Tropical seagrass-associated macroalgae distributions and trends relative to water quality

Authors

Ligia Collado-Vides, Southeast Environmental Research Center, Florida International UniversityFollow
Valentina G. Caccia, Southeast Environmental Research Center, Florida International UniversityFollow
Joseph N. Boyer, Southeast Environmental Research Center, Florida International UniversityFollow
James W. Fourqurean, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow

Abstract

Tropical coastal marine ecosystems including mangroves, seagrass beds and coral reef communities are undergoing intense degradation in response to natural and human disturbances, therefore, understanding the causes and mechanisms present challenges for scientist and managers. In order to protect our marine resources, determining the effects of nutrient loads on these coastal systems has become a key management goal. Data from monitoring programs were used to detect trends of macroalgae abundances and develop correlations with nutrient availability, as well as forecast potential responses of the communities monitored. Using eight years of data (1996–2003) from complementary but independent monitoring programs in seagrass beds and water quality of the Florida Keys National Marine Sanctuary (FKNMS), we: (1) described the distribution and abundance of macroalgae groups; (2) analyzed the status and spatiotemporal trends of macroalgae groups; and (3) explored the connection between water quality and the macroalgae distribution in the FKNMS. In the seagrass beds of the FKNMS calcareous green algae were the dominant macroalgae group followed by the red group; brown and calcareous red algae were present but in lower abundance. Spatiotemporal patterns of the macroalgae groups were analyzed with a non-linear regression model of the abundance data. For the period of record, all macroalgae groups increased in abundance (Ab_i) at most sites, with calcareous green algae increasing the most. Calcareous green algae and red algae exhibited seasonal pattern with peak abundances (Φ_i) mainly in summer for calcareous green and mainly in winter for red. Macroalgae Ab_i and long-term trend (m_i) were correlated in a distinctive way with water quality parameters. Both the Ab_i and m_i of calcareous green algae had positive correlations with NO₃⁻, NO₂⁻, total nitrogen (TN) and total organic carbon (TOC). Red algae Ab_i had a positive correlation with NO₂⁻, TN, total phosphorus and TOC, and the m_i in red algae was positively correlated with N:P. In contrast brown and calcareous red algae Ab_i had negative correlations with N:P. These results suggest that calcareous green algae and red algae are responding mainly to increases in N availability, a process that is happening in inshore sites. A combination of spatially variable factors such as local current patterns, nutrient sources, and habitat characteristics result in a complex array of the macroalgae community in the seagrass beds of the FKNMS.

Comments

Post Print Version.

Copyright © 2006 Elsevier.

The definitive publisher-authenticated version is available online at http://dx.doi.org/10.1016/j.ecss.2007.03.009

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Collado-Vides, L., V.G. Caccia, J.N. Boyer, J.W. Fourqurean. 2007. Tropical seagrass-associated macroalgae distributions and trends relative to water quality. Estuarine Coastal and Shelf Science 73: 680-694.