Environmental assessment of two artificial reef systems off southern Portugal (Faro and Olhao): A question of location

摘要

This study investigates environmental assessment of artificial reef systems deployed at different areas in terms of nutrient cycling and seabed organic enrichment.. Two identical artificial reef systems: Olhao Artificial Reef-OAR (37 degrees 00'55 '' N and 007 degrees 44'54 '' W) and Faro Artificial Reef-FAR (36 degrees 58'65 '' N and 008 degrees 00'91 '' W) were deployed in Southern Portuguese coast, adjacent to a highly productive coastal lagoon (Ria Formosa) in 1990 and monitorized over two years (1992-1993). Water samples were collected within OAR and FAR systems, inside the lagoon (L) and in a non-recf area (NRA) to evaluate nutrient dynamics. Settled particles and sediment cores were also sampled within OAR and FAR to determine aluminium, calcium, silicon and chlorophyll a and organic and inorganic carbon, nitrogen and phosphorous. Results obtained showed that: (i) water column nutrients evidenced seasonal and spatial variability. The maximum nutrients concentration was recorded inside the lagoon and in OAR, mainly during warmer periods. Ammonium, nitrate and silicate in OAR were statistically higher (p<0.01, n = 18) than in FAR and NRA; (ii) particulate organic carbon and nitrogen in FAR settled particles were significantly higher)<0.005) than those collected at OAR; and (iii) organic carbon and nitrogen, calcium, aluminium and chlorophyll et in OAR Upper sediment were higher than at FAR. The overall results suggest that OAR is a productive system, emphasizing its contribution to the trophic chain Pull out, while FAR presented oceanic oligotrophic water. (C) 2008 Elsevier Ltd. All rights reserved.