Environmental Control on Fish and Macrocrustacean Spring Community-Structure,on an Intertidal Sandy Beach

The inter-annual variability of the fish and macrocrustacean spring community on an intertidal sandy beach near the Canche estuary (North of France) was studied from 2000 to 2013 based on weekly spring sampling over an 11-year period. Twenty-eight species representing 21 families were collected during the course of the study. The community was dominated by a few abundant species accounting for > 99% of the total species densities. Most individuals caught were young-of-the-year indicating the importance of this ecosystem for juvenile fishes and macrocrustaceans. Although standard qualitative community ecology metrics (species composition, richness, diversity, evenness and similarity) indicated notable stability over the study period, community structure showed a clear change since 2009. Densities of P. platessa, P. microps and A. tobianus decreased significantly since 2009, whereas over the period 2010-2013, the contribution of S. sprattus to total species density increased 4-fold. Co-inertia and generalised linear model analyses identified winter NAO index, water temperature, salinity and suspended particular matter as the major environmental factors explaining these changes. Although the recurrent and dense spring blooms of the Prymnesiophyte Phaeocystis globosa is one of the main potential threats in shallow waters of the eastern English Channel, no negative impact of its temporal change was detected on the fish and macrocrustacean spring community structure.     

Peracetylated 1,6-dibromo-D-glucitol as efficient precursor of 1,6-diiodo and some mono-, disubstituted and heterocyclic D-glucitol derivatives

2,3,4,5-Tetra-O-acetyl-1,6-dibromo-1,6-dideoxy-D-glucitol (1a) obtained from D-glucitol was easily transformed into the 1,6-diiodo derivative in excellent yield (97%) by reaction with an excess of sodium iodide in refluxing butanone in 2 h. When the reaction time was prolonged to 24 h and the crude product was acetylated, 1,2,3,4,5-penta-O-acetyl-6-deoxy-6-iodo-D-glucitol and D-glucitol hexaacetate were isolated in 50 and 26% yields, respectively. The monodehalogenation then took place regioselectively at C-1. This regioselectivity allowed the synthesis of some mono- and disubstituted derivatives of D-glucitol. Thus, the peracetylated derivatives of D-glucitol, 6-bromo, 6-bromo-1-S-butyl, 6-bromo-1-S-octyl, 6-S-butyl, 6-S-butyl-1-S-octyl, 1-S-butyl, 1,6-di-S-octyl and 6-S-phenyl were synthesised in good to excellent yields. With S= as binucleophilic reagent, 1a gave mainly the thiepane derivative (75%) plus the 1-S-acetyl-2,6-anhydro-D-glucitol derivative as a by-product (10%).     

Regioselective synthesis of alditol vicinal bis-cyclic thionocarbonates via alditol stannylene acetal complexes as a short and efficient route to alpha,omega-diiodoalditol derivatives.

The bis-cyclic thionocarbonates of alditols (pentitols and hexitols) were quickly and easily obtained from alditol stannylene complexes and phenyl chlorothionoformate (PhOC(S)Cl) in good yields. Acetylation of isolated free alditol bis-thionocarbonates and subsequent iodination using methyl iodide under pressure led to alpha,omega-diiodo derivatives of alditols in good to excellent isolated yields (67-93%).