Leatherback Turtles in the Eastern Gulf of Mexico: Foraging and Migration Behavior During the Autumn and Winter

We deployed 19 satellite tags on foraging adult leatherback turtles, including 17 females and 2 males, captured in the northeastern Gulf of Mexico in 2015, 2018, and 2019 in order to study regional distribution and movements. Prior to our study, limited data were available from leatherbacks foraging in the Gulf of Mexico. Tag deployment durations ranged from 63 to 247 days and turtles exhibited three distinct behavior types: foraging, transiting, or rapidly switching between foraging and transiting. Some females were tracked to nesting beaches in the Caribbean. Most of the leatherbacks remained on and foraged along the west Florida continental shelf whereas a few individuals foraged in waters of the central Gulf of Mexico during the autumn and winter. In addition, migration of adult females through the Yucatan Channel indicate that this is a seasonally important area for Caribbean nesting assemblages.

New insights into the crustal architecture and tectonic evolution of the Eastern Gulf of Mexico.

<p>The Gulf of Mexico is an intraplate oceanic basin where rifting started in the Late Triassic, leading to drifting by Middle Jurassic and ensuing oceanic accretion, which ceased by the Early Cretaceous. Its tectonic evolution encompasses multiple rifting phases dominated by orthogonal extension, major strike-slip structures, transtensional basins, variable magmatism, and salt deposition. This complex tectonic history is captured in the rifted margins of the Gulf of Mexico, especially along the eastern part of the basin; where considerable debate remains regarding the crustal configuration and tectonic evolution.</p><p>This study presents new insights into the crustal types and an updated tectonic framework for the Florida margin. An integrated analysis of seismic, gravity, and magnetic data allows us to characterise the continental crust, which shows wide zones of hyperextension that we relate to pull-apart basins, magmatic underplating, seaward dipping reflection (SDR) packages, and a narrow zone of exhumed mantle. In addition, we identified NW-SE trending sinistral strike-slip faults altering the typical crustal configuration expected in a rifted margin.</p><p>Our results suggest the need for a new plate model of the Florida margin at the Eastern Gulf of Mexico that invokes the polyphase rifting, accounts for the Yucatan’s block counter-clockwise rotation, explains the increase in magma supply, and captures the influence of strike-slip faults on the crustal boundaries and the magmatic budget.    </p>

Habitat specific trade-offs in growth and survival by hogfish Lachnolaimus maximus in southeast Florida

The hogfish Lachnolaimus maximus, an economically important, reef-associated protogynous teleost, has gained additional interest from fisheries managers due to evidence of overfishing in the southeastern United States. This study collected data on age and growth of hogfish in southeast Florida (SEFL), an understudied part of the species’ range. Hogfish (n = 227) were collected from three reef tracts at different depths between January 2016 and August 2017. The average maximum potential length (L∞) was 414 mm overall and showed evidence of Lee’s Phenomenon occurring relative to the eastern Gulf of Mexico, an area of presumed lower fishing pressure, where L∞ was 920 mm. Hogfish growth was also found to vary significantly by reef location in SEFL. Otolith-based aging revealed that SEFL hogfish growth past age 3 significantly decreased as reef depth increased between the three reef tracts [length at age 9 (L9) = 564, 405, 351 mm FL]. By L9, hogfish from the shallowest reef tract (4–6 m) were on average 61% longer and four times the weight of individuals collected from the deepest reef tract (15–25 m). Annual survival also increased with depth (42%, 65%, 73%), with a linear relationship to growth at L9 where R2 = 1.0, indicating there are inherent trade-offs between growth and longevity in hogfish of southeast Florida.

Spatial and Temporal Characteristics of the Submesoscale Energetics in the Gulf of Mexico

The submesoscale energetics of the eastern Gulf of Mexico (GoM) are. diagnosed using outputs from a 1/48° MITgcm simulation. Employed is a recently-developed, localized multiscale energetics formalism with three temporal scale ranges (or scale windows), namely, a background flow window, a mesoscale window, and a submesoscale window. It is found that the energy cascades are highly inhomogeneous in space. Over the eastern continental slope of the Campeche Bank, the submesoscale eddies are generated via barotropic instability, with forward cascades of kinetic energy (KE) following a weak seasonal variation. In the deep basin of the eastern GoM, the submesoscale KE exhibits a seasonal cycle, peaking in winter, maintained via baroclinic instability, with forward available potential energy (APE) cascades in the mixed layer, followed by a strong buoyancy conversion. A spatially-coherent pool of inverse KE cascade is found to extract energy from the submesoscale KE reservoir in this region to replenish the background flow. The northern GoM features the strongest submesoscale signals with a similar seasonality as seen in the deep basin. The dominant source for the submesoscale KE during winter is from buoyancy conversion and also from the forward KE cascades from mesoscale processes. To maintain the balance, the excess submesoscale KE must be dissipated by smaller-scale processes via a forward cascade, implying a direct route to fine-scale dissipation. Our results highlight that the role of submesoscale turbulence in the ocean energy cycle is region- and time-dependent.