El Niño episodes coincide with California moray Gymnothorax mordax settlement around Santa Catalina Island, California

Abstract

The hypothesis that El Niño events influence the settlement patterns of the California moray Gymnothorax mordax is tested. The pelagic larval duration (PLD) of larval G. mordax is unknown, but studies on leptocephalus of related species suggest that larvae are long-lived, up to 2 years. Gymnothorax mordax, an elusive predatory species and the only muraenid off the coast of California, is considered abundant in the waters around Catalina Island. Thirty-three individuals were collected from Two Harbors, Catalina Island, and otoliths were taken to provide estimates of their age. Settlement year for each individual was backcalculated using estimated age from otolith measurements. These ages were then cross referenced with the Oceanic Niño Index (ONI) developed by the National Oceanographic and Atmospheric Administration (NOAA) to correlate estimated age of settlement with known El Niño years. Of the 33 individuals collected, 30 settled at Catalina Island during El Niño years. The oldest individual in the data-set was 22 years old, placing G. mordax as one of the longer-lived predatory fishes in the system. The present study represents the first account of wild G. mordax ages and suggests that El Niño events have an important role in driving the settlement of recruits towards the northern edge of their range.

Evidence of local adaptation in a waterfall-climbing Hawaiian goby fish derived from coupled biophysical modeling of larval dispersal and post-settlement selection

“…While it is evident that larval dispersal and spatial coagulation of larval cohorts [80] vary because of dynamic nearshore and offshore oceanographic conditions [81–85], our AD modeling also illustrates the importance of considering large-scale, climatic variation in assessments of population connectivity. ENSO and other large-scale climate-driven phenomena can exhibit small temporal-scale variability that enhance or suppress larval dispersal [85–89]. Consistent with evidence of ENSO influencing population connectivity of ocean-dwelling species across the Hawaiian archipelago and elsewhere in the Pacific [19, 90], we found that ENSO likely influences S. stimpsoni larval dispersal (Figure 1).…”

They Came From the Pacific: How Changing Arctic Currents Could Contribute to an Ecological Regime Shift in the Atlantic Ocean

“…However, with even the shortest Pacific to Atlantic connectivity timescales being greater than 2 years, our results suggest that the tipping point for any species requiring a single‐summer transit to avoid Arctic winters is highly improbable. The >2‐year connectivity timescales found here are beyond the PLD of rock lobsters at 18 months (Bradford et al, ) or even California morays at ~2 years (Higgins et al, ) but does not necessarily preclude a stepping‐stone style transit with species reproducing along the journey (Selkoe & Toonen, ). Planktonic species, such as the diatom N. seminae which inspired this study (Reid et al, ), are not limited by PLD, and so >2‐year transits cannot automatically be ruled out on that basis.…”

Eat whole and less often: ontogenetic shift reveals size specialization on kelp bass by the California moray eel, Gymnothorax mordax

“…Kernel density plots are displayed on the right with mean size (vertical lines) of kelp bass consumption by L H range (mm) and age class, in parentheses. L H were converted to age class date following the regression line presented in Higgins et al ( 2017 ) …”

“…This may in part help explain why we observed significantly smaller kelp bass sizes consumed in 2015 relative to all other years, where they had the largest L value. During the entirety of 2015, Santa Catalina Island was enveloped by the strongest El Niño since 1983 (Higgins et al 2017 ). This resulted in a complete loss of kelp canopy cover (B.H., C.L.…”

“…The paucity of dietary information stems from the fact that California morays were thought to be relatively rare (Graham 2004 ; Froeschke et al 2006 ). Recent work, however, revealed that the larvae of these cryptic predators are brought to Catalina Island during episodic El Niño events (Higgins et al 2017 ) resulting in an abundant and relatively large biomass (~ 173.83 kg) of G. mordax within the rocky reefs of Two Harbors, Catalina Island (Higgins and Mehta 2017 ). As El Niño events have been shown to greatly alter the distribution of larval fish and resultant fish assemblages (Cowen 1985 ; Allen et al 2002 ), one would anticipate temporal variation in predator–prey size relationships.…”