Responses of Biofilm-Forming Halophilic Calothrix and Coelastrella Strains to Environmental Stressors Associated with Climate Change.

Ultraviolet radiation (UVR) reaching the surface of earth has been recognized as a major environmental stressor for marine organisms due to the potential of UVB (280 - 315 nm) to induce DNA damage such as cyclobutane pyrimidine dimers (CPDs) that can lead to cell death. Despite inhabiting a UV-rich environment, the levels of DNA damage in reef fish and factors influencing these levels are unknown. Whether reef fish are able to avoid UVR and repair UV-induced DNA damage is unclear despite the importance of these protection mechanisms in other animals. The presence of UV-absorbing Mycosporine-like Amino Acids (MAAs) in the external mucus of reef fish has been confirmed, however the efficiency of these compounds in preventing CPDs has not been studied. The aim of this PhD was to assess the impact of ambient and elevated levels of UVR on reef fish in terms of UV-induced DNA damage, and to evaluate the protective mechanisms available to fish with and without UV vision. In order to determine the net level of DNA damage in skin samples of 15 species of fish from the reefs surrounding Lizard Island, a CPD-specific antibody was used in an ELISA. Analysis using a boosted regression tree shows that the most important factors governing CPDs were species and size, with higher damage being detected in smaller individuals. Other factors such as family, depth and the presence or absence of UV vision contributed the least to the variation in damage. The length of exposure to natural levels of UVR over the course of a day was found to have no significant influence on net DNA damage levels, which were relatively low in situ, compared to levels that were detected in later experiments using elevated UVR. The first protection mechanism, behavioural avoidance to UVR, was tested using behavioural experiments in which fish with (Pomacentrus amboinensis) and without UV vision (Thalassoma lunare) were given a choice between UV-protected and UV-exposed compartments. Additionally, foraging behaviour of settlement-stage larvae of P. amboinensis was determined under ambient levels of UVR. Automated analysis of video footage using MatLab shows that neither species showed a specific avoidance response to varying levels of UVB. Although P. amboinensis showed a preference for deeper sections of the experimental tanks, fish spent equal amounts of time in exposed and protected compartments. The foraging activity and distance to shelter of P. amboinensis that were exposed to UVR were significantly reduced compared to fish that were observed under light conditions that lacked UVR. Next, the efficiency of natural sunscreens, MAAs, in preventing CPDs was tested in P. amboinensis and T. lunare. The levels of MAAs in the mucus of the two species were either reduced or maintained during captivity before exposure to a short pulse of high UVR. Spectrometric measurements of light transmission through mucus samples collected after irradiation were used to quantify the amount of MAAs available for protection. In both species, DNA damage levels in skin samples from UVR exposed individuals was higher than in control groups that were exposed to light lacking the UV component. Spectrometric measurements of external mucus of both species revealed a clear link between higher mucus absorbance, i.e. MAA levels, and lower DNA damage levels. Furthermore, a significant increase in mucus absorption was observed in P. amboinensis after UV exposure. The last protection mechanism, the ability to revert DNA damage via photoreactivation and dark repair was investigated in four species (P. amboinensis, Pomacentrus moluccensis, Lethrinus variegatus and Siganus corallinus). All species examined showed significant increases of DNA damage after exposure to elevated UVR levels. Interspecific variation in the susceptibility to UVR was observed, with L. variegatus showing the highest damage levels. Significant reductions in DNA damage levels were found in P. moluccensis and L. variegatus that were exposed to photoreactivating light after the initial damage accumulation. Individuals of P. moluccensis that were shielded from any light exposure post UVR exposure also showed less DNA damage at the end of the experiment. This is the first study to address levels of UV-induced DNA damage in reef fish under natural conditions as well as under elevated doses of UVR that could occur in a changing climate. The relatively low levels of CPDs in a diverse group of reef fish indicate that current levels of UVR pose only low threat and underline the importance of protection mechanisms against UVR. Increases in UVR could have an impact not only on adult fish capable of adjusting their protection mechanisms, but also settlement stage larvae which show some of the highest levels of DNA damage in situ as well as mortality during slight increases of UVR. Whether these and other effects such as decreased foraging activity have broader implications on the recruitment and reproduction of reef fish and the community structure on coral reefs needs to be examined in the future.

