Biological inventory: Habitats, Fish Use, Pond Water Quality Gold Creek Delta,

Juneau, Alaska

June-July 3013

Patricia Harris for Bosworth Botanical Consulting, August 2013

Baseline habitat information in the Gold Creek delta was gathered in summer 2013 to contribute to a functional assessment of the area and design of the City and Borough of Juneau’s Seawalk Project. This portion of the report describes habitats in general and then provides more detailed habitat information along an intertidal transect. We also report water quality and fish use of the larger tide pool and intertidal flats.

General Habitat Descriptions (descriptions follow those outlined by C. Pohl May 2013)

Upland tree, shrub, and grass/herb meadow. (Areas A-F Table 1, Fig.1 ) This association

occupies a narrow band between steep rip-rapped slopes and the edges of pavement along the

ADFG and Cycle Alaska parking lots, Egan Highway, and high traffic areas in the DOT/CBJ truck

wash-down area. Elevation ranges from 21 to 30 feet MLLW. Soils are sand and gravel and well

drained. Vegetation is a mix of native and introduced species, some of which are considered

invasive. The broadest portion of this habitat (Area E) extends from the south corner of the

Department of Labor Building to Egan Drive. Lower gradient slopes here allow for more species

diversity and lush growth of both native and cultivated species than in the rest of the band and

build-up of some organic materials. A small section is being maintained as a picnic area, with

mowed grass and cultivated spruce and pine. Some meadow species extend into the supratidal

(extreme high high water) at the intersection of this band and Egan where there is no rip rap.

Upper beach rip rap slopes. This habitat consists of large boulders and chunks of

concrete and asphalt at 15 to 25 feet (MLLW); in the bridge abutment area tip rap extends

below 0 feet. Slopes are steep, sometimes exceeding 40%. Below the rip rap in the truck

washing area at the end of 9th Street, the beach is less steep and covered with uniformly sized

gravel, apparently an artifact of snow removed from Juneau streets and dumped there.

Vascular vegetation, chiefly beach rye, is limited to small pockets of gravel or sand among the

boulders. Lichen species have colonized boulders in the upper portions of this habitat.

Mid to High Intertidal. (Area G Table 1, Fig. 1 ) This habitat is found at elevations 10 to

15 feet (base of rip rap slope) along Egan and on a spit that extends from the corner of the

ADFG parking lot. Soils are silty to sandy with infrequent cobble. Most noticeable here are the

alkali grass areas, where the percent cover increased greatly over the summer, and other salt

tolerant vascular plants.

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Mid to Low intertidal. (Area H Table 1, Fig.1) This habitat extends from approximately

11 foot elevation seaward to 0 feet MLLW. Beach gradient is low (average 1%) in the flats and

becomes steeper on both sides of the spit. Sediments are mainly sand and silt with an

occasional cobble on the flats but are coarser on the channel side where the slope is steeper

(10% in places). Fucus and Ulva are major floral species; Blue mussel (Mytilus trossulus),

barnacles (Balanus and Semibalanus species) are very common especially on the channel side

of the spit and are often associated with Fucus. Sitka periwinkle (Littorina sitchensis) is

commonly associated with Fucus at higher elevations.

Tide pools and stream channels. (Areas J Table 2, Fig. 1) A large tidal pond is in front of

the Dept. of Labor, and at the foot of 9th street, there is a smaller pond. Depth of the larger

pond is -5.3 feet MLLW; however, the depth of water is controlled by the elevation of its outlet

so that minimum depth is ≥ 13 feet. At an elevation of +5 feet, smaller pond goes dry at most

tides below that height. Fucus occupies margins of the larger pond from 11 feet MLLW to 8

feet. And below that, Ulva spp dominate. Fucus also surrounds the little pond at elevations

approximately 9 to 6 feet. Ulva and Alaria marginata and Porphyra were common in the

smaller pond and in the larger pond’s outlet channel and on banks of Gold Creek in the

intertidal.

Low intertidal. (Area I Table 1, Fig.1 ) This fairly narrow band below mussels and

barnacles is exposed only at minus tides and is characterized by fine sediments and algal

species Alaria marginata and Ulva lacttuca.

Transect Survey of Intertidal habitats

A 60’ wide transect was established from the toe of the riprap along Egan Drive, bearing

approximately 210 degrees SW to the -4 foot elevation along Gastineau Channel and includes

two sediment sample locations and the proposed location of the fill island (Hans Elhert, C2MH

Hill, pers. com.). The transect was surveyed in the third week of June to describe the biotic

assemblages. Organisms were named to the lowest taxa possible in the field, and assemblages

were named for the most prominent organisms present at the time of survey. Survey data are

reported in Table 2 and portrayed in Fig. 2 and 3.

