designing a marine protected area from the bottom up: a synthetic approach to benthic habitat...

7/30/2019 Designing a Marine Protected Area from the Bottom Up: A synthetic approach to benthic habitat mapping in the S

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Designing a Marine Protected Area from the Bottom Up

A synthetic approach to benthic habitat mapping in the San Juan Islands

Luis Camilli

[email protected]

Center for Habitat Studies

Moss Landing Marine Laboratories

8272 Moss Landing RoadMoss Landing, CA 95039-9674
mailto:[email protected]:[email protected]


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Abstract

Bathymetric mapping and groundtruthing techniques were combined in a

Geographical Information System (GIS) to produce benthic habitat maps of the San Juan

Islands of Washington State. Multibeam SONAR data for Griffin Bay and surrounding

channels was collected in a collaborative effort between the Canadian Hydrographic

Survey and Moss Landing Marine Laboratories Center for Habitat Studies in April of

2005. Analysis of Remotely Operated Vehicle surveys, sediment grab samples, and

multibeam backscatter analysis were combined with ancillary biological studies from the

region in consideration of Griffin Bay as a potential location for a Marine Protected Area.

IntroductionManagement of individual species without considering larger ecosystem

dynamics upon which they depend is a common criticism of species management plans

(Ward et al. 1999). Ecological processes and critical habitats are not distributed

homogeneously; hence reserve networks must be designed on the basis of spatially

explicit quantitative data (Sala et.al. 2002). Furthermore, spatial and temporal scales of

biological activity in aquatic systems are often tightly coupled to scales of physical

phenomena such as thermoclines, currents, or gyres (Steele 1989). While there are many

ecological and oceanographic factors to consider in designing an effective Marine

Protected Area (MPA), general assumptions of a bottom up approach to habitat

modeling predict benthic topological complexity as a good surrogate for benthic habitat

complexity and species diversity (Ardron et. al. 2002).


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Ecological hierarchy theory assumes that scale interdependencies are hierarchical,

in that processes at one scale create patterns at another scale (Levin 1992). This

paradigm also maintains that wider or coarser scales approximate the boundary

conditions of narrower or finer scales by constraining the behavior and dynamics of the

processes occurring at finer scales (Pereira 2002).

This study applies a holistic synthesis of micro scale resolution (


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areas for managing coastal marine biological diversity. (Ward et.al. 1999) In order to

accurately describe and effectively apply the ecological and biological attributes of

underwater habitat and to facilitate comparison between scientific disciplines, a deep

water classification scheme has been developed to describe and communicate

geophysical data that is collected remotely (Green et.al. 1999).

Study Area

Regional Geography and Geology

Located in the Puget Sound of Washington state, the San Juan Islands form a

geologically complex province surrounded by the Cascade Mountains, Vancouver Island,

and the Olympic Peninsula (Fig 1). A compound assemblage of early Paleozoic through

Eocene rock defines the physiography of the San Juan Islands and can be represented by

two main blocks separated by the Haro fault (Johnson & Whetten). During the

Pleistocene the Strait of Juan de Fuca probably evolved as the result of a combination of

both tectonic and glacial process. Rapid retreat of glacial continental ice and high

isostatic rebound occurred between 13,600 and 11,300 years Before Present (Dethier

1995). The San Juan Archipelago is bounded by Rosario Strait to the east, Haro Strait to

the north and west, and the Strait of Juan de Fuca to the west and south. The archipelago

is composed of 176 islands, San Juan, Orcas, Lopez and Shaw Islands being the largest.

Intermittent sand and cobble beaches lead to deep glacier scoured channels ,often

exceeding 100 meters in depth, with extreme tidal currents (up to 7 knots) predominating.

Regional MPAs


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In response to declines in rockfish populations, the San Juan County Marine

Resource Committee (MRC) was created in 1996 and established eight Voluntary No

Take Zones in 1998. Currently in the San Juan Islands, MPAs consist mainly of rocky

habitat designed as refuges for rockfishes, lingcod, and other rocky habitat fishes. This

may not be suitable for species such as clams or other invertebrates which use soft

sediments for habitat. Since then Washington Department of Fish and Wildlife has

instituted 15 statutory marine reserves in Puget Sound designed to protect bottomfish,

shellfish, or intertidal invertebrates from non-tribal harvest with some areas having

Salmon, Herring and Crab excepted from the rule (NOAA 2002). Nationally, Marine

Protected Areas (MPAs) were established by Executive Order (E.O.) 13158 on May 26,

2000.