Protection against ultraviolet (UV) radiation is the major function of sunscreen lotions and UV-protective coatings for vehicles, homes, equipment and clothing. Sunscreen formulations have been optimized to become protective over a broader spectrum of UV radiation and maintain greater photostability. They are comprised of organic and inorganic components that act as chemical and physical UV protectors, respectively. Some of the organic components are limited by their spectrum of protection and photostability. Studies using solid lipid nanoparticles, recently explored organic molecules, inorganic components and antioxidants attempt to further optimize UV protection. In this review, we examine traditional and emerging nanoparticle components and highlight novel ideas in UV protection which may provide pathways for future studies.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 295:135-156 (2005) - doi:10.3354/meps295135 Effects of starvation, ammonium concentration, and photosynthesis on the UV-dependent accumulation of mycosporine-like amino acids (MAAs) in the coral Stylophora pistillata J. Malcolm Shick1,*, Christine Ferrier-Pagès2, Renaud Grover2, Denis Allemand2,3 1School of Marine Sciences, University of Maine, 5751 Murray Hall, Orono, Maine 04469-5751, USA2Centre Scientifique de Monaco, Avenue Saint-Martin, 98000 Monaco, Principality of Monaco3UMR 1112 INRA-UNSA, University of Nice-Sophia Antipolis, Parc Valrose, BP 71, 06108 Nice Cedex 2, France *Email: shick@maine.edu ABSTRACT: This study addresses several unresolved questions regarding the biosynthesis, metabolism, regulation, and diversity of MAAs in zooxanthellate scleractinian corals. Starved colonies of Stylophora pistillata accumulated the same concentrations of mycosporine-like amino acids (MAAs) as fed corals after 28 d of exposure to photosynthetically available radiation (PAR) and ultraviolet radiation (UVR), suggesting that dietary MAAs are of little quantitative importance in this phototrophic symbiosis. Starved corals continued to accumulate MAAs and conserved them disproportionally compared with declining protein and chlorophyll a, indicating the priority placed on maintaining this UV-sunscreen defense. In 2 different colonies (SP1 and SP2) exposed to enriched (10 µM) ammonium and PAR + UVR during starvation, the final concentrations of MAAs and chlorophyll a were identical. However, under ambient ammonium (<0.4 µM), SP2 produced MAAs at the expense of chlorophyll a, whereas SP1 maintained chlorophyll a levels but synthesized less MAA. Ammonium consistently affected only the accumulation of primary, Symbiodinium-MAAs (mycosporine glycine, shinorine, porphyra-334, and mycosporine-2 glycine) and not secondary MAAs derived from the former, probably in the host's tissues. Mycosporine-2 glycine and palythine (a secondary MAA) were synthesized by SP1 but not SP2, suggesting (1) genotypic differences between the zooxanthellae in SP1 and SP2, and (2) a biosynthetic relationship between these 2 MAAs that we proposed previously. Exposure to UVR alone did not support large-scale biosynthesis of MAAs in S. pistillata, and accumulation of the full suite of MAAs required PAR + UVR; together with an inhibitory effect of DCMU, this indicates that photosynthesis is required for the UV-stimulated, de novo biosynthesis of MAAs. Cultures of zooxanthellae isolated from S. pistillata and exposed to PAR + UVR showed increased levels of shinorine, and some production of mycosporine-glycine. Host extract had no qualitative effect on the MAAs produced by these zooxanthellae. KEY WORDS: Mycosporine-like amino acids (MAAs) · Coral · Zooxanthellae · Ultraviolet radiation (UVR) · Dissolved ammonium · Photosynthesis Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 295. Online publication date: June 23, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