Fish

Minnow traps were set on 6/7 and 6/14 on a rising tide and retrieved on a falling tide

(approximately 5 hours soak time). At each sampling period, 5 traps were set at the mouth of

Gold Creek and 5 traps were set around the perimeter of the larger pond. Both metal and mesh

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traps were used and baited with catfood and/or herring. Total catch was 30 fish. Pacific

staghorn sculpin (Leptocottus armatus) were the most numerous species, comprising 56% of

the catch; crescent gunnels (Pholis laeta ) were also common (33% of the catch). Tidpool

sculpin (Oligocottus maculosus) and shorthorn sculpin (Myoxocephalus scorpius) were also caught

in the creek.

Beach seine. The flats (elevation 9-12’) in the area of the proposed island were sampled

with a small beach seine June 20 on a falling tide, when water depth was 2-3’. Four sets were

made from the alkali grass island (elev. 11’), sampling a different area on each set. Total catch

was 18, dominated by coho salmon (Oncorhynchus kisutch) (64% of the catch)(mean fork length

107 mm). Several chum salmon (O. keta)(mean fork length 116mm), king salmon () (mean fork

length 116) and staghorn sculpin were caught as well as one dolly varden (Salvelinus malma)

(fork length 150mm).

The entire pond was seined with a larger net, pulling from the outlet to the opposite

shore when tide height was about 8’. A total of 219 fish were captured; the majority was chum

salmon (73% of the catch, mean fork length 56 mm). Coho salmon comprised 20% of the catch

(mean fork length 105mm) and crescent gunnel , Pacific staghorn sculpin, shorthorn sculpin,

pink salmon (O. nerka), starry flounder (Platichthys stellatus), and king salmon (O. tshawytscha)

comprised the rest of the catch.

Salmonids were observed feeding on the surface of the pond frequently, and were last

seen when the site was visited in late July. Occasionally fry were observed in drainage channels

as the tide went out. On one occasion, fry trapped in channels were identified as chum salmon

(mean FL 41 mm).

Most of the salmon we caught were likely DIPAC (Douglas Island Pink and Chum)

Hatchery fish; native fry are usually out of Gastineau Channel by mid-June . Hatchery chum

were released later than usual this year because they were small at the usual release date due

to cold winter water temperatures, and sizes at release varied due to differing feeding

treatments (pers. com Eric Prestigard, DIPAC). King salmon and coho fry were released about a

week before we seined and were represented in our catch as well chum salmon.

Pond Temperatures, Relative Light Levels, and Water Quality

Temperature and light loggers were deployed in the pond on June 20 and retrieved on

June 24 to observe diurnal and tide-related changes in those parameters. One logger recorded

relative light levels and temperatures at the bottom of the pond (-5’); two loggers recorded

data at the pond’s surface at low tide (≤ 8’). As the tide rose, one of the loggers continued to

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record at the 8’ depth, the other remained at the surface and recorded surface conditions

regardless of tide height. (Elevation of the pond at low tide is controlled by the outlet stream

elevation (8 feet); high tides during the sampling period ranged from 15.7 to 19.5 feet.)

Temperatures (Fig. 4) and relative light levels at the pond bottom were more stable and

much lower than surface levels. Bottom temperature, mean 10.27 C◦, varied only 0.72 degrees

over the 4 days, whereas surface temperatures, mean 13.12 C◦, varied 3.95 degrees. Very little

light reached the bottom of the pond….on average, only about 0.14% of surface illumination.

Greatest differences occurred during high tides in peak daylight hours (900 – 1500 hrs).

Temperatures and light levels recorded at middle depth, where the logger was on the surface at

low tide and submerged when the tide height exceeded 9 feet, were variable as well, but

changes were not as great as recorded by the logger that was always on the surface. At the

surface and middle depth, temperatures were most similar when both loggers were at the

surface, i.e. low tide, and most dissimilar at high tides in peak daylight hours.

Pond salinity and dissolved oxygen were sampled with YSI probes at high tide (18’) and

low tide (8’) on June 26 at the bottom, surface at high tide, and surface at low tide. We

attempted to sample the bottom at the deepest part of the pond, thinking that the dissolved

oxygen would be lowest and salinity highest there.

Salinity and dissolved oxygen varied with depth and tide stage. Salinity increased with

depth at both high and low tide. At high, tide salinity ranged from 15.6 ppt at the surface to

20.8 at the bottom; at low tide from 18.2 ppt surface to 22 ppt bottom. Dissolved oxygen

decreased with depth, most dramatically at low tide. Highest values (9.17 mg/l) were recorded

on the surface at high tide; oxygen at the bottom at low tide was recorded as 0 mg/l. That low

reading is somewhat suspect, however. Anoxic sediments were observed along pond shores at

low tides, previously, but there was no evidence of anoxic conditions in our seine haul a few

days before water sampling. Anoxic sediment or decaying vegetation in the haul would have

confirmed oxygen deficiency.

