. We present community analyses of discrete-depth samples of mesozooplankton and micronekton to full-ocean depth collected in the area where the Mid-Atlantic Ridge is crossed by the Subpolar Front. The results show that the distributional discontinuity associated with the front, which is strong near the surface, decreases with increasing depth. Both the frontal separation near the surface and the community convergence at increasing depths were clearer for mesozooplankton than for micronekton

Beached bachelors: an extensive study on the largest recorded sperm whale <i>Physeter macrocephalus</i> mortality event in the North Sea

Between the 8th January and the 25th February 2016, the largest sperm whale Physeter macrocephalus mortality event ever recorded in the North Sea occurred with 30 sperm whales stranding in five countries within six weeks. All sperm whales were immature males. Groups were stratified by size, with the smaller animals stranding in the Netherlands, and the largest in England. The majority (n = 27) of the stranded animals were necropsied and/or sampled, allowing for an international and comprehensive investigation into this mortality event. The animals were in fair to good nutritional condition and, aside from the pathologies caused by stranding, did not exhibit significant evidence of disease or trauma. Infectious agents were found, including various parasite species, several bacterial and fungal pathogens and a novel alphaherpesvirus. In nine of the sperm whales a variety of marine litter was found. However, none of these findings were considered to have been the primary cause of the stranding event. Potential anthropogenic and environmental factors that may have caused the sperm whales to enter the North Sea were assessed. Once sperm whales enter the North Sea and head south, the water becomes progressively shallower (<40 m), making this region a global hotspot for sperm whale strandings. We conclude that the reasons for sperm whales to enter the southern North Sea are the result of complex interactions of extrinsic environmental factors. As such, these large mortality events seldom have a single ultimate cause and it is only through multidisciplinary, collaborative approaches that potentially multifactorial large-scale stranding events can be effectively investigated

Climate Change and invasibility of the Antarctic benthos

Benthic communities living in shallow-shelf habitats in Antarctica (&lt;100-m depth) are archaic in their structure and function. Modern predators, including fast-moving, durophagous (skeleton-crushing) bony fish, sharks, and crabs, are rare or absent; slow-moving invertebrates are the top predators; and epifaunal suspension feeders dominate many soft substratum communities. Cooling temperatures beginning in the late Eocene excluded durophagous predators, ultimately resulting in the endemic living fauna and its unique food-web structure. Although the Southern Ocean is oceanographically isolated, the barriers to biological invasion are primarily physiological rather than geographic. Cold temperatures impose limits to performance that exclude modern predators. Global warming is now removing those physiological barriers, and crabs are reinvading Antarctica. As sea temperatures continue to rise, the invasion of durophagous predators will modernize the shelf benthos and erode the indigenous character of marine life in Antarctica

Catchability of pelagic trawls for sampling deep-living nekton in the mid-North Atlantic

Material collected in summer 2004 from the Mid-Atlantic Ridge between Iceland and the Azores with three pelagic trawls was used to estimate relative catchabilities of common fish, cephalopod, decapod, and jellyfish species. Catchability is defined as the ratio of numbers caught between two trawls, standardized for towed distance. Taxon-specific catchability coefficients were estimated for two large pelagic trawls with graded meshes, using a smaller pelagic trawl with a uniform mesh size as the reference trawl. Two of the trawls were equipped with multiple opening–closing codends that allowed sampling of different depth layers. Generalized linear and mixed models suggest that most of the taxa have catchabilities much lower than expected from the area of opening alone, indicating that only a few species are herded by the large mesh at the mouth of larger trawls. Catchability coefficients across taxa show a very large spread, indicating that the sampled volume for the larger trawls with graded meshes was highly taxon-specific. Part of this variability can be explained by body size and taxonomic group, the latter probably reflecting differences in body form and behaviour. The catchability estimates presented here form the basis for combining data for quantitative analyses of community structure

Anterior interosseous nerve syndrome: retrospective analysis of 14 patients

Introduction: The anterior interosseous nerve (AIN) is a only motor nerve innervating the deep muscles of the forearm. Its compression is rare. We present a retrospective analysis of 14 patients with an AIN syndrome with a variety of clinical manifestations who underwent operative and conservative treatment. Patients and methods: Fourteen patients (six female, eight male, mean age 48 ± 9 years) were included. In six patients, the right limb was affected, and in eight patients the left limb. Conservative treatment was started for every patient. If no signs of recovery appeared within 3 months, operative exploration was performed. Final assessment was performed between 2 and 9 years after the onset of paralysis (mean duration of follow-up 46 ± 11 months). Patients were examined clinically for return of power, range of motion, pinch and grip strengths. Also the disability of the arm, shoulder, and hand (DASH) score was calculated. Results: Seven of our 14 patients had incomplete AIN palsy with isolated total loss of function of flexor pollicis longus (FPL), five of FPL and flexor digitorum profundus (FDP)1 simultaneously, and two of FDP1. Weakness of FDP2 could be seen in four patients. Pronator teres was paralysed in two patients. Pain in the forearm was present in nine patients. Four patients had predisposing factors. Eight patients treated conservatively exhibited spontaneous recovery from their paralysis during 3-12 months after the onset. In six patients, the AIN was explored 12 weeks after the initial symptoms and released from compressing structures. Thirteen patients showed good limb function. In one patient with poor result a tendon transfer was necessary. The DASH score of patients treated conservatively and operatively presented no significant difference. Conclusion: AIN syndrome can have different clinical manifestations. If no signs of spontaneous recovery appear within 12 weeks, operative treatment should be performed