Behavior such as ontogenetic vertical migration (OVM) limits the transport of marine larvae with short pelagic larval durations (PLDs), but its effect on the supposed long-distance dispersal of larvae with long PLDs is unknown. We conducted laboratory tests of ontogenetic change in larval phototaxis and examined size-specific patterns of larval distribution in the plankton to characterize OVM in the Caribbean spiny lobster Panulirus argus during its long (6 mo) PLD. We then used a coupled biophysical model to explore the consequences of OVM and hydrodynamics on larval P. argus dispersal in the Caribbean Sea. Larvae reared in the laboratory were positively phototatic for the first 2 mo and then avoided light thereafter, similar that seen in the planktonic distribution of same-sized larvae. Simulations of larval dispersal from 13 spawning sites in the Caribbean Sea predicted that twice as many larvae would recruit to nurseries if they displayed OVM compared with passive dispersers. Larvae with OVM typically settled < 400 km from where they were spawned, while passive dispersers often settled >1000 km away. OVM also produced an asymmetrical bimodal pattern of dispersal dominated by larvae that settled near their origin (~60%), but showed a second peak of larvae that dispersed over long distances (~20%). Hydrodynamics created subregional differences in the potential for self-recruitment. Our findings suggest that (1) larval behavior constrains the dispersal of even long-lived larvae, particularly in tandem with retentive oceanographic environments, and (2) larval sources of P. argus in the Caribbean Sea cannot be estimated from passive transport and surface circulation.

American lobsters Homarus americanus are known to move offshore during the fallto-winter transition and inshore, into shallower, warmer water in the spring and summer. To determine whether all types of lobsters in New Hampshire coastal waters exhibit this movement pattern, we fitted 45 lobsters (ovigerous and non-ovigerous females, and males) with ultrasonic transmitters and tracked their movements over 3 successive seasons from 2006 to 2009. The major goals of this study were to determine (1) if ovigerous females express different seasonal movement patterns than males or non-ovigerous females; (2) what environmental cues might trigger offshore movements in the fall; and (3) the location of ovigerous females when their eggs hatch in the spring−summer. Most lobsters (82%) moved > 0.5 km, whereas the rest remained close to their original release location. Of the lobsters that moved, 51% moved < 5 km, 19% moved 5−10 km, and 30% moved >10 km. There were no significant differences in the seasonal movements of ovigerous females compared with non-ovigerous females, but females as a group moved significantly farther than males. The ovigerous lobsters that moved offshore tended to remain there until the time when their eggs most likely hatched. In conclusion, the seasonal movements of ovigerous lobsters in coastal waters significantly influence the location and timing of larval hatch and, ultimately, settlement.

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The generality of ecological patterns depends inextricably on the scale at which they are examined. We investigated patterns of crab distribution and the relationship between crabs and vegetation in salt marshes at multiple scales. By using consistent monitoring protocols across 15 U.S. National Estuarine Research Reserves, we were able to synthesize patterns from the scale of quadrats to the entire marsh landscape to regional and national scales. Some generalities emerged across marshes from our overall models, and these are useful for informing broad coastal management policy. We found that crab burrow distribution within a marsh could be predicted by marsh elevation, distance to creek and soil compressibility. While these physical factors also affected marsh vegetation cover, we did not find a strong or consistent overall effect of crabs at a broad scale in our multivariate model, though regressions conducted separately for each site revealed that crab burrows were negatively correlated with vegetation cover at 4 out of 15 sites. This contrasts with recent smaller-scale studies and meta-analyses synthesizing such studies that detected strong negative effects of crabs on marshes, likely because we sampled across the entire marsh landscape, while targeted studies are typically limited to low-lying areas near creeks, where crab burrow densities are highest. Our results suggest that sea-level rise generally poses a bigger threat to marshes than crabs, but there will likely be interactions between these physical and biological factors. Beyond these generalities across marshes, we detected some regional differences in crab community composition, richness, and abundance. However, we found striking differences among sites within regions, and within sites, in terms of crab abundance and relationships to marsh integrity. Although generalities are broadly useful, our findings indicate that local managers cannot rely on data from other nearby systems, but rather need local information for developing salt marsh management strategies.