Epipelagic Squid Research Articles

Insights into the distribution and ingestion of prey-like plastic fishing lures in Mediterranean rough-toothed dolphins

Rough-toothed dolphins (Steno bredanensis) form an isolated subpopulation in the Mediterranean Sea that resides only in the eastern basin. Due to the paucity of records, the conservation threats these dolphins face and their ecology and distribution are poorly understood. While most observations indicate that individuals are found in two isolated clusters in the eastern basin, we hereby present five observations -three visual, one acoustic and one stranding- that possibly extend the range of this subpopulation to the entire offshore waters of the eastern basin. The stomach content remains of the stranded individual revealed a diet based on epipelagic squids and octopods. The stranded dolphin had also consumed seven plastic bags and nine squid-like plastic fishing lures, which had caused a complete gastric blockage and probably led to the stranding. High pollution loads from macroplastics in the Mediterranean Sea may evolve into a new potential threat for this subpopulation.

Life History of the Arctic Squid Gonatus fabricii (Cephalopoda: Oegopsida) Reconstructed by Analysis of Individual Ontogenetic Stable Isotopic Trajectories.

Cephalopods are important in Arctic marine ecosystems as predators and prey, but knowledge of their life cycles is poor. Consequently, they are under-represented in the Arctic ecosystems assessment models. One important parameter is the change in ecological role (habitat and diet) associated with individual ontogenies. Here, the life history of Gonatus fabricii, the most abundant Arctic cephalopod, is reconstructed by the analysis of individual ontogenetic trajectories of stable isotopes (δ13C and δ15N) in archival hard body structures. This approach allows the prediction of the exact mantle length (ML) and mass when the species changes its ecological role. Our results show that the life history of G. fabricii is divided into four stages, each having a distinct ecology: (1) epipelagic squid (ML < 20 mm), preying mostly on copepods; (2) epi- and occasionally mesopelagic squid (ML 20-50 mm), preying on larger crustaceans, fish, and cephalopods; (3) meso- and bathypelagic squid (ML > 50 mm), preying mainly on fish and cephalopods; and (4) non-feeding bathypelagic gelatinous females (ML > 200 mm). Existing Arctic ecosystem models do not reflect the different ecological roles of G. fabricii correctly, and the novel data provided here are a necessary baseline for Arctic ecosystem modelling and forecasting.

Trophic Dynamics and Feeding Ecology of Skipjack Tuna (Katsuwonus pelamis) off Eastern and Western Taiwan.

The skipjack tuna (Katsuwonus pelamis) is a mesopredator fish species with seasonal abundance in waters off Taiwan. Regional ecological and life-history information has been historically lacking for this species. In recent years, stable isotope analysis (SIA) of carbon and nitrogen has been used to assess predator feeding ecology and broader ecosystem trophic dynamics. This study evaluated comparative skipjack feeding ecology in distinct regions off Taiwan, combining traditional stomach content analysis with SIA of individuals off western (n = 43; 2020) and eastern (n = 347; 2012–2014 and n = 167; 2020) Taiwan. The stomach content analysis showed the most important prey to be ponyfish (Photopectoralis bindus) in western Taiwan and epipelagic squids (Myopsina spp.) and carangids (Decapterus macrosoma;) in eastern Taiwan from 2012 to 2014 and epipelagic carangids (Decapterus spp.) and flying fishes (Cheilopogon spp.) in eastern Taiwan in 2020, suggesting that the skipjack tuna is a generalist predator across regions. In contrast, time-integrated diet estimates from Bayesian mixing models indicated the importance of cephalopods and crustaceans as prey, potentially demonstrating more mesopelagic feeding in less productive waters during skipjack migrations outside the study regions. Skipjack off western Taiwan had a slightly higher estimated trophic position than in the waters off eastern Taiwan, potentially driven by the varying nutrient-driven pelagic food web structures. Skipjack SI values increased with body size off eastern Taiwan but not in western waters, suggesting that opportunistic predation can still result in different predator–prey size dynamics between regions.

