scholarly journals Gill slits provide a window into the respiratory physiology of sharks

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Wade J VanderWright ◽  
Jennifer S Bigman ◽  
Cayley F Elcombe ◽  
Nicholas K Dulvy
Keyword(s):  
Metabolic Rate ◽  
Surface Area ◽  
Life Histories ◽  
Extinction Risk ◽  
Order Approximation ◽  
Fork Length ◽  
Respiratory Physiology ◽  
Gill Slit ◽  
Field Guide ◽  
Gill Surface Area

Abstract Metabolically important traits, such as gill surface area and metabolic rate, underpin life histories, population dynamics and extinction risk, as they govern the availability of energy for growth, survival and reproduction. Estimating both gill surface area and metabolic rate can be challenging, especially when working with large-bodied, threatened species. Ideally, these traits, and respiratory physiology in general, could be inferred from external morphology using a faster, non-lethal method. Gill slit height is quick to measure on live organisms and is anatomically connected to the gill arch. Here, we relate gill slit height and gill surface area for five Carcharhiniform sharks. We compared both total and parabranchial gill surface area to mean and individual gill slit height in physical specimens. We also compared empirical measurements of relative gill slit height (i.e. in proportion to total length) to those estimated from field guide illustrations to examine the potential of using anatomical drawings to measure gill slit height. We find strong positive relationships between gill slit height and gill surface area at two scales: (i) for total gill surface area and mean gill slit height across species and (ii) for parabranchial gill surface area and individual gill slit height within and across species. We also find that gill slit height is a consistent proportion of the fork length of physical specimens. Consequently, relative gill slit height measured from field guide illustrations proved to be surprisingly comparable to those measured from physical specimens. While the generality of our findings needs to be evaluated across a wider range of taxonomy and ecological lifestyles, they offer the opportunity that we might only need to go to the library and measure field guide illustrations to yield a non-lethal, first-order approximation of the respiratory physiology of sharks.

scholarly journals Interspecific Differences in the Metabolic Rate, Gill Dimension and Hematology of Fish in an Amazonian Floodplain Lake

2020 ◽  
Vol 8 (1) ◽  
pp. 38
Author(s):  
Wallice P. Duncan
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Surface Area ◽  
Floodplain Lake ◽  
Blood Oxygen ◽  
Metabolic Rates ◽  
Benthic Species ◽  
Pelagic Species ◽  
Oxygen Capacity ◽  
Gill Surface Area

It has been hypothesized that respiratory physiology in fish is closely associated with ecological traits. Therefore, data on gill morphometrics (lamellae frequency, gill surface area and barrier thickness), metabolic rate (oxygen consumption) and blood oxygen capacity (hematology) were analyzed in several fish, including benthic, bentho-pelagic and pelagic species collected in an Amazon floodplain lake. Similar to other teleostean species, the 2nd and 3rd gill arches have numerous large filaments in both pelagic and benthic species, as these characteristics tend to increase the gill surface area. A large gill area (4 to 7 cm2 g-1, mass-specific) is associated with a high (100 to 300 mg O2 h-1 kg-1) routine oxygen consumption rate and has been observed in active pelagic swimmers, such as Cichla monoculus and Pygocentrus nattereri. Benthic dwelling fish (e.g., Pterygoplichthys pardalis and Sorubim lima) have low metabolic rates (20 to 50 mg O2 h-1 kg-1), small gill dimensions (2 to 3 cm2 g-1, mass-specific), low hemoglobin levels (3 to 5 g dL-1), reduced numbers of circulating red blood cells (1 to 2 Í106 mm-3) and low hematocrit values (25 to 35%) compared to pelagic species. These results demonstrated that pelagic fish have high routine oxygen consumption rates compatible with their large gill surface area and high blood oxygen capacity, whereas benthic species have low metabolic rates, small gill dimensions and reduced blood oxygen capacity.

