Direct effects and prey-mediated effects of global change in projections of early life stages of pelagic predators

Global change will impact the distribution and abundance of
predators through a combination of abiotic variables, such as temperature,
and biotic variables, such as prey availability. However, there is a poor
understanding of how distribution projections with biotic variables differ
from those with abiotic variables, particularly in resource limited and
marine systems. We address this knowledge gap using the planktonic larvae
of iconic and economically important pelagic fish predators. We leverage a
multidecadal, long-term sampling program from the western
Atlantic Ocean to assess the efficacy of using zooplankton prey (copepods,
larvaceans and cladocerans) and climate variables to predict the
distribution of larvae of seven pelagic fish species, including tunas,
billfishes and mahi-mahi. These data (2 excel files, plus an additional
excel file), as well as earth system model data (4 netcdf files) that
inform projections are included here. We also include 5 R scripts that
processed data, configured models, produced plots, etc. Results revealed
that zooplankton prey, particularly larvaceans, showed high importance for
predicting the distribution of smaller tunas. Temperature showed high
importance for true tuna (Thunnus spp.), billfish and mahi-mahi.
Statistical models linking predator, prey and abiotic variables were
forced with climate projections from an ensemble of earth system models to
assess zooplankton and fish larvae distribution changes. Redistributions
and declines of zooplankton prey led to minimal changes in abundance and
distribution for most larval taxa. However, direct climate change effects,
driven partially by ocean warming, led to increases in abundance and
northward distribution shifts for multiple larval taxa. These climate
change-zooplankton–fish larvae relationships highlight that future
distribution and abundance changes of predators can be dampened when
assessing impacts of prey availability changes. We also show that in a
resource-limited system, key pelagic predators, many of which produce
lucrative fisheries, are spatiotemporally linked with their preferred
zooplankton prey.