Gyory Joanna

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  • Article
    The role of season and salinity in influencing barnacle distributions in two adjacent coastal mangrove lagoons
    (University of Miami - Rosenstiel School of Marine and Atmospheric Science, 2011-07-01) Starczak, Victoria R. ; Perez-Brunius, Paula ; Levine, Hazel E. ; Gyory, Joanna ; Pineda, Jesus
    Barnacles are often abundant on roots and branches of mangrove trees in tidal channels and coastal lagoons of the Pacific coast of Panama. Yet, in some coastal lagoons, barnacles are absent. We investigated pre- and post-settlement factors that affect barnacle distributions in two adjacent coastal lagoons in Bahía Honda, Panama, one with moderate to large barnacle populations, and the other with nearly non-existent populations. Although mean barnacle recruitment was higher on mangrove root segments during the dry season (December-April) than in the wet season (May-November), it was not significantly different between the two coastal lagoons. The coastal lagoon with fewer barnacles is considered an estuary, with high freshwater flow and low salinities (0.1) during the wet season that were lethal to barnacle nauplii and cyprids. Furthermore, coastal water was not observed to enter the lagoon, even during flood tides. In contrast, more barnacles were found in the lagoon with higher salinities (8.5). During the dry season, freshwater flow was greatly reduced in both lagoons, resulting in a similar salinity range (22-33). We conclude that the lack of barnacles in the estuarine coastal lagoon is largely due to high flushing rates and low salinities that reduce larval concentrations during the wet season. Moreover, low adult abundance in the lagoon's interior may further reduce larval supply and settlement.
  • Preprint
    Turbidity triggers larval release by the intertidal barnacle Semibalanus balanoides
    ( 2012-11-12) Gyory, Joanna ; Pineda, Jesus ; Solow, Andrew R.
    Gravid adults of the common intertidal barnacle Semibalanus balanoides (L.) brood fully developed larvae until individuals perceive some cue from the environment that triggers synchronous larval release. The prevailing hypothesis has been that phytoplankton blooms trigger release because they provide a food source for nauplius larvae. Through observations and field experiments, we tested the hypothesis that turbidity from any source, not just phytoplankton blooms, can trigger release. We documented five larval release events at three sites in the northeastern United States. Two events coincided with chlorophyll increases, and all five coincided with turbidity increases. In experiments, the larval release response was equivalent when adults were exposed to diatoms or inert synthetic beads, and it was significantly higher than under exposure to filtered seawater. We also tested the hypothesis that turbidity can decrease the risk of cannibalism for newly-released nauplii. Under experimentally manipulated conditions, adults consumed significantly fewer nauplii in a high-turbidity environment. We suggest that reproduction in this species may have evolved to coincide roughly with the local onset of winter/spring phytoplankton blooms, but the timing of larval release may have been fine-tuned further by cannibalism and predation pressures. The potential for turbid conditions to serve as a refuge for planktonic larvae of other marine organisms merits further investigation.