John Fleng Steffensen

University of Copenhagen · Department of Biology

The Greenland shark (Somniosus microcephalus) is the longest-lived vertebrate known, with an estimated lifespan of ~ 400 years. Here, we present a chromosome-level assembly of the 6.45 Gb Greenland shark, rendering it one of the largest non-tetrapod genomes sequenced so far. Expansion of the genome is mostly accounted for by a substantial expansion...

Cartilaginous fishes have large and elaborate olfactory organs, but only a small repertoire of olfactory receptor genes. Here, we quantitatively analyze the olfactory system of 21 species of sharks and rays, assessing many features of the olfactory organ (OOR) (number of primary lamellae, branches of the secondary folds, sensory surface area, and d...

Introduction: Hypoxia, an increasingly common stressor in coastal environments, lowers the scope for aerobic activity such as sustained swimming. This study examines the effect of self-depleting progressive hypoxia on swimming performance and oxygen consumption of the pile perch, Phanerodon vacca, at their optimal speed (Uopt =29 cm·s−1). P. vacca...

In the context of global warming and the concurrent decrease in ectothermic fish body size, the mechanisms driving this phenomenon remain a subject of scientific debate. This study, utilizing the Atlantic cod (Gadus morhua) as a model organism, delves into the behavioral size-dependent temperature preference in the context of climate change. A sign...

Billfish rostra potentially have several functions; however, their role in feeding is unequivocal in some species. Recent work linked morphological variation in rostral micro‐teeth to differences in feeding behavior in two billfish species, the striped marlin (Kajikia audax) and the sailfish (Istiophorus platypterus). Here, we present the rostral m...

Simple Summary This study establishes how trout’s swimming energy changes under various oxygen levels and temperatures, leading to the development of a model that predicts oxygen conditions inside the cages. A case study using the model reveals that a 10 °C rise in temperature causes oxygen concentration to drop threefold, necessitating a 3.7-fold...

The Atlantic bluefin tuna (ABFT) is a highly prized species of large pelagic fish. Studies of their environmental physiology may improve understanding and management of their populations, but this is difficult for mature adults because of their large size. Biologging of heart rate holds promise in investigating physiological responses to environmen...

Global warming affects the metabolism of ectothermic aquatic breathers forcing them to migrate and undergo high‐latitudinal distribution shifts to circumvent the temperature‐induced mismatch between increased metabolic demand and reduced water oxygen availability. Here the authors examined the effects of temperature on oxygen consumption rates in a...

Nei Like DNA Glycosylase 1 (NEIL1) is a DNA glycosylase, which specifically processes oxidative DNA damage by initiating base excision repair. NEIL1 recognizes and removes bases, primarily oxidized pyrimidines, which have been damaged by endogenous oxidation or exogenous mutagenic agents. NEIL1 functions through a combined glycosylase/AP (apurinic/...

Oral communication presented during a session dedicated to the scientific career and achievements of Prof John Fleng Steffensen and entitled "Session Fish environmental physiology: A tribute to John Fleng Steffensen "

The abstract of this oral communication is on page 10 of the PDF.

Fish perform rapid escape responses to avoid sudden predatory attacks. During escape responses, fish bend their bodies into a C-shape and quickly turn away from the predator and accelerate. The escape trajectory is determined by the initial turn (Stage 1) and a contralateral bend (Stage 2). Previous studies have used a single threat or model predat...

Recent comparative studies of billfishes (Istiophoridae and Xiphiidae) have provided evidence of differences in the form and function of the rostra (bill) among species. Here, we report the discovery of a new structure, lacuna rostralis, on the rostra of sailfish Istiophorus platypterus, which is absent on the rostra of swordfish Xiphias gladius, s...

How ectothermic animals will cope with global warming is a critical determinant of the ecological impacts of climate change. There has been extensive study of upper thermal tolerance limits among fish species but how intraspecific variation in tolerance may be affected by habitat characteristics and evolutionary history has not been considered. Int...

