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The Laurentian Great Lakes region in North America is experiencing climate-driven disturbances that threaten the public safety of the region and is forcing communities to respond. Communities vary in their ability to respond to these disturbances based on their existing capacities and access to resources, but responses in the region are uneven and create vulnerabilities to disasters. A virtual workshop was conducted to understand the community responses to climate-driven disturbances in the Great Lakes and identify the essential capacities for effective responses. Results show that the region as a whole has not responded adequately, and although the resources exist to respond, they are not adequately organized, and inequalities between urban and rural communities can exacerbate these challenges. Community capacities identified as critical for resilience include leadership, scientific knowledge, and connection to broader regional networks to access additional resources, but there are challenges with the complacency of some communities and deficiencies in mental health services. [ABSTRACT FROM AUTHOR]

Unattended sensor networks are a cost-effective strategy to enhance the resolution of environmental datasets and are required to understand how large aquatic ecosystems respond to complex stressors (e.g., climate change). We made unattended and continuous measurements of the quantum yield of photosystem II ([φ.sub.PSII]) photochemistry in the surface mixed layer of Lake Erie during three lake-wide cruises to observe how phytoplankton physiology varied across nutrient and taxonomic gradients. Three prominent diel [φ.sub.PSII] patterns were noted. The diel maximum consistently occurred at sunrise or sunset, nocturnal measurements were consistently lower than diel maxima, and daytime values were strongly diminished by nonphotochemical quenching. The diurnal pattern was modeled as a function of irradiance to a mean accuracy of 0.03 to 0.04. Contrary to previously published reports in Lake Erie, [φ.sub.PSII] was largely insensitive to indices of nutrient deficiency through space and time. This finding was consistent with much recent literature about [φ.sub.PSII] and suggests that Lake Erie phytoplankton, like many others, can tune their photosynthetic machinery to maintain relatively high efficiency of photochemistry in photosystem II even when deficient in phosphorus or nitrogen. Les reseaux de capteurs surveilles a distance constituent une strategie economique pour ameliorer la resolution d'ensembles de donnees environnementales et sont necessaires a la comprehension de la reaction des grands ecosystemes aquatiques a des facteurs de stress complexes tels que les changements climatiques. Nous avons pris des mesures a distance et en continu du rendement quantique de la photochimie du photosysteme II ([φ.sub.PSII]) dans la couche de melange superficielle du lac Erie durant trois croisieres a la grandeur du lac afin d'observer les variations de la physiologie du phytoplancton le long de gradients taxinomiques et de nutriments. Trois grands motifs nycthemeraux du [φ.sub.PSII] ont ete notes. Le maximum nycthemeral se produisait uniformement au lever ou au coucher du soleil, les mesures nocturnes etaient uniformement inferieures au maximum nycthemeral et les valeurs diurnes etaient fortement reduites par l'extinction non photochimique. La modelisation du motif diurne en tant que fonction de l'eclairement energetique a donne une exactitude moyenne de 0,03 a 0,04. Contrairement a des publications anterieures concernant le lac Erie, le [φ.sub.PSII] etait en bonne partie insensible aux indices de deficit de nutriments dans l'espace et le temps. Ce resultat concorde avec de nombreuses etudes recentes concernant le φPSII et donne a penser que le phytoplancton du lac Erie, comme bien d'autres, peut ajuster ses mecanismes photosynthetiques de maniere a maintenir une efficacite relativement elevee de la photochimie dans le photosysteme II, meme en situation de deficit de phosphore ou d'azote. [Traduit par la Redaction], Introduction Phytoplankton production dictates the flow of energy and mass in large aquatic ecosystems, including the Laurentian Great Lakes. Accurate monitoring of phytoplankton health and productivity is critical to understand [...]

