Modeled buoyancy of eggs and larvae of the deep-sea shrimp Aristeus antennatus (Crustacea: Decapoda) in the northwestern Mediterranean Sea

Abstract

Information on the buoyancy of eggs and larvae from deep-sea species is rare but necessary for explaining the position of non-swimming larvae in the water column. Due to embryonic morphology and ecology diversities, egg buoyancy has important variations within one species and among other ones. Nevertheless, it has hardly been explored if this buoyancy variability can be a strategy for deep-sea larvae to optimize their transport beyond their spawning areas. In the northwestern Mediterranean Sea, protozoea and mysis larvae of the commercial deep-sea shrimp Aristeus antennatus were recently found in upper layers, but to present, earlier stages like eggs and nauplii have not been collected. Using a Lagrangian transport model and larval characteristics, we evaluate the buoyancy and hydrodynamic effects on the transport of A. antennatus' larvae in the northwestern Mediterranean Sea. The transport models suggested that 75% of buoyant eggs released between 500 and 800 m depth (i.e., known spawning area), reached the upper water layers (0-75 m depth). Then, according to the modeled larval drifts, three spawning regions were defined in the studied area: 1) the northern part, along a continental margin crossed by large submarine canyons; 2) the central part, with two circular circulation structures (i.e., eddies); and 3) the southern part, with currents flowing through a channel. The number of larvae in the most upper layer (0-5 m depth) was higher if the larval transport model accounted for the ascent of eggs and nauplii (81%) instead of eggs reaching the surface before hatching (50%). The larvae reaching the most water upper layer (0-5 m depth) had higher rates of dispersal than the ones transported below the surface layer (deeper than 5 m depth). The results of larval dispersal simulations have implications for the understanding of A. antennatus larval ecology and for management decisions related to the shrimp fisheries in the northwestern Mediterranean Sea.

Summer decapod crustacean larval communities along the eastern Spanish Mediterranean coast

“…Species richness, Shannon diversity index and Pielou evenness index were calculated for each station, as well as the average abundance and frequency of occurrence (in %) for each species and taxonomical group. For the spatial analysis, the studied area (GSA6) was divided into three zones according to environmental characteristics such as temperature, salinity, bathymetry and surface circulation, influencing the larval dispersal, as mentioned in previous studies in the area [ 35 , 45 ]. The Northern zone englobes the deep submarine canyons from the Gulf of Lions to the coast of Barcelona with a strong effect of the saltier and cooler Northern current flowing southwest.…”

“…Moreover, a hydrodynamic model run in this area, designed as the fisheries management unit Geographical Subarea 6 (or GSA 6) by the General Fisheries Commission for the Mediterranean (GFCM), showed diverse circulation patterns the dispersal patterns of particles, and particularly larvae of A . antennatus ( Fig 1 ; [ 35 , 36 ]). The area is mainly influenced by the Northern Current [ 37 ], which has been found to transport larvae southwestward [ 38 ], whereas that its interaction with the Balearic current may generate seasonal eddies restricting the dispersal of larvae or transporting them offshore [ 38 , 39 ].…”

Spatial heterogeneity of Pelagia noctiluca ephyrae linked to water masses in the Western Mediterranean

“…However, the morphology and [45]. Coastline is from Instituto Hidrográfico de la Marina [52] and isobaths (every 400 m) are from EMODnet [43].…”

Finding lobsters: investigating a period of unusually low settlement of

“…For example, the distribution of marine species during their early larval stages can have varying consequences through high mortality because of current movements away from recruitment locations (Chiswell and Booth 2008) or survival through retention in eddy systems (Hill et al 1996;Cetina-Heredia et al 2019) and connecting populations (Chiswell et al 2003;Cowen and Sponaugle 2009;Nolasco et al 2018;Pires et al 2020). Furthermore, understanding these mechanisms for a single species influences their spatial management scales and their likely responses to environmental disturbances or shifts (Kvile et al 2018;Clavel-Henry et al 2020).…”

“…After 3 months, the wider dispersal of particles by 2012 highlights that there has been less entrainment of particles within eddy structures, likely reducing their return pathway to the coast. The entrainment of phyllosoma and other long-lived larvae within eddies is regarded as positive for prey availability and transport (Mullaney and Suthers 2013;Cetina-Heredia et al 2019;Woodings et al 2019;Clavel-Henry et al 2020). It has previously been suggested that the period of unusually low settlement may have occurred because of a 'rogue' eddy system entraining newly hatched larvae from the key spawning areas and transporting them offshore (Brown 2009;Säwström et al 2014;Waite et al 2019).…”