Light in the Polar Night

How much light isa vailable for biological processes during Polar Night? This question appears simple enough. But the reality is that conventional light sen- sors for measuring visible light (~350 to ~700 nm) have not been sensitive enough to answer it. Beyond this technical challenge, “light” is a general term that must be qualified in terms of “light climate” before it has meaning for biological systems. In this chapter, we provide an answer to the question posed above and explore aspects of light climate during Polar Night with relevance to biology, specifically, how Polar Night is defined by solar elevation, atmospheric light in Polar Night and its propaga- tion underwater, bioluminescence in Polar Night and the concept of Polar Night as a deep-sea analogue, light pollution, and future perspectives. This chapter focuses on the quantity and quality of light present during Polar Night, while subsequent chapters in this volume focus on specific biological effects of this light for algae (Chap. “Marine Micro- and Macroalgae in the Polar Night”), zooplankton (Chaps.“Zooplankton in the Polar Night” and “Biological Clocks and Rhythms in Polar Organisms”), and fish (Chap. “Fish Ecology in the Polar Night”)

Bioluminescence in the marine ostracod Cypridina americana (Miiller, 1890) off Manzanillo, Mexico (Myodocopa: Cypridininae)

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Bioluminescence in a Complex Coastal Environment: 2. Prediction of Bioluminescent Source Depth From Spectral Water-leaving Radiance

Many bioluminescence observations are made from the ocean\u27s surface. However, the depth of the bioluminescent source is difficult to estimate on the basis of surface observations alone, given the variable light attenuation of unknown concentrations of water column constituents such as phytoplankton, colored dissolved organic matter, and detritus. Part 1 of this paper showed that bioluminescent water-leaving radiance signals are detectable, even in extremely turbid and dynamic coastal waters. Here, in part 2 of this paper, we analyze the water-leaving radiance patterns of bioluminescence modeled by HydroLight 4.2 to determine if the depth of the bioluminescent source can be estimated from its spectral signature. We find that the depth of the bioluminescent source is contained within the spectral signal and can be elucidated by simple neural networks. These networks can predict the depth of a bioluminescent layer with great accuracy, solely on the basis of the spectral shape of bioluminescent water-leaving radiance in a variety of water column and bottom type conditions. In addition, we found that as little as three wavelengths from the spectrum of water-leaving radiance are sufficient for an accurate determination of the depth of the bioluminescent source

Bioluminescence in the high Arctic during the polar night

This study examines the composition and activity of the planktonic community during the polar night in the high Arctic Kongsfjord, Svalbard. Our results are the first published evidence of bioluminescence among zooplankton during the Arctic polar night. The observations were collected by a bathyphotometer detecting bioluminescence, integrated into an autonomous underwater vehicle, to determine the concentration and intensity of bioluminescent flashes as a function of time of day and depth. To further understand community dynamics and composition, plankton nets were used to collect organisms passing through the bathyphotometer along with traditional vertical net tows. Additionally, using a moored bathyphotometer closed to the sampling site, the bioluminescence potential itself was shown not to have a diurnal or circadian rhythm. Rather, our results provide evidence for a diel vertical migration of bioluminescent zooplankton that does not correspond to any externally detectable changes in illumination

Molecular detection of bioluminescent dinoflagellates in surface waters of the Patagonian Shelf during early austral summer 2008

We investigated the distribution of bioluminescent dinoflagellates in the Patagonian Shelf region using “universal” PCR primers for the dinoflagellate luciferase gene. Luciferase gene sequences and single cell PCR tests, in conjunction with taxonomic identification by microscopy, allowed us to identify and quantify bioluminescent dinoflagellates. We compared these data to coincidental discrete optical measurements of stimulable bioluminescence intensity. Molecular detection of the luciferase gene showed that bioluminescent dinoflagellates were widespread across the majority of the Patagonian Shelf region. Their presence was comparatively underestimated by optical bioluminescence measurements, whose magnitude was affected by interspecific differences in bioluminescence intensity and by the presence of other bioluminescent organisms. Molecular and microscopy data showed that the complex hydrography of the area played an important role in determining the distribution and composition of dinoflagellate populations. Dinoflagellates were absent south of the Falkland Islands where the cold, nutrient-rich, and well-mixed waters of the Falklands Current favoured diatoms instead. Diverse populations of dinoflagellates were present in the warmer, more stratified waters of the Patagonian Shelf and Falklands Current as it warmed northwards. Here, the dinoflagellate population composition could be related to distinct water masses. Our results provide new insight into the prevalence of bioluminescent dinoflagellates in Patagonian Shelf waters and demonstrate that a molecular approach to the detection of bioluminescent dinoflagellates in natural waters is a promising tool for ecological studies of these organisms

Characterization Naval Station San Diego Approved for public release; distribution is unlimited.

This report summarizes a study that was carried out to characterize the current status of San Diego Bay sediment quality in the vicinity of Naval Station San Diego (NAVSTA). The objective of this study was to provide an assessment of the extent and potential ecological consequences of sediment contamination. The study focused on two issues: the characterization of contaminated sediments, and the evaluation of processes that control the levels, transport, and biological exposure of this contamination. Sediments were characterized on the basis of a range of physical, chemical, and toxicological testing. Processes that were evaluated included contaminant sources, sediment transport, sediment-water exchange, and degradation. As part of the study, new technologies for assessment and remediation were demonstrated alongside traditional methods. On the basis of comparison to Effects Range Median (ERM) levels and background contamination levels in relatively "clean" regions of the California coast, this study describes which particular contaminants appear to be elevated and in what spatial areas elevated levels were found. In general, concentrations of copper, mercury, and zinc were measured at elevated levels, concentrations of silver, lead, PAHs, and PCBs were occasionally found at elevated levels, and concentrations of arsenic, chromium, and nickel were mostly found to lie below ERM thresholds and at or near background levels. Contaminants often tended to co-occur (e.g., copper and zinc), and were often associated with regions of high fines content (i.e., clay and silt). Spatially, contaminant levels exceeded ERM thresholds in the region along the quay wall between Piers 2-5. Within this region, silver, copper, mercury, zinc, and PCBs were found at levels exceeding the ERM. M..