We examined the response of four species of New Zealand marine algae (Ecklonia radiata, Apophlaea lyallii, Rhodymenia spp., Ulva lactuca) and a sea urchin (Evechinus chloroticus) to spatial variation in ultraviolet radiation (UV‐R) by examining the concentration of UV‐R absorbing compounds known as mycosporine‐like amino acids (MAAs). The purpose was to understand how, and the degree to which, local marine species could potentially respond to any future increases in incident UV‐R in the New Zealand marine environment. The research was undertaken in Doubtful Sound, where we observed a gradient of water column UV‐R transmission along the 40 km length of the fiord. We examined spatial differences in MAAs along the UV‐B gradient in the macrophytes and temporal changes in MAAs in sea urchin gonads. Among the algae, thallus MAA concentrations (nmol mg–1 protein) ranged from 12.5 to 87.8 in E. radiata, from 433.1 to 1446.4 in A. lyallii, 12.7 to 103.4 in Rhodymenia spp., but were not detected in U. lactuca. For E. chloroticus, gonadal MAA concentrations ranged from 83.9 to 224.3 nmol mg–1 protein spatially, and over the year from 1.85 to 14.12 nmol mg–1 dry weight (DW) depending on site and gametogenic cycle. Laboratory manipulations indicated that concentrations of MAAs in E. chloroticus gonads and eggs are influenced by diet. MAA concentration could be correlated with UV‐B intensities in two of the algal species. E. chloroticus MAA concentrations could also be correlated with UV‐B transmission, which we concluded was a reflection of the greater ingestion and accumulation of MAA‐rich macrophytes at those sites where higher ambient UV‐R induced greater MAA concentrations to occur in the algae. Given this, we suggest that one response of marine species to increases in UV‐B would be an increase in the synthesis and/or accumulation of MAAs for photoautotrophs and a dietary accumulation of those MAAs in E. chloroticus, an important herbivore in this system.

Colonies of Stylophora pistillata unexposed to ultraviolet radiation (UVR) in laboratory aquaria contained minimal amounts of mycosporine‐like amino acids (MAAs). The concentration of MAAs increased rapidly during exposure to broadband UVR, then stabilized between 14 and 28 d of exposure. The four MAAs known to be produced by diverse zooxanthellae (Symbiodinium spp.) in culture were the first to increase in coral colonies, followed by six additional MAAs. Decreases in these four primary MAAs between days 14 and 28 were balanced by stoichiometric increases in the six secondary MAAs, suggesting a precursor‐product relationship. Discontinuing UV exposure caused rapid declines in the concentrations of primary MAAs, while secondary MAAs continued to increase, likely a manifestation of different rates of turnover of the putative enzymes involved in the de novo biosynthesis of primary MAAs and their conversion to secondary MAAs. The continued production of certain MAAs after UV exposure ceased indicates that UV is not required catalytically but is a signal that induces the enzymes of the biosynthetic pathway. Biochemically inhibiting the biosynthesis of primary MAAs after a pool of these MAAs had accumulated did not affect their conversion to secondary MAAs. Doubling the UV irradiance increased the rate of accumulation, first, of primary MAAs and, later, of secondary MAAs. Under normal UV irradiance, the eventual decline in the accumulation rate of primary MAAs was quantitatively explained by their conversion to secondary MAAs. Under doubled UV irradiance, where MAA concentrations were higher, the deceleration of accumulation of primary MAAs was twice as great as the acceleration in secondary MAAs, suggesting a regulation of the de novo biosynthesis of MAAs, perhaps by their own progressive, concentration‐dependent attenuation of UVR.