Genetic analysis of the diet of red‐footed boobies (Sula sula) provisioning chicks at Ulupa'u Crater, O'ahu

Abstract The diet of red‐footed boobies (Sula sula) provisioning chicks was quantified using 106 regurgitations collected from 81 adults over two study years with contrasting oceanographic conditions: 2014 and 2015. A total of 1,049 prey items were sorted into three broad categories (fish, squid, and other, consisting of highly‐digested ‘mush’ and parasitic isopods) and assigned a categorical freshness value of 1 (perfect condition), 2 (superficial digestion), or 3 (highly digested and incomplete). A total of 492 undigested prey items (freshness 1 and 2) were measured and sampled for genetic identification with 401 (82%) successfully identified. Rarefaction analyses suggested robust diet sampling, with 32 documented species: 29 fishes and three squids. While the prey‐specific index of relative importance highlighted that fish dominated the diet in 2014 (32.3% fish, 15.1% squid) and in 2015 (29.9% fish, 22.3% squid), diet composition varied significantly between the two study years. The purpleback flying squid (Stenoteuthis oulaniensis) accounted for 98.7% (232 of 236) of the identified squid specimens. Mantle lengths were significantly longer in 2015 (7.2 ± 1.1 SD cm) than in 2014 (6.3 ± 1.7 SD cm). These results indicate a higher relative abundance and size of the epipelagic squids available to foraging red‐footed boobies in 2015, during warm‐water conditions associated with the positive phase of the El Niño Southern Oscillation. Due to their diverse diet, red‐footed boobies are useful bioindicators of epipelagic nekton assemblages during changing oceanographic conditions. Moreover, their reliance on the purpleback flying squid makes these seabirds ideal samplers of the juveniles of this poorly studied species. Understanding how interannual and longer‐term oceanographic variability affects central‐place foraging seabirds and the recruitment and abundance of their squid prey is critical for precautionary ecosystem‐based fisheries management of oceanic islands and the surrounding marine environment.

Slow swimming, fast strikes: effects of feeding behavior on scaling of anaerobic metabolism in epipelagic squid.

Many pelagic fishes engage prey at high speeds supported by high metabolic rates and anaerobic metabolic capacity. Epipelagic squids are reported to have among the highest metabolic rates in the oceans as a result of demanding foraging strategies and the use of jet propulsion, which is inherently inefficient. This study examined enzymatic proxies of anaerobic metabolism in two species of pelagic squid, Dosidicus gigas and Doryteuthis pealeii (Lesueur 1821), over a size range of six orders of magnitude. We hypothesized that activity of the anaerobically poised enzymes would be high and increase with size as in ecologically similar fishes. In contrast, we demonstrate that anaerobic metabolic capacity in these organisms scales negatively with body mass. We explored several cephalopod-specific traits, such as the use of tentacles to capture prey, body morphology and reduced relative prey size of adult squids, that may create a diminished reliance on anaerobically fueled burst activity during prey capture in large animals.

The jumbo squid, Dosidicus gigas (Ommastrephidae), living in oxygen minimum zones I: Oxygen consumption rates and critical oxygen partial pressures

Dosidicus gigas is a large, metabolically active, epipelagic squid known to undertake diel vertical migrations across a large temperature and oxygen gradient in the Eastern Pacific. Hypoxia is known to cause metabolic suppression in D. gigas. However, the precise oxygen level at which metabolic suppression sets in is unknown. Here we describe a novel ship-board swim tunnel respirometer that was used to measure metabolic rates and critical oxygen partial pressures (Pcrit) for adult squids (2–7kg). Metabolic rate measurements were validated by comparison to the activity of the Krebs cycle enzyme, citrate synthase, in mantle muscle tissue (2–17kg). We recorded a mean routine metabolic rate of 5.91μmolg−1h−1 at 10°C and 12.62μmolg−1h−1 at 20°C. A temperature coefficient, Q10, of 2.1 was calculated. D. gigas had Pcrits of 1.6 and 3.8kPa at 10 and 20°C, respectively. Oxygen consumption rate (MO2) varied with body mass (M) according to MO2=11.57M−0.12±0.03 at 10°C. Citrate synthase activity varied with body mass according to Y=9.32M−0.19±0.02.

