Early life history of Metridia pacifica brodsky (Copepoda: Calanoida) from the southeastern Bering Sea and Gulf of Alaska

Thesis (M.S.) University of Alaska Fairbanks, 199

Distribution, Growth And Egg Production Of Euphausiids In The Northern Gulf Of Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 2006The euphausiids Thysanoessa inermis, Thysanoessa spinifera and Euphausia pacifica are key pelagic grazers and important prey for many vertebrates in the Gulf of Alaska (GOA). This thesis provides the first account of distribution, egg production, growth, development, and temporal variability in abundance of the euphausiids in relation to environmental variations in the northern GOA. T. inermis and T spinifera were abundant on the shelf within 120-130 km from the coast, while E. pacifica originated from offshore and was advected onto the shelf during summer. E. pacifica produced multiple broods with brood size strongly related to ambient chlorophyll a concentrations. In contrast, T. inermis released eggs once in the season and its brood size did not depend on chlorophyll content. Early development of these species showed a remarkably similar response to changes in temperature. The highest molting increments were observed during the spring phytoplankton bloom for T. inermis, and in summer for T. spinifera and E. pacifica, suggesting coupling with food availability. The molting rates were strongly influenced by temperature. Growth rates depended on euphausiid size, and were close to 0 in early spring, reaching maximum values in May (0.123 mm d-1 or 0.023 d -1 for T. inermis) and July (0.091 mm d-1 or 0.031 d-1 for T. spinifera). The growth rates for E. pacifica remained below 0.07 mm d -1 (0.016 d-1) throughout the season. The relationship between T. inermis weight specific growth rate (adjusted to 5�C) and ambient chlorophyll-a concentration fit a Michaelis-Menten curve (r2=0.48), but such relationships were not significant for T. spinifera or E. pacifica. Reproduction of T. inermis occurred during April in 1998 and 2003, and was extended through May in 1999-2002. The spawning of T. inermis and T. spinifera was related to the spring diatom bloom on the inner shelf, while the spawning of E. pacifica occurred later in season, when the water temperature increased. A strong increase in abundance of T. inermis, associated with the extended colder phase in the North Pacific, indicates that progressive cooling in 1999-2002 may have resulted in greater reproductive success of early spawning T. inermis on the inner shelf

Alliance for Coastal Technologies: Advancing Moored pCO2 Instruments in Coastal Waters

The Alliance for Coastal Technologies (ACT) has been established to support innovation and to provide the information required to select the most appropriate tools for studying and monitoring coastal and ocean environments. ACT is a consortium of nationally prominent ocean science and technology institutions and experts who provide credible performance data of these technologies through third-party, objective testing. ACT technology verifications include laboratory and field tests over short- and long-term deployments of commercial technologies in diverse environments to provide unequivocal, unbiased confirmation that technologies meet key performance requirements. ACT demonstrations of new technologies validate the technology concept and help eliminate performance problems before operational introduction. ACT’s most recent demonstration of pCO2 sensors is an example of how ACT advances the evolution of ocean observing technologies, in this case to address the critical issue of ocean acidification, and promotes more informed decision making on technology capabilities and choices

Performance Demonstration Statement for Sunburst Sensors SAMI-CO2

The plant glutathione peroxidase (GPX) family consists of multiple isoenzymes with distinct subcellular locations which exhibit different tissue-specific expression patterns and environmental stress responses. Contrary to most of their counterparts in animal cells, plant GPXs contain cysteine instead of selenocysteine in their active site and while some of them have both glutathione peroxidase and thioredoxin peroxidase functions, the thioredoxin regenerating system is much more efficient in vitro than the glutathione system. At present, the function of these enzymes in plants is not completely understood. The occurrence of thiol-dependent activities of plant GPX isoenzymes suggests that - besides detoxification of H2O2 and organic hydroperoxides - they may be involved in regulation of the cellular redox homeostasis by maintaining the thiol/disulfide or NADPH/NADP+ balance. GPXs may represent a link existing between the glutathione- and the thioredoxin-based system. The various thiol buffers, including Trx, can affect a number of redox reactions in the cells most probably via modulation of thiol status. It is still required to identify the in vivo reductant for particular GPX isoenzymes and partners that GPXs interact with specifically. Recent evidence suggests that plant GPXs does not only protect cells from stress induced oxidative damage but they can be implicated in plant growth and development. Following a more general introduction, this study summarizes present knowledge on plant GPXs, highlighting the results on gene expression analysis, regulation and signaling of Arabidopsis thaliana GPXs and also suggests some perspectives for future research

Go West: Sea-ice association of Polar cod and its prey in the western Arctic Ocean

Polar cod (Boreogadus saida), a key fish species in Arctic marine ecosystems, may be particularly susceptible to changing sea-ice habitats. It has been proposed that parts of the population get entrained with the growing sea ice in autumn, but how this happens and what proportion of the population becomes ice-associated is not known. The overall goal of the Go-West expedition was to test the hypothesis that entrainment of young Polar cod into the sea-ice habitat in the Chukchi and Beaufort seas during autumn is significant, and hence sea-ice association is an important survival strategy for Polar cod. During expedition SKQ201923S with RV Sikuliaq (06 November – 02 December 2019), we sampled Polar cod and its prey in the ice-water interface layer along with high resolution profiles of sea-ice and surface water properties with a Surface and Under-Ice Trawl (SUIT). We recorded backscatter of fish and zooplankton in the water column with the Sikuliaq’s EK80 echosounder, and sampled pelagic communities with two midwater trawls (Methot trawl and IKMT) and vertical zooplankton nets (CalVET and ring net). A conductivity-temperature—depth probe equipped with a rosette water sampler (CTD) sampled vertical profiles of temperature, salinity and fluorescence and was used to collect water samples for the analysis for chlorophyll a concentration, nutrient concentrations, trophic biomarkers and harmful algae (HAB). During four ice stations, we sampled the sea ice for the same parameters (except nutrients), and performed hyperspectral light measurements needed to derive ice algae biomass from hyperspectral profiles obtained from a sensor mounted on the SUIT. In addition, we performed respiration measurements on abundant zooplankton prey species of Polar cod. Altogether, we completed 11 SUIT stations (1 in open water, 10 under ice), 4 ice stations and 3 midwater trawls. All SUIT deployments were succesful, expanding Sikuliaq’s capability of advanced scientific operations in ice-covered waters. Polar cod were caught at all SUIT stations, totalling 153 fish. Most fish appeared to be first-year juveniles between 6 and 8 cm in size, pending age determinations. Fish abundance increased with increasing ocean depth, sea-ice draft and abundance of the ice amphipod Onisimus spp.. The mesozooplankton community in the upper 50 m was dominated by the copepod Metridia longa. Respiration experiments indicated that Metridia and, surprisingly, Calanus glacialis from shelf stations were in an active metabolic state. Chlorophyll a concentrations were low (< 0.5 mg m-3) in the water column. Conversely, visual inspection of ice core filters indicated that ice algal biomass had already begun to accumulate in the autumn sea ice. The trophic relationships between ice algae, zooplankton and sea-ice fauna and Polar cod will be analyzed in detail based on hundreds of biological samples, including diet and trophic biomarker samples. Investigations of otolith microchemistry and population genetics studies on each sampled fish will help elucidate their origins and migration patterns. Preliminary results of this expedition support our hypothesis that juvenile Polar cod associate with sea ice in autumn and show that prey is available to sustain them at the onset of winter