The distribution of estuarine fish larvae: Nutritional condition andco-occurrence with predators and prey

Abstract

-Fish larvae were collected monthly between March and September 1997 in the Mira and Guadiana estuaries (southern Portugal). Hydrological parameters were registered and zooplankton samples were obtained simultaneously. Densities of fish larvae (ind·100 m -3 ) were calculated from 211 samples and larval nutritional condition measured as RNA/DNA ratios were obtained for 346 individuals, using a fluorimetric method for nucleic acid quantification. Correlating variables were further studied using multiple regression analysis in order to assess the relative importance of abiotic and biotic factors affecting within-year trends in abundance and nutritional condition of estuarine fish larvae. Results indicated that: 1) the abundance of fish larvae seems conditioned by temperature and predation; and 2) their nutritional condition is dependent on temperature and prey availability. Temperature is an important variable structuring estuaries and therefore conditions the behaviour and physiology of fish larvae. Furthermore, the co-occurrence of predators and larvae might be related to similar feeding patterns or comensalism. Whenever feeding conditions are suitable, they usually determine enhanced growth and nutritional condition. However, predation seems to control this latter relationship through its effect on larval mortality. © 2000 Éditions scientifiques et médicales Elsevier SAS Fish larvae / distribution / RNA/DNA ratios / nutritional condition

Larval fish distribution in shallow coastal waters off North Western Iberia (NE Atlantic)

“…Temperature is an important environmental variable influencing ichthyoplankton assemblages in coastal waters and is related to seasonality patterns of larval fish abundance (Kingsford, 1988;Tzeng and Wang, 1993;Rakocinski et al, 1996;Harris et al, 1999). Environmental factors, such as salinity and temperature, have been shown to play an important role in the occurrence, density and growth of the larval stages of fishes (Rakocinski et al, 1996;Esteves et al, 2000). Sabatés (1990) highlights the importance of seasonality in larval fishes community structure.…”

“…Zooplankton abundance is sometimes related to larval fish abundance (Haldorson et al, 1992), namely the seasonality of abundance of larval fish can be strongly correlated with densities of copepod nauplii (Monteleone, 1992). Esteves et al (2000), in the southern Portuguese coastal area, stated that the nutritional condition of fish larvae individuals is dependent on prey availability. Our data revealed no significant correlations between phytoplankton biomass and larval fish abundances and between zooplankton biomass and larval fish abundances.…”

Ichthyoplankton dynamics in the Guadiana estuary and adjacent coastal area, South-East Portugal

“…Several ichthyoplankton studies of limited temporal and/or spatial coverage have been carried out in the Guadiana estuary (SE Portugal) (Chícharo and Teodósio, 1991;Esteves et al, 2000;Chícharo et al, 2000). Chícharo and Teodósio (1991) and Chícharo et al (2000) studied ichthyoplankton community composition, whereas Esteves et al (2000) investigated factors influencing larval abundance and nutritional condition.…”

“…Chícharo and Teodósio (1991) and Chícharo et al (2000) studied ichthyoplankton community composition, whereas Esteves et al (2000) investigated factors influencing larval abundance and nutritional condition.…”

Response of Gilthead Seabream (Sparus aurata L., 1758) Larvae to Nursery Odor Cues as Described by a New Set of Behavioral Indexes

“…Nucleic acid concentrations of 101 and 96 post-flexion S. aurata larvae in satiation and starvation conditions, respectively, were quantified according to Esteves et al (2000) and Caldarone et al (2001). Due to tissue effects on RNA and DNA concentration, whole larvae were analyzed (Olivar et al, 2009).…”