The northern Gulf of Mexico (nGOM) is a highly productive region and supports some of the world’s largest fisheries. Mesozooplankton represent a key linkage in coastal food webs for larval fish, both as food and as competition. While many studies have investigated seasonal patterns of mesozooplankton off the Louisiana coast and in the Mississippi Bight, there is little information about mesozooplankton communities on the Texas shelf. In this study, we investigated environmental drivers of mesozooplankton community variability over space and time. Samples were collected on the Texas shelf near Galveston Bay at seasonal intervals following Hurricane Harvey. Total mesozooplankton abundance were found to be highest in September. Diversity exhibited a hump-shaped pattern over the 6 months sampled, with the highest diversity occurring in October 2017. Taxa richness did not vary over the sampling period. Significant differences in mesozooplankton community structure were found only between September 2017 and March 2018. Community abundance was greatest nearshore, and zooplankton diversity was greatest on the shelf. Community structure was found to be driven by both temperature and salinity. Spatial and temporal patterns of specific larval fish prey are presented.

Heatwaves are becoming more frequent and intense with climate change, but the demographic and evolutionary consequences of heatwaves are rarely investigated in herbaceous plant species. We examine the consequences of a short but extreme heatwave in Oregon populations of the common yellow monkeyflower (Mimulus guttatus) by leveraging a common garden experiment planted with range wide populations and observational studies of eleven local populations. In the common garden, 89% of seedlings died during the heatwave including >96% of seedlings from geographically local populations. Some populations from hotter and drier environments had higher fitness, however others from comparable environments performed poorly. Observational studies of local natural populations drastically differed in the consequences of the heatwave: one population was completely extirpated and nearly half had a >50% decrease in fitness. However, a few populations had greater fitness during the heatwave year. Differences in mortality corresponded to the impact of the heatwave on soil moisture where retention of soil moisture throughout the heatwave led to greater survivorship. Our results suggest that not all populations experience the same intensity or degree of mortality during extreme events and such heterogeneity could be important for genetic rescue or to facilitate the distribution of adaptive variants throughout the region.

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