Spatial distribution of the parasite Kroyeria carchariaeglauci Hesse, 1879 (Copepoda: Siphonostomatoida: Kroyeriidae) on gills of the blue shark (Prionace glauca (L., 1758))

1987 ◽  
Vol 65 (5) ◽  
pp. 1275-1281 ◽  
Author(s):  
George W. Benz ◽  
Kevin S. Dupre
Keyword(s):  
Spatial Distribution ◽  
Natural Selection ◽  
Distribution Pattern ◽  
Surface Area ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Homogeneous Groups ◽  
Secondary Lamellae ◽  
Gill Filaments ◽  
Gill Surface Area

Five blue sharks (Prionace glauca) were examined for gill-infesting copepods. Three species of siphonostomatoid copepods were collected: Gangliopus pyriformis, Phyllothyreus cornutus, and Kroyeria carchariaeglauci. The spatial distribution of K. carchariaeglauci was analyzed. The number of K. carchariaeglauci per shark was positively related to gill surface area and host size. Copepods were unevenly distributed amongst hemibranchs; flanking hemibranchs could be arranged into three statistically homogeneous groups. Female K. carchariaeglauci typically attached themselves within the middle 40% of each hemibranch; males were more evenly dispersed. Eighty percent of all K. carchariaeglauci attached themselves to secondary lamellae, the remainder were in the underlying excurrent water channels. Most K. carchariaeglauci were located between 10 and 25 mm along the lengths of gill filaments. Overall, the spatial distribution of K. carchariaeglauci was quite specific in all study planes. Explanation of this distribution is set forth in terms of natural selection pressures; however, the equally plausible explanation that the distribution pattern exhibited by these copepods is phylogenetically determined and may have little to do with contemporary selective constraints should not be ignored.

Circulatory and Ventilatory Responses of Rainbow Trout (Salmo gairdneri) to Artificial Manipulation of Gill Surface Area

1971 ◽  
Vol 28 (10) ◽  
pp. 1609-1614 ◽  
Author(s):  
John C. Davis
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Rainbow Trout ◽  
Surface Area ◽  
Salmo Gairdneri ◽  
Ventilatory Responses ◽  
Arterial Blood ◽  
Gill Area ◽  
Gill Surface Area ◽  
The Brain

Reductions in surface area of the gill were artificially produced by ligating various gill arches and occluding their blood supply. Rainbow trout (Salmo gairdneri) responded to a 40–57% reduction in gill area, by increasing cardiac output and ventilation volume, and probably by redistributing blood within the remaining functional gill area. Fish with blood flow to gill arches one and three only, could maintain arterial PO2 at 90–100 mm Hg, whereas, in those with blood flow to arches three and four only, arterial PO2 fell to around 40 mm Hg. The presence of a chemoreceptor site for the regulation of arterial PO2 associated with the efferent blood vessels of arch number one is discussed. Such a receptor may be located in the pseudobranch or in the portion of the brain supplied with arterial blood from the first gill arch.

Surface Area of the Euphausiid Thysanöessa raschii and Its Relation to Body Length, Weight, and Respiration

1977 ◽  
Vol 34 (2) ◽  
pp. 225-231 ◽  
Author(s):  
Gareth C. H. Harding
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Surface Area ◽  
Body Length ◽  
External Surface ◽  
Dry Weight ◽  
External Surface Area ◽  
Marine Crustaceans ◽  
Respiratory Surface ◽  
Wet Weight

A method is described for estimating the surface area of marine crustaceans. The external surface area of the euphausiid Thysanöessa raschii (M. Sars) is proportional to length2.4, dry weight0.95, and wet weight0.84. Oxygen consumption is proportional to wet weight0.82, which indicates that respiration should be proportional to respiratory surface area. The implications of this finding regarding the relations of metabolic rate, size, and surface area are discussed in a broader framework by comparing them with similar studies on vertebrates and other invertebrates.

scholarly journals Slow Life History Leaves Endangered Snake Vulnerable to Illegal Poaching

2020 ◽  
Author(s):  
Chris Jolly ◽  
Brenton von Takach ◽  
Jonathan Webb
Keyword(s):  
Life History ◽  
Population Growth ◽  
Life Histories ◽  
Extinction Risk ◽  
Adult Mortality ◽  
Sensitivity Analyses ◽  
Wildlife Trade ◽  
Pet Trade ◽  
The Impact ◽  
Negative Population

