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- Swimming abilities of temperate pelagic fish larvae prove that they may control their dispersion in coastal areasPublication . Baptista, Vânia; Morais, Pedro; Cruz, Joana; Castanho, Sara; Ribeiro, L.; Pousão-Ferreira, P.; Leitão, Francisco Miguel de Sousa; Wolanski, E.; Teodosio, Maria AlexandraThe Sense Acuity and Behavioral (SAAB) Hypothesis proposes that the swimming capabilities and sensorial acuity of temperate fish larvae allows them to find and swim towards coastal nursery areas, which are crucial for their recruitment. To gather further evidence to support this theory, it is necessary to understand how horizontal swimming capability varies along fish larvae ontogeny. Therefore, we studied the swimming capability of white seabream Diplodus sargus (Linnaeus, 1758) larvae along ontogeny, and their relationship with physiological condition. Thus, critical swimming speed (U-crit) and the distance swam (km) during endurance tests were determined for fish larvae from 15 to 55 days post-hatching (DPH), and their physiological condition (RNA, DNA and protein contents) was assessed. The critical swimming speed of white seabream larvae increased along ontogeny from 1.1 cm s(-1) (15 DPH) to 23 cm s(-1) (50 and 55 DPH), and the distance swam by larvae in the endurance experiments increased from 0.01 km (15 DPH) to 86.5 km (45 DPH). This finding supports one of the premises of the SAAB hypothesis, which proposes that fish larvae can influence their transport and distribution in coastal areas due to their swimming capabilities. The relationship between larvae's physiological condition and swimming capabilities were not evident in this study. Overall, this study provides critical information for understanding the link between population dynamics and connectivity with the management and conservation of fish stocks.
- Does consistent individual variability in pelagic fish larval behaviour affect recruitment in nursery habitats?Publication . Baptista, Vânia; Costa, Eudriano; Carere, Claudio; Morais, Pedro; Cruz, Joana; Cerveira, Inês; Castanho, Sara; Ribeiro, Laura; Pousao-Ferreira, Pedro; Leitão, Francisco; Teodosio, MariaIndividual animals across all taxa differ consistently in behaviour, i.e. they show personality traits. This inter-individual variability has significant ecological and evolutionary consequences, since it affects a range of population-level processes. Here, we focus on the selection and recruitment of nursery habitats in temperate fish larvae. The "Sense Acuity and Behavioural Hypothesis" has proposed that fish larvae could detect and follow environmental cues to actively choose suitable nursery habitats. We empirically tested this hypothesis questioning if this non-random active process occurs and if it could be linked to consistency in individual behaviours. Individual larvae of the white seabream Diplodus sargus (Linnaeus, 1758) were tested repeatedly at different ages in a two-channel choice-chamber apparatus exposing them to a flow with different stimuli, as nursery habitats (lagoon, coastal), different temperatures or salinities and recording exploratory activity and preference in the different conditions. Most larvae changed behaviour during ontogeny, but they were also significantly consistent in their behaviour, revealing strong individuality; yet, no significant preference for the presented stimuli emerged, nor it was related to individuality. Exploratory activity was higher when larvae showed unresponsive or inconclusive behaviours, meaning that the larvae tried to find a different stimulus from the one that we were offering or had random habitat selection. Individual behavioural consistency could influence the process of searching for suitable nursery habitats and, consequently, dispersion and connectivity of white seabream population. Characterizing the behaviour of temperate pelagic marine fish larvae may shed light on fish recruitment variability, help refining larval dispersion models and possibly help understanding effects of climate change on population distribution and connectivity. Significance statement A Chinese idiom says that "It is easier to change mountains and rivers than to alter one's character." What about fish? Well, fish can exhibit individuality traits that control autoecological and demecological processes. For example, shy fish have lower fitness while the rate of invasion progress is faster in populations with bolder individuals. Individuality studies rarely focused on fish larvae, except for coral fish. So, we tested if temperate fish larvae display consistent behaviour throughout ontogeny. This goal delves into the Sense Acuity And Behavioural Hypothesis which incorporated behaviour into the hypotheses deeming to explain fish recruitment variability. We found that temperate fish larvae display consistent individual behavioural differences in exploratory activity since early in ontogeny. This confirms the deterministic role of pelagic fish larvae behaviour on population connectivity processes, namely to control their dispersion and choose a nursery habitat.