Presentation Abstract

Seascape connectivity is an emerging feature influencing marine ecosystem function. Connectivity, via the interplay of habitat configuration, its physical structure, and associated food webs, may alter the provision of nursery habitat, influencing the success of fish populations and harvests thereof. We quantified the effects of adjacent habitat type on seagrass nurseries for rockfish. We compared seagrass sites with contrasting structure and productivity in adjacent habitats: kelp forest and sand. To elucidate the spatially-dependent flow of material in the seagrass meadow, we estimated the proportion of basal contributions (producers) to the food web using an isotopic mixing model on YOY (young-of-the-year) rockfish consumers. To estimate population responses to spatial connectivity, we enumerated YOY rockfish recruitment by SCUBA, alongside invertebrate prey and fish predators at all sites. Using GLMMS, we modelled the relative effects of adjacent habitat type, seagrass trophic interactions (prey availability and predator presence), and structural complexity, on YOY rockfish recruitment. We found that kelp carbon was the highest basal contributor to YOY rockfish consumers across all seagrass sites, but auxiliary contributions varied among site. YOY rockfish at highly complex and productive seagrass sites (adjacent to kelp forests and interior meadow) consumed higher quality prey, corresponding to increased body condition. Adjacency to kelp forests, seagrass structural complexity, and prey biomass increased YOY rockfish densities. However, the positive effect of kelp adjacency was dampened by seagrass complexity; likely due to predator spill-over into complex seagrass habitat. Overall, recruitment and trophic dynamics (e.g. basal contributions, prey-predators interactions) in the seagrass meadow were influenced by seascape configuration, revealing that nursery function is spatially-mediated by adjacent habitats, and their structural complexity and productivity. With declining marine habitats worldwide, we illustrate the importance of considering connectivity among nearshore habitats for conservation planning, supporting an ecosystem approach that considers the full seascape matrix of intermixed habitats.

Session Title

Seagrass Cross-Border Connections: Stressors and Disturbance

Keywords

Seagrass, Kelp, Seagrass nursery function, Rockfish

Conference Track

SSE4: Ecosystem Management, Policy, and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE4-246

Start Date

5-4-2018 2:30 PM

End Date

5-4-2018 2:45 PM

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 5th, 2:30 PM Apr 5th, 2:45 PM

Seagrass nursery function enhanced by habitat connectivity

Seascape connectivity is an emerging feature influencing marine ecosystem function. Connectivity, via the interplay of habitat configuration, its physical structure, and associated food webs, may alter the provision of nursery habitat, influencing the success of fish populations and harvests thereof. We quantified the effects of adjacent habitat type on seagrass nurseries for rockfish. We compared seagrass sites with contrasting structure and productivity in adjacent habitats: kelp forest and sand. To elucidate the spatially-dependent flow of material in the seagrass meadow, we estimated the proportion of basal contributions (producers) to the food web using an isotopic mixing model on YOY (young-of-the-year) rockfish consumers. To estimate population responses to spatial connectivity, we enumerated YOY rockfish recruitment by SCUBA, alongside invertebrate prey and fish predators at all sites. Using GLMMS, we modelled the relative effects of adjacent habitat type, seagrass trophic interactions (prey availability and predator presence), and structural complexity, on YOY rockfish recruitment. We found that kelp carbon was the highest basal contributor to YOY rockfish consumers across all seagrass sites, but auxiliary contributions varied among site. YOY rockfish at highly complex and productive seagrass sites (adjacent to kelp forests and interior meadow) consumed higher quality prey, corresponding to increased body condition. Adjacency to kelp forests, seagrass structural complexity, and prey biomass increased YOY rockfish densities. However, the positive effect of kelp adjacency was dampened by seagrass complexity; likely due to predator spill-over into complex seagrass habitat. Overall, recruitment and trophic dynamics (e.g. basal contributions, prey-predators interactions) in the seagrass meadow were influenced by seascape configuration, revealing that nursery function is spatially-mediated by adjacent habitats, and their structural complexity and productivity. With declining marine habitats worldwide, we illustrate the importance of considering connectivity among nearshore habitats for conservation planning, supporting an ecosystem approach that considers the full seascape matrix of intermixed habitats.