Simple ecological trade-offs give rise to emergent cross-ecosystem distributions of a coral reef fish

Abstract

Ecosystems are intricately linked by the flow of organisms across their boundaries, and such connectivity can be essential to the structure and function of the linked ecosystems. For example, many coral reef fish populations are maintained by the movement of individuals from spatially segregated juvenile habitats (i.e., nurseries, such as mangroves and seagrass beds) to areas preferred by adults. It is presumed that nursery habitats provide for faster growth (higher food availability) and/or low predation risk for juveniles, but empirical data supporting this hypothesis is surprisingly lacking for coral reef fishes. Here, we investigate potential mechanisms (growth, predation risk, and reproductive investment) that give rise to the distribution patterns of a common Caribbean reef fish species, Haemulon flavolineatum (French grunt). Adults were primarily found on coral reefs, whereas juvenile fish only occurred in non-reef habitats. Contrary to our initial expectations, analysis of length-at-age revealed that growth rates were highest on coral reefs and not within nursery habitats. Survival rates in tethering trials were 0% for small juvenile fish transplanted to coral reefs and 24–47% in the nurseries. As fish grew, survival rates on coral reefs approached those in non-reef habitats (56 vs. 77–100%, respectively). As such, predation seems to be the primary factor driving across-ecosystem distributions of this fish, and thus the primary reason why mangrove and seagrass habitats function as nursery habitat. Identifying the mechanisms that lead to such distributions is critical to develop appropriate conservation initiatives, identify essential fish habitat, and predict impacts associated with environmental change.

Orientation from open water to settlement habitats by coral reef fish: behavioral flexibility in the use of multiple reliable cues

“…This behavior could serve as a mechanism to maximize successful settlement or recruitment to preferred habitat . It has been shown that seagrass beds have lower predation risk compared with coral reefs (Grol et al 2011, Kimirei et al 2013. Adaptive be havior that leads to successful orientation and recruitment to seagrass beds can thus ultimately lead to increased survival, which is critical for population maintenance.…”

“…This preference for seagrass cues might reflect innate behavior that has been genetically selected for through higher survival rates of fish with this trait, and could be a similar mechanism as that of, for example, reef fish that may use chemical cues from terrestrial forest vegetation to navigate towards coastal environments (Dixson et al 2008). Preferential selection for this trait could result from higher survival chances of fish that locate and settle in seagrass habitat (Grol et al 2011) irrespective of the presence of conspecifics, compared with those that are more attracted to conspecifics irrespective of seagrass presence.…”

“…Although fish may potentially not be considered naïve once they have settled, it is unlikely that fish lose their attraction to preferred chemical cues directly after settlement. Various studies have used recent settlers where larvae were not available (Dixson et al 2008, Huijbers et al 2008 and have shown that recently settled fish showed the same cue preference even if they had been collected from different settlement habitats (Grol et al 2011, Huijbers et al 2011. One study even showed that habitat preference (for mangrove) persisted up to the adult stage for any size of settled fish collected from reef, seagrass, or rubble habitat (Huijbers et al 2011).…”

Factors Affecting Japanese Pond Smelt (<i>Hypomesus nipponensis</i>) Stock Trajectory in Lake Kasumigaura and Kitaura

“…In understanding population dynamics it is important to study the habitat of the fish as this plays a significant role in their survival both as juveniles and as they grow into adult forms [22]. Here, a habitat is the interaction of a fish species with biotic and abiotic factors to support a healthy population [23].…”

Variación entre hábitats de la densidad y composición por tallas en peces de arrecife de la región noroccidental de Cuba

“…Many fish species move among different coastal habitats created by mangroves, seagrass beds, and coral reefs during their life cycles (Grol, Nagelkerken, Rypel & Layman, 2011). Consequently, conservation efforts to protect species and biodiversity are developing to provide protection of habitats including linking corridors for all life stages (Mumby et al, 2004;Sale et al, 2005).…”