Spatial variation in timing of marine subsidies influences riparian phenology through a plant-pollinator mutualism

Abstract

Citation: Lisi, P. J., and D. E. Schindler. 2011. Spatial variation in timing of marine subsidies influences riparian phenology through a plant-pollinator mutualism. Ecosphere 2(9):101. doi:10.1890/ES11-00173.1Abstract. Migratory animals are well-recognized for transporting energy and nutrients across habitat boundaries as resource subsidies but less is known about the secondary effects of these subsidies in supporting biodiversity in recipient ecosystems. In southwestern Alaska, fly-pollinated plants in the carrot family (Apiaceae) flower during the annual arrival of semelparous Pacific salmon to their natal streams to spawn. Blowflies (Calliphoridae) are an important consumer of salmon carcasses as larvae and pollinate Apiaceae as adults. Stable isotope analyses indicate that adult blowflies received the majority (85%) of their carbon and nitrogen from salmon carcasses and the remainder from riparian plants. A large terrestrial signature was passed maternally to blowfly eggs but quickly replaced by marine-derived resources as eggs developed into larvae on salmon carcasses. We also monitored the flowering phenology of kneeling Angelica (Angelica genuflexa) across salmon bearing streams (n ¼ 20) that differ in the timing of salmon spawning. We found that salmon spawning date explained a substantial amount of the observed seasonal variation in peak flowering dates among streams and, when combined with longitude, explained 88% of the variation in seasonal phenology of Angelica among streams. By comparison, distance from the ocean, stream temperature, slope, aspect, and elevation in the riparian area had no relationship with Angelica bloom date. Together, these results suggest that spatial variation in salmon spawning timing is transmitted via the phenology of salmon-dependent consumers that affect the bloom timing of a common riparian plant.

Earlier Migration Timing, Decreasing Phenotypic Variation, and Biocomplexity in Multiple Salmonid Species

“…Because the phenologies of other organisms are adapted to the timing of salmon spawning, these changes have the potential to influence other ecological interactions (e.g. mayfly emergence [10], plant-pollinator interactions [11], wildlife behavior [72]) and both human and non-human consumers of adult salmon will need to adjust their behavior to continue to consume Auke Creek salmon. On the other hand, the window of time that juvenile salmon migrate out to the ocean and are available as prey resources for fish (e.g.…”

“…An important aspect of salmonid biology that may need to respond to climate change is migration timing because this trait is closely adapted to local environmental conditions, particularly temperature [4], and influences individual fitness by affecting survival and reproductive success [5]–[8]. Due to their important ecological role [1], [2] and predictable migratory timing [9], many species are thought to have adapted their phenologies to correspond with the presence of adult salmon in freshwater [10], [11]. Thus, changes in this trait may have substantial ecological ramifications [1], [2], [12], and understanding the response of salmonids to climate change is imperative for conserving functional coastal human and ecological communities [2], [6].…”

Delayed insect access alters carrion decomposition and necrophagous insect community assembly

“…For instance, carrion nutrient transfer between ecosystems can result from blow fly (Diptera: Calliphoridae) consumption and dispersal (Hocking and Reimchen 2006, Hocking et al 2009, Parmenter and MacMahon 2009 or vertebrate scavenging (Wilson andWolkovich 2011, Beasley et al 2012). Necrophagous arthropod attraction, colonization, development, and migration can affect nutrient transformation and release and thus local biodiversity (Hocking and Reimchen 2006, Lisi and Schindler 2011, Tomberlin et al 2011, Hawlena et al 2012, which can ultimately impact landscape biodiversity depending on the density and frequency of carrion (Yang et al 2008, Barton et al 2013. While many organisms utilize these ephemeral resources the mechanisms governing attraction, consumption, utilization and nutrient transformation of carrion are only beginning to be investigated.…”

“…Decomposing carcasses such as whale falls (Smith and Baco 2003) or anadromous salmon, Oncorhynchus spp. (Salmoniformes: Salmonidae) (Hocking and Reimchen 2006), can be the primary resource subsidy for their associated ecosystems (Lisi and Schindler 2011). Carrion decomposition reintroduces essential nutrients such as nitrogen, potassium, calcium and magnesium into an ecosystem (Towne 2000, Carter et al 2007, Parmenter and MacMahon 2009.…”

Salmon subsidize an escape from a size spectrum

“…They overwinter in the soil near carcasses for at least eight months, and during this time are consumed by at least 21 soil invertebrate and 16 vertebrate species [33], including large-bodied species such as the carrion beetle Nicrophorus investigator, but also small-bodied parasitic wasps and rove beetles (Family Staphilinidae). In the late spring and summer, the surviving larvae pupate into adult flies and emerge from the soil en masse, which can affect the bloom timing of local plant species [54], and provides one mechanism by which top predators such as songbirds may have higher densities along these same salmon streams and estuaries [55 -57].…”