Exposure of Loggerhead Sea Turtle Nests to Waves in the Florida Panhandle

Wave wash-over poses a significant threat to sea turtle nests, with sustained exposure to waves potentially resulting in embryonic mortality and altered hatchling locomotor function, size, and sex ratios. Identifying where and under what conditions wave exposure becomes a problem, and deciding what action(s) to take (if any), is a common issue for sea turtle managers. To determine the exposure of sea turtle nests to waves and identify potential impacts to hatchling productivity, we integrated a geographic information system with remote sensing and wave runup modeling across 40 nesting beaches used by the Northern Gulf of Mexico Loggerhead Recovery Unit. Our models indicate that, on average, approximately 50% of the available beach area and 34% of nesting locations per nesting beach face a significant risk of wave exposure, particularly during tropical storms. Field data from beaches in the Florida Panhandle show that 42.3% of all nest locations reported wave exposure, which resulted in a 45% and 46% decline in hatching and emergence success, respectively, relative to their undisturbed counterparts. Historical nesting frequency at each beach and modeled exposure to waves were considered to identify priority locations with high nesting density which either experience low risk of wave exposure, as these are good candidates for protection as refugia for sustained hatchling production, or which have high wave exposure where efforts to reduce impacts are most warranted. Nine beaches in the eastern Florida Panhandle were identified as priority sites for future efforts such as habitat protection or research and development of management strategies. This modeling exercise offers a flexible approach for a threat assessment integration into research and management questions relevant to sea turtle conservation, as well as for other beach species and human uses of the coastal environment.

Control of actin dynamics during cell motility

Actin polymerization is essential for cells to migrate, as well as for various cell biological processes such as cytokinesis and vesicle traffic. This brief review describes the mechanisms underlying its different roles and recent advances in our understanding. Actin usually requires “nuclei”—preformed actin filaments—to start polymerizing, but, once initiated, polymerization continues constitutively. The field therefore has a strong focus on nucleators, in particular the Arp2/3 complex and formins. These have different functions, are controlled by contrasting mechanisms, and generate alternate geometries of actin networks. The Arp2/3 complex functions only when activated by nucleation-promoting factors such as WASP, Scar/WAVE, WASH, and WHAMM and when binding to a pre-existing filament. Formins can be individually active but are usually autoinhibited. Each is controlled by different mechanisms and is involved in different biological roles. We also describe the processes leading to actin disassembly and their regulation and conclude with four questions whose answers are important for understanding actin dynamics but are currently unanswered.

Predicting Wave Wash Overs for Sea Turtle Nests

To better protect coastal species, researchers developed a model that predicts harmful wash overs with 83% accuracy.

SHIP WAVES IN NAVIGATION CHANNELS

Ships moving through water generate surface waves which in many navigation channels cause severe wave-wash damage to the bank* In some waterways, rather extensive protection works have been constructed to reduce this destructive action to levee faces (Hertzberg, 1954). This action, termed "foreshore erosion", has been described by Lewis (1956) for the lower Mississippi River as follows: "The attack, interestingly enough, takes place at lowwater . It is due largely to the waves created by passing ocean-going ships and is augmented by shallow draft traffic. It may be asked at this point why this attack is new, in view of the fact that ship and barge traffic has long existed on the river in very substantial volume? The answer is that the recent technological advances in ocean-going and river transportation have greatly increased maximum and average speeds, and accordingly, the wave making potentials."

Effects of motorised boat passes on the time budgets of New Zealand dabchick, Poliocephalus rufopectus

New Zealand dabchicks, Poliocephalus rufopectus, are small grebes restricted to the North Island of New Zealand; with a total population of only ~1200–1500 birds, they are classed as endangered. We conducted experiments to examine the effects of boat passes of different speeds and frequencies on the time budgets of the New Zealand dabchick. We also examined whether New Zealand dabchicks became habituated to boat passes. We found that a single boat pass caused a significant short-term change in New Zealand dabchick behaviour compared with pre–boat pass patterns. This change in behaviour was more pronounced when the frequency of boat passes was higher, and may impose energetic constraints on New Zealand dabchicks. Differences between behaviour before and after the boat pass were no longer evident 15 minutes after the boat pass. We found no significant effects of boat speed (5 v. 10 knots) on the behaviour of New Zealand dabchicks. There was evidence of habituation to boat traffic in high-use recreational sites. Further studies are required to investigate the influence of other human activities and the influence that boat and wave wash have on the nesting and breeding success of the New Zealand dabchick.