Fish perform rapid escape responses to avoid sudden predatory attacks. During escape responses, fish bend their bodies into a C-shape and quickly turn away from the predator and accelerate. The escape trajectory is determined by the initial turn (Stage 1) and a contralateral bend (Stage 2). Previous studies have used a single threat or model predat...

Increasing ocean temperatures and the resulting poleward range shifts of species has highlighted the importance of a species preferred temperature and thermal range in shaping ecological communities. Understanding the temperatures preferred and avoided by individual species, and how these are influenced by species interactions is critical in predic...

Animals' selection of environments within a preferred range is key to understanding their habitat selection, tolerance to stressors and responses to environmental change. For aquatic animals, preferred environmental ranges can be studied in so-called shuttle-boxes, where an animal can choose its ambient environment by shuttling between separate cho...

Preliminary manual for dummies for GUDP FitFish aquaculture o2 model. ver 1

GUDP FitFish Aquaculture O2 model example: The model can be tested from this link to the Aquaculture O2 model: http://o2aquaculturemodel.pythonanywhere.com/ Below is a an example of the model output:

ow to DIY cheap static respirometers: 3-D print the end caps, coat them w clear spray paint used for cars, and use a glass tube. Bingo! We will upload a file for your 3D-printer shortly. For invertebrates you may use a Pyrex glass beaker or bowl and just one printed endcap at the top. Place the invertebrate on a mesh with a small (glass coated) mag...

How to DIY cheap static respirometers: 3-D print the end caps, coat them clear spray paint used for cars, and use a glass tube. Bingo! We will upload a file for your 3D-printer shortly. For invertebrates you may use a Pyrex glass beaker or bowl and just one printed endcap at the top. Place the invertebrate on a mesh with a small (glass coated) magn...

Fast escape responses to a predator threat are fundamental to the survival of mobile marine organisms. However, elasmobranchs are often underrepresented in such studies. Here, we measured the escape latency (time interval between the stimulus and first visible reaction) of mechanically-induced escape responses in the Pacific spiny dogfish, Squalus...

Old And Cold: Biology of Greenland Shark main website @ UniCph

Highly variable thermal environments, such as coral reef flats, are challenging for marine ectotherms and are thought to invoke the use of behavioural strategies to avoid extreme temperatures and seek out thermal environments close to their preferred temperatures. Common to coral reef flats, the epaulette shark (Hemiscyllium ocellatum) possesses ph...

How ectothermic animals will cope with global warming, especially more frequent and intense heatwaves, is a critical determinant of the ecological impacts of climate change. There has been extensive study of upper thermal tolerance limits among fish species but how intraspecific variation in tolerance may be affected by habitat characteristics and...

Anadromous sub-populations of stenohaline freshwater fish are vastly understudied in the estuarine environment. The purpose of the present study was therefore to study the population ecology, growth rate, and physico-chemical environment of an anadromous sub-population of European perch (Perca fluviatilis) from the western Baltic Sea. Fish (301) we...

UW FHL Fish Swim Course Resting or Static Respirometry

UW FHL Fish Swim Course Teachers

Swim Tunnels we use or have used @ UW FHL Fish Swim Courses

Manual for SwisTrack - free real-time software for tracking one or more fish - allowing experiments with feed-back on the animal.

How to build a temperature instrument with analog output

3D view of the Steffensen shuttle box system - preliminary version

The Greenland shark (Somniosus microcephalus, Squaliformes: Somniosidae) is a long-lived Arctic top predator, which in combination with the high historical and modern fishing pressures, has made it subject to increased scientific focus in recent years. Key aspects of reproduction are not well known as exemplified by sparse and contradictory informa...

