Meeting Abstract
Demographic population connectivity can be assessed via a variety of methods, but all of the standard approaches require significant effort and funding to implement. In systems that are characterized by strong latitudinal gradients in spawning time (or larval release) and settlement, regional scale connectivity can also be estimated by spatial variation in the correlations among these events. I monitored the timing of larval release in 9 widely separated barnacle (Semibalanus balanoides) populations in the Gulf of Maine and the temporal patterns of settlement in a subset of 7 of these populations during the spring and summer of 2017. Populations were distributed inshore of two different oceanographic regimes; the Eastern and Western Maine coastal current systems (EMCC vs. WMCC). Laboratory estimates of pelagic larval duration were combined with cross-correlation analyses to infer connectivity from timing data. Larval release data indicated the existence of two gradients in spawning time that ran in opposite directions along the coast. Settlement was bimodally distributed in the south, grading into a unimodal distribution further north. Cross-correlation results suggest that early season settlement in populations inshore of the WMCC was driven by larval supply from populations in that same region, but late season settlement was derived from natal population associated with the EMCC, while settlement inshore of the EMCC was entirely derived from natal populations within that same region. Although this approach does not fully resolve population-level connectivity patterns, it is relatively inexpensive and easy to implement and regional scale patterns are often adequate for many management purposes.
