Land–Ocean Connectivity Through Subsidies of Terrestrially Derived Organic Matter to a Nearshore Marine Consumer
Land–ocean coupling in the form of riverine inputs of terrestrial matter can constitute an energetic subsidy to food webs in nearshore coastal areas. In regions with distinctly seasonal rainfall patterns, the strength and spatial footprint of any terrestrial signal in receiving marine food webs is predicted to mirror seasonal changes in fluvial forcing. Here, we test this prediction in a subtropical bay by isotopically (δ13C and δ15N) characterizing the main primary producers and reconstructing (using a Bayesian stable isotope mixing model) their contributions to the diet of thinstripe hermit crabs (Clibanarius vittatus). Seasonal rainfall flushed terrestrial carbon out of coastal watersheds, and this material made a sizable (up to 28%) contribution to the diet of marine consumers, in addition to mangroves, seagrass and algae. Our isotope model indicates that inputs of terrestrial grasses and other littoral vegetation were 15% greater as a result of increased fluvial forcing. In addition, the spatial footprint of the terrestrial signal in marine consumers propagated more widely throughout the bay during high-rainfall periods. Given the widespread conversion of natural watershed habitats for agriculture and urban development, understanding the nature, temporal dynamics and strength of such land–ocean coupling will become increasingly important.
Keywordsterrestrial input δ13C δ15N hermit crabs spatial variability Brazil
This research was funded by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) through the BIOTA-Araçá Project (2011/50317-5) and scholarship grants to DG (2013/07576-5; 2018/06162-6) and MP (2012/09937-2). Isotopic analysis was done at the University of California, Davis.
- Amaral ACZ, Corte GN, Rosa JS, Denadai MR, Colling LA, Borzone C, Veloso V, Omena EP, Zalmon IR, Rocha-Barreira CD, de Souza JRB, da Rosa LC, de Almeida TCM. 2016. Brazilian sandy beaches: characteristics, ecosystem services, impacts, knowledge and priorities. Braz J Oceanogr 64:11.CrossRefGoogle Scholar
- Carrilho C. 2015. Identificação e valoração econômica e sociocultural dos serviços ecossistêmicos da Baía do Araçá - São Sebastião, SP, Brasil. Programa de Pós-Graduação em Ciência Ambiental, Instituto de Energia e Ambiente: Universidade de São Paulo, p170Google Scholar
- Choi TS, Kim JH, Kim KY. 2001. Seasonal changes in the abundance of Ulva mats on a rocky intertidal zone of the southern coast of Korea. Algae 16:337–41.Google Scholar
- Lartigue J, Fontanella FM, Cebrian J, Arbaczauskas S. 2003. Evidence that ultraviolet radiation may depress short-term photosynthetic rates of intertidal Ulva lactuca and consumption by a generalist feeder (Clibanarius vittatus). Gulf Mex Sci 21:71–8.Google Scholar
- Marin X. 2013. ggmcmc: graphical tools for analyzing Markov Chain Monte Carlo simulations from Bayesian inference.Google Scholar
- Plucênio RM, Dechoum M, Castellani TT. 2013. Invasão Biológica em Restinga: O Estudo de caso de Terminalia catappa L. (Combretaceae). Número Temático: Diagnóstico e Controle de Espécies Exóticas Invasoras em Áreas Protegidas: Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio).Google Scholar
- Sarma VVSS, Gupta SNM, Babu PVR, Acharya T, Harikrishnachari N, Vishnuvardhan K, Rao NS, Reddy NPC, Sarma VV, Sadhuram Y, Murty TVR, Kumar MD. 2009. Influence of river discharge on plankton metabolic rates in the tropical monsoon driven Godavari estuary, India. Estuar Coast Shelf Sci 85:515–24.CrossRefGoogle Scholar
- Semmens B, Stock B, Jackson A, Ward E, Parnell A, Phillips D, Inger R, Bearhop S. in prep. MixSIAR: a new generation of Bayesian mixing model.Google Scholar
- Williams AB. 1984. Shrimps, lobsters, and crabs of the Atlantic Coast of the Eastern United States, Maine to Florida. California: Smithsonian Institution Press. p 550.Google Scholar