Chapters authored
Seabed Biodiversity Shifts Identify Climate Regimes: The 2011 Climate Regime Shift and Associated Cascades
Using search programs for a long-term SCUBA taxonomic database (3865 dives) for Strait of Georgia seabed sites, 1077 taxa were screened to select rare or highly abundant taxa and to present the data according to climate regime categories. Ocean Niño Index (ONI) climate regime shifts are defined here as the year of the end of the first La Niña closely paired with an El Niño by ≤2 months separation, where anomalies for both El Niño and La Niña exceed 1.0 on the ONI scale. For both rare and abundant taxa, patterns of increased or decreased abundance frequently correspond to years defining climate regimes. Cascading effects of climate regime shifts may occur via changes in community composition. The sea star wasting disease (SSWD) syndrome eliminated urchin predators so that urchins have decreased abundance of a kelp species that is nursery habitat for spot prawns. We conclude that 2011 was a climate regime shift. This 2011 regime shift coincided with loss of 11 seabed species in the Strait of Georgia, none of them at their southern range extreme.
Part of the book: Selected Studies in Biodiversity
Formation, Persistence, and Recovery of Glass Sponge Reefs: A Case Study
Glass sponge reefs (bioherms) are known to occur on glacial deposits but have not previously been observed to develop on fjord bedrock ridges. It is assumed that sexual reproduction dominates reef recruitment and that sedimentation can cover intact sponge skeletons. Over a decade of scuba diving research at a small fjordic bioherm, including installation of bar-coded marker stakes, transplants of loose fragments and survey transects of substrate depth with an avalanche probe have led to new insights into the dynamics of bioherm formation and persistence. We present evidence for recovery of sponge growth from scree slopes of collapsed fragments and logged the temporal changes associated with sponge fragmentation and recovery. Bar-coded stakes were installed in 2014 to enable verification of location and sponge identity through time. Photo documentation of growth, collapse, and regrowth is presented. Research on a sponge garden on glacial sediments reveals that earliest sedimentation may center around prostrate boot sponges and bristly tunicates among the cloud and vase sponges. Although hexactinellid boot sponges do not contribute to the geologic base of bioherms, they may take part as a successional community in the substrate conditioning that could result in the genesis of a glass sponge reef or bioherm.
Part of the book: Invertebrates