Project Description
The concept of a "complex adaptive system" (CAS) has emerged as a central element in complexity theory as developed in recent years at the Santa Fe Institute and elsewhere. This concept embodies the idea that inherent in complexity, per se, are self-organizational tendencies that transcend the particulars of any complex system under investigation. |
The phytoplankton genus Phaeocystis produces prodigious blooms of gelatinous colonies, releases copious amounts of DMS, and significantly alters material flows among trophic levels and export from the upper ocean. A potentially salient property from a CAS standpoint is the ability of Phaeocystis to transform between solitary cell and gelatinous colonial life cycle stages, a process which changes organism biovolume by 6-9 orders of magnitude, and which is hypothesized to be mediated by chemical communication. The colony skin confers protection against grazers, viruses, and parasitoids. Phaeocystis utilizes chemistry and/or changes in size as defenses against predation, and its ability to create refuges from biological attack is known to stabilize predator-prey dynamics in model systems. The life cycle form in which it occurs determines whether primary production flows through the traditional "great fisheries" food chain or the more regenerative microbial food web.
We believe that Phaeocystis is a model organism from which to begin the study of biocomplexity in marine pelagic ecosystems. Our central question is: how do physical (light, temperature, particle distributions, hydrodynamics), chemical (nutrient resources), biological (grazers, viruses, bacteria, other phytoplankton), and self-organizational (stability, indirect effects, distributed control) mechanisms interact with life-cycle transformations of Phaeocystis to mediate ecosystemic patterns of trophic structure, biodiversity, and energy flow? Ultimately our goal is to understand and predict why Phaeocystis occurs when and where it does, and the bio-feedbacks between the smaller single species CAS (Phaeocystis) and the larger multi-trophic level CAS (ecosystem). The significance of this need is emphasized by the research and synthesis activities of a SCOR working group, “Marine Phytoplankton and Global Climate Regulation: the Phaeocystis Species Cluster”.
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In the SKIO study experiments quantified the impact of various physical, chemical, and biological factors on Phaeocystis life cycle transformations. Bioassays were conducted to quantify chemical communication between life cycle stages and other organisms, e.g. grazers and competing phytoplankton. Concurrent studies focused on the sensing and genetic response of Phaeocystis to environmental cues. Genetic probes were developed to recognize and quantify Phaeocystis solitary cells in situ, and to identify genetic regulatory elements involved in controlling Phaeocystis life history. Mesocosm experiments were conducted in Bergen, Norway, where Phaeocystis blooms reliably develop. Field studies were conducted in the fjords of Norway, to quantify how biocomplexity operates in the water column and the feedbacks to the ecosystem. An ecosystem model was developed as an investigative tool to deconvolve how physics, chemistry, and biology interact to regulate planktonic structure and function. A life history submodel of Phaeocystis was also developed and embedded within the ecosystem model to explore the mutuality of the bio-feedback between these complex adaptive systems of different organizational scales. |