Development and validation of a rapid LC-MS/MS method for the quantification of mycosporines and mycosporine-like amino acids (MAAs) from cyanobacteria

Chapter 15 - Ultraviolet-screening compound mycosporine-like amino acids in cyanobacteria: biosynthesis, functions, and applications

Mycosporine like amino acids (MAAs) were detected in low concentration in sea ice algae growing in situ at Cape Evans, Antarctica. Four areas of sea ice were covered with plastics of different UV absorption exposing the bottom- ice algal community to a range of UV doses for a period of 15 days. Algae were exposed to visible radiation only; visible + UV radiation; and visible + enhanced UV radiation. MAA content per cell at the start of the experiment was low in snow-covered plots but higher in samples from ice with no snow cover. During the study period, the MAA content per cell reduced in all treatments, but the rate of this decline was less under both ambient UV and visible radiation than under snow covered plots. While low doses of UVB radiation may have stimulated some MAA production (or at least slowed its loss), relatively high doses of UVB radiation resulted in almost complete loss of MAAs from ice algal cells. Despite this reduction in MAA content per cell, the diatoms in all samples grew well, and there was no discernible effect on viability. This suggests that MAAs may play a minor role as photoprotectants in sea ice algae. The unique structure of the bottom ice algal community may provide a self-shading effect such that algal cells closest to the surface of the ice contain more MAAs than those below them and confer a degree of protection on the community as a whole.

Reports of bathymetric decrease in the total mycosporine-like amino acid (MAA) concentration of benthic invertebrates suggest that light gradients may be important determinants of MAA content. With the pronounced diel light changes, distinct temporal variations in MAA concentrations might also be expected. We examined the changes in the abundance of MAA in three shallow-water scleractinian corals, Pavona divaricata, Galaxea fascicularis and Montipora digitata from Okinawa, Japan, in relation to daily cycles in solar radiation and tested whether the species have different capabilities for protection against UVR depending on their MAA composition. The results show that symbiotic algae freshly isolated from the investigated coral species do not contain MAAs and that distribution of these compounds resided only within the animal tissue. Total MAA content in the tissue of P. divaricata, G. fascicularis and M. digitata rose rapidly at midday and significantly dropped at night. The observed variations were by a factor of two and, thus, very dramatic. For all the investigated coral species, total MAA concentrations were significantly correlated with the diurnal cycle in solar radiation, during both winter and summer seasons. Seawater temperature was significantly correlated with MAA levels only in the June experiment, but represented no more than 20% of the MAA variation in all three coral species, whereas solar radiation explained 60–70% of the MAA fluctuations. This suggests that MAAs are an integral component of the hard coral’s biochemical defense system against high solar irradiance stress. The diurnal increase in total MAA concentrations was due to an increase in the concentration of imino-MAA species of up to 2–2.5-fold of their pre-dawn values. In contrast, the oxocarbonyl-MAA mycosporine-glycine (Myc-Gly) showed the lowest (Tukey–Kramer HSD test: P<0.05) values at midday, compared to afternoon and night hours. Analysis of diel changes in chlorophyll fluorescence and chlorophyll a content of the investigated species revealed that P. divaricata and G. fascicularis were less sensitive to the high levels of ambient irradiance compared to M. digitata. In P. divaricata and G. fascicularis, Myc-Gly, an MAA with an antioxidant function, is the most abundant MAA, contributing about 70% to the total MAA pool, whereas the major MAA factions in M. digitata were represented by oxidatively robust imino-MAAs. We speculate that MAAs furnish scleractinian corals with protection from biologically damaging ultraviolet radiation through both the direct sunscreening activity of imino-MAAs and the antioxidant properties of oxocarbonyl-MAAs and suggest that the predominance, in the host tissue, of MAA species with an antioxidant ability may render corals more tolerant to high photosynthetically active and ultraviolet radiation.

