Effects of temperature and latitude on larval traits of two estuarine fishes in differing estuary types

Variations in abiotic conditions across large latitudinal gradients can strongly influence the early life history of coastal marine organisms. We investigated the effects of temperature and latitude on the larval traits of 2 estuarine fish species. The arrow goby Clevelandia ios and the endangered tidewater goby Eucyclogobius newberryi were studied in 18 estuaries along the coast of California, spanning similar to 8 degrees of latitude. These 2 species were selected because of their dissimilar preferences for estuary type: the arrow goby prefers cooler, fully tidal systems, whereas the tidewater goby prefers warmer lagoons that experience some degree of seasonal isolation from the ocean. Recently settled individuals were collected from July to October 2011, and temperatures within each estuary were recorded to determine how temperature affected larval duration, settlement, and growth rates. Temperatures were more variable among estuaries inhabited by the tidewater goby (10 degrees C range) than among those inhabited by the arrow goby (5 degrees C range). Larval traits of both species differed among sites, but more so for the tidewater goby, a difference that was tied to the greater differences in temperatures among sites in the seasonally closed estuaries it inhabited. In both species, fish that experienced warmer temperatures had shorter larval durations and faster growth rates and were smaller at settlement. Since the length of the larval period has been related to survival and dispersal distance, future variations in temperature due to climate change could have predictable influences on population density and connectivity in estuarine species.