Long-term changes in phytoplankton phenology and community structure in the Bahía Blanca Estuary, Argentina

• Published in: Marine biology Vol. 157; no. 12; pp. 2703 - 2716
• Main Authors: Guinder, Valeria A, Popovich, Cecilia A, Molinero, Juan Carlos, Perillo, Gerardo M. E
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.12.2010; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Brackish water ecosystems; Chaetoceros; chlorophyll; climate; Climate change; Community structure; Cyclotella; Estuaries; food webs; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; High temperature; Life Sciences; Marine & Freshwater Sciences; Marine biology; Microbiology; Oceanography; Original Paper; Phenology; physicochemical properties; Physiological aspects; Phytoplankton; Sea water ecosystems; Species composition; species diversity; Synecology; temperature; Thalassiosira; weather; Winter; Zoology; Argentina; South America; America; Phytoplankton; Cyclotella; Chlorophyll Concentration; Phytoplankton Community; Phytoplankton Bloom; Community structure; Estuaries; Plant community; Phenology; Long term
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-010-1530-5

The phytoplankton of the Bahía Blanca Estuary, Argentina, has been surveyed since 1978. Chlorophyll a, phytoplankton abundance, species composition and physico-chemical variables have been fortnightly recorded. From 1978 to 2002, a single winter-early spring diatom bloom has dominated the main pattern of phytoplankton interannual variability. Such pattern showed noticeable changes since 2006: the absence of the typical winter bloom and changes in phenology, together with the replacement of the dominant blooming species, i.e. Thalassiosira curviseriata, and the appearance of different blooming species, i.e. Cyclotella sp. and Thalassiosira minima. The new pattern showed relatively short-lived diatom blooms that spread throughout the year. In addition, shifts in the phytoplankton size structure toward small-sized diatoms, including the replacement of relatively large Thalassiosira spp. by small Cyclotella species and Chaetoceros species have been noticed. The changes in the phenology and composition of the phytoplankton are mainly attributed to warmer winters and the extremely dry weather conditions evidenced in recent years in the Bahía Blanca area. Changing climate has modified the hydrological features in the inner part of the estuary (i.e. higher temperatures and salinities) and potentially triggered the reorganization of the phytoplankton community. This long-term study provides evidence on species-specific and structural changes at the bottom of the pelagic food web likely related to the recent hydroclimatic conditions in a temperature estuary of the southwestern Atlantic.