&lt;p&gt;Ozone depletion is a humaninduced global phenomenon that allows increased ultraviolet radiation (UVR) to the Earth's surface. Although UVR is known to be harmful, relatively little is known about how increased UVR impacts natural ecosystems. Ecosystems in New Zealand are particularly at risk, because ozone depletion is much greater here, with levels of biologically harmful UVR up to two times greater than in northern latitudes. In the intertidal environment, potentially negative abiotic stressors are associated with low tide; and organisms inhabiting this environment are particularly vulnerable to UVR. Furthermore, embryos and larvae deposited in this habitat are especially susceptible to these stressors. The aim of this study is to identify the effect of UVR and other environmental stressors on the development of mollusc embryos in New Zealand. Surveys of microhabitats in which egg mass deposition occurs, and what effect this site of deposition has on the survivorship of embryos, revealed that encapsulated embryos of the two common pulmonate limpets Benhamina obliquata and Siphonaria australis are highly vulnerable to the environmental stressors associated with different microhabitats. In particular, egg masses deposited in the sun for both species suffered high mortality. Although, B. obliquata is more susceptible to UVR damage than is S. australis, B. obliquata predominantly deposits egg masses in dry shaded microhabitats while S. australis deposits the majority of its offspring in sunny tidal pools, which surprisingly equated to highest embryonic mortality. Results of manipulative experiments reflected those found in the surveys: egg masses exposed to full spectrum light incurred the greatest embryonic mortality; additionally environmental stressors (e.g. tidal pool conditions and desiccation) synergistically enhanced this mortality. UVR in North America is significantly lower compared to New Zealand; this allowed a unique opportunity to use identical methods to examine the responses of ecologically similar, related species (bubble shell snails in the genus Haminoea), from two regions where UVR naturally differs. Results from surveys and manipulative experiments revealed that the New Zealand species Haminoea zelandiae suffered high embryonic mortality under full spectrum light and this mortality was enhanced by periods of desiccation. The North American species Haminoea vesicula also suffered significant mortality during periods of desiccation, but there were no signs of UVR damage. These results appear to be driven by speciesspecific vulnerability to these stressors and not to ambient UVR intensity in the regions at the time of study. Relative concentrations of the chemical sunscreen compounds, mycosporinelike amino acids (MAAs), varied depending on several factors, but the biggest differences were among species. Analyses revealed that B. obliquata had the highest concentration of MAAs despite suffering high embryonic mortality when exposed to direct sunlight. MAA concentrations in S. australis were intermediate, with H. zelandiae having the lowest concentrations of all three species. MAA concentration for B. obliquata was dependent on stage of development and initial sun exposure at egg mass deposition site, suggesting interactions between MAAs, environmental conditions and embryonic development that need to be further explored. MAA concentrations were higher in S.australis egg masses deposited in spring compared to those deposited in early autumn, which may be driven by a shift in diet or nutrient levels. MAA concentrations did not appear to be correlated with ambient levels of UVR or embryonic survival in S.australis. However, MAA concentrations were related to UV irradiance in both Haminoea species with higher MAA concentrations observed in egg masses initially deposited in the sun compared to those found in the shade. Combined these results suggest: (1) increased UVR due to ozone depletion together with increases in temperatures due to climate change are likely to have strong impacts on the early life stages of these species, unless behavioural and physiological adaptations occur; (2) New Zealand species may be at particularly high risk from UVR damage compared to those from the Northern hemisphere; (3) the role of MAAs as photo-protection in these mollusc species is likely to be species specific, with a variety of abiotic and biotic factors influencing their uptake and sequestration. These experiments in part demonstrate how New Zealand's mollusc species are responding to humaninduced changes in UVR levels.&lt;/p&gt;

