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TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 EELGRASS 4
      2.1 INTRODUCTION 4
      2.2 METHODS 4
      2.3 RESULTS 6
      2.4 DISCUSSION 9
            2.4.1 Distribution in Project Vicinity 9
            2.4.2 Functional Assessment 11

3.0 SOFT-SHELL CLAMS AND MARINE WORMS 19
      3.1 INTRODUCTION 19
      3.2 METHODS 20
      3.3 RESULTS 21
      3.4 DISCUSSION 23
           3.4.1 Historical Perspective - Soft-Shell Clams 23
            3.4.2 Soft-shell Clam Habitat 26
            3.4.3 Factors Affecting Soft-shell Clam Populations 28
            3.4.4 Soft-Shell Clam Fishery 29
            3.4.5 Created Clam Flats 31
            3.4.6 Baitworms 34

4.0 LOBSTER, SEA SCALLOP AND SEA URCHIN FISHERIES 35
      4.1 INTRODUCTION AND METHODS 35
      4.2 RESULTS 36

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4.3 DISCUSSION 39

5.0 PLANKTON 42

6.0 BENTHIC COMMUNITIES 48

      6.1 INTERTIDAL COMMUNITIES 48
            6.1.1 Benthic Communities at the Causeway 49
            6.1.2 Intertidal Benthic Communities at the Proposed Terminal Site 54
            6.1.3 Intertidal Habitat Functional Assessment 55

      6.2 SUBTIDAL COMMUNITIES 58
            6.2.1 Subtidal Benthic Communities at the Terminal Site 61
            6.2.2 Subtidal Habitat Functional Assessment

7.0 FISHERIES 63

8.0 LITERATURE CITED 78

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NORMANDEAU ASSOCIATES FINAL REPORT

1.0 INTRODUCTION

This report presents results of investigations of various marine resources in the vicinity of Sears Island, Maine in upper Penobscot Bay during 1992 (Figure 1-1). These investigations were undertaken to supplement baseline information on intertidal and nearshore habitat conditions and utilization of fisheries resources as a basis for evaluating impacts of the Maine Department of Transportation’s (MDOT) proposed Sears Island Dry Cargo Terminal. These investigations included studies of eelgrass (Zostera marina), soft-shell clams (Mya arenaria). marine worms (primarily baitworms Glycera dibranchiata and Nereis virens), lob­sters (Homarus americanus), sea scallops (Placopecten magellanicus) and sea urchins (Strongylocentrotus droebachiensis). The northwest shoreline, in the area covered by the High Intensity Wildlife Survey (NAI 1993a), was encompassed in these investigations because this entire area was being reviewed for alternative port locations at the time. Information on other marine resources is recapitulated from the EIS.

The scope for field studies was developed and then conducted by Norniandeau Associates Inc. (NAI) and an Interagency Technical Team in August and September 1992. Representatives from MDOT, Maine Department of Marine Resources (MDMR), U.S. Environmental Protection Agency Region I (USEPA), and National Marine Fisheries Service (NMFS) developed a qualitative survey approach for eelgrass. eelgrass habitat and intertidal habitat (emphasizing harvestable species, soft-shell clams and baitworms). U.S. Fish and Wildlife Service and U.S. Army Corps of Engineers deferred to USEPA and NMFS on recommendations for study design. Biologists from USEPA and NMFS participated in the field surveys for these resources. These surveys encompassed the northwest shoreline of Sears Island.

Current utilization of fisheries resources was investigated by updating the telephone survey conducted in 1986 for the EIS. The 1986 survey focused on lobster and scallop harvesting. At the request of NMFS, interviewees were also queried about potential sea urchin harvesting in 1992.

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Figure 1-1

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Subsequent sections of this report focus on individual resources: eelgrass and shallow subtidal habitat (Section 2.0); intertidal habitat, and soft-shell clam and bait worm resources (Section 3.0); and selected fisheries resources (Section 4.0). Each section documents methods and results of the specific studies undertaken and places results in the context of historical or regional information where possible. Finally, information on plankton (Section 5.0), benthic communities (Section 6.0) and finfish (Section 7.0), summarized from the EIS, is presented.

