Phenotypic plasticity in larval swimming behavior in estuarine and coastal crab populations

Abstract

The timing of vertical migrations by newly-hatched larvae determines the extent of transport away from adult populations and exposure to predatory fishes, but it is largely unknown whether larval swimming behavior is a fixed trait or changes adaptively in response to different ocean conditions that are encountered between habitats. We determined whether larvae of the shore crab, Pachygrapsus crassipes, hatched in the San Francisco Estuary and those hatched nearby on the outer coast undertake tidal and diel vertical migrations. Vertical swimming of larvae that were released by females collected from the two locations were recorded in the laboratory for up to four days in constant darkness without a tidal cycle to detect the presence of endogenous tidal and diel vertical migrations. P. crassipes larvae from the outer coast population did not exhibit rhythmic vertical migrations, remaining near the surface throughout the day, whereas larvae from the estuarine population did undertake complex vertical migrations relative to tidal and diel cycles. Although current patterns differ on the open coast and in the estuary, remaining in surface waters at both locations would favor seaward transport of larvae to offshore nursery areas. However, undertaking tidal vertical migrations in estuaries would expedite seaward transport while increasing the risk of fish predation during the daytime. The differences in behaviors are likely phenotypic, because larvae came from neighboring populations and intermingle in offshore larval nursery areas. This spatial variation in larval swimming behavior among habitats enhances transport to offshore nursery areas.

Vertical salmon lice behaviour as a response to environmental conditions and its influence on regional dispersion in a fjord system

“…It is recognized that planktonic organisms use circulation systems to increase their retention in favourable areas and to avoid drifting into areas with low survival or growth opportunities (Tapia & Pineda 2007, Miller & Morgan 2013. The key behavioural mechanism in achieving this is vertical positioning and migration ).…”

Morfogeometría del caparazón del cangrejo Damithrax spinosissimus (Decapoda: Mithracidae) en tres islas del Caribe suroccidental

“…Las variaciones ambientales antes descritas también pueden explicar las diferencias de conformación del caparazón de D. spinosissimus entre islas. Además, los disturbios de tipo antropogénico, debido a las plumas de sedimentos del canal del Dique (Alvarado & Corchuelo 1992), pueden tener un efecto negativo en las larvas, no solo por causar mortalidad (Pardo, véliz, Wehrtmann, & Klaus,1997;Gebauer, Paschke & Anger, 2003), sino porque pueden afectar el desarrollo ontogénico (Anger, 2003;Pechenic, 1999), o enviar señales quí-micas que favorezcan el auto-reclutamiento (Rodríguez, Ojeda, & Inestrosa, 1992;Miller & Morgan, 2013). La capacidad sensorial de las larvas de los crustáceos, permite que los individuos continuamente monitoreen las condiciones ambientales, lo cual puede estimular una respuesta rápida y continua frente a los cambios del medio.…”

Biogeographic, ontogenetic, and environmental variability in larval behaviour of American lobster Homarus americanus

“…For example, plasticity in larval response to tidal circulation was suggested as a mechanism to help larvae reach favourable nursery habitats in coastal and offshore populations of shore crab Pachygrapsus crassipes, where genetic differences are not expected (Miller & Morgan 2013). Conversely, oceanographic conditions that strongly influence dispersal may restrict gene flow and lead to local adaptation in populations of acorn barnacles Semibalanus balanoides (Bertness & Gaines 1993).…”

“…Vertical swimming that places larvae in specific flow conditions (e.g. selective tidal stream transport; Miller & Morgan 2013, Moksnes et al 2014 or at different positions in the water column as a function of time of day (Cowen et al 2006), and/or ontogeny (Butler et al 2011), can strongly influence horizontal transport. Vertical swimming by meroplankton can therefore influence horizontal transport by exposing larvae to heterogeneous physical flow environments (Queiroga & Blanton 2005, Fiksen et al 2007, Leis 2007, Cowen & Sponaugle 2009) and temperatures, thus influencing both dispersal and development.…”

“…Larval fish studies link variability in swimming to latitudinal gradients among species (Leis et al 2013), but intra-specific variation in response to different environments remains unresolved (but see Guan et al 2008). Observations of larval shore crabs highlight intra-specific variation in swimming behaviour among different coastal (Pachygrapsus crassipes Miller & Morgan 2013) and tidal environments (Carcinus maenas Moksnes et al 2014), highlighting potential influence of intra-specific variation in behaviour on larval transport trajectories. For species with pelagic durations that span weeks to months, population differences in behaviour and dispersal can lead to genetic differences (Bertness & Gaines 1993, Stobutzki 1998) and potentially to local adaptation (Yamahira & Conover 2002, Moksnes et al 2014.…”