Trace metals are stable, persistent elements which are naturally present in seawater in minute amounts. A threat may be posed to marine organisms if concentrations of these metals are raised above natural background levels reaching potentially toxic levels. The significance of a trace metal introduced by activities such as OCS oil and gas operations depends on its relationship to the organism: that is, the concentration of the metal, the form in which it exists (e.g., dissolved, particulate, complex, or absorbed), and how these two factors affect an organism (e.g., incorporation into protein, foodweb biomagnification). The term "heavy metal" is commonly used to refer to a metal (e.g., chromium, vanadium, manganese, iron, copper) having a density greater than 5 g/cm3 (US EPA, 1980a). 3

Background levels of trace metals in the water column have been measured in and around the 106-Mile Disposal Site located within the proposed lease sale area. Kester et al. (1977) found levels there to be typical of other uncontaminated shelf-slope and open ocean areas (US EPA, 1981a). Table III.A.5-1 presents concentrations of cadmium, copper, and lead as determined by Kester et al. (1977) with some comparative concentrations from other Atlantic Ocean areas including the New York Bight Apex--an area subject to considerable contamination.

Sources:

(a) From data in Table A-12 (US EPA, 1981) and Table A-8 (US EPA, 1980a)

Concentration of trace metals in sediments, as reported by Greig et al. (1976) and Pearce et al. (1975), along the mid-Atlantic continental slope and rise are generally elevated in comparison to continental shelf values (US EPA, 1980a). This difference in concentration was considered natural (as opposed to being a result of ocean dumping) and attributed partly to particlesize differences between shelf and slope sediments since contaminants are usually more concentrated in finer grain sediments characteristic of the slope region (US EPA, 1980a; US EPA, 1981a). Sediment samples from the midAtlantic continental shelf analyzed by Harris et al. (1977) and Harris et al. (1979) also showed a general increase in trace metal concentration seaward across the shelf corresponding to an increase in silt-clay content. Pearce et al. (1975) conjectured that elevated trace metal concentrations in slope sediments in the vicinity of the Hudson Canyon may be caused by the transport of contaminants from inshore sources down the canyon (US EPA, 1980a). Suspended particulate matter in continental shelf waters originates from three general sources: transport from rivers, resuspension of bottom sediments, and organic matter produced on the shelf itself. Whereas river transport can be important in the nearshore area, the resuspension of bottom (lithogenic) sediments and organic (biogenic) matter are the dominant sources for outer continental shelf areas (Meade et al., 1975).

Meade et al. (1975) reported a surface water concentration of 100 to 500 ug/1 for suspended particulates (mostly combustible plankton and their non-combustible remains) for U.S. eastern continental shelf waters; subsurface water concentrations were 500 to 2,000 ug/1, consisting mostly of non-combustible

Surveys conducted by the USGS during 1975-77 determined that particulate matter in the Middle Atlantic Bight waters was generally low, usually not exceeding 1,000 ug/1 (Milliman et al., 1979). Except for nearshore areas, bottom waters of the outer shelf showed the highest concentrations. Even during the spring, when biological activity produced an increase in combustible particles in surface waters, bottom particles on the outer shelf continued to be comprised largely of bottom sediments.

A study to characterize the distribution and exchange of sediments and particulate matter in and around Baltimore Canyon and at two mid-Atlantic slope areas was conducted in 1981-82 (Gardner, 1983). Results of this study showed that resuspension of sediments is much greater in the canyon than on the slope and that resuspension in the canyon occurs predominantly at tidal frequencies as opposed to being random or storm-induced, as on the shelf. Within the canyon there is a down-canyon and a deeper up-canyon sediment transport component, leading to the implication that between these is a zone of convergence where seaward transport occurs (Gardner, 1983).