Dissolved oxygen levels were optimal to acceptable (9 - 7 mg/l) for juvenile salmon in

surface waters to a depth of about 5 feet at both tide stages. The bottom oxygen level (5.28

mg/l) at high tide was less favorable but not fatal. However at low tide, extremely low oxygen

at the pond bottom may limit fish to shallower depths for short periods. Changes in bottom

salinity and dissolved oxygen from low tide to high tide and the velocity of flooding tides into

the pond suggest some mixing of water with changing tides.

2 = cultivar3 = weed /invasive4 = not observed on spit

* unidentified upland grass spp n=4

Approximate

Common name Scientific name A B C D E F G H I Elevation (MLLW) range Occurrence

alder Alnus spp A B C D E F 22'- pavement common

red osier dogwood Cornus stolonifera B C D F 22'- pavement occasional

willow spp Salix spp A B C F 22'- pavement common

mountain ash 2, 3Sorbus acuparia ? A C D F 22'- pavement occasional

cottonwood Populus balsamifera C F 22'- pavement occasional

currant Ribes spp F

grass spp* A E 23' bank top occasional, common in E

dandelion 3Taraxacarum officinale A 23' bank top common

strawberry Fragaria spp A 23' bank top limited

river beauty Epilobium latifolium A 23' bank top limited

beach pea Lathyrus maritimus A 23' bank top occasional

oxyeye daisy 2, 3

B 23' bank top occasional

campanula 2, 3

Campanula spp B 23' bank top limited

fireweed Epilobium angustifolium B E 23' bank top occasional, common in E

siberian aster Aster sibiricus B 23' bank top limited

clover 2

Trifolium spp B 23' bank top common

horsetail Equisetum spp B 23' bank top occasional

beach rye Elymus mollis B D E 23' bank top common

silver weed Potentila anserina B 23' bank top limited

tansy 2, 3Tanecetum vulgare B 23' bank top limited

Table 1. Distribution of plant species observed at the Gold Creek Delta , Juneau , Alaska June and July 2013. Locations are mapped in Figure

1.

Locations (see Figure 1)

slope area intertidal area

Table 1. cont.

Approximate

Common name Scientific name A B C D E F G H I Elevation (MLLW) range Occurrence

little willow herb Epilobium leptocarpum B 23' bank top limited

dock Rumex spp B 19' -23' occasional

yarrow Achillea spp B 23' bank top occasional

cursed crowfoot 3

Ranunculus repens B 23' bank top common

pineapple weed 3Matricaria matricaroides B 23' bank top limited

plantain 3

Plantago major B 23' bank top limited

goatsbeard Aruncus slyvester B E 23' bank top limited

cow parsnip Heraculeum lanatum B E 23' bank top occasional

sweet rocket 2, 3

Hesperis matronalis B E 23' bank top occasional

salmonberry Rubus spectabilis C 21' to pavement limited

raspberry 2 Rubus idaeus C 23' to pavement limited

pine Mugo? 2

Pinus spp 25' limited

spruce 2 Picea spp not sitchensis E 25' limited

spirea 2 Spirea spp E 25-30' limited

thimbleberry Rubus parviflorus E ≥ 23' limited

sitka rose 2

Rosa rugosa E F ≥ 23' common

lupine Lupinus spp F 30' common

chocolate lily Fritillaria camchatcensis E 24' limited

cleavers Galium aparine E ≥ 23' limited

Angelica Angelica lucida E ≥ 23' limited

beach lovage Ligusticum scotium E ≥ 23' limited

Geum Geum macrophyllum E ≥ 23' limited

intertidal areaslope area

Locations (see Figure 1)

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Table 1. cont

Approximate

Common name Scientific name A B C D E F G H I Elevation (MLLW) range Occurrence

beach rye Elymus mollis A B C E G ≥ 17' common

Lynbye's sedge 4 Carex lyngbyei G 13-14' occasional (2 patches)

milkwort Glaux maritima G 11-12' common

arrow grass Triglochin maritima G 11' occassional

orache Atriplex drymaroides? G 11-15' common

goosetongue Plantago maritima G 11-14' common

prickly pearlwort Sagina maxima G 10-11' occassional

alkalai grass Pucinellia spp G 11-14' common in patches

beach greens Honckenya peploides G 13-14' occassional

Fucus

Fucus distichus subsp.

