Subtle effects of biological invasions: cellular and physiological responses of fish eating the exotic pest Caulerpa racemosa.
The green alga Caulerpa racemosa var. cylindracea has invaded Mediterranean seabed including marine reserves, modifying the structure of habitats and altering the distributional patterns of associated organisms. However, the understanding of how such invasion can potentially affect functional properties of Mediterranean subtidal systems is yet to be determined. In this study, we show that C. racemosa changes foraging habit of the native white seabream, Diplodus sargus. In invaded areas, we found a high frequency of occurrence of C. racemosa in the stomach contents of this omnivorous fish (72.7 and 85.7%), while the alga was not detected in fish from a control area. We also found a significant accumulation of caulerpin, one of the main secondary metabolites of C. racemosa, in fish tissues. The level of caulerpin in fish tissues was used here as an indicator of the trophic exposure to the invasive pest and related with observed cellular and physiological alterations. Such effects included activation of some enzymatic pathways (catalase, glutathione peroxidases, glutathione S-transferases, total glutathione and the total oxyradical scavenging capacity, 7-ethoxy resorufin O-deethylase), the inhibition of others (acetylcholinesterase and acylCoA oxidase), an increase of hepatosomatic index and decrease of gonadosomatic index. The observed alterations might lead to a detrimental health status and altered behaviours, potentially preventing the reproductive success of fish populations. Results of this study revealed that the entering of alien species in subtidal systems can alter trophic webs and can represent an important, indirect mechanism which might contribute to influence fluctuations of fish stocks and, also, the effectiveness of protection regimes.
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, CoNISMa, Lecce, Italy.
Serena
S
Felline
Roberto
R
Caricato
Adele
A
Cutignano
Stefania
S
Gorbi
Maria Giulia
MG
Lionetto
Ernesto
E
Mollo
Francesco
F
Regoli
Antonio
A
Terlizzi
D000704:Analysis of Variance; D000818:Animals; D046068:Caulerpa; D002851:Chromatography, High Pressure Liquid; D003247:Conservation of Natural Resources / Q000379:methods*; D004789:Enzyme Activation / Q000502:physiology; D020387:Food Chain; D005766:Gastrointestinal Contents; D006066:Gonads / Q000254:growth & development; D007211:Indoles / Q000378:metabolism; D058865:Introduced Species; D007558:Italy; D008099:Liver / Q000254:growth & development / Q000378:metabolism; D008386:Marine Biology; D013058:Mass Spectrometry; D008522:Mediterranean Sea; D018482:Muscle, Skeletal / Q000378:metabolism; D009929:Organ Size / Q000502:physiology; D021541:Sea Bream / Q000502:physiology*
D007211:Indoles; C000392:caulerpin