Event Title

Spatial and temporal population cohesion in intertidal clams

Presentation Abstract

Although long-term datasets can be particularly useful for parsing out factors influencing populations, few studies have utilized continuous datasets to quantify population synchrony in bivalve mollusks. Dynamic factor analysis was used on a clam biomass dataset spanning 28 years and four distinct regions in the southern Salish Sea to determine (1) if native intertidal clam populations exhibit spatial or temporal coherence and (2) what environmental covariates influence population trends. The model with the most data support included three predominant trends to describe decadal change in mean clam biomass. Results demonstrate that intertidal clam population coherence can vary spatially and temporally by species. Intraspecific coherence was the highest in Leukoma staminea, followed by Saxidomus gigantea, with lowest synchrony in Clinocardium nuttallii. Population dynamics on three beaches (two in Hood Canal and one in Admiralty Inlet) showed similar temporal trends regardless of species. No other beaches showed synchrony in temporal trends across species indicating that species-specific trends (regardless of location) were more common than beach-specific trends (regardless of species). Eight covariates were evaluated in their ability to explain variability in annual mean biomass not captured in the latent trends. Of these, the North Pacific Gyre Oscillation lagged four years prior to the observation year received the strongest data support. While this large-scale oceanographic factor may play a valuable and previously undescribed role in population variation of venerid clams, local factors are also likely to account for variance not explained by our model.

Session Title

Long-term Changes in Salish Sea Kelp Forests and the Benthos: Evidence of Response to Chemical Contaminants, Nutrient Loading, and Climate Change Pressures

Conference Track

SSE16: Long-Term Monitoring of Salish Sea Ecosystems

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE16-34

Start Date

6-4-2018 11:00 AM

End Date

6-4-2018 11:15 AM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 6th, 11:00 AM Apr 6th, 11:15 AM

Spatial and temporal population cohesion in intertidal clams

Although long-term datasets can be particularly useful for parsing out factors influencing populations, few studies have utilized continuous datasets to quantify population synchrony in bivalve mollusks. Dynamic factor analysis was used on a clam biomass dataset spanning 28 years and four distinct regions in the southern Salish Sea to determine (1) if native intertidal clam populations exhibit spatial or temporal coherence and (2) what environmental covariates influence population trends. The model with the most data support included three predominant trends to describe decadal change in mean clam biomass. Results demonstrate that intertidal clam population coherence can vary spatially and temporally by species. Intraspecific coherence was the highest in Leukoma staminea, followed by Saxidomus gigantea, with lowest synchrony in Clinocardium nuttallii. Population dynamics on three beaches (two in Hood Canal and one in Admiralty Inlet) showed similar temporal trends regardless of species. No other beaches showed synchrony in temporal trends across species indicating that species-specific trends (regardless of location) were more common than beach-specific trends (regardless of species). Eight covariates were evaluated in their ability to explain variability in annual mean biomass not captured in the latent trends. Of these, the North Pacific Gyre Oscillation lagged four years prior to the observation year received the strongest data support. While this large-scale oceanographic factor may play a valuable and previously undescribed role in population variation of venerid clams, local factors are also likely to account for variance not explained by our model.