Realm: Marine
Climate: Temperate
Biome: Temperate shelf and seas ecoregions
Central latitude: 41.570974
Central longitude: -70.509903
Duration: 7 years, from 1903 to 1909

41346 records

606 distinct species

Across the time series Nassarius trivittatus is the most frequently occurring species

Methods

Three types of dredging apparatus were employed by us. (I) The beam trawl. ofwhich descriptions and figures may be found in several previous reports of the UnitedStates Fish Commission (Verrill. 1883; Tanner. 1884. 1897). The trawls employed inthe present work were quite diminutive in comparison with those used in commercialtrawling. having a beam length (width of aperture) of from 6 to 9 feet. and a depth ofnet not much exceeding 10 feet. This appliance can be employed to best advantage ona level bottom of hard sand or fine gravel. upon which the lead line fits closely. It iswell adapted to scraping 'up the larger mollusks. fishes. crustacea. echinoderms. algre.etc.. which lie upon the surface. but not to penetrating the sand or gravel; and it consequentlyfails to disturb those forms which burrow in even a slight degree. For thisreason. and because of the large size of its meshes. the beam trawl was commonly notemployed alone; but a dredge of the next type was ordinarily appended to the lowerend of the bag. '(2) The ordinary naturalists' dredge. of the type originally devised by O. F. Muller(see Verrill. 1883; Tanner. 1884. 1897; Agassiz. 1888). This. as is well known. consistsof a heavy. rectangular. iron frame. to which is fitted the mouth of a bag of stoutnetting. In the commoner pattern the two longer sides of the frame consist of sharp.outwardly flaring edges. adapted to cutting into the sand. gravel. or mud; and thedredge is practically certain to drag in such a way that one or the other of these edges islowermost.A modification of this type of dredge which was freely used during the present workwas the rake dredge. which differs from the ordinary pattern in possessing heavy teethalong the cutting edge. The frame. in both types. is fitted with two heavy movableiron arms. to which the dredge line is attached. Commonly acomparatively light ropewas fastened to one of these hahdles. so that in case an obstruction was encounteredthis line might part and allow the dredge frame to free itself without escaping altogether.The dredge net was protected from tearing by a sheathing of heavy canvas. which wasattached to the frame outside of the net and formed a bag. open at the lower end. Thenetting commonly employed in these dredges had a t-inch or a r-inch mesh a in theupper portion. while the lower end was quite closely woven. Such meshes were likelyto retain not only the stones. shells. and the great majority of living organisms. buteven considerable quantities of the bottom material. Fine loose sand. however. and inless degree mud. were likely to be washed out almost completely during the reeling inof the dredge line. Where such bottoms were encountered the canvas sheathing of thedredge was frequently tied up at the lower end. or sometimes a simple canvas bag alone(mud bag) was attached to the frame. During the last season of the regular dredgingwork (1905) the mud bag was nearly always employed in connection with the beamtrawl. It is obvious that a much fairer bottom sample could be collected in this way.'The dimensions of the frame in the type most commonly used during the Fish Hawkdredging were 12 by 22 inches. A smaller size (8 by 16 inches) was. however. sometimesused in the Phalarope and Blue Wing work.(3) The third type of dredge employed was the oyster dredge. This was intermediatein size between the beam trawl and the scrape dredge and was very heavilyconstructed. being well adapted to use upon rocky bottoms. The scraping edge at themouth of this implement was armed with powerful spikes or teeth. designed to dig deeplyinto the sand or gravel. The bag of the dredge was made up of iron rings. linkedtogether after the fashion of chain armor. In order to retain the smaller organisms.this chainwork bottom was commonly lined with fine netting. The oyster dredge wasemployed on bottoms too stony for the other appliances. or where it was desired topenetrate more deeply beneath the surface.The Fish Hawk is a steam vessel having a length of 146 feet at the water line. orof 156 feet over all. a beam of 27 feet. and a draft of about 7 feet. She carries adequatemachinery for the reeling in of heavy dredges. and despite her limited speed and unseaworthyconstruction is an extremely serviceable vessel for scientific operations in quietwaters. A full description of the Fish Hawk has already been given by Tanner (1884).and therefore need not be repeated here.The material taken by the Fish Hawk dredges was commonly emptied into a seriesof trays. constituting the table sieve of Verrill and Chester (Verrill. 