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Research Project
Vital rates of pelagic fish larvae (VITAL)
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Ontogeny of swimming capacity in plaice (Pleuronectes platessa) larvae
Publication . Silva, Luis; Moyano, Marta; Illing, Björn; Faria, Ana Margarida; Garrido, Susana; Peck, Myron A.
Little is known regarding the swimming ability
of the larvae of European plaice (Pleuronectes platessa) in
relation to changes in total length (TL), dry weight (DW)
and developmental stage, which is surprising given the
importance of transport processes to the recruitment dynamics
of this species in the North Sea and elsewhere. We investigated
ontogenetic changes in the critical swimming speed
(Ucrit) of plaice from hatching to the onset of metamorphosis
(50 days post-hatch, dph) at 8 °C. The mean (±SD) TL and
DW growth rates were 1.59 ± 0.81 and 7.7 ± 0.35 % d−1,
respectively. Larvae were unable to swim at against a minimum
current speed of <0.5 cm s−1 until 10 dph (7 mm TL),
after which Ucrit significantly increased with increasing TL
until the onset of metamorphosis and subsequent settlement.
Mean (±SD) Ucrit was 0.38(0.35), 1.59(0.54), 2.27(0.49) and
2.99(0.37) cm s−1 for stage I (6.61 ± 2.64 mm TL), stage II
(7.75 ± 0.60 mm TL), stage III (9.10 ± 1.00 mm TL) and
stage IV (11.59 ± 0.85 mm TL) larvae, respectively. Larval TL, DW, DNA content, RNA content and Ucrit significantly
increased, whereas sRD significantly declined as larvae
developed from stage I to V. Although inter-individual differences
in Ucrit (coefficient of variation, CV = 33 %) were as
large as those in biochemical and morphological condition
(CV’s of 21–42 %), differences in Ucrit were not significantly
related to those in nutritional condition and larvae with lower
DNA/DW had also better swimming abilities. These estimates
should be useful to ongoing efforts to create individual-
based models of the transport, foraging and growth of
plaice larvae in the North Sea.
Small pelagics in a changing ocean : Biological responses of sardine early stages to warming
Publication . Faleiro, Filipa; Pimentel, Marta; Pegado, Maria Rita; Bispo, Regina; Lopes, Ana Rita; Diniz, Mário S.; Rosa, Rui
Small pelagic fishes are known to respond rapidly to changes in ocean climate. In this study, we evaluate the effects of future environmental warming (+2°C) during the early ontogeny of the European sardine, Sardina pilchardus. Warming reduced the survival of 30-day-old larvae by half. Length at hatching increased with temperature as expected, but no significant effect was observed on the length and growth at 30 days post-hatching. Warming did not significantly affect the thermal tolerance of sardine larvae, even though the mean lethal temperature increased by 1°C. In the warm conditions, sardine larvae showed signs of thermal stress, indicated by a pronounced increase in larval metabolism (Q 10 = 7.9) and a 45% increase in the heat shock response. Lipid peroxidation was not significantly affected by the higher temperature, even though the mean value doubled. Warming did not affect the time larvae spent swimming, but decreased by 36% the frequency of prey attacks. Given the key role of these small pelagics in the trophic dynamics off the Western Iberian upwelling ecosystem, the negative effects of warming on the early stages may have important implications for fish recruitment and ecosystem structure.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
3599-PPCDT
Funding Award Number
PTDC/MAR/111304/2009