Interactions between range‐expanding tropical fishes and the northern Gulf of Mexico red snapper Lutjanus campechanus

Abstract

Experimental investigation of the intensity of potential competitive interactions among increasingly abundant tropically-associated grey Lutjanus griseus and lane snapper Lutjanus synagris and resident northern Gulf of Mexico (nGOM) red snapper Lutjanus campechanus was undertaken in large outdoor mesocosms. In pair-wise interaction trials, compared with L. synagris, L. campechanus demonstrated significantly increased roving behaviour and predatory activity. While no significant difference in these activities was observed between L. campechanus and L. griseus, when all three snappers (Lutjanidae) were grouped together L. campechanus swimming activity significantly decreased in the presence of both tropically-associated species. Overall, L. campechanus were more active and aggressive predators and appear to be competitively resistant to L. griseus and L. synagris. As lower latitude species have continued to become increasingly prevalent in nGOM habitats and regional warming continues to affect resident reef-associated fishes, these findings contribute to the assessment of the effects of warming-related species shifts upon nGOM fishes and document current partial resilience of L. campechanus to climate-related expansions of tropical confamilials.

Ecological interactions between Gulf of Mexico snappers (Teleostei: Lutjanidae) and invasive red lionfish (Pterois volitans)

“…While salinity range differed with lionfish-lane snapper interaction trials, most effects appeared to be reflective of species behaviors than the influence of salinity. As other lane snapper behaviors were unaffected by salinity and a similar snapper interaction study found no influence of salinity on lane snapper behavior [ 42 ], we are confident that these differential interactions were not heavily influenced by salinity range, especially given no effect on lane snapper or lionfish swimming activities.…”

“…Although this design does not factor for prey depletion, additional investigation [ 59 ] has highlighted the value of holding initial prey constant to inform about stochastic predation, which may be more likely to occur with increasing predator richness and density. A similar study [ 42 ] has demonstrated that juvenile snappers prey upon blue crabs of this size range.…”

“…While snappers and lionfish have been documented undertaking crepuscular activities [ 31 , 54 – 56 ], these species have likewise been observed interacting and feeding in their natural habitats during the day [ 44 – 47 , 49 , 57 ]. Previous investigation [ 42 ] has additionally shown interactions among the three snapper species as being pronounced during these times of study, while lionfish have been classified as diurnal feeders [ 51 ].…”

“…During acclimation and holding periods, all snappers and lionfish were fed 0.25 kg (per tank) of squid ( Loligo sp.) twice weekly, following previous mesocosm investigations using red snapper [ 42 , 50 ]. Lionfish were additionally fed twenty juvenile blue crabs (1.0–2.5 cm carapace width) every other day, given lionfish predatory feeding demands [ 51 – 52 ].…”

“…campechanus ) to determine their comparative vulnerabilities to red lionfish competition. These snappers co-occur in nGOM offshore hardbottom and structured reef habitats where space and prey resources are both limited [ 42 ], and have been observed interacting during similar times of day for shared resources [ 42 – 47 ]. Given their habitat and prey overlap with red lionfish [ 23 , 48 ], and presumed effects of lionfish on their densities [ 49 ], competition between snappers and lionfish for shared resources is expected to be high.…”