scholarly journals Warming, not CO2-acidified seawater, alters otolith development of juvenile Antarctic emerald rockcod (Trematomus bernacchii)

Polar Biology ◽  
2021 ◽  
Author(s):  
Andrew W. Naslund ◽  
Brittany E. Davis ◽  
James A. Hobbs ◽  
Nann A. Fangue ◽  
Anne E. Todgham

AbstractThe combustion of fossil fuels is currently causing rapid rates of ocean warming and acidification worldwide. Projected changes in these parameters have been repeatedly observed to stress the physiological limits and plasticity of many marine species from the molecular to organismal levels. High latitude oceans are among the fastest changing ecosystems; therefore, polar species are projected to be some of the most vulnerable to climate change. Antarctic species are particularly sensitive to environmental change, having evolved for millions of years under stable ocean conditions. Otoliths, calcified structures found in a fish’s inner ear used to sense movement and direction, have been shown to be affected by both warming and CO2-acidified seawater in temperate and tropical fishes but there is no work to date on Antarctic fishes. In this study, juvenile emerald rockcod (Trematomus bernacchii) were exposed to projected seawater warming and CO2-acidification for the year 2100 over 28 days. Sagittal otoliths were analyzed for changes in area, perimeter, length, width and shape. We found ocean warming increased the growth rate of otoliths, while CO2-acidified seawater and the interaction of warming and acidification did not have an effect on otolith development. Elevated temperature also altered the shape of otoliths. If otolith development is altered under future warming scenarios, sensory functions such as hearing, orientation, and movement may potentially be impaired. Changes in these basic somatic abilities could have broad implications for the general capabilities and ecology of early life stages of Antarctic fishes.

2013 ◽  
Vol 5 (1) ◽  
pp. 70-80 ◽  
Author(s):  
María Eugenia Haro ◽  
Ines Navarro ◽  
Ralph Thompson ◽  
Blanca Jimenez

Energy policies are taken throughout the world to reduce fossil fuel emissions from transportation sources. Agriculturally based biofuels are currently the only alternatives to liquid fossil fuels. However, as biofuel production spreads, so too do its cascading impacts on environment and food security. This paper analyzes the impact of Mexican ethanol-sugarcane policy on water resources. The water footprint of sugarcane (WFsc) was quantified for an agricultural region in Jalisco, Mexico, and used to estimate anthropologic water demand and stress index. This analysis was performed using historical climate data, and for projected changes under scenarios A2 and B1, using ECHAM and GFDL models. The average historical water footprint of sugarcane was estimated as 104.9 m3/ton, total average water demand as 152.3 Mm3/year and a historical water scarcity index as 59%. Under climate change, the footprint might increase 2% by 2020 and 3–4% by 2050. The available water is predicted to fall 4–7% by 2020, and 6–8% by 2050, with negative effects on water stress. Due to the strong influence of local factors on water footprint and stress, additional research is needed for all Mexican sugarcane regions, in order to evaluate the feasibility of the policy regarding the use of ethanol for transportation.


Diversity ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 230 ◽  
Author(s):  
Fernando Espino ◽  
Fernando Tuya ◽  
Armando del Rosario ◽  
Néstor E. Bosch ◽  
Josep Coca ◽  
...  

In recent decades, numerous marine species have changed their distribution ranges due to ocean warming. The Spotfin burrfish, Chilomycterus reticulatus, is a reef fish with a global distribution along tropical, subtropical and warm-temperate areas of the Pacific, Indian and Atlantic oceans. In this work, we analyzed the presence of this species, between 1990 and 2019, at two islands of the Canarian Archipelago under varying oceanographic conditions: El Hierro (the westernmost island, under more tropical conditions) and Gran Canaria (a central-east island, under more cooler conditions). We expected that, under increased ocean temperatures in recent decades, the number of sightings has increased in Gran Canaria relative to El Hierro. We compiled information from different sources, including interviews and local citizenship databases. A total of 534 sightings were reported: 38.58% from El Hierro and 61.43% from Gran Canaria. The number of sightings on Gran Canaria has significantly increased through time, at a rate of 0.1 sightings per year; at El Hierro, however, the number of sightings has not significantly changed over time. Sea Surface Temperature has linearly increased in both El Hierro and Gran Canaria islands over the last three decades. Positive Sea Surface Temperature anomalies, particularly in 1998 and 2010, including high winter minimum temperatures, provide an ideal oceanographic context to favour the arrival of new individuals and, consequently, the increase in the number of sightings in Gran Canaria. Still, potential donor areas of fish recruits remain unknown.