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2.0 EELGRASS

2.1 INTRODUCTION

Evidence that the attached vascular plant, eelgrass (Zostera marina), has occurred in the Long Cove area historically was presented in the EIS (USDOT and MDOT 1987). During 1974 and 1975, Central Maine Power authorized an extensive survey of marine resources in the waters around Sears Island. Included in this survey were investigations on the distribution and production of eelgrass (NAI 1975). Beds of eelgrass were mapped in Long Cove north of the causeway (in mid-September 1974 and mid-June 1975) and at the head of Stockton Harbor (in mid-June 1975; NAI 1975). Beds in both areas extended from mean low water to about -2 feet (-0.6 in). Although a transect was examined for flora in the vicinity of the proposed cargo terminal on Sears Island, no eelgrass was reported.

On October 1 and 2, 1986, divers swam 1500 foot (457 meter) long transects emanating from the shorelines of Mack Point, Long Cove and Sears Island (USDOT and MDOT 1987). On these transects, divers recorded information on habitat conditions, including substrate characteristics and vegetation. Eelgrass was observed on only one transect in Long Cove. No eelgrass was recorded on either of the transects located off of Sears Island. However, the primary focus of these investigations was to collect information on commercially important fisheries resources.

2.2 METHODS

Members of the Sears Island Marine Resources Technical Team, including MDOT, MDMR, NMFS, USEPA and NAI, convened to develop appropriate protocol for evaluating existing eelgrass conditions in the proposed project area. Low-tide aerial photographs of the western shoreline of Sears Island, flown in August 1990, were reviewed for evidence of eelgrass but were inconclusive. A preliminary field survey, designed to identify substrate conditions and presence of eelgrass, was developed by the team. It was determined that representatives from NMFS and USEPA would participate with NAI in the preliminary field

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survey so that the results could be evaluated immediately and areas requiring additional investigations could be identified.

The area encompassing alternative project locations on the northwest portion of Sears Island was examined for eelgrass on August 31, 1992. Survey boundaries correspond to the High Intensity Study Area established for the wildlife survey (NAI 1993a). The maximum depth that eelgrass was expected to occur in the area was -18 feet (-5.5 m) MLW, based on anticipated water clarity. This was assumed to be the seaward limit of the survey, subject to modification in the field based on initial findings.

Starting at the southern end of the survey area, field personnel, including represen­tatives from NMFS, USEPA and NAI were split into three groups. Two biologists waded along the shoreline; mid-depth areas (-6 to -8 feet, or -1.8 to -2.4 m, deep at MLW) were observed through a viewbox and by a snorkler. SCUBA divers swam along the -11 foot (-3.3 m) MLW contour. North of the existing jetty, the tide was too high to observe eelgrass successfully from the shoreline. In this area, divers swam longshore transects at depths less than -7 feet (-2.1 m)(MLW), although they were instructed to determine the offshore location of eelgrass if it were beyond this depth zone. Observers recorded substrate conditions and semiquantitative observations on eelgrass. For the day of the eelgrass survey, NOAA Tide Tables predicted low tide (-1.0 ft, or -0.3 m, MLW) to occur at 0743 (daylight savings time) and high tide (+11.2 ft. or +3.4 m, MLW) at 1403 (DST) in the Searsport area. The survey was conducted between 0700 and 1400 hr (DST). Calm wind and wave conditions prevailed throughout the survey, so no adjustments to depth due to these factors were considered necessary. Actual depth, based variously on divers depth gauges and a Hummingbird Model LCR400 depth meter, and time were recorded at seaward edge of eelgrass beds so that depths could be corrected to mean low water.

