In situ Estimation of Coral Recruitment Patterns From Shallow to Mesophotic Reefs Using an Optimized Fluorescence Imaging System

Coral recruitment represents a key element for coral reef persistence and resilience in the face of environmental disturbances. Studying coral recruitment patterns is fundamental for assessing reef health and implementing appropriate management strategies in an era of climate change. The FluorIS system has been developed to acquire high resolution, wide field-of-view (FOV) in situ images of coral recruits fluorescence and has proven successful in shallow reef environments. However, up to now, its applicability to mesophotic coral ecosystems remains unknown due to the complexity of the system and the limited time available when working at mesophotic depth. In this study we optimized the FluorIS system by utilizing a single infrared-converted camera instead of the bulkier regular dual-camera system, substantially reducing the system complexity and significantly decreasing the acquisition time to an average of 10 s for a set of 3 images. Moreover, the speed-FluorIS system is much more economical, decreasing the cost of the full set-up by roughly 40% compared to the original dual-camera system. We tested the utility of the speed-FluorIS by surveying coral recruits across shallow and mesophotic reefs of the Red Sea (Gulf of Eilat) and Bermuda, two of the most northerly reefs in the world with markedly different substrate and topography, and demonstrate that the modified system enables fast imaging of fluorescence to study coral recruitment patterns over a broader range of depths and reef topographies than previous fluorescence methods. Our single-camera system represents a valuable, non-invasive and rapid underwater tool which will help standardize surveys and long-term monitoring of coral recruits, contributing to our understanding of these vital and delicate early life stages of corals.

Differences in Motor Unit Recruitment Patterns and Low Frequency Oscillation of Discharge Rates between Unilateral and Bilateral Isometric Muscle Contractions.

Introduction: Distinct cortical activities contribute to unilateral and bilateral motor control. However, it remains largely unknown whether the behavior of motor neurons differs between unilateral and bilateral isometric force generation. Here, we first investigated motor units (MUs) recruitment patterns during unilateral and bilateral force generation. Considering that the force control is primarily regulated by low-frequency synaptic inputs to motor neurons, we also examined the relation between MU discharge rate and force output during unilateral and bilateral muscle contractions.Methods: Using advanced electromyography (EMG) sensor arrays and spike-triggered averaging techniques, we examined a large population of MUs in the right first dorsal interosseous (FDI) muscle during unilateral and bilateral force tracking tasks. Using the principal component analysis, we analyzed the first common component (FCC) of MU discharge rate to describe the force fluctuations during unilateral and bilateral contractions. Results: We found that MU discharge rate decreased during bilateral compared with unilateral contractions. MU recruitment threshold increased, while the amplitude and duration of MU action potential (MUAP) remained unchanged during bilateral compared with unilateral contractions. We found that the coefficients of variation (CV) for the force and FCC signal increased during bilateral compared with unilateral contractions. Notably, the FCC signal captured a great amount of MU discharge variability, and its CV correlated with the CV of the force signal. Conclusion: Our findings suggest that MU recruitment patterns are altered during bilateral compared with unilateral isometric force generation, likely related to changes at the low-frequency portion of the synaptic drive.

Population Genomics of the Commercially Important Gulf of Mexico Pink Shrimp Farfantepenaeus duorarum (Burkenroad, 1939) Support Models of Juvenile Transport Around the Florida Peninsula

The Gulf of Mexico pink shrimp, Farfantepenaeus duorarum, supports large fisheries in the United States and Mexico, with nearly 7,000 tons harvested from the region in 2016. Given the commercial importance of this species, management is critical: in 1997, the southern Gulf of Mexico pink shrimp fishery was declared collapsed and mitigation strategies went into effect, with recovery efforts lasting over a decade. Fisheries management can be informed and improved through a better understanding of how factors associated with early life history impact genetic diversity and population structure in the recruited population. Farfantepenaeus duorarum are short-lived, but highly fecund, and display high variability in recruitment patterns. To date, modeling the impacts of ecological, physical, and behavioral factors on juvenile settlement has focused on recruitment of larval individuals of F. duorarum to nursery grounds in Florida Bay. Here, we articulate testable hypotheses stemming from a recent model of larval transport and evaluate support for each with a population genomics approach, generating reduced representation library sequencing data for F. duorarum collected from seven regions around the Florida Peninsula. Our research represents the first and most molecular data-rich study of population structure in F. duorarum in the Gulf and reveals evidence of a differentiated population in the Dry Tortugas. Our approach largely validates a model of larval transport, allowing us to make management-informative inferences about the impacts of spawning location and recruitment patterns on intraspecific genetic diversity. Such inferences improve our understanding of the roles of non-genetic factors in generating and maintaining genetic diversity in a commercially important penaeid shrimp species.

Co-contraction training: myoelectric activity and recruitment strategies in an unorthodox resistance training technique.

Objective To elucidate the muscle recruitment patterns and interindividual variability during co-contraction training sessions for lower limbs. Methods Ten active male young adults underwent two days of tests, in which they performed, for each leg, a maximal isometric voluntary contraction protocol followed by a co-contraction training set. We acquired myoelectric (EMG) activity from the sartorius, biceps femoris long and short heads, semitendinosus, semimembranosus, rectus femoris, vastus lateralis and vastus medialis and tensor facia latae during both protocols. We used iterative HLM analyses and bootstrap ANOVAs to explain within and between participant variances. Results On average, participants started recruiting 36% of their maximum EMG amplitude, showing decays of 0.41% per repetition and increasing 7.45% from day 1 to day 2. Participants who started with higher recruitment showed greater decays over repetitions and vice-versa. The training stimulated similarly the ratio of participants’ flexors and extensors. However, participants demonstrated different average muscle recruitment patterns with some individuals modifying, largely, their recruitment over repetitions/days. Between and within-variability in recruitment pattern was maintained throughout repetitions and days. We found no consistent similarity in terms of pairs of participants as to find common types of recruitment. Conclusion Co-contraction training seems to be effective to recruit thigh muscles of both legs along an entire set of repetitions and days. Despite the accounted variations in intramuscular recruitment, co-contraction training evokes similar muscular in flexor’s and extensor’s recruitment among participants.

Spatial and Temporal Variation of Scleractinian Coral Recruitment in Balok Coastal Waters and Bidong Island, Malaysia

Understanding coral recruitment is important as increasing of regional decline of coral reef worldwide. This study aimed to investigate the spatial and temporal coral recruitment patterns around reef sites in Balok coastal waters and Bidong Island, Malaysia. Recruitment density was determined by quantifying number of coral recruits settled on the terra-cotta tiles and artificial reef settlement plates. In Balok coastal waters, a total of 159 coral recruits were counted with 0.09 ± 0.03 n/m2 mean recruitment density per plate, while in Bidong Island, a total of 319 coral recruits were counted with 0.19 ± 0.02 n/m2 mean recruitment density per plate. Coral recruits were dominated by genus Pocillopora followed by Stylopora and Seriatopora in Bidong. Meanwhile in Balok, genus Platygyra was dominant coral recruits followed by Porites and Fungia. Additionally, minor spawning event was predicted in Balok coastal waters in September due to increase number of Platygyra coral. Recruitment density varied significantly between locations, types of settlement plates and plate’s orientation at both study areas. Current findings highlighted the significant use of artificial reef plates to increase the chances of larval settlement. This research also provides important information in assessing coral resilience towards different environmental conditions between coastal and sheltered reef areas.