Barufi J.B., Mata M.T., Oliveira M.C. and Figueroa F.L. 2012. Nitrate reduces the negative effect of UV radiation on photosynthesis and pigmentation in Gracilaria tenuistipitata (Rhodophyta): the photoprotection role of mycosporine-like amino acids. Phycologia 51: 636–648. DOI: 10.2216/10.77.1Photoprotection of the agarophyte red alga Gracilaria tenuistipitata against ultraviolet radiation (UVR) was investigated in algae submitted for 1 week to photosynthetically active radiation (PAR, 260 μmol photons m−2 s−1) or PAR + UVR (UV-A, 8.13 W m−2 and UV-B, 0.42 W m−2) under different nitrogen concentrations: 0, 0.1, and 0.5 mM of NO3−. Photosynthetic pigments decreased during the time of the experiment mainly under low nitrogen supply and UVR. Incubation under high nitrogen supply (0.5 mM) sustained the photosynthetic levels over time. In contrast, mycosporine-like amino acids (MAAs) increased up to eightfold in the presence of UVR and 0.5 mM NO3−. Under PAR + UVR, maximal quantum yield was positively correlated to MAA abundance, whereas under PAR no correlation was found. The photosynthetic yield of algae cultivated during seven days under PAR + UVR was less affected by a 30-min exposure of high UVR (16 W m−2) and fully recovered after transferring to low PAR irradiances, whereas algae kept under PAR were more affected by UV exposure and no full recovery was observed. Growth rates decreased after three days in the presence of UVR and under low nitrate supply. However, these rates were similar when compared with treatments of PAR and PAR + UVR after seven days, with the exception of samples in 0 mM NO3−, indicating that the acclimation after one week's exposure is related to nitrate supply. In conclusion, the lowest negative effect of UVR on photosynthesis and growth rate in high N-supply-grown algae could be explained by the stimulation of photoprotection mechanisms, such as accumulation of MAAs. Photostimulation of MAA accumulation by UVR under high N supply was observed in G. tenuistipitata even after 20 years in culture without the induction of this photomorphogenic light signal.

Ultraviolet radiation (UVR) is the photochemically most reactive waveband of incident solar irradiation. Despite high absorption in aquatic environments, UVR causes numerous biochemical, genetic, and cytotoxic effects in aquatic organisms. To counteract UVR stress, many of those species are able to synthesize, accumulate, or acquire UV-sunscreen compounds for photoprotection from their diet. The most abundant UV sunscreens in marine and freshwater organisms are mycosporine-like amino acids (MAAs), which exhibit high molar extinction coefficients in the UVR range along with a strong photo- and heat stability. In this study, we investigated the qualitative and quantitative MAA distribution patterns in the eyes of 39 fish species, mainly from the temperate northern hemisphere (Baltic Sea, Northern Atlantic), using state-of-the-art analytical methods. The fish eyes of the most investigated species (33 taxa) contained MAAs, between one and seven different compounds. The MAAs palythine, asterina-330, palythene, and usujirene were present (as previously reported), and three new compounds, aplysiapalythine A, porphyra-334, and shinorine, were identified. Total MAA concentrations covered a wide range from trace amounts to &amp;gt; 4.2 mg g−1 dry weight, thereby providing the first quantitative data on MAAs in fish eyes. The highest MAA contents were measured in Sprattus sprattus, which are comparable to those of intertidal red seaweeds. The trophic transfer of MAAs from primary producers via zooplankton to the fish is discussed, along with the localization in the fish eye as well as possible additional functions.

The photoprotective and acclimation capacity against ultraviolet radiation (UVR) was assessed for the dinoflagellate Heterocapsa sp. We examined the effect of UVR and N availability on photosynthetic activity and on the accumulation of photoprotective substances such as mycosporine‐like amino acids (MAAs) and xanthophyll cycle pigments. Cells were cultivated under two different light treatments, photosynthetically active radiation (PAR) and PAR + UVR, and at two NaNO3 concentrations, mid nitrogen (MN, 0.1 mmol L−1) and high nitrogen (HN, 1 mmol L−1) for 6 d. MAA and photosynthetic pigment contents as well as maximum quantum yield of fluorescence (Fv : Fm) and electron transport rate were analyzed at the initial time and after 3 and 6 d of experimentation. Fv : Fm decreased because of UVR and N limitation. N enrichment reduced the deleterious effect of UVR on photosynthesis. The content of photosynthetic pigments and MAAs was higher at HN than at MN supply and a positive effect of UVR on MAA and pigment accumulation was observed, suggesting that under HN conditions the deleterious UVR effect is counteracted by MAAs. Under N limitation thermal energy dissipation takes place by the xanthophyll cycle, i.e., an increase of the de‐epoxidation degree was observed under these culture conditions. However, UVR seems to favor diadinoxanthin accumulation; thus, no photoprotection through the xanthophyll cycle seems available in cells exposed to PAR + UVR and MN. We conclude that not only MAA accumulation but also N availability is very important to determine the photoprotective capacity against UVR of Heterocapsa sp.