An assessment of the distribution of eelgrass in Penobscott Bay is currently being conducted by Dr. F. Short (UNH). Initial evaluation of aerial photographs (taken October 1992) has been completed and Dr. Short is supplementing these results with low-altitude reconnaissance (in 1993-1994) and, in some cases, ground-truthing (in 1994) to improve the accuracy of these delineations. Dr. Short has provided NAI with preliminary information

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concerning areas he ground-truthed in July 1994 (Sandy Point in Stockton Springs to Browns Head in East Northport). These results are briefly described where they are relevant to the 1992 survey.

2.3 RESULTS

Sketch maps of subtidal substrate conditions and approximate eelgrass cover were prepared from observers’ field notes (Figures 2-1 and 2-2). The substrate offshore of Sears Island consisted predominantly of a silt or sand matrix with varying proportions of gravel, cobble, boulders, and mussels (Figure 2-2). Eelgrass shoots were observed in most substrate conditions, with the exceptions of ledge, on boulders and a mussel bed associated with cobble. Eelgrass was observed even in very gravelly areas where wave-induced abrasion could be high. In some areas north of the jetty, dead shoots were observed within the beds.

Eelgrass was not observed in water depths greater than -7 feet (-2.1 m) MLW in 1992. Eelgrass was observed growing close to the edge of the dredged area approximately 200 feet (61 m) south of the jetty. The post-dredging bathymetric survey (Owen Haskell Inc. 1985) indicated that the depth of the top of the 1:1 dredged slope in this area was shallower than -7 ft (-2.1 m) MLW in 1985. In July 1994, eelgrass was observed to occur in depths up to -9.7 ft (-2.9m) MLW in the vicinity of the proposed project (F. Short, UNH, pers. comm. 8/2/94).

Although eelgrass was not quantitatively sampled, estimates of cover were made. Relative cover provides an indication of whether the eelgrass was scattered or concentrated in a cohesive bed. Areas where eelgrass occurred as scattered shoots with distances between shoots generally greater than 1.5 ft (0.5 m) were categorized as sparse. The small patch category encompassed areas where inter-shoot distances were generally smaller but densely vegetated patches were less than approximately 1.5 ft (0.5 m) in diameter and unvegetated areas were distinct. The large patch category included areas where the vegetation was relatively uniformly distributed but substrate was clearly visible. In comparison, the very

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Figure 2-1

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Figure 2-2

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dense category was used for areas where eelgrass dominated the field of vision. These categories describe conditions existing on August 31, 1992.

The eelgrass beds along the Sears Island shoreline provided habitat for other organisms. Juvenile starfish, mussels and snails were observed on eelgrass blades. Winter flounder, cancer crabs, green crabs and starfish were observed within vegetated areas. Epiphytes occurred on some plants.

2.4 DISCUSSION

2.4.1 Distribution in Project Vicinity

The distribution of eelgrass in the vicinity of Sears Island is probably limited by light penetration rather than other factors. The lower depth limit in 1992 was approximately -7 ft (-2.1 m) MLW; in 1994, eelgrass was observed at greater depths (-9.7 ft; -2.9m MLW). Eelgrass occurred in most substrate types identified in the nearshore area, ranging from silt and fine sands to cobble. Substrate conditions (Figure 2-1), in conjunction with current regime, may partially account for the varied distribution in the project area. Fonseca et al. (1983) distinguished three current regimes (low <50 cm/sec, medium >50 to <90 cm/sec, and high >90 cm/sec maximum monthly surface velocity) that control sedimentary conditions in eelgrass beds. Fonseca et al. (1983) found that the low current regime allowed even distribution of silt-clay particles; fine particle distribution under a high current regime was related to the canopy height and vertical gradient in velocity and therefore not uniform. Near-surface tidal currents up to 52 cm/sec have been measured in the immediate vicinity of the proposed terminal (NAI 1975; 1991), placing this area in the medium current regime (Fonseca et al. 1983). Other researchers (reported in Thayer et al. 1984) found that a current regime of 20-40 cm/sec promoted the most luxuriant growth. The current regime around Sears Island (docu­mented in NAI 1975) generally falls in the range suitable for eelgrass growth, except in the southeastern portion. Short (1994) observed this distribution pattern to exist in 1994 while ground truthing 1992 aerial photographs.