Ocean dumping activities in the Middle Atlantic Bight are discussed in section III.D.2. The only major activity affecting water quality within the proposed lease sale area has been that associated with disposal of industrial (and some municipal sewage sludge) waste at the 106-Mile Ocean Waste Disposal Site. Disposal at this site, which is located in the northeast portion of the proposed lease sale area (Visual No. 1), has been in progress since 1961 resulting in short term water quality impacts restricted to the upper water column (US EPA, 1980a; Federal Register, May 4, 1984). EPA has now designated two smaller sites (for industrial waste and municipal sludge) within and as a replacement for the 106-Mile Site. Water quality impacts from these two new sites is anticipated to also be short-term and limited (Federal Register, May 4, 1984).

b. Nearshore

Some nearshore (coastal) areas of the Middle Atlantic Bight have degraded water quality resulting from pollution inputs associated with estuary and/or river outflows and ocean dumping operations. In turn, these degraded water quality conditions may be responsible for diseases in marine organisms, possibly causing fin rot in winter flounder in the New York Bight Apex area, or requiring the closing of shellfish harvesting areas because of bacterial contamination, as is the case along some coastal areas of New Jersey and New York (US EPA, 1978).

The NOAA Northeast Monitoring Program (NEMP), through various monitoring and assessment activities, has been appraising the "health" of marine waters of the northeastern United States. According to the 1981 NEMP report (USDOC, NOAA, 1983a), the New York Bight Apex continues to show the most acute and spatially extensive alterations of all the benthic (bottom) systems monitored by NEMP along the mid-Atlantic coastal area. (The designation "New York Bight" refers to an 11,350 sq nmi area of the Atlantic Ocean extending north and east to Montauk, Long Island; the "Apex" being a 584 sq nmi area within the Bight immediately adjacent to the New York-New Jersey metropolitan area.) The 1981 NEMP report further stated that the outflow of the Chesapeake Bay may be exerting subtle effects on the benthic animals to at least 37 km south of the Bay mouth. No impacts have been detected off Delaware Bay or at the other coastal sites monitored.

The New York Bight receives considerable pollutant loadings from ocean-dumped wastes (see Visual No. 1 and section III.D.2) as well as from municipal and industrial discharges through ocean outfalls, from surface and groundwater runoff to the Hudson River-Raritan Bay estuaries, and from atmospheric fallout. Water quality problems include sewage-related high BODs, excessive bacterial densities, oil and grease, and high concentrations of heavy metals, polychlorinated biphenyls (PCBs), and other potentially toxic concentrations of suspended matter, resulting from the dumping of dredged material and sewage sludge as well as from estuarine runoff (US EPA, 1978).

Relatively high levels of hydrocarbons have been found in the New York Bight. A study conducted in conjunction with the Marine Ecosystem Analysis Program (MESA) on the New York Bight found values of non-volatile hydrocarbons in New York Harbor waters to range from 14 to 270 ug/1 (ppb), with an average concentration of 39 ug/1, or about 10 times higher than that found in the open ocean (Searl et al., 1977). Within the 1981 NEMP study area, the highest levels of petroleum hydrocarbons reported (31,000 ppb) in sediment were from the New York Bight Apex (USDOC, NOAA, 1983a).

Concentrations of dissolved trace metals in the New York Bight vary both seasonally and spatially and are generally higher than reported for the open ocean. These higher concentrations are caused by loadings from the coastal metropolitan area, particularly from barged wastes, and by the high concentrations of suspended matter that serve to maintain metals in suspension. Accordingly, concentrations are highest in the Bight Apex where pollutant loadings are greatest. Also, particularly high levels occur in summer, when oxygen depletion in bottom waters mobilizes metals, and in winter, after storm activity, when suspended sediments contribute metals to the water column (US EPA, 1978).

Planktonic organisms are defined as floating or weakly swimming organisms that cannot maintain their distribution against the movement of the water masses in which they live. Some species may swim strongly enough to appreciably modify their vertical distribution and demonstrate diel (24-hr) migration patterns, but their horizontal distribution is dictated by the direction of water mass movement. The plankton can be divided into many segments or components, depending on which yardstick is used. The most common ones are trophic level, size, life cycle, and vertical location in the water column. The planktonic community basically is divided into two major trophic categories: phytoplankton--the autotrophic organisms which photosynthesize light; and zooplankton--the heterotrophic organisms which feed on other plankton. Plankton often is divided by size classes such as ultraplankton--<2 um (1 um = 0.001 mm) nannoplankton--2 to 20 um, microplankton-20 to 200 um, and macroplankton-->200 um. The ultraplankton is comprised primarily of bacterioplankton while the nannoplankton contains mostly small phytoplankton. The larger phytoplankton and the smaller zooplankton may be represented in the microplankton size class; however, the large zooplankton predominates in the macroplankton category. A zooplankton species may be placed into one of two major categories depending on the life cycle of the organism: holoplankton--those organisms which spend their entire life in the water column; and meroplankton--those organisms which are in the water column for only part of their life cycle. Lastly, those organisms which are found predominately at the surface of the water are termed neuston. The neuston layer is usually the top 20 cm of water; however, various studies sample the neuston layer to different depths because of the variability of the sampling equipment. Many species have been termed "facultative neuston" because they undergo vertical migrations, and are found in the neuston layer only at certain times during the 24-hour day.

