Presentation Abstract

Like many coastal areas globally, the Salish Sea has undergone rapid urbanization over recent decades. Terrestrial research suggests urbanization facilitates a variety of mesopredators by enhancing food and shelter resources and by limiting apex predation. Yet urbanization’s effect on mesopredators in the marine environment has rarely been examined. The giant Pacific octopus, Enteroctopus dofleini, is an iconic mesopredator of the Pacific Northwest due to its size and cognition, and is thought to reach a particularly large maximum size in inland waters of the Salish Sea. We examined the spatial distribution patterns and habitat use of giant Pacific octopus in Puget Sound using a combination of field surveys and citizen-contributed data from the Reef Environmental Education Foundation (REEF). Specifically, we sought to determine: (1) Whether octopus distribution was related to land-based urbanization indices, (2) Whether octopus abundance correlated with anthropogenic debris, and (3) Whether octopus diets differed relative to urbanization intensity. Our findings suggest that effects from urbanization may depend heavily on the depth of benthic habitats. In deeper subtidal areas (> 24 m), the estimated probability of octopus occurrence increased with adjacent land-based urbanization. Conversely, octopus in shallower subtidal zones (< 18 m) were less likely to occur as urbanization intensity increased. This pattern appears to be unrelated to utilization of prey resources by octopus, as accompanying surveys of octopus middens showed no depth-specific differences in diet relative to urbanization. However, additional video transect surveys at paired sites with high versus low concentrations of anthropogenic debris indicated that artificial structures, which may be extensive in deep-water habitats within heavily urban areas, facilitate higher octopus abundances by serving as den sites. We suggest that den provisioning by urban artificial structures may be a key mechanism driving urban-related distribution patterns of giant Pacific octopus, and should be explored further through future research.

Session Title

Species and Habitats of Emerging Concern

Keywords

Urbanization, Citizen science, Giant pacific octopus

Conference Track

SSE11: Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE11-344

Start Date

6-4-2018 11:30 AM

End Date

6-4-2018 11:45 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, 11:30 AM Apr 6th, 11:45 AM

Urban-related distribution patterns of an iconic Salish Sea mesopredator, the giant Pacific octopus (Enteroctopus dofleini)

Like many coastal areas globally, the Salish Sea has undergone rapid urbanization over recent decades. Terrestrial research suggests urbanization facilitates a variety of mesopredators by enhancing food and shelter resources and by limiting apex predation. Yet urbanization’s effect on mesopredators in the marine environment has rarely been examined. The giant Pacific octopus, Enteroctopus dofleini, is an iconic mesopredator of the Pacific Northwest due to its size and cognition, and is thought to reach a particularly large maximum size in inland waters of the Salish Sea. We examined the spatial distribution patterns and habitat use of giant Pacific octopus in Puget Sound using a combination of field surveys and citizen-contributed data from the Reef Environmental Education Foundation (REEF). Specifically, we sought to determine: (1) Whether octopus distribution was related to land-based urbanization indices, (2) Whether octopus abundance correlated with anthropogenic debris, and (3) Whether octopus diets differed relative to urbanization intensity. Our findings suggest that effects from urbanization may depend heavily on the depth of benthic habitats. In deeper subtidal areas (> 24 m), the estimated probability of octopus occurrence increased with adjacent land-based urbanization. Conversely, octopus in shallower subtidal zones (< 18 m) were less likely to occur as urbanization intensity increased. This pattern appears to be unrelated to utilization of prey resources by octopus, as accompanying surveys of octopus middens showed no depth-specific differences in diet relative to urbanization. However, additional video transect surveys at paired sites with high versus low concentrations of anthropogenic debris indicated that artificial structures, which may be extensive in deep-water habitats within heavily urban areas, facilitate higher octopus abundances by serving as den sites. We suggest that den provisioning by urban artificial structures may be a key mechanism driving urban-related distribution patterns of giant Pacific octopus, and should be explored further through future research.