Voyage of the argonauts in the pelagic realm: physiological and behavioural ecology of the rare paper nautilus, Argonauta nouryi

AbstractRosa, R., and Seibel, B. A. 2010. Voyage of the argonauts in the pelagic realm: physiological and behavioural ecology of the rare paper nautilus, Argonauta nouryi. – ICES Journal of Marine Science, 67: 1494–1500. The metabolic demands of a rare paper nautilus, Argonauta nouryi, in the eastern tropical Pacific (ETP) are evaluated. After adjusting for temperature and size, the rates of oxygen consumption and of aerobic and anaerobic metabolic potential (as evidenced by citrate synthase and octopine dehydrogenase activities, respectively) of A. nouryi were much higher than those in holopelagic octopods that exhibit float-and-wait predation strategies. In fact, the rates were similar to those found in small epipelagic squids and benthic octopods. The critical oxygen partial pressure was 4.9 kPa at 20°C, suggesting that the strong oxygen minimum layer found at intermediate depths in the ETP may constrain the vertical distribution of A. nouryi to the upper few metres of the water column. We also report the occurrence of a chain of shelled females at the surface, in which each animal was attached, as if on the benthos, to the next individual in the chain. Although it may constitute an effective strategy to increase the rates of mate encounter in the vast open ocean, there may be an important ecological trade-off for such behaviour, namely the increase in visibility at the surface with concomitant attraction of predators.

Clicking for calamari: toothed whales can echolocate squid Loligo pealeii

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 1:141-150 (2007) - DOI: https://doi.org/10.3354/ab00014 Clicking for calamari: toothed whales can echolocate squid Loligo pealeii P. T. Madsen1,2,*, M. Wilson1, M. Johnson2, R. T. Hanlon3, A. Bocconcelli2, N. Aguilar de Soto4, P. L. Tyack2 1Zoophysiology, Department of Biological Sciences, University of Aarhus, Building 1131, 8000 Aarhus C, Denmark 2Woods Hole Oceanographic Institution, and 3Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA 4La Laguna University Tenerife, Canary Islands, Spain *Email: peter.madsen@biology.au.dk ABSTRACT: Squid play an important role in biomass turnover in marine ecosystems and constitute a food source for ~90% of all echolocating toothed whale species. Nonetheless, it has been hypothesized that the soft bodies of squid provide echoes too weak to be detected by toothed whale biosonars, and that only the few hard parts of the squid body may generate significant backscatter. We measured the acoustic backscatter from the common squid Loligo pealeii for signals similar to toothed whale echolocation clicks using an energy detector to mimic the mammalian auditory system. We show that the dorsal target strengths of L. pealeii with mantle lengths between 23 and 26 cm fall in the range from –38 to –44 dB, and that the pen, beak and lenses do not contribute significantly to the backscatter. Thus, the muscular mantle and fins of L. pealeii constitute a sufficient sonar target for individual biosonar detection by toothed whales at ranges between 25 and 325 m, depending on squid size, noise levels, click source levels, and orientation of the ensonified squid. While epipelagic squid must be fast and muscular to catch prey and avoid visual predators, it is hypothesized that some deep-water squid may have adopted passive acoustic crypsis, with a body of low muscle mass and low metabolism that will render them less conspicuous to echolocating predators. KEY WORDS: Squid · Predator · Prey · Echolocation · Toothed whale · Target strength Full text in pdf format PreviousNextCite this article as: Madsen PT, Wilson M, Johnson M, Hanlon RT, Bocconcelli A, Aguilar de Soto N, Tyack PL (2007) Clicking for calamari: toothed whales can echolocate squid Loligo pealeii. Aquat Biol 1:141-150. https://doi.org/10.3354/ab00014 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 1, No. 2. Online publication date: November 27, 2007 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2007 Inter-Research.

On the depth and scale of metabolic rate variation: scaling of oxygen consumption rates and enzymatic activity in the Class Cephalopoda(Mollusca)

Recent ecological theory depends, for predictive power, on the apparent similarity of metabolic rates within broad taxonomic or functional groups of organisms (e.g. invertebrates or ectotherms). Such metabolic commonality is challenged here, as I demonstrate more than 200-fold variation in metabolic rates independent of body mass and temperature in a single class of animals, the Cephalopoda, over seven orders of magnitude size range. I further demonstrate wide variation in the slopes of metabolic scaling curves. The observed variation in metabolism reflects differential selection among species for locomotory capacity rather than mass or temperature constraints. Such selection is highest among epipelagic squids (Lolignidae and Ommastrephidae) that, as adults, have temperature-corrected metabolic rates higher than mammals of similar size.

