Effects of Geostrophic Kinetic Energy on the Distribution of Mesopelagic Fish Larvae in the Southern Gulf of California in Summer/Fall Stratified Seasons

Abstract

Effects of geostrophic kinetic energy flux on the three-dimensional distribution of fish larvae of mesopelagic species (Vinciguerria lucetia, Diogenichthys laternatus, Benthosema panamense and Triphoturus mexicanus) in the southern Gulf of California during summer and fall seasons of stronger stratification were analyzed. The greatest larval abundance was found at sampling stations in geostrophic kinetic energy-poor areas (<7.5 J/m3), where the distribution of the dominant species tended to be stratified. Larvae of V. lucetia (average abundance of 318 larvae/10m2) and B. panamense (174 larvae/10m2) were mostly located in and above the pycnocline (typically ~ 40 m depth). In contrast, larvae of D. laternatus (60 larvae/10m2) were mainly located in and below the pycnocline. On the other hand, in sampling stations from geostrophic kinetic energy-rich areas (> 21 J/m3), where mesoscale eddies were present, the larvae of the dominant species had low abundance and were spread more evenly through the water column, in spite of the water column stratification. For example, in a cyclonic eddy, V. lucetia larvae (34 larvae/10m2) extended their distribution to, at least, the limit of sampling 200 m depth below the pycnocline, while D. laternatus larvae (29 larvae/10m2) were found right up to the surface, both probably as a consequence mixing and secondary circulation in the eddy. Results showed that the level of the geostrophic kinetic energy flux affects the abundance and the three-dimensional distribution of mesopelagic fish larvae during the seasons of stronger stratification, indicating that areas with low geostrophic kinetic energy may be advantageous for feeding and development of mesopelagic fish larvae because of greater water column stability.

Hydrographic and fish larvae distribution during the “Godzilla El Niño 2015–2016” in the northern end of the shallow oxygen minimum zone of the Eastern Tropical Pacific Ocean

“…larvae were more abundant in the surface mixed layer, in association with high temperature values (Figure ), while B. bathymaster and D. laternatus larvae dominated in the thermocline and shallow hypoxic layer (<44 µmol/kg), in association with low dissolved oxygen concentrations and temperature values (Figure ). These findings correspond with previous studies in adjacent areas like the southern Gulf of California [ Apango‐Figueroa et al ., ; Contreras‐Catala et al ., ] and the southern California Current System [ Koslow et al ., ; Davies , ]. However, during the ENSO event in June 2015, all four species were most abundant in the surface mixed layer, implying that the species adapted to hypoxia, inverted their normal pattern of distribution, possibly because the elevation of the suboxic water (<4.4 µmol/kg) reduced the thickness of the hypoxic layer (Figures and ).…”

“…Fish larvae of tropical species that inhabit a range from the southern California Current system to northern Chile in the Tropical and Subtropical Oriental Pacific, with planktonic phases of ∼8–12 days [ Moser , ], may provide a good biological indicator of interannual changes because of their wide distribution in the ocean and their differential response to the structure of the water column [ Moser and Smith , ; Apango‐Figueroa et al ., ; Davies et al ., ; Contreras‐Catala et al ., ]. Good indicators would include (i) larvae of Vinciguerria lucetia , which have high abundance and frequency in the oceanic domain and have showed strong affinity to the surface mixed layer and thermocline; (ii) larvae of Diogenichthys laternatus and Bregmaceros bathymaster , which have been recorded predominantly in the thermocline and shallow hypoxic layer; and (iii) larvae of Auxis spp., which have been recorded mainly in the surface mixed layer.…”

Zooplankton abundance during summer in the Bay of La Paz (southwestern Gulf of California, Mexico)

“…For example, Palomares-García et al (2013) documented that the epipelagic copepods distribution is closely related to the water column's temperature, showing the highest abundances during the summertime (July). Contreras-Catala et al (2016) evidenced a strong relationship between the mesopelagic fish larvae populations and the water column's stratification, which depends on the temperature distribution. More recently, Ambriz-Arreola et al (2017) documented that the distribution of some euphausiids species is strongly related to the water column's thermal structure, with their maximum abundance close to the thermocline.…”

“…In the southern Gulf of California, during summer, the occurrence of mesoscale structures, such as fronts and eddies, affected the sea surface temperature (SST) distribution, with values >28°C (Lavín et al, 2009). In this region, the influence of different environmental variables on particular zooplankton groups was previously reported, showing that the zooplankton population dynamic and its response depends on the presence of physical structures with different scales that exert a significant influence over the euphausiids (Ambriz-Arreola et al, 2017), the mesopelagic fish larvae (Contreras-Catala et al, 2016), and the epipelagic copepods (Palomares-García et al, 2013). In the Bay of La Paz, a relationship between the abundance of zooplankton functional groups and the cold-water masses associated with a mesoscale cyclonic eddy has been documented, showing a radial distribution from the center of the eddy to the periphery, with the highest zooplankton biomass at the center.…”

Larval Fish Habitats and Deoxygenation in the Northern Limit of the Oxygen Minimum Zone off Mexico

“…Baseline information on the present state of the pelagic ecosystem is needed at local scales to evaluate future changes caused by the loss of oxygen in this OMZ. Fish larvae of tropical and subtropical species that inhabit the northeast Pacific Ocean (Moser, ) are good biological indicators of dissolved oxygen changes because of their sensitivity to the hydrographic gradients in the water column (Apango‐Figueroa et al, ; Contreras‐Catala et al, ; Davies et al, ; Moser & Smith, ; Sánchez‐Velasco et al, ).…”