Considerations for Evaluating Ultraviolet Radiation-Induced Genetic Damage Relative to Antarctic Ozone Depletion

Springtime ozone depletion over the Antarctic results in increased UVB in local marine environments. It has been established that decreases in primary productivity occur with decreases in ozone concentrations, but the impact of increased UVB on the functioning and stability of the ecosystem has not yet been determined. Very little has been done to evaluate the potential for genetic damage caused by the increase in UVB, and this type of damage is most significant relative to the fitness and maintenance of populations. An essential problem in evaluating genotoxic effects is the lack of appropriate techniques to sample and quantify genetic damage in field populations under ambient UVB levels. In addition, it is currently not feasible to estimate exposure levels for organisms in their natural habitats

Bio-optical properties of the marine diazotrophic cyanobacteria Trichodesmium spp. I. Absorption and photosynthetic action spectra

The optical absorption, fluorescence excitation and emission, and photosynthetic action spectra were measured in vivo on intact colonies of Trichodesmium from the Caribbean Sea. The optical cross-sections were dominated by ultraviolet-A (UVA) absorption, which was a consequence of massive accumulations of mycosporinelike amino acids. The visible region of the spectrum was decomposed into several bands, among which chlorophyll a (Chl a), carotenoids, and individual phycobilipigments could be discerned. There was a clear diel periodicity in the ratio of the optical absorption cross-sections of phycourobilin (PUB) to phycoerythrobilin (PEB), increasing from around 1.7 at night to 2.1 at midmorning. The diel cycle in PUB/PEB is consistent with a reversible interconversion of the two pigments. The ratio of PUB/PEB was inversely correlated with the transfer of excitation energy to photosystem II (PSII). Light absorbed by PUB was not transferred to PSII with a high efficiency, but rather, a significant fraction was reemitted at 565 nm as fluorescence. These observations suggest that the PUBs and PEBs in Trichodesmium act as a dynamic biophysical energy valve that modify the rate of excitation energy delivered to PSII in response to changes in ambient light regime. The low-temperature (77 K) fluorescence emission spectra reveal an extremely weak 685-nm emission signal in relation to that at 730 nm. Based on a simple model, these data suggest that the ratio of PSI/PSII reaction centers in Trichodesmium is about 24:1. Such an extraordinary bias against PSII may help minimize damage to nitrogenase from O₂ production in PSII, but it also reduces the photosynthesis-enhanced growth and makes Trichodesmium virtually undetectable by chlorophyll fluorescence. The unique bio-optical properties of Trichodesmium can be used to develop algorithms to study its temporal and spatial distributions from remotely sensed information

Southern Ocean Action Plan (2021-2030) in support of the United Nations Decade of Ocean Science for Sustainable Development

In 2017, the United Nations proclaimed a Decade of Ocean Science for Sustainable Development (hereafter referred to as the UN Ocean Decade) from 2021 until 2030 to support efforts to reverse the cycle of decline in ocean health. To achieve this ambitious goal, this initiative aims to gather ocean stakeholders worldwide behind a common framework that will ensure ocean science can fully support countries in creating improved conditions for sustainable development of the world’s oceans. The initiative strives to strengthen the international cooperation needed to develop the scientific research and innovative technologies that can connect ocean science with the needs of society at the global scale. Based on the recommendations in the Implementation Plan of the United Nations Decade of Ocean Science for Sustainable Development (Version 2.0, July 2021), the Southern Ocean community engaged in a stakeholder - oriented process to develop the Southern Ocean Action Plan. The Southern Ocean process engaged a broad community, which includes the scientific research community, the business and industry sector, and governance and management bodies. As part of this global effort, the Southern Ocean Task Force identified the needs of the Southern Ocean community to address the challenges related to the unique environmental characteristics and governance structure of the Southern Ocean. Through this community-driven process, we identified synergies within the Southern Ocean community and beyond in order to elaborate an Action Plan that provides a framework for Southern Ocean stakeholders to formulate and develop tangible actions and deliverables that support the UN Ocean Decade vision. Through the publication of this Action Plan, the Southern Ocean Task Force aims to mobilise the Southern Ocean community and inspire all stakeholders to seek engagement and leverage opportunities to deliver innovative solutions that maintain and foster the unique conditions of the Southern Ocean. This framework provides an initial roadmap to strengthen links between science, industry and policy, as well as to encourage internationally collaborative activities in order to address existing gaps in our knowledge and data coverage

