Larval Fish Swimming Behavior Alters Dispersal Patterns From Marine Protected Areas in the North-Western Mediterranean Sea

Abstract

Most demersal fishes undergo a dispersal phase as larvae, which strongly influences the connectivity among adult populations and, consequently, their genetic structure and replenishment opportunities. Because this phase is difficult to observe directly, it is frequently simulated through numerical models, most of which consider larvae as passive or only vertically migrating. However, in several locations, including the Mediterranean Sea, many species have been shown to swim fast and orient. Here we use a Lagrangian model to study connectivity patterns among three Mediterranean Marine Protected Areas (MPAs) and compare simulations in which virtual larvae are passive to simulations in which oriented swimming is implemented. The parameterization of behavior is based on observations for two groups of species of the family Sparidae: species with small larvae (i.e., 9-11 mm), displaying a maximum swimming speed of 6 cm s −1 and a pelagic larval duration of 13-19 days (e.g., Diplodus annularis L., Oblada melanura L.) and species with large larvae (i.e., 14-16 mm), displaying a maximum swimming speed of 10 cm s −1 and a PLD of 28-38 days (e.g., Spondyliosoma cantharus L.). Including larval behavior in the model (i) increased the overall proportion of successful settlers, (ii) enhanced self-recruitment within the MPAs, but also (iii) increased the intensity, and (iv) widened the export of eggs and larvae (recruitment subsidy) from the MPAs; overall, it significantly changed connectivity patterns. These results highlight the need to gather the observational data that are required to correctly parameterize connectivity models.

Swimming Abilities of Temperate Pelagic Fish Larvae Prove that They May Control Their Dispersion in Coastal Areas

“…The size range of larvae tested is also shown. Biophysical models addressing the influence of larval behavior on dispersal (i.e., the ability to follow cues thanks to their horizontal and vertical movements) provide additional evidence on the extraordinary capacities of temperate fish larvae to control their dispersion in coastal areas [2,10,11,30]. Such models suggest that temperate fish larvae are active swimmers only requiring to make use of modest swimming speeds (1-10 cm s −1 ) to control their transport and distribution in coastal areas and to avoid offshore advection [2,30].…”

“…However, when post-flexion larvae are in the range of nursery cues, they orientate their swimming to follow odor, sound, and visual cues (see Figure 2 in [2]). Thus, the development of swimming capabilities and behaviors that interact with physical transport processes influences larval dispersion outcomes [6,[8][9][10][11], settlement location [12], and recruitment success [13].…”

“…Some fish larvae can swim at speeds higher than coastal currents, in a highly directional way and for long distances [14,15]. Fish larvae can also adjust their vertical position [10] to enter currents that facilitate their transport, and in search of a nursery habitat [16]. These swimming capabilities also impact other ecological processes, such as the response of larvae to predators, foraging abilities [4,17,18], interaction with conspecifics, and the biotic and abiotic conditions larvae may experience [19].…”

Genome-wide Assessment Elucidates Connectivity and the Evolutionary History of the Highly Dispersive Marine Invertebrate Littoraria Flava (Littorinidae:Gastropoda)

“…2A). The first PC distinguished two genetic clusters ( with planktonic larvae [70][71][72]. Since no study has adopted a similar genomic approach in studying the genetic structure of a marine invertebrate organism in the Brazilian coastline, we could not compare the results of the present study with the findings of other studies on other high dispersal species along the same area.…”

Larval lake sturgeon production and drift behaviour in the Menominee and Oconto Rivers, Wisconsin

“…These observations suggest that larvae may actively avoid fast and turbulent water currents. Active swimming behaviour can alter dispersal patterns for other larval fishes (Faillettaz, Paris, & Irisson, 2018; Johnston, Gaboury, Janusz, & Janusz, 1995). The ability of drifting lake sturgeon larvae to avoid (or be attracted to) flow conditions may be advantageous for predator avoidance and provide opportunities to detect physical conditions associated with higher survival (larger substrates or vegetation).…”