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A mathematical model is developed to investigate the effect of harvesting zone configuration upon total biomass yield of a resource species with size dependent continuum spatiotemporal population dynamics. Size (with the interpretation of average mass per individual at each spatiotemporal point) is modeled as an additional state variable along with population density in contrast to the traditional approach of viewing size as a structure parameter. The model takes a form of a coupled system of partial differential equations (PDE) of reaction–diffusion type for the population density and first-order hyperbolic transport type for the mass state variable. The model was investigated both analytically and numerically and is illustrated by applying it to the harvesting of a brown shrimp population in the Gulf of Mexico distributed within a patched network of hypothesized marine protection areas (MPAs) and fishing zones. The results highlight the critical role that size dependent mobility plays in determining optimal MPA network configurations. [ABSTRACT FROM AUTHOR]

Climate change impacts physical and chemical properties of the oceans, and these changes affect the ecology of marine organisms. One important ecological consequence of climate change is the distribution shift of marine species toward higher latitudes. Here, the prevalence of nearly 150 species of fish and invertebrates were investigated to find changes in their distributions over 35 years along a subtropical coast within the Gulf of Mexico. Our results show that 90 species increased their occupancy probability, while 33 decreased (remaining species neither increase or decrease), and the ranges of many species expanded. Using rarefaction analysis, which allows for the estimation of species diversity, we show that species diversity has increased across the coast of Texas. Climate-mediated environmental variables are related to the changes in the occupancy probability, suggesting the expansion of tropical species into the region is increasing diversity., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2019.)