Faunal responses to turbidity in a man-modified bay (Bilbao, Spain)

• Published in: Marine environmental research Vol. 47; no. 4; pp. 331 - 347
• Main Authors: SAIZ-SALINAS, J. I, URKIAGA-ALBERDI, J
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.05.1999
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Marine; Sea water ecosystems; Spain, Bilbao; Synecology; North Atlantic; Europe; Atlantic Ocean; Spain; ANE, Spain, Pais Vasco, Vizcaya, Bilbao; Marine environment; Community structure; Animal community; Turbidity; Environmental factor; Invertebrata; Spatial variation; Anthropogenic factor
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/S0141-1136(98)00124-X

The relationship between rocky shore faunal assemblages and measured environmental variables in a small bay (Bilbao, Spain) affected by large anthropogenic interferences were examined using multivariate statistical techniques (CANOCO, PRIMER). Redundancy analysis (RDA), with forward selection of environmental variables and associated Monte Carlo permutation tests, suggested that total suspension solids (TSS sub(s)) and salinity (Sal sub(s)) at the water surface made significant (<0.05) contributions to explaining the variation in the investigated faunal assemblages. Alternatively, the BIO-ENV analysis selected a subset of three environmental variables, related to turbidity, as the best explanatory variables. A constrained RDA with TSS sub(s) as the only explanatory variable revealed that turbidity was a strong variable, and accounted for a statistically significant proportion of the variance in the faunal data set. Further analyses of faunal data using a smaller subset of 14 top dominant taxa produced spatial patterns as clearly as the analysis with the full species data set (63 species). This indicated that nearly 75% of the taxonomic information could be deemed redundant for the purposes of this study. In conclusion, the weight of evidence suggests that turbidity, mainly from estuarine runoff, is causing a severe stress to the hard-bottom faunal assemblages.