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Historical presence of eelgrass in the vicinity of Sears Island was noted in the EIS (USDOT and MDOT 1987). Beds of eelgrass had been studied in Long Cove and Stockton Harbor during 1974 and 1975. At that time coverage was about one acre (0.4 hectare) in Long Cove (near Kidder Point) and three acres (1.2 ha) in Stockton Harbor. Timson (1976) identified eelgrass beds only at the head of Long Cove. Short found this area to be a macroalgae-covered mussel bed in 1994 (pers. comm., 8/2/94). During a 1986 transect survey to document substrate and biological (especially species of fisheries value) conditions in Long Cove and the northwestern shoreline of Sears Island, divers observed a small patch off the eastern shore of Mack Point (USDOT and MDOT 1987). No eelgrass was observed along Sears Island at that time.

In Stockton Harbor, eelgrass has been documented as undergoing relatively long-term (decadal) fluctuations in standing crop. Eelgrass was reportedly virtually absent from the northwestern shoreline of Cape Jellison during the 1980s but was present in dense stands in 1991 and 1992 (NAT 1992a). The same pattern occurred in Long Cove (W. Hamilton, Searsport Harbonnaster, 11/15/93, personal communication). Wasting disease was documented as contributing to extensive dieback of eelgrass in southern Maine and New Hampshire during the 1980s (Short et al. 1986) and may have been a factor in the population shifts in the Penobscot Bay region. In 1992, biologists from NAI observed dead shoots within the bed, an indication that wasting disease could have been present at that time. Typically dead leaves float out of the bed, usually carried to the wrack line. Wasting disease tends to cause release of internal gases so dead leaves sink rather than float (Dr. F. Short, UNH, pers. comm., 11/30/93). Because the beds were not examined in greater detail for evidence of wasting disease, there is no information available to evaluate the extent of disease locally. However, as the beds observed around Sears Island in July 1994 (Short 1994) appeared to be healthy, it is unlikely that the disease is prevalent

Maine Department of Marine Resources is in the process of mapping eelgrass resources in Cobscook Bay, Penobscot Bay, Casco Bay and the Piscataqua River and plans to map other areas in the future (S. Barker, MDMR, 2/2/94, pers. comm.). The only regional information presently available is Short’s (1994) review and ground truthing of aerial photographs of portions of upper Penobscot Bay. Aerial photographs taken in early October

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1992 covering the areas from Sandy Point (Stockton Springs, north of Cape Jellison) to Brown’s Head (East Northport, south of Belfast) were examined for evidence of eelgrass and ground truthed in July, 1994 (Short 1994). Relatively large beds of eelgrass were observed at Sandy Point, the head of Stockton Harbor, southwestern Cape Jellison, the entire perimeter of Sears Island (except the southeastern and southern portion) the mouth of the Passawassakeag River (Belfast) and the cove near Browns Head (East Northport). Smaller patches occurred in several other locations, including near Delta Chemical in Stockton Harbor and east and south of Mack Point (Short 1994). Ground truthing revealed variability in depth distribution in the areas examined. Off Sandy Point, eelgrass was limited to areas shallower than -2.3 ft (-0.7 m) MLW and to -8.3 ft (-2.5 m) MLW off Browns Head. Along the western shore of Sears Island, eelgrass occurred to -9.7 ft (-2.9 m) MLW in 1994. Preliminary review of aerial photographs from the rest of Penobscot Bay suggests that large eelgrass beds are present in the Bagaduce River and along Islesboro Island (F. Short, U7NH, 8/2/94, pers. comm.). In particular, the 1994 observations around Sears Island indicate how eelgrass coverage can change among years. Short (1994) found a virtually continuous band of eelgrass south of the proposed terminal site, including the cobbly area in the southern portion of the area investigat­ed that was unvegetated in 1992 (see Figures 2-1 and 2-2).

