Biogeographic Analyses


The biogeographic analyses component is the cornerstone of the overall assessment to support the joint management plan revision process. The data, analyses,upporting information are linked using statistical and GIS tools to visualize the location of significant biological areas or "hot spots." There were many different ways to analyze and organize the biological data compiled for this assessment. To efficiently support the management plan revision process, only a limited number of analytical options were selected based on reviewer's comments on the Interim Product, mission of the NMSP, technical review meetings, and peer review workshops. These key analyses are presented in this document and on the CD-ROM. In addition to these results, spatial data and information on the companion CD-ROM enable NMSP staff, advisory councils, and research partners to conduct additional analyses not specifically addressed in this product.

A critical step in the biogeographic analyses component was the extensive effort to have data, analytical approaches, and results peer reviewed. Initial results from the suite of analyses were presented to experts on marine ecosystems of north/central California, as well as to the originators of the data sources in an attempt to improve the analyses. The role of expert review and input has been considerable, and the contributions made by experts have significantly enhanced the analyses.

Assessment Process

Biogeographic Assessment ProcessTo aid in focusing on the most important analyses, the biogeographic assessment process displayed in Figure 6 was utilized. This process is currently being implemented through a joint NMSP and NCCOS Biogeography Branch effort to initiate biogeographic assessments across all sanctuaries within the next five years. The process is organized around development of biogeographical data layers, integrated analyses, and specific products to aid in sanctuary management plans (Kendall and Monaco 2003). Thus, the integration of partner's comments and use of the biogeographic assessment process resulted in the analyses and results presented in this document.

Biogeographic data assembled for this project were derived from many sources (see section 4 in PDF Folio), including NOAA Fisheries, academia, state government, and data housed within the NMS and Biogeography Programs. The biogeographic data cut across various themes, such as species distributions and habitats, and are integrated using a common spatial framework in a GIS. The GIS enables a user to select particular data layers to be displayed, combined, and manipulated in a wide variety of ways to achieve specific analytical objectives.

The use of the GIS enabled species-specific data, such as distribution and abundance data or community metrics (e.g., species richness statistics), to be directly linked to specific areas or habitats they correspond to across the study area. The GIS also facilitated integration of multiple data types and sources into a common spatial and temporal framework (Gill et al., 2001). The following suite of map products quantitatively defined significant biological areas that are within or adjacent to existing boundaries of Cordell Bank, Gulf of the Farallones, and Monterey Bay National Marine Sanctuaries. The GIS-based products are intended to aid in evaluating current sanctuary boundaries relative to biological resources and habitats, explore options for environmental protection of existing NMS areas, identify additional biologically important areas, and evaluate alternative management strategies.

To develop this capability, a suite of analyses were conducted that were most appropriate in addressing NMSP natural resource management issues. The biogeographic assessment framework aided in targeting the suite of analytical approaches to define biologically significant areas in support of the sanctuary management plan reviews. Categories of analysis include: temporal and spatial analysis of individual species' distributions, species assemblage analyses, habitat suitability modeling, and community metrics within and across species groups. Important individual species maps were developed from a number of data sets to visualize species presence and/or abundance data within the study area by season. Where possible, well-established breeding colonies, rookeries, and high concentrations of species are displayed on the digital maps. The single species maps enabled various groupings of species within a group, such as by family (e.g. rockfish), and comparison of spatial patterns between groups. Analysis of spatial patterns resulted in information on the relationships between individual species, between assemblages of species, and of the relationship of species to specific environmental and habitat parameters. Furthermore, the compilation and integration of individual species maps were used to calculate community metrics, such as total richness or diversity of fish and marine bird species, at a specific location.

To define species assemblages, multivariate techniques were applied to various data sets to group organisms found at specific sampling sites. The assemblage analyses defined species groups across the study area. By visualizing the assemblages geographically, areas of overlap became apparent and group habitat affinities, such as depth range, were delineated.

Species habitat suitability index modeling (HSI) studies were undertaken for 20 fish and invertebrate species in an attempt to characterize areas within the study region that suffered a lack of sampling data, particularly in near-shore habitats. The integration of HSI models into a GIS provides a spatial depiction of species habitat suitability models for individual species by integrating information on species habitat affinities and the distribution of those habitats in space and time (Brown et al., 2002; Monaco and Christensen 1997). The modeling component of the biogeographic analyses is a necessary step due to the incomplete distribution of sampling data across the entire study area. Thus, species that were representative of the assemblages described above and/or other key species were selected for modeling their potential distribution. The composite set of species habitat suitability models contributed to defining significant biological areas within the region.

Measures of community structure for fishes and marine birds were calculated independently by species group, compared, and, where applicable, integrated. Convergence of overlapping spatial patterns defined significant biological areas based on a number of criteria (e.g., high species abundance, high species diversity).

Thus, the biogeographic analyses component was a result of interpreting or visualizing the analytical results from statistical analyses, ecological modeling, and integration of results across biota and habitats. The cumulative results aided in assessing the biogeographic patterns in the study with regard to the distribution of individual species, species assemblages, and species habitat utilization patterns.