The Sonoran Desert is intimately connected to the Gulf of California, the desert's own sea. In fact, the terrestrial desert is far more connected to the ocean than you may suspect. The moisture that drives the summer monsoons is evaporated off the closed basin of the Gulf of California. The maritime influence provides ideal growing conditions for many succulent desert plant species.
Research at the Desert Laboratory encompasses a broad range of questions and study systems from islands to marine protected areas and the connections between the land and the sea.
Marine Subsidies Produce Cactus Forests on Desert Islands
Land-sea connections permeate the world’s coastal regions, where nutrient transfer between biomes is concentrated. Seabirds have long-been recognized as a vector and engineer of terrestrial habitats, especially islands. In zones of nutrient upwelling such as the Gulf of California, copious seabird guano is commonplace on bird islands. Several bird islands host regionally unique cactus forests, especially of the large columnar cactus, cardón (Pachycereus pringlei). Seabirds on these islands shape arid vegetation through a string of connections from upwelling currents that stimulate primary productivity and abundant pelagic fish populations to some of the densest populations of cacti in the world. The tissue of cactus populations on seabird islands is remarkably enriched, with globally high δ15N values representing natural fertilization. The use of isotopic markers shows the significance of trophic chains in mediating the diversity and structure of seemingly disconnected ecosystems in an arid land-sea setting.
Brown Booby (Sula leucogaster) on the cardón cactus (Pachycereus pringlei) on Isla San Pedro Mártir, Mexico. Guano, accumulated from nesting seabirds on the arid islands of the Gulf of California produce globally dense forests of columnar cacti – an example of a land-sea connection that mediates terrestrial plant community structure.
Islands have figured prominently in many of the greatest scientific advances in what Darwin termed the mystery of mysteries, the appearance of life in geologically recent environments. The web of ecological complexity is simplified on island systems. Variables are reduced and responses and adaptations to causal factors are evident, allowing insights that are blurred elsewhere.
The islands of the Gulf of California, Mexico are a powerful test bed for Island Biogeography theory. They occur along a wide gradient of island size and geologic origin. Nearly every way to be an island (landbridge, oceanic, recent, old, large small, etc.) is represented in the Gulf of California. Likewise, the marine environment contains some of the highest primary productivity values in the world (Douglas et al., 2007), presenting a striking contrast of arid lands in the midst of marine abundance and diversity.
Researchers of the Desert Laboratory, working closely with the Comcaac (Seri People) have led a renewed effort to understand these island systems and their remarkable aridland diversity.
Felger, R.S., B.T. Wilder in collaboration with H. Romero-Morales. 2012. Plant Life of a Desert Archipelago: Flora of the Sonoran Islands in the Gulf of California. University of Arizona Press, Tucson. 624 pages. (plant-life-of-a-desert-archipelago)
Wilder, B.T., R.S. Felger, E. Ezcurra. 2019. Controls of plant diversity and composition on a desert archipelago. PeerJ 7:e7286 DOI 10.7717/peerj.7286 (controls_of_plant_diversity_and_composition_on_a_desert_archipelago.pdf)
Wilder, B.T., C.O’Meara, L. Monti, G. Nabhan. 2016. The importance of indigenous knowledge in curbing the loss of language and biodiversity. BioScience 66:499–509 (wilder_et_al._2016_bioscience.pdf; supplementary data)
Wilder, B.T. 2014. Historical Biogeography of the Midriff Islands in the Gulf of California, Mexico. Dissertation, UC, Riverside, Plant Biology. (Plant Biology)