UW FHL Fish Swimming Course 2019 Reports

Wave-induced surge conditions are found in shallow marine ecosystems worldwide; yet, few studies have quantified how cyclical surges may affect free swimming animals. Here, we used a recently adapted respirometry technique to compare the energetic costs of a temperate fish species (Cymatogaster aggregata) swimming against a steady flow versus cycli...

Coral reef species, like most tropical species, are sensitive to increasing environmental temperatures, with many species already living close to their thermal maxima. Ocean warming and the increasing frequency and intensity of marine heatwaves are challenging the persistence of reef-associated species through both direct physiological effects of e...

Billfishes are well-known for their distinctive elongated rostra, a.k.a. bills. The functional significance of billfish rostra has been frequently discussed and the recent discovery of an oil gland (glandula oleofera) at the base of the rostrum in swordfish, Xiphias gladius , has added an interesting facet to this discussion regarding the potential...

The present study determined the effect of body mass and acclimation temperature (15–28°C) on oxygen consumption rate (ṀO2) and the size dependency of preferred temperature in European perch Perca fluviatilis. Standard metabolic rate (SMR) scaled allometrically with body mass by an exponent of 0.86, and temperature influenced SMR with a Q10 of 1.9...

Unsteady, dynamic flow regimes commonly found in shallow marine ecosystems such as coral reefs pose an energetic challenge for mobile organisms that typically depend on station holding for fitness-related activities. The majority of experimental studies, however, have measured energetic costs of locomotion at steady speeds, with only a few studies...

Linking morphological differences in foraging adaptations to prey choice and feeding strategies has provided major evolutionary insights across taxa. Here, we combine behavioural and morphological approaches to explore and compare the role of the rostrum (bill) and micro-teeth in the feeding behaviour of sailfish (Istiophorus platypterus) and strip...

Changes in environmental salinity challenge fish homeostasis and may affect physiological performance, such as swimming capacity and metabolism, which are important for foraging, migration, and escaping predators in the wild. The effects of salinity stress on physiological performance are largely species specific, but may also depend on intra-speci...

Many vertebrate animals employ anaerobic pathways during high-speed exercise, even if it imposes an energetic cost during postexercise recovery, expressed as excess postexercise oxygen consumption (EPOC). In ectotherms such a fish, the initial anaerobic contribution to exercise is often substantial. Even so, fish may recover from anaerobic pathways...

Shark swam slowly by our baited video platform at a depth of 225 meters close to Quqertarsuaq/Godhavn May 2019 - but didn't take the bait. https://youtu.be/Lw0KCMW6Cw8

UW FHL Fish Swimming Course Reports 2011

UW FHL Fish Swimming Course Reports 2017

During the last century, the blooms of the toxic haptophyte Prymnesium parvum have been responsible for massive fish kills in both aquaculture and wild populations. Despite decades of research, the ichthyotoxic properties of P. parvum, and how this alga affects fish, is still debated. Using a novel device to measure the respirometry, ventilation vo...

Shark skin has for many years inspired engineers to produce biomimetic structures reducing surface drag or acting as an anti-fouling layer. Both effects are presumed to be consequences of the structure of shark skin that is composed of arrays of so-called dermal denticles. However, the understanding of the full functional role of the dermal denticl...

Objective— Pathological neovascularization is crucial for progression and morbidity of serious diseases such as cancer, diabetic retinopathy, and age-related macular degeneration. While mechanisms of ongoing pathological neovascularization have been extensively studied, the initiating pathological vascular remodeling (PVR) events, which precede neo...

Current knowledge on the feeding ecology of the Greenland shark (Somniosus microcephalus), a potential top predator in arctic marine ecosystems, is based on small sample sizes as well as narrow size ranges of sharks. Therefore, potential size-related feeding patterns remain poorly documented. Using stomach content data (N=88) and stable isotope val...

Long-lived species share life history traits such as slow growth, late maturity, and low fecundity, which lead to slow recovery rates and increase a population’s vulnerability to disturbance. The Greenland shark (Somniosus microcephalus) has recently been recognized as the world’s longest-lived vertebrate, but many questions regarding its biology,...

