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Table 2.1.
Gulf of
Maine benthic assemblages as identified by
Watling (1998). (Geographical
distribution of assemblages is shown in Figure 2.4.)
|
| Benthic
Assemblage |
Benthic Community Description |
| 1 |
Comprises all sandy offshore
banks, most prominently Jeffreys Ledge, Fippennies Ledge, and Platts Bank;
depth on top of banks ~70 m; substrate usually coarse sand with some gravel;
fauna characteristically sand dwellers with an abundant interstitial
component |
| 2 |
Comprises the rocky offshore
ledges, such as Cashes Ledge, Sigsbee Ridge, and Three Dory Ridge; substrate
either rock ridge outcrop or very large boulders, often with covering of very
fine sediment; fauna predominantly sponges, tunicates, bryozoans, hydroids,
and other hard-bottom dwellers; overlying water usually cold MIW |
| 3 |
Probably extends all along
coast of GOM in water depths <60 m; bottom waters warm in summer and cold
in winter; fauna rich and diverse, primarily polychaetes and crustaceans,
probably consists of several (sub-) assemblages due to heterogeneity of
substrate and water conditions near shore and at mouths of bays |
| 4 |
Extends over soft bottom at
depths of 60-140 m, well within the cold MIW; bottom sediments primarily fine
muds; fauna dominated by polychaetes, shrimp, and cerianthid anemones |
| 5 |
Mixed assemblage comprising
elements from the coldwater fauna as well as a few deeper water species with
broader temperature tolerances; overlying water often a mixture of MIW and
MBW, but generally colder than 7 °C most of year; fauna sparse, diversity low, dominated
by a few polychaetes, with brittle stars, sea pens, shrimp, and cerianthids
also present |
| 6 |
Comprises fauna of deep basins;
bottom sediments generally very fine muds, but may have a gravel component in
offshore morainal regions; overlying water usually 7-8°C, with little
variation; fauna shows some bathyal affinities but densities are not high,
dominated by brittle stars and sea pens, and sporadically by a tube-making
amphipod |
| 7 |
True upper slope fauna that
extends into the Northeast Channel; water temperatures are always >8°C
and salinities are at least 35 ppt; sediments may be either fine muds or a
mixture of mud and gravel |