Environmental factors affecting maerl bed structure in Brittany (France)

Type Article
Date 2015
Language English
Author(s) Dutertre Mickael1, Grall Jacques2, Ehrhold AxelORCID3, Hamon Dominique1
Affiliation(s) 1 : IFREMER, ODE, DYNECO, Lab Ecol Benth, F-29280 Plouzane, France.
2 : Inst Univ Europeen Mer, UMS 3113, Observ Domaine Cotier, F-29280 Plouzane, France.
3 : IFREMER, REM, GM, Lab Environm Sedimentaires, F-29280 Plouzane, France.
Source European Journal Of Phycology (0967-0262) (Taylor & Francis Ltd), 2015 , Vol. 50 , N. 4 , P. 371-383
DOI 10.1080/09670262.2015.1063698
WOS© Times Cited 13
Keyword(s) Benthic habitats, Brittany, environmental factors, estuary, large spatial scale, maerl
Abstract This study used a large spatial scale approach in order to better quantify the relationships between maerl bed structure and a selection of potentially forcing physical factors. Data on maerl bed structure and morpho-sedimentary characteristics were obtained from recent oceanographic surveys using underwater video recording and grab sampling. Considering the difficulties in carrying out real-time monitoring of highly variable hydrodynamic and physicochemical factors, these were generated by three-dimensional numerical models with high spatial and temporal resolution. The BIOENV procedure indicated that variation in the percentage cover of thalli can best be explained (correlation = 0.76) by a combination of annual mean salinity, annual mean nitrate concentration and annual mean current velocity, while the variation in the proportion of living thalli can best be explained (correlation = 0.47) by a combination of depth and mud content. Linear relationships showed that the percentage cover of maerl thalli was positively correlated with nitrate concentration (R2 = 0.78, P < 0.01) and negatively correlated with salinity (R2 = 0.81, P < 0.01), suggesting a strong effect of estuarine discharge on maerl bed structure, and also negatively correlated with current velocity (R2 = 0.81, P < 0.01). When maerl beds were deeper than 10 m, the proportion of living thalli was always below 30% but when they were shallower than 10 m, it varied between 4 and 100%, and was negatively correlated with mud content (R2 = 0.53, P < 0.01). On the other hand, when mud content was below 10%, the proportion of living thalli showed a negative correlation with depth (R2 = 0.84, P < 0.01). This large spatial scale explanation of maerl bed heterogeneity provides a realistic physical characterization of these ecologically interesting benthic habitats and usable findings for their conservation and management.
Full Text
File Pages Size Access
13 4 MB Access on demand
Author's final draft 39 606 KB Open access
Top of the page