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Aim: Genetic connectivity is a key component of species resilience to climate change in terms of recovery capacity following disturbance and capacity to disperse to novel locations as the climate warms and isotherms shift poleward. We aimed to strengthen our understanding of resilience in this context by characterizing patterns of connectivity and genetic diversity in a broadcast spawning coral across a tropical-- temperate transition zone. We hypothesize genetic differentiation between tropical and temperate populations and decreasing genetic diversity with higher latitudes. Location: Western Australia (WA). Taxon: Turbinaria species complex. Turbinaria reniformis' Oken, 1815 (Scleractinia: Dendrophylliidae). Methods: A total of 930 target corals were sampled from 10 locations between 13 and 32° latitude spanning a 9°C mean temperature range. In situ species identification of T. reniformis is hindered by morphological plasticity and homoplasy with sister species. We combined Sanger sequencing of two mitochondrial DNA markers and high-throughput genotyping by sequencing (GBS) to isolate a single genetic Turbinaria lineage from our dataset through which patterns of genetic flow and diversity along the WA coastline could be explored using population- and individual-based clustering analyses. Results: Mitochondrial DNA sequence variation was low among Turbinaria samples and could not resolve individual species. Using GBS, we identified three genetically distinct lineages. Subsequent analyses within one of these lineages revealed strong spatial subdivision with 2-3 genetic clusters. While temperate populations were genetically diverged from more tropical sites, we did not observe declines in genetic diversity with latitude. Main conclusions: Tropical populations of T. 'reniformis' in Western Australia exhibit strong genetic connectivity, which extends to a southern limit at sub-tropical Shark Bay. Temperate populations are genetically isolated from their tropical counterparts but have relatively high genetic diversity. While the maintenance of genetic variation in temperate populations may provide some resilience to future climate scenarios, their isolation may increase their vulnerability. [ABSTRACT FROM AUTHOR]

Abstract: Hydrodynamic data (time series of tidal velocities and vertical stratification) were collected during the winter of 2009 in Shark Bay, Western Australia, to document water exchange between the bay and the ocean. The net loss of freshwater through evaporation causes salinity levels in Shark Bay to be higher than the adjacent ocean, leading to its classification as an inverse estuary. The observations revealed pulses of near-bed dense water outflows (velocity ∼0.10ms−1) at weekly to fortnightly intervals, associated with periods of turbulent mixing when tidal velocities and winds were both weak. Although tidal mixing appeared to be the main control on the formation of the outflows, wind mixing during strong wind events was also sufficient to destratify the water column and interrupt the density-driven circulation. These data represent the first direct measurements of exchange flows in the entrance channels of Shark Bay and reveal a mechanism to maintain the balance of salinity as well as contribute to the exchange of material (e.g., larvae) between the bay and the ocean. [Copyright &y& Elsevier]