Sea cucumber fisheries in the Kingdom of Tonga: regeneration biology, ecology, and environmental chemistry

The goals of this thesis were to address the environmental and anthropogenic factors which may be influencing sea cucumber decline in the nearshore environment around Tongatapu. Physiology, regeneration biology, ecology, biochemistry and environmental chemistry techniques were used to contribute biologically-meaningful data to the Tonga Fisheries Division, to assist in informing management decisions of this important resource. The regeneration study was undertaken to determine the energetic costs of a traditional fishing method on the fishery species Stichopus horrens, and the sustainability of traditional fishing practices. The findings of this research component indicate that S. horrens can survive and regenerate organs following their harvest, but that this process comes at an energetic cost. The second component of this research involved the quantification of sea cucumber species and their length-distribution in the nearshore environment of Tongatapu. The results of the ecological surveys indicate that sea cucumber stocks are low in some areas, and that this is relatively unrelated to habitat variables. Finally, trace metal concentrations of sediment and holothuroid tissue samples from Tongatapu Island group were determined and used to conduct ecological and human health risk assessments. Sediments were low in all trace metals except Hg, which exceeded the ‘low’ trigger values but were lower than the ‘high’ trigger values. The human health risk assessment identified that consumption of holothuroids from this region may result in exposure to Ni, As, and Zn above regulatory limits

Unmanned Aerial Vehicles (UAVs) for Monitoring Macroalgal Biodiversity: Comparison of RGB and Multispectral Imaging Sensors for Biodiversity Assessments

Developments in the capabilities and affordability of unmanned aerial vehicles (UAVs) have led to an explosion in their use for a range of ecological and agricultural remote sensing applications. However, the ubiquity of visible light cameras aboard readily available UAVs may be limiting the application of these devices for fine-scale, high taxonomic resolution monitoring. Here we compare the use of RGB and multispectral cameras deployed aboard UAVs for assessing intertidal and shallow subtidal marine macroalgae to a high taxonomic resolution. Our results show that the diverse spectral profiles of marine macroalgae naturally lend themselves to remote sensing and habitat classification. Furthermore, we show that biodiversity assessments, particularly in shallow subtidal habitats, are enhanced using six-band discrete wavelength multispectral sensors (81% accuracy, Cohen’s Kappa) compared to three-band broad channel RGB sensors (79% accuracy, Cohen’s Kappa) for 10 habitat classes. Combining broad band RGB signals and narrow band multispectral sensing further improved the accuracy of classification with a combined accuracy of 90% (Cohen’s Kappa). Despite notable improvements in accuracy with multispectral imaging, RGB sensors were highly capable of broad habitat classification and rivaled multispectral sensors for classifying intertidal habitats. High spatial scale monitoring of turbid exposed rocky reefs presents a unique set of challenges, but the limitations of more traditional methods can be overcome by targeting ideal conditions with UAVs

High fructose led to bipolar-like phenotype in adolescent rats

39 p.-5 fig.-1 tab.BACKGROUND AND PURPOSE: Children and adolescents are the top consumers of high fructose corn syrup (HFCS) sweetened beverages. Even though the cardiometabolic consequences of HFCS consumption in adolescents are well known, the neuropsychiatric consequences have yet to be determined.EXPERIMENTAL APPROACH: Adolescent rats were fed for a month with 11% weight/volume carbohydrate containing HFCS solution, which is similar to the sugar sweetened beverages of human consumption. The metabolic, behavioural and electrophysiologic characteristics of HFCS-fed rats were determined. Furthermore, the effects of TDZD-8, a highly specific GSK-3 inhibitor, on the HFCS-induced alterations were further explored.KEY RESULTS: HFCS-fed adolescent rats displayed bipolar-like behavioural phenotype with hyperexcitability in hippocampal CA3-CA1 synapses. This hyperexcitability was associated with increased presynaptic release probability and increased readily available pool of AMPA receptors to be incorporated into the postsynaptic membrane, due to decreased expression of the neuron-specific alpha3-subunit of Na+ /K+ -ATPase (NKA) and an increased ser845-phosphorylation of GluR1 subunits of AMPA receptors, respectively. TDZD-8 treatment was found to restore behavioural and electrophysiological disturbances associated with HFCS consumption by inhibition of GSK-3, the most probable mechanism of action of lithium for its mood-stabilizing effects.This study shows that HFCS consumption in adolescent rats led to bipolar‐like behavioural phenotype with neuronal hyperexcitability, which is known to be one of the earliest endophenotypic manifestations of bipolar disorder. Inhibition of GSK‐3 with TDZD‐8 attenuated hyperexcitability and restored HFCS‐induced behavioural alterations.Funding from Hacettepe University Scientific Research Project Coordination Unit (Grant no. TSA-2017-15515 to Yildirim Sara) and partial funding from MINECO (Grant no. SAF2012-37979-C03-01 and SAF2016-76693-R to Ana Martinez) are acknowledgedPeer reviewe