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  • OceanRep  (4)
  • Copernicus Publications (EGU)  (2)
  • Urban & Fischer  (2)
  • 1
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    Copernicus Publications (EGU)
    In:  Biogeosciences (BG), 8 . pp. 3697-3707.
    Publication Date: 2020-10-16
    Description: Due to atmospheric accumulation of anthropogenic CO2 the partial pressure of carbon dioxide (pCO2) in surface seawater increases and the pH decreases. This process known as ocean acidification might have severe effects on marine organisms and ecosystems. The present study addresses the effect of ocean acidification on early developmental stages, the most sensitive stages in life history, of the Atlantic herring (Clupea harengus L.). Eggs of the Atlantic herring were fertilized and incubated in artificially acidified seawater (pCO2 1260, 1859, 2626, 2903, 4635 μatm) and a control treatment (pCO2 480 μatm) until the main hatch of herring larvae occurred. The development of the embryos was monitored daily and newly hatched larvae were sampled to analyze their morphometrics, and their condition by measuring the RNA/DNA ratios. Elevated pCO2 neither affected the embryogenesis nor the hatch rate. Furthermore the results showed no linear relationship between pCO2 and total length, dry weight, yolk sac area and otolith area of the newly hatched larvae. For pCO2 and RNA/DNA ratio, however, a significant negative linear relationship was found. The RNA concentration at hatching was reduced at higher pCO2 levels, which could lead to a decreased protein biosynthesis. The results indicate that an increased pCO2 can affect the metabolism of herring embryos negatively. Accordingly, further somatic growth of the larvae could be reduced. This can have consequences for the larval fish, since smaller and slow growing individuals have a lower survival potential due to lower feeding success and increased predation mortality. The regulatory mechanisms necessary to compensate for effects of hypercapnia could therefore lead to lower larval survival. Since the recruitment of fish seems to be determined during the early life stages, future research on the factors influencing these stages are of great importance in fisheries science.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 2
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    Copernicus Publications (EGU)
    In:  Biogeosciences (BG), 7 . pp. 3915-3919.
    Publication Date: 2020-10-16
    Description: Ocean acidification, as a consequence of increasing marine pCO2, may have severe effects on the physiology of marine organisms. However, experimental studies remain scarce, in particular concerning fish. While adults will most likely remain relatively unaffected by changes in seawater pH, early life-history stages are potentially more sensitive – particularly the critical stage of fertilization, in which sperm motility plays a central role. In this study, the effects of ocean acidification (decrease of pHT to 7.55) on sperm motility of Baltic cod, Gadus morhua, were assessed. We found no significant effect of decreased pH on sperm speed, rate of change of direction or percent motility for the population of cod analyzed. We predict that future ocean acidification will probably not pose a problem for sperm behavior, and hence fertilization success, of Baltic cod.
    Type: Article , PeerReviewed
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  • 3
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    Urban & Fischer
    In:  Archive of Fishery and Marine Research, 51 (1-3). pp. 187-200.
    Publication Date: 2019-03-06
    Description: Abstract Vinciguerria nimbaria larvae caught in August/September 1998 above the plateau and in the deep water area around the Great Meteor Seamount were analysed for nutritional condition and growth based on RNA/DNA ratios, size in length, dry weight, and otolith increment pattern. Data analysis was based on the following hypothesis: Due to its oceanographic features ("Taylor" column, retention area) the Great Meteor Seamount favours growth and nutritional condition for larval fish. Vinciguerria larvae caught above the plateau of the seamount showed significantly higher dry weights compared to the oceanic area, although the nutritional condition as measured by RNA/DNA ratios and dry-weight to larval-size relationships did not show any significant differences. Age-structure analysis based on otolith increments and growth rates indicated no significant differences between the sampling areas. Kurzfassung Beeinflusst die Große Meteorbank Wachstum und Ernahrungszustand von Fischlarven, insbesondere Vinciguerria nimbaria? Der Ernahrungszustand und das Wachstum von Vinciguerria-nimbaria-Larven, die im August/September 1998 iiber dem Plateau und im Tiefseebereich der Großen Meteorbank gefangen wurden, wurden mittels RNA/DNA-Analysen, Langen- und Gewichtsbestimmungen und anhand der Otolith-Tagesringstruktur analysiert. Folgende Hypothese wurde gepriift: Aufgrund ihrer hydrographischen Besonderheiten (Taylor-Säule, "Retention"-Bereich) ermöglicht die Meteorbank besseres Wachstum und eine bessere Ernahrungslage fur Fischlarven. Vinciguerria-Larven aus dem Bereich oberhalb des Seeberges hatten im Vergleich zum ozeanischen Bereich signifikant hi:ihere Trockengewichte, die RNA/DNA-Verhaltnisse und die Gewichts-Langen-Beziehungen zwischen den beiden Untersuchungsgebieten sowie die Altersverteilungen und Wachstumsraten zwischen beiden Gebieten ergaben keine signifikanten Unterschiede.
    Type: Article , PeerReviewed
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  • 4
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    Urban & Fischer
    In:  Archive of Fishery and Marine Research, 45 (1). pp. 17-43.
    Publication Date: 2019-03-04
    Description: Anchovy larvae (Engraulis anchoita) were sampled from an area of upwelling in the subtropical waters over the Brazilian shelf and from an area over the Argentinian shelf characterized by a tidal mixing front. They were analysed for their nutritional condition by measuring RNA/DNA ratios. The degree of starvation occurring in the two geographic areas was correlated to length distribution, developmental stage and position in the water column. It was shown that starving larvae (5 to 80 %) were mainly found in the smaller length classes (4 to 10 mm SL), but some larvae between 16 to 20 mm SL were also determined as starving (4 to 6 %). Larvae found in the stratified water column had higher RNA/DNA ratios reflecting a better nutritional condition than in the mixed water body. The degree of starvation at the same developmental stage was higher in Brazil than in the Argentinian area. RNA/DNA ratios of larvae from the Argentinian area showed a significant shift to higher values (indicating a better condition) than in Brazil. Results on the nutritional condition of the larvae based on RNA/DNA ratios were compared with zooplankton data and larval gut analyses determined on the same cruise. Speculations on the survival strategies of these two anchovy populations are given
    Type: Article , PeerReviewed
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