Although considered a stenohaline freshwater species, European perch (Perca fluviatilis) inhabit brackish waters. The present study determined the maximum salinity tolerance and osmoregulatory capability on individuals originating from brackish water and from freshwater populations. The fish were acclimated for 3 weeks to salinities of 0, 10, 12.5,...

This study investigated the oxygen consumption of the putative oxygen conformer marbled swamp eel Synbranchus marmoratus during progressive hypoxia. Earlier studies have not reached an agreement on whether S. marmoratus is a conformer or a regulator. Our results support the view that S. marmoratus is an oxygen regulator, like most bony fishes.

Tropical coral reef flats can be 3–4 °C warmer than surrounding deeper reef slopes, and some experience daily temperature fluctuations of up to 12 °C, which will be exacerbated as global temperatures continue to rise. Epaulette sharks (Hemiscyllium ocellatum), predominantly found on reef flats, may have evolved behavioural and/or physiological stra...

We conducted in vitro inflations of freshly excised ventral aortas of the Greenland shark, Somniosus microcephalus, and used pressure-diameter data to estimate the point of transition from high to low compliance, which has been shown to occur at the mean blood pressure in other vertebrates including fishes. We also determined the pressure at which...

Fish swimming energetics are often measured in laboratory environments which attempt to minimize turbulence, though turbulent flows are common in the natural environment. To test whether the swimming energetics and kinematics of shiner perchCymatogaster aggregata(a labriform swimmer) were affected by turbulence, two flow conditions were constructed...

Blooms of the planktonic alga Prymnesium parvum pose a global threat, causing fish kills worldwide. Early studies on the exposure of fish to P. parvum indicate that toxic effects are related to gill damage. The more strictly defined concept of adverse outcome pathways has been suggested as a replacement for the mode of action in toxicology studies....

Fast-start escape responses are used by fish when dealing with predatory threats that require a quick response with high velocity. Recent work on archerfish has suggested that the kinematics of a fast start towards a prey is similar to that of escape response from a threat. Here we test the hypothesis that untrained predatory fish would respond to...

The Greenland shark (Somniosus microcephalus. Bloch & Schneider 1801) is a polar elasmobranch that is hypothesised to possess a unique metabolic physiology due to its extreme large size, the cold waters it inhabits and its slow swimming lifestyle. Our results therefore provide the first insight into the metabolic physiology of this unique shark, wi...

Conventionally, dynamic energy budget (DEB) models operate with animals that have maintenance rates scaling with their body volume, and assimilation rates scaling with body surface area. However, when applying such criteria for the individual in a population level model, the emergent behaviour of the conventional model apparently only reflects juve...

No dongle required. If you have the oxygen sensor you can automate your resting aquatic respirometry setup for about 100 US $. The program is Phyton and you can adapt it if you wish. A version for swimming respirometry is currently tested in Denamrk, Japan and the US and will be released shortly. Many thanks to Maorten Bo Søndergaard Svendsen for w...

Low-oxygen areas are expanding in the oceans as a result of climate change. Work carried out during the past two decades suggests that, in addition to impairing basic physiological functions, hypoxia can also affect fish behaviour. Given that many fish species are known to school, and that schooling is advantageous for their survival, the effect of...

The costs and benefits of group living often depend on the spatial position of individuals within groups and the ability of individuals to occupy preferred positions. For example, models of predation events for moving prey groups predict higher mortality risk for individuals at the periphery and front of groups. We investigated these predictions in...

For full text visit (Springer Nature content sharing initiative): http://rdcu.be/kt2P Assessment of maximum aerobic scope, as a proxy for scope of activity, in ectotherms can be instrumental in predicting distributional responses to e.g. global warming. The waters of the Arctic regions represent one of the most vulnerable ecosystems to climate cha...