Griffin Bay

Griffin Bay (480 30 0 N, 1230 00 W) is located on the east side of San Juan

Island, in the San Juan Island Archipelago of Puget Sound. Since 1960, Friday Harbor

Sand and Gravel (FHSG) has been located on Jacksons beach on the northern shoreline

of Griffin Bay. Mining operations ceased in 1999.

MethodsA 14 meter hydrographic research vessel, the Otter Bay, was used to collect

multibeam SONAR data for Griffin Bay and surrounding channels in April of 2005 in a

collaborative effort between the Canadian Hydrographic Survey and Moss Landing

Marine Laboratories Center of Habitat Studies.


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Equipment

The Otter Bay was equipped with a hull mounted Kongsberg SIMRAD EM3000

multibeam echo sounder operating at 300 kHz with 127 beams and 1.5 degree beam

width. The effective depth for this instrument is 1 meter to 250 meters with 100 %

coverage. The sensor array also provided a nearfield sidescan emulation using

multibeam backscatter intensity with 5 centimeter resolution. Time Variable Gain was

adjusted automatically using an EM 3000 dynamic Moving Vessel Profiler (MVP).

Conductivity Temperature Depth (CTD) casts were performed twice during the survey to

verify acoustic calibrations of the MVP. Tidal height was measured each day from a

datum on the station dock to synchronize the multibeam system with local tidal

oscillations.

Analysis

Analysis and processing of acoustic multibeam SONAR data was conducted with

Caris HIPS and SIPS Version 5.4 software to create a 0.5 meter grid. Backscatter was

analyzed to verify indurations of substrate. Bathymetry was imported into ArcGIS

version 9.0 Geographical Information System and georectified to a WGS 1984 datum and

a Universal Transverse Mercator projection. A benthic habitat map, using a classification

scheme developed at the Center for Habitat Studies at Moss Landing Marine Laboratories

(Green et.al. 1999), was created based on interpretation of bathymetry, backscatter,

video drop cameras, and sediment samples (Fig. 3).

A second map of species assemblages was prepared for use as a heuristic in

designing a potential MPA for Griffin Bay. Bathymetry, backscatter, ROV video

analysis, and ancillary maps and biological data collected from the area were

incorporated in a synthetic manner to create a map for use by resource managers and


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biologists (Fig 4). ROV tracklines from a 2004 survey in Griffin Bay were plotted on the

habitat map and analyzed for species presence/absence. The ROV data also served as a

guide for groundtruthing additional areas not surveyed in 2004. A sediment grab was

used in conjunction with a tethered drop camera (which was deployed from a smaller, 5-

meter vessel) to interpret ambiguous or noisy bathymetric and backscatter data.

Results

Corroborative data

Rocky Habitat

The bathymetry of North Griffin Bay shows large aggregations of complex,

differentially eroded bedrock that is very rugose and of hard induration. Studies from the

area indicate the potential for an area like this to be excellent habitat for Rock fish

species. For example, Copper (Sebastes. caurinus), quillback (S. maliger), and brown

rockfishes (S. auriculatus) prefer high relief rocky habitats, while Lingcod (Ophiodon

elongatus) and kelp greenling (Hexagrammos decagrammus) are more generalists,

preferring a wider range of substrates and being less dependent on complexity and relief

factors than rockfishes (Pacunski and Palsson, 2001). Other fish species using North

Griffin Bay areLepidopsetta bilineata (Rock sole), Pleuronectes vetulus (English sole),

Platichthys stellatus (Starry flounder) and Syngnathus griseolineatus (Bay pipefish).

(Rodgers 2002).

Analysis of the 2004 ROV video showed these same rocky areas to be highly

prolific not only in terms of Sole and Rockfish species, but also heavily encrusted with

sessile invertebrates like mytridium, anemones, tube worms, scallops, clams and motile

invertebrates such as echinoderms, gastropods, and even a giant cephalopod (octopus).


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A study from the University of Washington, Friday Harbor Laboratories suggests that

North Griffin Bay is also a nursery area for four species of shrimp Pandalus danae,

Pandalus goniurus, Pandalus platyceros and Crangon spp. (Rodgers 2002).

Soft substrate habitat

Dungeness crabs are a major part of recreational and commercial fisheries of the

Pacific Northwest. Crab pots were abundant during the Griffin Bay survey in shallow

areas near a 10 meter isobath (personal observation) and during video transects.