2.4.2 Functional Assessment

Adamus et al.’s (1987) evaluation methodology for wetlands attributed a number of functions and values to submerged aquatic beds (e.g. eelgrass):

• sediment stabilization - reduction of sediment erosion and export;

• sedimentltoxicant retention - increasing deposition, accumulation, especial­ly of fine-grained particles;

• nutrient removal/transformation - uptake of nutrients from water column, and conversion to plant material;

• production export - annual dieback of above ground growth allowing transport out of local area;

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• aquatic diversity/abundance (fish and invertebrates) - increase in habitat complexity, food availability for other species;

• wildlife diversity/abundance for migration - increase in food resources for migrating avifauna.

Investigations of eelgrass beds in the mid-Atlantic region (i.e., Chesapeake Bay and North Carolina) have indicated that eelgrass habitat provides a nursery function for finfish as well (Thayer et al. 1984). In this role, it provides both refuge and forage for juvenile fish.

Historic information available on eelgrass distribution in the vicinity of Sears Island is incomplete. It appears that there have been periods when it was virtually absent and periods, including 1992, when it has been widespread. A single-year study cannot project future conditions. Therefore, the relative densitites of eelgrass observed in 1992 do not necessarily indicate whether these eelgrass beds have the potential to provide the functions attributed to this resource. Because even low shoot densities increase habitat complexity, providing substrate for other organisms, it is assumed that the beds near the proposed project area can provide the functions typically attributed to eelgrass.

Sediment Stabilization; Sediment/Toxicant Retention

As a general rule, eelgrass beds could be assumed to function well in stabilizing sediments since the root-rhizome standing crop can exceed the above-ground standing crop (Thayer et al. 1984), even during the active growing season. Although above-ground shoots die back during the fall in New England, roots and rhizomes, which bind the sediments, are perennial, allowing year round stabilization of the, sediments. When above-ground growth is present, the bed can attenuate waves and currents, further reducing erosive forces. These characteristics also contribute to the ability to retain sediments (and associated toxicants, if present). Density of shoots and rhizomes, as indicated by pattern of coverage of the eelgrass bed, affect the ability of an eelgrass bed to stabilize or retain sediments. Sparsely distributed plants are less likely to perform this function well than a dense bed could. Eelgrass beds in high energy areas are characterized by varying topography - mounds and scour areas (Thayer

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et al. 1984). The relatively low energy environment in the study area off Sears Island results in a uniform topography, suggesting that shoot density in the area could be uniform. Although this was not observed to be true in 1992, distribution could have been controlled by other factors, particularly if the bed has been in a period of resurgence.

Nutrient Removal/Transformation

Eelgrass has been demonstrated to absorb nutrients both through leaves and roots (Thayer et aI. 1984). However, in the presence of high concentrations of dissolved nutrients, eelgrass does not compete well with phytoplankton, epiphytes or macroalgae (Short 1991). Penobscot Bay has been identified as having a medium susceptibility to nutrient inputs because of the relatively low flushing rate and upstream loading of nutrients (NOAAIEPA 1988); it would require more than an 800% increase in either nitrogen or phosphorus loading to reclassify the bay as having a high susceptibility to eutrophication. The Sears Island eelgrass beds contribute to nutrient removal and retention.

Production Export

Senescent leaves are usually transported from the bed into the wrack line, where they serve as temporary habitat for amphipods and other crustaceans. Storm events could transport the wrack into deeper waters, but most of the biomass probably remains onshore until it is decomposed. Decomposed shoots would be more readily available to enter the marine detritus-based food web. Since leaves are shed throughout the growing season, as well as during the more pronounced die off in the fall, the eelgrass beds off Sears Island contribute throughout the year to the detrital load of the local system, supplementing the salt marsh, plankton and upriver sources. Although, on a unit basis (g C/m2/yr), eelgrass production is lower than benthic macroalgae and saltmarsh species (Diaz et al. 1982), available information on Sears Island, Long Cove and Stockton Harbor (Timson 1976; USFW 1992; Short 1994) indicates that eelgrass covers more surface area than saltmarsh and may occur at a similar

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level to macroalgae. Thus, eelgrass is presently a relatively important contributor to the local detrital load.

