Effect of food deprivation in late larval development and early benthic life of temperate marine coastal and estuarine caridean shrimp

Abstract

Decapod crustaceans larvae commonly rely on the ingestion of exogenous planktonic food to survive and metamorphose. During larval development, decapods are exposed to variable periods of food shortage. Unfavorable trophic scenarios affect larval decapods differently and the post-settlement effects of nutritional stress during late larval development are still largely unknown. Facultative secondary lecithotrophy (FSL) can be described as the ability of decapodids to moult to the first juvenile stage in the absence of food, while retaining its ability to successfully capture, ingest and catabolize dietary prey. The finding of FSL in decapodids increased the need to understand how this feeding plasticity may affect benthic juveniles. The present work investigated if the last zoeal stage, the decapodid and the first juvenile instar of four marine and estuarine temperate caridean shrimp (Lysmata seticaudata, Palaemon elegans, P. serratus and Palaemonetes varians) display FSL. In all tested species, the last zoeal stage was unable to advance to decapodid in the absence of food. However, the decapodid was able to moult to the first juvenile instar, either in the presence or absence of food, confirming the existence of FSL in all tested species. Decapodids deprived of food displayed longer intermoult periods than fed conspecifics (± 5 and ± 4 days, respectively). Neither first juvenile instars produced from fed nor starved decapodids were able to advance to the second juvenile instar in the absence of food, confirming that FSL is lost in the first juvenile instar. Juveniles produced from fed decapodids were able to endure starvation for longer periods than conspecifics originating from starved decapodids (± 9 and ± 3 days, respectively). Under optimal feeding, first juvenile instars produced from fed or starved decapodids were able to advance to the second instar and presented similar intermoult periods (± 4 days). The absence of FSL in the last zoeal stage may be a larval strategy to maximize the energetic stores available for decapodids searching for suitable settlement sites (e.g. estuarine species such as P. varians), or early juvenile instars facing suboptimal trophic scenarios (as they can endure longer periods of food deprivation). FSL in decapodids may allow them to rapidly moult to the first juvenile stage and increase their survival by improving their foraging and predator avoidance behaviors. Our results suggest that nutritional stress may have a higher impact on the settlement dynamics of coastal caridean shrimp when affecting the last zoeal stage rather than decapodids (able to cope with food deprivation). The negative effects imposed by nutritional stress to the decapodid (when facing starvation and having to catabolize energetic reserves) appear to be “carried-over” post-settlement.