Phytotaxa ◽  
2019 ◽  
Vol 401 (4) ◽  
pp. 199 ◽  
Author(s):  
CHRISTOPHER S. LOBBAN ◽  
MATT P. ASHWORTH ◽  
JERILYN J.M. CALAOR ◽  
EDWARD C. THERIOT

A study was made of the ultrastructural variation in a group of conopeate Nitzschia species, primarily marine species from Guam but also including one freshwater species from Costa Rica. Fourteen new species are described: Nitzschia alcyoneae, Nitzschia asteropeae, Nitzschia carahii, Nitzschia celaenoae, Nitzschia dagmannii, Nitzschia electrae, Nitzschia guamensis, Nitzschia jordanii, Nitzschia lascrucensis, Nitzschia maiae, Nitzschia meropeae, Nitzschia schefterae, Nitzschia spathulatoides, and Nitzschia taygeteae. The valves in all these taxa had a central raphe-sternum on a raised keel; from the keel arise silica flaps, the conopea, and the valve face was depressed below the conopea to form conopeal canals. The valve surface was thus differentiated into three regions, in which the areola pattern sometimes differed: the exposed valve face, the valve depression, and the peri-raphe zone, i.e., the exposed part of the keel wall between the conopeum and the raphe-sternum. We refer to this suite of characters as the tholophora (canopy-bearing) morphology. In one species, N. maiae sp. nov., the conopea occurred only at the apex and there was no valve depression. Thirty-eight morphological characters were used in addition to the usual morphometric data (length, width, densities of striae and fibulae); these included, inter alia, a remarkable range of areola shapes on the three valve regions and the copulae—oval/circular pores, transapical slits, longitudinal slits, small pores fields, continuous pores fields, and larger quadrate pores closed by hymenes or cribra; the extent of the conopea along the valve; the presence of longitudinal ribs on the valve, conopea, or copulae; and the extent of internal development of silica below the striae. Phylogenetic analysis of gene sequences from six species was entirely congruent with analysis of morphological characters.


Polar Biology ◽  
2019 ◽  
Vol 42 (11) ◽  
pp. 2017-2030
Author(s):  
Matteo Antonucci ◽  
Ikram Belghit ◽  
Cristina Truzzi ◽  
Silvia Illuminati ◽  
Pedro Araujo

Abstract Antarctic fish (Trematomus bernacchii) are an ideal group for studying the effect of ocean warming on vital physiological and biochemical mechanisms of adaptation, including changes in the fatty acid composition to higher heat tolerance in the sub-zero waters of the Southern Ocean. Despite the awareness of the impact of ocean warming on marine life, bioclimatic models describing the effect of temperature and time on fatty acid levels in marine species have not been considered yet. The objective of the present study was to investigate changes in the concentrations of fatty acids in liver from T. bernacchii in response to an increase in temperature in the Antarctic region. Changes in the concentrations of fatty acids in liver from T. bernacchii were observed after varying simultaneously and systematically the temperature and time. The fatty acid profiles were determined by gas chromatography prior to acclimation (− 1.8 °C) and after acclimation (0.0, 1.0, and 2.0 °C) at different times (1, 5, and 10 days). The observed changes were graphically visualized by expressing the fatty acid concentration in absolute units (mg g−1) as a function of the temperature and time using polynomial models. Major changes in fatty acid composition were observed at day 1 of exposition at all temperatures. At day 5, the fish seem to tolerate the new temperature condition. The concentrations of saturated fatty acids were almost constant throughout the various conditions. The concentrations of monounsaturated fatty acids (in particular 18:1n − 9) decrease at day 1 for all temperatures. In contrast, there was an increase in the concentrations of polyunsaturated fatty acids (in particular 20:5n − 3 and 22:6n − 3) with increasing temperatures after 1, 5, and 10 days of exposure. The proposed models were in agreement with reported studies on polar and temperate fish, indicating possibly similar adaptation mechanisms for teleost to cope with global warming.


2017 ◽  
Vol 153 ◽  
pp. 24-36 ◽  
Author(s):  
Kristin M. Kleisner ◽  
Michael J. Fogarty ◽  
Sally McGee ◽  
Jonathan A. Hare ◽  
Skye Moret ◽  
...  

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