The FluoroProbe (FP; bbe Moldaenke, GmbH) is increasingly deployed as a means to measure in situ abundance and composition of phytoplankton communities, yet few rigorous evaluations have been made of its performance. In this study, phytoplankton strains were grown under standardized conditions to test FP performance across a range of biomass concentrations (0.2 to 20 µg chlorophyll a (chl a) x [L.sup.-1]). FP estimates of in vivo chl a were compared with chl a values from acetone extraction analysis. Overall, in vivo chl a detected by the FP was well correlated with extracted values ([r.sup.2] = 0.85, n = 409, p < 0.0001). However, the difference between in vivo FP measures and the acetone extracted method was high in some cases. Accuracy did not change over a range of chromophoric dissolved organic matter concentrations. Calibration with each laboratory strain improved FP accuracy over the standard instrument factory settings. The performance of two different instruments was not significantly different (p = 0.38), showing good data intercompatibility. In the majority of experiments involving multiple phytoplankton groups at various proportions and concentrations, the FP resolved all groups. The FP is a cost-effective and practical method for identifying trends in phytoplankton dynamics but has limitations with respect to accurate total chl a measurement. Si le FluoroProbe (FP; de bbe Moldaenke, GmbH) est de plus en plus utilise pour mesurer l'abondance et la composition de communautes de phytoplancton in situ, peu devaluations rigoureuses de sa performance ont ete realisees. Nous avons fait pousser des lignees de phytoplancton dans des conditions normalisees afin d'evaluer la performance du FP dans une fourchette de concentrations de la biomasse (de 0,2 a 20 µg chl a x [L.sup.-1]). Les estimations de la chl a in vivo obtenues avec le FP ont ete comparees aux valeurs de chl a produites par l'analyse avec extraction a l'acetone. Globalement, la chl a in vivo detectee par le FP montrait une bonne correlation avec les valeurs obtenues par extraction ([r.sup.2] = 0,85, n = 409, p < 0,0001). Toutefois, il y avait dans certains cas une grande difference entre les mesures in vivo par FP et par la methode avec extraction a l'acetone. L'exactitude ne variait pas dans une fourchette de concentrations de matiere organique dissoute chromophore. L'etalonnage avec chaque lignee de laboratoire ameliorait l'exactitude du FP par rapport a son reglage en usine normalise. Les performances de deux instruments distincts n'etaient pas significativement differentes (p = 0,38), montrant une bonne intercompatibilite des donnees. Dans la plupart des experiences mettant en cause des proportions et concentrations variees de differents groupes de phytoplancton, le FP arrivait a distinguer tous les groupes. Si le FP constitue une methode relativement peu couteuse et pratique pour cerner les tendances de la dynamique du phytoplancton, il presente toutefois des limites associees a l'exactitude des mesures de la chl a totale. [Traduit par la Redaction], Introduction In situ methods for measuring phytoplankton are indispensable tools for aquatic scientists. Current techniques in phytoplankton identification require time-demanding microscopic techniques by skilled taxonomists or solvent extraction and analysis [...]

Phytoplankton interactions with iron (Fe) were examined in surface waters of Lake Erie during summer thermal stratification. Lake-wide sampling in June and September 2005 was conducted using a continuous surface water sampler (1 m sampling depth) and in July at 18 hydrographic stations (5 m sampling depth). In situ measurements of photosynthetic efficiency (maximum quantum yield of photosystem II) and phytoplankton community composition were measured using fast repetition rate fluorometry and a phytoplankton pigment-specific fluorometer, respectively, during June and September. High ratios (73%-85%) of intracellular Fe to particulate Fe coincident with increases in chlorophyll a (Chl a) concentrations in the western and central basins in June and July imply that the majority of Fe in these regions was associated with intracellular pools. Correlations between intracellular Fe and Chl a were frequently observed when Heterokontophyta and Pyrrophyta dominated the phytoplankton community. Assimilation of Fe by the phytoplankton strongly influenced its partitioning between the dissolved and particulate phase. Dissolved iron ( Durant la stratification thermale de l'ete 2005, nous avons etudie les interactions entre le fer (Fe) et le phytoplancton dans les eaux de surface du lac Erie. L'ensemble du lac a ete echantillonne en juin et septembre a l'aide d'un echantillonneur en continu des eaux de surface (1 m de profondeur). De plus, en juillet, 18 stations hydrographiques ont ete echantillonnees a une profondeur de 5 m. En juin et septembre, l'efficacite photosynthetique (le rendement quantique maximal du photosysteme II) ainsi que la composition de la communaute de phytoplancton in situ ont ete determinees respectivement avec un fluorometre a taux de repetition eleve et par un fluorometre specifique pour les pigments du phytoplancton. En juin et juillet, dans les bassins lacustres central et occidental, les rapports eleves du fer intercellulaire par rapport au fer particulaire (73-85 %) et l'augmentation de la concentration de chlorophylle a (Chl a) indiquent que le fer est majoritairement associe a la fraction intracellulaire du plancton. Les relations entre la concentration du fer intracellulaire et Chl a sont frequemment observees lorsque les heterokontophytes et les dinoflagelles representent les taxons dominants de la communaute phytoplanctonique. L' assimilation du fer par le phytoplancton influence fortement sa distribution entre les phases dissoute et particulaire durant la periode estivale. En juillet et en septembre, la concentration de fer dissous (, Introduction Iron (Fe) is a key nutritional element to phytoplankton since it is an obligatory requirement for nitrogen assimilation (Raven 1988; Paerl and Zehr 2000), chlorophyll synthesis (Spiller et al. [...]

Fulvic acid interacts with the algal surface and acts as a source of phosphorus to P-deficient algae. This was gleaned from the results of an experiment to test the assumption under the free-ion model that the sole function of dissolved organic matter is to complex metals in solution. The model's applicability to the toxicity of aluminum to the green alga Chlorella pyrenoidosa in the presence of a soil fulvic acid was tested in defined media designed to restrict Al intercations to algae and soil fulvic acid.