Estimates from a University of Washington survey in South Griffin Bay found high

densities of Helmet crabs (Telmessus cheiragonus) and high densities of Dungeness crabs

(Cancer magister) in a range of vegetation and at all depths. (Raaum 2000). Video

analysis of 2004 ROV data from South Griffin Bay supports this. Dungeness crabs,

which are known to burrow in sandy bottoms and eelgrass beds, were observed in context

with dense aggregations of burrows in the soft unconsolidated sediments (mostly silt and

sand). This sediment is probably also serving as habitat for shrimp, mussels, small crabs,

clams, and worms which are the Dungeness crabs major food source.

In general, the bathymetry collected for South Griffin Bay shows a significant

change from the rocky high relief areas of North Griffin Bay changing to soft sediment.

An interesting phenomenon is that the crab fishing area is almost uniquely defined by a

long scarp feature (5 meter high wall) that is believed to be a paleoshoreline most likely

from the last ice age, and perhaps recently an active fault (Greene, pers. com). Subbottom

seismic profiling or core samples would help to verify this features origin and relation to

other regional fault systems.


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Vegetation:

Heterogeneity of vegetation types maybe important for MPAs. One study

examining kelp beds of Puget Sound in the Strait of Juan de Fuca found that substrate

plays a critical role in defining the understory community and that the greater substrate

diversity ofNereocystis beds offered a broader array of habitat types, and resulted in

higher numbers and species of invertebrates (Shaffer 1998). Our video analysis and the

results of the 2004 ROV survey showedLaminaria species common in most of Griffin

Bays rocky habitat surveyed. This coincides with a previous study indicating that large

Laminarian species dominate during spring and summer with a shift to fleshy red algae

during winter months (Shaffer 1998). The rocky substrate that is ubiquitous in North

Griffin Bay is probably providing the necessary attachment sites for the kelp holdfasts.

Other species observed from the video were dense patches of substory red alga

along with encrusting and geniculate corraline algae. South Griffin Bay had the most

extensive high-density eelgrass beds and may explain why it is such a prolific source for

crab fishing.

Currents and larval supply

Griffin Bays proximity to the San Juan Channel indicates another important

characteristic of its location. In Puget Sound, upwelling zones do not exist, but other

oceanographic features such as tidal gyres, tidal pumps, wind forcing, and estuarine

circulation may be significant to the success of marine refuges (Palsson 2001).

A drift card study of localized surface current circulations in the Puget Sound

showed that the San Juan channel near Griffin Bay may be an important site for larval

recruitment by functioning as a major collection zones for buoyant particles and imply


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the existence of a counter-clockwise circulation around the archipelago resulting from

ebb tidal eddies formed in the southern lee of the San Juan Archipelago (Klinger &

Ebbesmeyer 2001). This is important because larvae of many species (e.g., rockfish,

echinoderm, and decapods) spend long periods in the plankton and consequently their

recruitment into nearshore habitats will depend on larval behavior and on local and

regional surface circulation patterns (Allison et al. 1998; Strathmann 1987).

The effect of deep currents on the benthic substrate was evident in analysis of

bathymetric data from this survey which showed scouring predominant near rocky areas.

ROV video analysis and sediment grabs indicate these heavily scoured areas are mostly

coarse sand or shell hash (coquina). Other areas near the center of Griffin Bay and in the

San Juan Channel revealed large sand waves sometimes exceeding five meters. Lingcod

were observed in the depressions of these large sand waves and may be using the leeward

areas as a respite from the fast currents (Gunderson pers. com). The biological effects of

these strong currents on the benthic and demersel assemblages in this area need to be

investigated further.

Griffin Bay MPA?

Marine reserve boundaries are difficult to define because of inadequate

knowledge of biological diversity (i.e. species, habitats, ecosystems and ecological

processes) and difficult to defend in the face of multiple competing demands like

fisheries, mineral industries, recreation and geopolitical interests (Ward et al. 1999).

Although ecological information provides a better heuristic for conservation efforts,

conservation decisions will most likely be made in context of economic and political


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interests. It is therefore appropriate to analyze Griffin Bay as a potential Marine

Protected Area from both perspectives.

Data presented from this study indicates that Griffin Bay is operating as a unique

mesoscale ecological structure because two major systems exist within a relatively small

area. These are essentially a deep water, highly complex, fish and invertebrate

assemblage in North Griffin Bay, and a sediment infaunal seagrass assemblage in South

Griffin Bay. The fact that these two communities are contained within one bay

eliminates much concern for resource managers of deleterious edge effects resulting

from habitat fragmentation.