evanescens H 2-11' common

sea lettuce Ulva intestinalis H 8 - 10' common

Ulva prolifera H 7.5-8' common

Ulva lactuca I 0- -2' common

Alaria Alaria marginata I -2- -4' common

laverPorphyra spp (probably

cuneiformis)

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Locations (see Figure 1)

slope area intertidal area

common along Gold Creek

(June)

Association

in Fig. 3

# in Fig. 2

Species

transect

distance

(feet)

elevation

range

(feet)

cover % or

range

round mean

cover

Pu d 1 Pucinellia spp (alkaligrass) dense 0-10' 13 >50

G.Pl,Pu 2 Glaux maritima (sea milkwort) 10-40' 12-13 5-60 20

Plantago maritima (goosetongue) 0-15 5

Pucinellia spp (alkaligrass) 0-2 1

Triglochin maritima (arrow grass) 1

Atriplex spp >1

Sagina maxima (sticky pearlwort) occasional

Pu m 3 Pucinellia (alkaligrass) moderate 40-70' 11-13 5-50 20

Plantago maritima 1

Atriplex spp occasional

Sagina maxima (sticky pearlwort) occasional

F m 4 Fucus moderate* 70-100' 10-12 5-75 35

Atriplex spp occasional

Sagina maxima (sticky pearlwort) occasional

F s 5 Fucus sparse* 100-120 10-11 1-25 10

F d 6 Fucus dense 120-160' 9-11 100

F s/F d7 Fucus sparse*/Fucus dense

+160-235'

10-11/

5-10 1-25/100

F m 8 Fucus moderate* 235-285' 10 10-75 40

F s 9 Fucus sparse* 285-375' 8-10 <5

Up 10 Ulva prolifera 375-520' 8.5-7 10-70 45

pond outlet 520-525' 7

F d 11 Fucus dense 525-540' 7 100

F s/ F vs 12 Fucus sparse/very sparse 540-595' 7-7.8 1-5

Barnacle spp (Balanus, Semibalanus ) occasional

B,M,F13

Barnacle spp (Balanus, Semibalanus ) 595-660' 7.8-4 15-9545

Mytilus 1-90 25

Fucus 5-75 15

M,B 14 Mytilus 660-672' 4-0 1-100 20

Barnacle spp (Balanus, Semibalanus )

M, A, Ul 15 Mytilus 672-710' 0- -4 5-90%

Alaria,Ulva lactuca 10-50%

Table 2. Biotic associations along a 60 foot wide intertidal transect on the Gold Creek Delta, Juneau, Alaska, June

2013. Association abbreviations represent major species in the association and are used in Figure 3. Numbers

refer to the locations of each association in Figure 2.

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Table 2. cont. notes

*On the NE side of the spit (toward Egan Drive) where Fucus has moderate to sparse cover,

it is often associated with Ulva intestinalis (up to 5% cover) and barnacle spp (about 1% cover)

on cobbles

+ Fucus sparse most of this segment along the transect except pond margin slope from 10-5'

elevation…there dense

Dense Fucus often associated with Sitka periwinkles and juvenile mussels 20mm>

8

A

B C D

E F

G

H

I

A- F Upland tree, shrub, meadow and rip rap slope habitats

G-J Intertidal habitats

Transect

Sediment sample

J

Figure 1. General Habitats Gold Creek Delta, Juneau Alaska, CBJ Seawalk project June-July 2013

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J

* 2 1

3

pond outlet

9

4

5 6

7

8

10

11

12

13

14

15

Transect

Seine area

Figure 2. Biotic associations along a 60 foot wide intertidal transect and beach seine sample areas. gold Creek Delta, Juneau, Alaska June 2013. Numbers on transect refer to association descriptions in Table 2.

10

-4

0

4

8

12

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 525 550 575 600 625 650 675 700 725 750

Ele

vati

on

(fee

t)

Transect distance (feet) Egan Drive Gastineau Channel

Pud

G,Pl,Pu

Pum

Fm

Fs Fd Fs/ Fd Fm Fs

Up

outlet Fd Fs/Fvs B M F BM

M, A, Ul

Figure 3. Biotic associations along a 60 foot wide intertidal transect on the gold Creek Delta, Juneau, Alaska sampled June and July 2013. Association names are those in table 2. The Length of the bar for each association represents length along the transect and depth of bar represents the range of elevation occupied by the association. Elevations based on 1’ contour topography supplied by DOWL. 11

proposed island

8

9

10

11

12

13

14

15

16

L L L L L L L L L

C 0

Seawater Temperature

Surface

12'

bottom

6/20 6/21 6/23 6/24

Figure 4. Seawater temperatures (C0) recorded at 3 depths in the large tidal pond on the Gold Creek Delta June 20-24, 2013. Data indicate mean temperatures during periods of low slack and high slack tide. “L” indicates low slack periods.

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