Aquatic Diversity/Abundance

Incidental observations during this survey indicated that the eelgrass beds along the Sears Island shoreline provided habitat for several species of invertebrates and one species of fish. A detailed survey would likely result in a larger list of species, associated with the eelgrass beds. The variety of functions being provided to these organisms is exemplified by the types of organisms observed. Mussels attach to the blades using the plant for substrate. Snails could be grazing directly on the blades or on microbiota on the blades. Winter flounder and crabs could use the eelgrass bed for refuge from predators or for feeding. The eelgrass beds near Sears Island could be used by other species for similar functions.

Surveys conducted by Heck et al. (1980) and Colarusso (USEPA, 3/28/94, pers. comm.) provide an indication of the diversity of fish and invertebrates that inhabit eelgrass beds in New England. Heck et al. (1989) observed significantly higher (t-test) abundances of fish in eelgrass beds than over unvegetated sand during daytime collections in the Cape Cod National Seashore, MA. Although there were higher abundances of decapod crustaceans in vegetated areas, mean abundances were not statistically different (Heck et al. 1989). Although nighttime sampling in vegetated areas yielded higher abundances of crustaceans than daytime sampling, distribution of fish exhibited no consistent diurnal pattern. Unvegetated areas were not sampled at night.

A number of the fish species Heck et al. (1989) collected in their study were common in the upper Penobscot Bay (CMP 1974). Three-spine stickleback (Gasterosteus aculeatus), winter flounder (Pleuronectes americanus), longhorn sculpin (Myoxocephalus octodecemspinosus) and white hake (Urophycis tenuis) exhibited a tendency to utilize the Cape Cod eelgrass habitat during the daylight (Heck et al. 1989) and, so, would be likely to do so off Sears Island. American sand lance (Ammodytes americanus) occurred in higher abundanc­es over unvegetated substrate (Heck et al. 1989), thus would be unlikely to use the Sears

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Island eelgrass beds but may use other habitats in the project area. Several other species common in the vicinity of Sears Island, Atlantic herring (Clupea harengus), Atlantic silver-sides (Menidia menidia) and windowpane flounder (Scophthalmus aquosus) were caught in numbers too low to discern a distinct preference in Cape Cod (Heck et aI. 1989).

Colarusso (unpublished data) reported that, using several types of sampling gear, a survey of eelgrass beds in Boston Harbor and Broad Sound (MA) in 1993 yielded 24 species of finfish (Table 2-1) and 28 species of invertebrates (Table 2-2) (P. Colarusso, U.S. EPA, pers. comm. 3/28/94). He observed that pelagic finfish were collected in similar numbers in vegetated and unvegetated areas but that stomach analysis indicated that these species fed in the eelgrass beds. Of the finfish species collected in Colarusso’s study, 16 species were recorded in the vicinity of Sears Island during the mid-1970s (CMP, unpublished data, reported in USDOT and MDOT 1987). It is likely that these species would use eelgrass beds near Sears Island.

The three most abundant crustaceans collected by Heck et al. (1989), sand shrimp (Crangon .septemspinosus), green crab (Carcinus maenas) and rock crab (Cancer irroratus) are commonly found in upper Penobscot Bay (CMP 1982d). Short (U7NH, pers. comm. 3/17/94) has found green crabs to be more common outside of eelgrass beds. He has reported the use of eelgrass beds as nursery areas for juvenile lobsters (Short et al., in prep.). Colarusso (unpublished data) collected 28 species of benthic and epibenthic invertebrates (primarily motile species) in eelgrass beds in Boston Harbor and Broad Sound (MA). Of these species, 15 have been recorded from hard or soft substrates or plankton in the vicinity, of Sears Island (CMP 1982d), and could occur in the eelgrass beds adjacent to the island.

Nursery

The most common fish found in a shoreside survey in the vicinity of Sears Island included rainbow smelt, Atlantic silverside, alewife, threespine stickleback and blueback herring (see Section 7.0). Of these, rainbow smelt was also relatively abundant in its larval

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