Earlier studies of phytoplankton in the mid-Atlantic were limited in the number of across-shelf transects or were not comprehensive with regard to latitudinal and/or seasonal changes, resulting in incomplete information on spatial and temporal variation of phytoplankton community structures. Recent publications have reported on pooled data from several cruises over multiple years providing more comprehensive information (Marshall, 1982a; 1982b; Marshall and Cohn, 1983; O'Reilly and Busch, 1984; NEMP, 1981). The Northeast Monitoring Program (NEMP) reported that phytoplankton on the Middle Atlantic Bight shelf demonstrated seasonal fluctuations with highest cell concentrations evident between December and March. A secondary peak occurred between May and August after the summer low point (NEMP, 1981). Marshall (1976) stated that the coastal waters north of Cape Hatteras had a smaller number of dominants and lower species diversity than the waters south of Cape Hatteras. Marshall (1982a) reported on data collected on 25 Marine Resources Monitoring, Assessment and Prediction (MARMAP) cruises, and concluded that diatoms, dinoflagellates, cyanophyceans, and coccolithophores demonstrate seasonal variation. The author also stated that the

areas of seasonally increased abundance align with those areas of nutrient enrichment such as river inputs or upwelling phenomena. Figure III.B.1-1 shows the seasonal pattern of cell abundance as reported by Marshall (1982b). Generally, within 35 km of the coast, diatoms were more abundant and decreased in numbers and species over the outer shelf (NEMP, 1981). Marshall (1982b) presented a comprehensive description of phytoplankton distribution over the northeastern continental shelf. In summary, the author stated that small (<20 um) chain-forming diatoms are the most numerous inshore and during the seasonal blooms (spring and fall), while the larger (>100 um) species of diatoms can be found year-round but become relatively more important in the community over the mid-shelf and during summer and winter, when lower numbers of the smaller diatoms are present. Marshall (1982b) further noted that dinoflagellates decreased in number in the seaward direction, but not as quickly as the diatoms, and therefore became relatively more important in the phytoplankton community over the mid-shelf, beyond the shelf break, and over the outer shelf when not in areas of increased diatom abundance resulting from upwelling of nutrients. In addition, coccolithophores, cyanophyceans, and ultraplankton (or nannoplankton) are important components of the phytoplankton, with the cyanophyceans found predominantly in near coastal water, although coccolith ophores and ultraplankton are found over the entire shelf. Marshall and Cohn (1983) reported that known species from the MARMAP cruises total 678 species with diatoms having 274 species, dinoflagellates having 332 species, and all other groups having 19 species or less. O'Reilly and Busch (1984) have indicated that primary production in the mid-Atlantic shelf euphotic zone remained at about 1 g carbon/m2/day throughout the summer, and that the nannoplankton component was responsible for incorporating the majority of organic carbon over the year. The highest values of primary production were recorded in the apex of New York Bight and were approximately 2.5 g carbon/m2/day in spring, summer, and fall.

b.

zooplankters:

Zooplankton

In the Middle Atlantic Bight there are three basic sources of offshore Gulf Stream and slope waters; shelf waters of southern New England and Georges Bank; and in situ recruitment to the meroplanktonic community from spawning adults. Tropical and subtropical species are introduced into the Middle Atlantic Bight by means of the advective movements of anticyclonic Gulf Stream eddies which generally progress in a southwesterly direction in the mid-Atlantic (Grant, 1979). Grant (1979) also reports that boreal species of zooplankton are transported to the area in the general south-southwestern movement of mid-Atlantic shelf waters. In both cases, the survivorship of the various species depends on temperature, and therefore season, of the receiving waters--the boreal species normally evident in winter and spring and the tropical-subtropical species found in summer and fall. Grant (1979) also states that the presence of a Coastal Boundary Layer of water is evident throughout the mid-Atlantic and is a means of southward transport of coastal species.