Economic benefits are considerable for the crabbing industry because of South

Griffin Bays potential as a source for other areas (both larval and trophic) for Dungeness

crab and associated species. Since North Griffin Bay is thought to be a nursery for many

invertebrate species and obligate rockfish species, this will help to bolster fishing in

surrounding areas (sinks) by acting as a buffer to fishing pressure. Economically, Griffin

Bay is also important to tourism given its proximity to Friday Harbor, a major ferry port

and holiday destination. Finally, Griffin Bay is situated near the University of

Washingtons Friday Harbor Laboratories which could utilize Griffin Bay as an

ecological benchmark to monitor and decouple short term natural variability from

regional anthropogenic change.


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ConclusionsA Scottish mathematician once figuratively said a map is not the territory.

Indeed maps, in the literal sense, are simply another way to represent the externalities and

phenomena of our world. A synthetic approach to understanding complex underwater

ecosystems is often required when multiple criteria and constraints intersect. Use of

acoustic imaging and a bottom up approach combined with ancillary information

conceptualized through GIS is one such way to model underwater habitats for ecological

applications. These habitat maps of the San Juan archipelago were created for use as

tools to guide resource management in the short term and ultimately to help elucidate

larger scale, and longer period oceanographic and ecological processes.


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AcknowledgementsThanks to Dr. Gary Greene for organizing this unique collaborative effort between Moss

Landing Marine Laboratory Center for Habitat Studies and The Canadian Hydrographic

Survey. Our gratitude to Ron and Cathy MacDowell and a grant from the Sea Doc

Society for funding this project and facilitating in so many ways. It was a pleasure

working with the Canadian hydrographic research team Kalman Czotter, Knut Lyngberg

and Gordon Allison in collecting the high resolution bathymetric data on the Otter Bay.

Thank you, Brian Dieter for your outstanding teaching and assistance. Thanks also to Dr.

Don Gunderson of the University of Washington Friday Harbor Laboratories, and Dr.

Wayne Palsson of Washington Department of Fish and Wildlife for input, ideas, and

auxiliary data that was incorporated into this habitat survey.


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Literature cited

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Lowland, Washington. GSA Bulletin 107:1288-1303.

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7. Klinger, T., and Curtis Ebbesmeyer. 2001. Using oceanographic linkages to guideMarine Protected Area network design. School of Marine Affairs and Friday

Harbor Laboratories, University of Washington.

8. Levin, S. A. 1992. The problem of pattern and scale in ecology. Ecology 73:1943-1967.

9. Miller, B. E. 2002. Population estimates and habitat types of bottom fish assessedby a remotely operated vehicle (ROV) around the San Juan Islands, Washington.

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Washington Department of Fish and Wildlife.


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12.Pereira, G. M. 2002. A typology of spatial and temporal scale relations.Geographical Analysis 34.

13.Raaum, J. 2000. The effect of habitat on fish and crab species abundance,diversity and size in temperate coastal marine communities. Friday Harbor

Laboratories, University of Washington.

14.Rodgers, K. L. 2002. Survey of nearshore soft bottom demersal fish, shrimp andcrabs in North Griffin Bay, San Juan Island, Washington. Fish 492 Undergraduate

research apprenticeship University of Washington, Friday Harbor, Washington.

15.Sala, E., Octavio Aburto-Oropez, Gustavo Paredes, Ivan Parra, Juan C. Barrera,Paul K. Dayton. 2002. A general model for designing networks of marine

reserves. Science 298.

16.San Juan County, M. R. C. 1998. Marine Reserve Bottomfish Recovery Program.in San Juan Nature Institute.

17.Shaffer, J. A. 1998. Kelp bed habitats of the inland waters of western Washington.Washington Department of Fish and Wildlife Puget Sound Research 1998.

18.Steele, J. H. 1989. The ocean "landscape". Landscape Ecology 3:185-192.19.Trnka, H. 2000. Mapping of Marine Vegetation. University of Washington,

Friday Harbor, Washington.

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Coastal Research 16:627-640.

Personal Communication:

1. Don Gunderson School of Aquatic and Fisheries Sciences, University ofWashinton [email protected]. Gary Greene Center for Habitat Studies, Moss Landing Marine [email protected]

3. Wayne Palsson Washington Department of Fish and [email protected]
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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Figure 1

Satellite photo of San Juan Archipelago

Courtesy of Gulf Islands National Park


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Figure 2

Griffin Bay sunshaded 2 meter grid bathymetry


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Figure 3


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Figure 4

designing a marine protected area from the bottom up: a synthetic approach to benthic habitat...

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