Summary1. The prevalence of mycosporine‐like amino acids (MAAs) – a group of potential ultraviolet (UV)‐photoprotective compounds – was surveyed across 11 species of freshwater copepods from 20 lakes of varying ultraviolet radiation (UVR) transparency in North America, New Zealand and Argentina. Co‐occurring cladocerans were also analysed (seven species from 12 lakes). Many of the calanoid copepod populations were red with carotenoid pigmentation, allowing comparison of MAA and carotenoid accumulation as photoprotective strategies.2. In two Pennsylvania (U.S.A.) lakes, MAA and carotenoid contents were followed during the early spring to mid‐summer period of lake warming. A pronounced seasonal pattern of higher carotenoid/low MAA content in spring, shifting to low carotenoid/higher MAA content in summer, was observed in calanoids from the more UV transparent lake.3. All copepod samples contained MAAs. Visibly red calanoids, especially southern Hemisphere Boeckella, often had moderate to high concentrations (2.5–11 μg MAA mg−1 dw), but low concentrations (0.04–1 μg MAA mg−1 dw) in some N. American red calanoids show that high carotenoid pigmentation (e.g. 5–10 μg carotenoid mg−1 dw) does not necessarily imply high MAA content.4. No cladoceran sample had more than trace amounts of MAAs (&lt;0.05 μg mg−1 dw). Therefore, MAA accumulation does not seem to be a photoprotective strategy utilized by Daphnia (five species from nine lakes) or other cladocerans.5. Seven identifiable MAAs were widely distributed among both calanoids and cyclopoids. Shinorine was ubiquitous and was usually the most abundant MAA in N. American samples. In contrast, porphyra‐334 was the predominant MAA in the southern Hemisphere Boeckella.6. Copepods from higher UVR lakes tended to have a higher MAA content, but this relationship was statistically weak overall and taxon‐specific when found.

Field sampling and laboratory experiments examined whether ultraviolet radiation (UVR) affects the reproduction or the accumulation of mycosporine-like amino acids (MAAs) and ascorbic acid in ovaries of the green sea urchin Strongylocentrotus droebachiensis (Muller). Ovaries of sea urchins sampled across a depth gradient (0.5–10 m) in March 1998 did not differ in their gonadal index, or in concentrations of MAAs, or ascorbic acid. Concentrations of MAAs and ascorbic acid in ovaries were higher in sea urchins collected from a kelp bed compared with those collected from a community of crustose coralline algae. The concentrations of MAAs in ovaries varied seasonally, peaking in March, when sea urchins had high gonadal indices just before spawning. Ovaries of sea urchins maintained on controlled diets from October 1997 to April 1998 accumulated significantly higher concentrations of MAAs when fed a diet rich in MAAs than did ovaries of sea urchins fed an alga lacking MAAs, but the gonadal indices did not differ between diets. Sea urchins accumulated principally one MAA, shinorine, but not others that were available in high concentrations in their diet. Neither the gonadal index nor the ovarian concentrations of MAAs were affected by daily exposure of adult urchins to UVR for 6 months. Concentrations of ascorbic acid in ovaries did not differ among diets or UV-treatments. The percentages of nutritive phagocytes and gametic cells were not affected by diet or UVR, and did not co-vary with concentrations of MAAs or ascorbic acid in ovaries. These data support previous demonstrations that female sea urchins accumulate MAAs from their diet of macroalgae, but further show that the accumulation is selective for specific MAAs, particularly shinorine, and that adult S. droebachiensis do not accumulate MAAs in their ovaries or eggs in response to UV-exposure. These are also the first experimental studies to address whether MAAs are affected by or regulate gametogenesis, and indicate that they do not.