Abstract Global wildlife trade is a multibillion-dollar industry and a significant driver of vertebrate extinction risk. Yet, few studies have quantified the impact of wild harvesting for the illicit pet trade on populations. Long-lived species, by virtue of their slow life history characteristics, may be unable to sustain even low levels of harvesting. Here, we assessed the impact of illegal poaching on a metapopulation of endangered broad-headed snakes (Hoplocephalus bungaroides) at gated (protected) and ungated (unprotected) populations. Because broad-headed snakes are long-lived, grow slowly and reproduce infrequently, populations are likely vulnerable to increases in adult mortality. Long-term data revealed that annual survival rates of snakes were significantly lower in the ungated population than the gated population, consistent with the hypothesis of human removal of snakes for the pet trade. Population viability analysis showed that the ungated population has a strongly negative population growth rate and is only prevented from ultimate extinction by dispersal of small numbers of individuals from the gated population. Sensitivity analyses showed that the removal of a small number of adult females was sufficient to impose negative population growth and suggests that threatened species with slow life histories are likely to be especially vulnerable to illegal poaching.

scholarly journals Harvesting can stabilize population fluctuations and buffer the impacts of climate change

2021 ◽  
Author(s):  
Bart Peeters ◽  
Vidar GrØtan ◽  
Marlène Gamelon ◽  
Vebjørn Veiberg ◽  
Aline Magdalena Lee ◽  
...  
Keyword(s):  
Life Histories ◽  
Resource Competition ◽  
Extinction Risk ◽  
Population Models ◽  
Environmental Stochasticity ◽  
Environmental Drivers ◽  
Population Fluctuations ◽  
Vital Rates ◽  
Density Dependent ◽  
Environmental Perturbations

Harvesting can magnify the destabilizing effects of environmental perturbations on population dynamics and, thereby, increase extinction risk. However, population-dynamic theory predicts that impacts of harvesting depend on the type and strength of density-dependent regulation. Here, we used population models for a range of life histories and an empirical reindeer case study to show that harvesting can actually buffer populations against environmental perturbations. This occurs because of density-dependent environmental stochasticity, where negative environmental impacts on vital rates are amplified at high population density due to intra-specific resource competition. Simulations from our population models show that even low levels of proportional harvesting may prevent overabundance, thereby dampening population fluctuations and reducing the risk of population collapse and quasi-extinction induced by environmental perturbations. Thus, depending on the species’ life history and the strength of density-dependent environmental drivers, harvesting can improve population resistance to increased climate variability and extreme weather expected under global warming.

scholarly journals The metabolic pace of life histories across fishes

2020 ◽  
Author(s):  
Serena Wong ◽  
Jennifer S. Bigman ◽  
Nicholas K. Dulvy
Keyword(s):  
Life History ◽  
Metabolic Rate ◽  
Growth Performance ◽  
Body Mass ◽  
Life Histories ◽  
Life History Traits ◽  
Generation Length ◽  
Pace Of Life ◽  
Trade Offs ◽  
Maximum Body

AbstractAll life acquires energy through metabolic processes and that energy is subsequently allocated to life-sustaining functions such as survival, growth, and reproduction. Thus, it has long been assumed that metabolic rate is related to the life history of an organism. Indeed, metabolic rate is commonly believed to set the pace of life by determining where an organism is situated along a fast-slow life history continuum. However, empirical evidence of a relationship between metabolic rate and life histories is lacking, especially for ectothermic organisms. Here, we ask whether three life history traits – maximum body mass, generation length, and growth performance – explain variation in resting metabolic rate (RMR) across fishes. We found that growth performance, which accounts for the trade-off between growth rate and maximum body size, explained variation in RMR, yet maximum body mass and generation length did not. Our results suggest that measures of life history that encompass trade-offs between life history traits, rather than traits in isolation, explain variation in RMR across fishes. Ultimately, understanding the relationship between metabolic rate and life history is crucial to metabolic ecology and has the potential to improve prediction of the ecological risk of data-poor species.

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