1883). having gradedmeshes. the coarser ones naturally being uppermost. After a superficial examinationand preliminary search for specimens a stream of salt water was played upon the material.and the sand. mud. and small unattached organisms were thus washed into theunderlying. smaller-meshed trays. The contents of each tray were examined in turn.according to a system to be described later.The Tanner sounding apparatus a was employed at each of the Fish Hawk stations.together with the Sigsbee water specimen cup. and the Negretti-Zambra thermometer.Thus the temperature and density were recorded. as well as the depth of the water.It was later realized. however. that the figures for temperature and density obtainedduring the regular dredging operations were not sufficiently exact for the purposes ofthe work. and. likewise. that no fair comparison would be possible of the differentwaters in the region unless we possessed a set of determinations which had been madenearly or quite simultaneously throughout its entire extent. For this reason a new setof temperature and density observations. taken with standardized instruments andwithin the briefest period possible. was made after the completion of the dredgingwork. Such determinations were repeated several times at intervals of a few months.so that the seasonal conditions are now pretty well known. These will be discussed ina later section.The position of the vessel was determined in the earlier part of the work by meansof an azimuth compass located on the roof of the deck house. just abaft the pilot house.Bearings were taken upon two. sometimes three. landmarks. usually lighthouses. Thiswas commonly done just before the lowering of the dredge. The station. as recordedon the chart. was thus the point where the dredge haul commenced. while thedirection and amount of the drift was estimated rather roughly. Later. tripods wereerected upon a number of Coast Survey triangulation points and sextants were employedin locating the ship's position. Angles were taken simultaneously by two observers.one of whom found the angular distance between X and Y. the other that betweenY and Z. The position of the vessel was determined both at the beginning and at theend of the dredge haul. and frequently at one or two intermediate points. Thus uponthe maps the later stations in Vineyard Sound appear not as single circles but as straightor curved lines. at intervals in which are to .be found the points (a. b. c. etc.) at which? sextant readings were taken.The Phalarope is a steam vessel. originally designed as a yacht. having a length of82 feet at the water line. or of 92 feet over all. and a beam of 16 feet. She draws 7Ufeet of water. and her average speed is probably about II knots. The Phalarope carriesno dredging machinery and is not permanently equipped for this work. In landing thedredge a small derrick was employed. this being operated by hand power. The contentswere emptied upon a special movable platform built over the forward cabin. A set ofsieves was employed similar in principle but smaller than those used on the Fish HouikWith this vessel the use of the beam trawl was impracticable. and even the oyster dredgewas too heavy to be employed very frequently. though it was used to advantage undercertain conditions. The second type of dredge mentioned above was therefore the.principal one employed.Since the Phalarope dredging was. for the most part. done within a quarter of amile from land. it was found to be possible to locate the stations with a fair degree ofaccuracy by reference to features of the shore. Bearings upon lighthouses were notcommonly practicable. nor indeed were they believed to be especially desirable. Thesoundings indicated. with sufficient precision. the distance from land. and the directionof various landmarks was noted. An ideal degree of accuracy in locating these stationsmight have been attained through the sacrifice of much time and effort. but it is doubtfulwhether the scientific value of this report would thereby have been greatly enhanced.In the case of both vessels the same general procedure was adopted in respect tothe listing and the preservation of material. One or more of the authors of this reportaccompanied each dredging trip. and one or several assistants were detailed from thelaboratory staff. On many occasions specialists interested in particular groups oforganisms accompanied us on these expeditions and participated in the identifications.The more obvious and easily recognizable species were listed on the spot. mention beingmade of their relative abundance and other facts of interest. These observations weredictated to an assistant. At the same time samples of the sand. stones. mud. seaweed. etc..and any specimens concerning which the least doubt was entertained were preserved. witha record of the station from which they came. This material was later sorted over in thelaboratory and further species were identified and listed. Those concerning which therewas still any doubt were bottled and subsequently referred to the proper specialists. Unit of abundance = AggregatedPresence, Unit of biomass = NA

Citation(s)

Sumner, F. B., Osborn, R. C., Cole, L. J. & Davis, B. M. "A biological survey of the waters of Woods Hole and vicinity". Available at: http://www.iobis.org, accessed 2012.
Sumner, F. B., Osborn, R. C., Cole, L. J. & Davis, B. M. (1911) A biological survey of the waters of Woods Hole and vicinity. Bulletin of the U.S. Bureau of Fisheries, 31, 1.