NSF Award Abstract - #0083381

AWSFL008-DS3

BIOCOMPLEXITY: Bio-Feedback Basis of Self Organization in Planktonic Ecosystems
Using Phaeocystis as a Model Complex Adaptive System

Abstract

Abstract. Biocomplexity: The Bio-Feedback basis of Self Organization in Planktonic Ecosystems using Phaeocystis as a Model Complex Adaptive System.

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.

Phaeocystis is proposed as a model organism from which to begin the study of biocomplexity in marine pelagic ecosystems. The 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 the 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 formation of a recent Scientific Committee on Ocean Research (SCOR) working group, "Marine Phytoplankton and Global Climate Regulation: the Phaeocystis Species Cluster."

Laboratory experiments will quantify the impact of various physical, chemical, and biological factors on Phaeocystis life cycle transformations. Bioassays will be conducted to quantify chemical communication between life cycle stages and other organisms, e.g. grazers and competing phytoplankton. Concurrent studies will focus on the sensing and genetic response of Phaeocystis to environmental cues. Genetic probes will be developed to recognize and quantify Phaeocystis solitary cells in situ, and to identify genetic regulatory elements involved in controlling Phaeocystis life history. Mesocosm experiments will be conducted in Bergen, Norway, where Phaeocystis blooms can be reliably developed. Field studies will be conducted in the fjords of Tromso, Norway, to quantify how biocomplexity operates in the water column and the feedbacks to the ecosystem. This environment is well known, has a long database, has Phaeocystis blooms every spring, and is an excellent location for related cooperative studies, e.g. DMS/gas exchange. An ecosystem model will be developed as an investigative tool to deconvolve how physics, chemistry, and biology interact to regulate planktonic structure and function. A preliminary model is already available as a starting point. A life history submodel of Phaeocystis will also be developed and embedded within the ecosystem model to explore the mutuality of the bio-feedback between these complex adaptive systems of different organizational scales.