Light-limitation on predator-prey interactions: consequences for metabolism and locomotion of deep-sea cephalopods.

The present study attempts to correlate the metabolism and locomotory behavior of 25 species of midwater Cephalopoda from California and Hawaii with the maximal activities of key metabolic enzymes in various locomotory muscle tissues. Citrate synthase (CS) and octopine dehydrogenase (ODH) activities were used as indicators of aerobic and anaerobic metabolic potential respectively. CS activity in mantle muscle is highly correlated with whole-animal rates of oxygen consumption, whereas ODH activity in mantle muscle is significantly correlated with a species' ability to buffer the acidic end-products of anaerobic metabolism. Both CS and ODH activities in mantle muscle declined strongly with a species' habitat depth. For example, CS and ODH activities ranged respectively from 0.04 units g(-1) and 0.03 units g(-1) in the deep-living squid Joubiniteuthis portieri, to 8.13 units g(-1) and 420 units g(-1) in the epipelagic squid Sthenoteuthis oualaniensis. The relationships between enzymatic activities and depth are consistent with similar patterns observed for whole-animal oxygen consumption. This pattern is believed to result from a relaxation, among deep-living species, in the need for strong locomotory abilities for visual predator/prey interactions; the relaxation is due to light-limitation in the deep sea. Intraspecific scaling patterns for ODH activities may, for species that migrate ontogenetically to great depths, reflect the counteracting effects of body size and light on predator-prey detection distances. When scaled allometrically, enzymatic activities for the giant squid, Architeuthis sp., suggest a fairly active aerobic metabolism but little burst swimming capacity. Interspecific differences in the relative distributions of enzymatic activities in fin, mantle, and arm tissue suggest an increased reliance on fin and arm muscle for locomotion among deep-living species. We suggest that, where high-speed locomotion is not required, more efficient means of locomotion, such as fin swimming or medusoid arm propulsion, are more prevalent.

Decline in Pelagic Cephalopod Metabolism With Habitat Depth Reflects Differences in Locomotory Efficiency.

The metabolic rates of 33 species of pelagic cephalopods from California and Hawaii were measured and correlated with minimum depth of occurrence. Mean metabolic rates ranged from 0.07 {mu}mol O2g-1 h-1 for the deep-living vampire squid, Vampyroteuthis infernalis, to 8.79 {mu}mol O2 g-1 h-1 for Gonatus onyx, a vertically migrating squid. An individual of V. infernalis, which lives within the oxygen minimum layer off California, had the lowest mass-specific metabolic rate ever measured for a cephalopod (0.02 {mu}mol O2g-1 h-1, 1050 g wet weight). For species collected in sufficient quantity and size range, metabolism was related to body size. Critical partial pressures of oxygen (Pc) were determined for Hawaiian and Californian cephalopods. Pc values for Hawaiian animals were considerably higher than for those taken off California, a trend that corresponds to the higher levels of environmental oxygen in the Hawaiian waters. Buffering capacity ({beta}) of mantle muscle, assayed in eight cephalopod species, was used to estimate the capacity for glycolytic energy production. Mean {beta} ranged from 1.43 slykes for a bathypelagic octopod, Japetella heathi, to 77.08 slykes for an epipelagic squid. Sthenoteuthis oualaniensis. Significant declines with increasing depth of occurrence were observed for both metabolism and {beta}. The decline in metabolic parameters with depth is interpreted as a decreased reliance on locomotory abilities for predator/prey interactions in the light-limited deep sea. The decline in metabolism with depth observed for pelagic cephalopods was significantly steeper than that previously observed for either pelagic fishes or crustaceans. We suggest that since strong locomotory abilities are not a priority in the deep sea, deeper-living cephalopods may rely more heavily on means of locomotion that are more efficient than jet propulsion via mantle contractions--means such as fin swimming or medusoid swimming utilizing the arms and extensive webbing present in many deep-living species. The greater efficiency of deeper-living cephalopods may be responsible for the observation that the decline in metabolic rates with depth is more pronounced for pelagic cephalopods than for fishes or crustaceans.