Considerations for evaluating ultraviolet radiation-induced genetic damage relative to Antarctic ozone depletion. Environmental Health Perspectives 102(Suppl

Springtime ozone depletion over the Antarctic results in increased UVB in local marine environments. It has been established that decreases in primary productivity occur with decreases in ozone concentrations, but the impact of increased UVB on the functioning and stability of the ecosystem has not yet been determined. Very little has been done to evaluate the potential for genetic damage caused by the increase in UVB, and this type of damage is most significant relative to the fitness and maintenance of populations. An essential problem in evaluating genotoxic effects is the lack of appropriate techniques to sample and quantify genetic damage in field populations under ambient UVB levels. In addition, it is currently not feasible to estimate exposure levels for organisms in their natural habitats.- Environ Health Perspect 102(Suppl 12):61-64 (1994) Key words: Antarctic, DNA damage, ozone depletion, ultraviolet radiation Every spring for approximately the past 20 years, over 50 % of the ozone in the stratosphere over the Antarctic disappears (1-4). At the surface of the earth, decreases in atmospheric ozone concentrations are manifested as increases in biologically harmful ultraviolet B radiation (UVB, 280-320 nm) (5,6). There are several aspects o

EFFECTS OF NATURAL UV RADIATION ON ANTARCTIC CYANOBACTERIAL MATS (19th Symposium on Polar Biology)

Microbial mats dominated by cyanobactena are the most abundant living forms in non-oceanic Antarctic ecosystems. The ultraviolet radiation increase may affect drastically the organisms living in the polar regions and especially those of terrestrial ecosystems exposed to full sunshine. The aim of this work was to investigate the effect of UV radiation on terrestrial Antarctic communities. Dominant species in these microbial assemblages belonged to the filamentous, non-heterocystous cyanobactena group (e g Phormidium, Lyngbya, Oscillatona, etc). Heterocystous (e g Nodular 10) and coccoid (e g Synechococcus) cyanobactena were subdommant although very abundant. We studied the effect of natural UV radiation on cyanobactenal mats, using a series of narrow band UV filters After two weeks of differential exposure to UV (PAR, PAR + UVA, PAR + UVB, PAR + UVA + UVB) population structure, pigment composition and physiological activities were analyzed. Although statistical analyses revealed that mats under the four UV regimes assayed were not significantly different in community structure nor in pigment composition, surface appearance of mats was different between treatments. Physiological analyses indicated that the photosynthesis/respiration balance might be affected by UV radiation. The apparent contradiction between analytical data of pigments and surface appearance can be explained by considering that UV regime might have induced changes in the position of the microrgamsms of the mat by mean of migration. This process is suggested to be one of the responses of escaping from an increasing UVB radiation environment

Distribution of Invertebrate Larvae in Relation to Physical Structure and UVB-light Intensity in the Water Column off Anvers Island, Antarctic Peninsula

The antarctic coastal zone is inhabited by a diverse and abundant fauna of benthic (bottom-dwelling) invertebrates. Benthic adults are largely shielded from UV-B damage by the overlying water column. Many also possess morphological, biochemical, and behavioral defenses, including shells and UV-absorbing compounds. Many antarctic invertebrates reproduce by releasing gametes freely into the water (Pearse, McClintock and Bosch 1991). Their embryonic and larval life stages are spent adrift in the water column. Embryos and larvae that are dispersed into surface waters may be exposed to potentially damaging levels of UV-B light, particularly during periods of ozone depletion. During the spring and summer in 1996-1997 and 1997-1998 at Palmer Station (64° 46’ S, 64° 04’ W), our group studied the effects of UV-B on the eggs, embryos, and larvae of benthic marine invertebrates. One primary objective of this work was to determine the vertical and seasonal distribution of larvae, relative to the penetration of UV-B and to the physical structure (density, salinity, temperature) of the water column. Initial results from this component of our study are presented here