Ratay, S.E., S. Vanderplank, B.T. Wilder. 2014. Island specialists: Shared flora of the Alta and Baja California Pacific islands. Western North American Naturalist 7:161–220. (ratay_etal_2014_monwnan.pdf)
Wilder, B.T., J.L. Betancourt, C. Epps, R. Crowhurst, J.I. Mead, E. Ezcurra. 2014. Local extinction and unintentional rewilding of bighorn sheep (Ovis canadensis) on a desert island. PLoS ONE 9(3): e91358. doi:10.1371/journal.pone.0091358. (wilder_et_al._2014_bighorn.pdf)
Velarde, E., B.T. Wilder, R.S. Felger, E. Ezcurra. 2014. Floristic diversity and dynamics of Isla Rasa, Gulf of California, Mexico – A globally important seabird site. Botanical Sciences 92(1):89–101. (velarde_et_al._2014_veg)
Gallo-Reynoso, J.P, R.S. Felger, B.T. Wilder. 2012. Near colonization of a desert island by a tropical bird: Military macaw (Ara militaris) at Isla San Pedro Nolasco, Gulf of California. The Southwestern Naturalist 57:461–464. (2012_desert_island_by_a_tropical_bird.pdf)
Felger, R.S., B.T. Wilder, J P. Gallo-Reynoso. 2011. Floristic diversity and long-term vegetation dynamics of San Pedro Nolasco Island, Gulf of California, Mexico. Proceedings of the San Diego Society of Natural History 43:1–42. (felger_et_al._2011_nolasco_flora.pdf)
Wilder, B.T. & R.S. Felger. 2010. Cardons, guano, and isolation: The flora and vegetation of San Pedro Mártir Island, Gulf of California, Mexico. Proceedings of the San Diego Society of Natural History 42:1–24. (proceedings42_wilder_felger.pdf)
Wilder, B.T., R.S. Felger, H. Romero. 2008. Succulent plant diversity of the Sonoran Islands, Gulf of California, Mexico. Haseltonia 14:128–161. (h165_wilder.pdf)
Wilder, B.T., R.S. Felger, T. R. Van Devender, H. Romero-Morales. 2008. Canotia holacantha on Isla Tiburón, Gulf of California, Mexico. Canotia 4(1):1–7. (wilder_et_al_canotia_april08_vol4_1.pdf)
Wilder, B.T., R.S. Felger, H. Romero-Morales, A. Quijada-Mascareñas. 2007. New plant discoveries for Sonoran Islands, Gulf of California, Mexico. Journal of Botanical Research Institute of Texas 1:1203–1227. (35_wilder_etal_sonoranislands_1203-1227.pdf)
eDNA in the Gulf of California: Tracking changes in biodiversity and fishing in Marine Protected
The Gulf of California has been widely recognized as a marine biodiversity hotspot. Nearly 6,000 macroscopic marine animal species have been described (4,854 invertebrates and 1,115 vertebrates) of which about 16% are endemic to the GOC, making it one of the top 10 marine ecosystems for endemic species in the world. The Gulf’s high levels of primary productivity produces ~500,000 tons of seafood annually, which comprises over 60% of Mexico’s fisheries by volume and half of the jobs (~32,600) related to fisheries in the nation.
The Gulf however stands at a crossroads between rapid biodiversity loss and over exploitation of marine resources. Marine reserves – no-take zones or areas of the ocean that are fully protected from all extractive and destructive activities – can be effective management tools for enhancing fisheries, conserving biodiversity, and adapting to climate change. Yet, one of the key challenges is the difficulty of monitoring biodiversity changes and potential over fishing within and outside these managed areas. This key data gap can limit effectiveness, design, their role as a network, and the ability to develop social capital among stakeholders about their benefits.
Environmental DNA (eDNA) provides a quick, inexpensive, high-throughput method for monitoring biodiversity changes in the Gulf of California, and oceans around the world. Active research is focused on:
Developing an eDNA monitoring protocol designed to obtain data with direct usefulness for management of some commercial and threatened reef fish species of the Gulf of California;
Expanding on and using traditional SCUBA biodiversity surveys to calibrate eDNA rapid surveys;
Conduct network wide marine reserves biodiversity surveys, with particular attention to commercial and endangered species.