Benthic Surveys Research Articles

A summer benthic survey in Conception Bay, Newfoundland, emphasizing zoogeography of annelids and amphipods

A limited benthic survey was made in August in Conception Bay, Newfoundland, using a 0.2-m2 van Veen grab sampler. Nine stations were sampled in a relatively shallow (62–79 m), soft-bottom (predominantly silt) region with low bottom water (0.2–1.4 °C) and sediment (0.5–2.0 °C) temperatures. Annelids (32 species) and amphipods (18 species) were the common invertebrates collected, with annelids being more numerous, both in numbers of individuals and of species. Deposit-feeding annelids outnumbered carnivores, with subsurface deposit feeders more abundant than surface feeders. Sedentary individuals predominated. Most annelid species had boreal–temperate affinities, with few arctic species being present. Detritivorous amphipods predominated, followed by scrapers and scavengers. Nearly all were burrowers. All the amphipod species were arctic–boreal in distribution and most do not range as far south as do the annelids. Molluscs were small and uncommon and they, like the remaining uncommon components of the biomass, were not identified to any extent.

Submersible surveys of benthos near a turbidity cloud

Seabed impacted by settling solids from a turbidity plume can be surveyed by submersible using a ‘bounce’ technique to determine depth of the turbidity front, and hence depth above which benthos observations are practical. The protocol adopted was that after frontal depth was determined by a preliminary dive, the site for the benthic survey was selected. On arrival on the seabed a reconnaisance was made for the observers to agree on the identification of visible benthos. Then 100 × 1 m 2 transects were surveyed using a 1 m 2 quadrat attached to the submersible in view of the port-side observer. At the site investigated, two shallow water stations (depths 13–15 m, and 16–18 m) showing light deposits of mine tailings were seen to support associations of large epifauna and infauna. The first station had an almost single-species stand of the burrowing anenome Pachycerianthus fimbriatus at approximately 100 · 100 m −2, and the second a diverse species association with several starfish and other species at 1–2 · 100 m −2. Burrow holes (up to 3–5 cm diameter) of various sizes indicated that large infaunal species were present. At a deeper station (36–27 m) with heavy tailings and almost no burrow holes, a single Dungeness crab, Cancer magister, and an unidentified shrimp were seen in the 100 m 2 transect. Each dive site was inshore (shallower) from a routinely monitored benthos station shown repeatedly to support a population of small infauna in the tailings. Burrow holes have the potential for determining the identity and abundance of large infaunal species present if an identification system can be developed. The technique of epifaunal and burrow hole surveys (by submersible and scuba diver), combined with infaunal and sediment core surveys and contemporary theory on infaunal succession, provides the potential for a procedure to map the distribution in shallow water of tailings impact and benthic recovery (succession).

Profiling coral reef productivity and calcification using pH and oxygen electrodes

An instrument package carrying pH and oxygen electrodes and a thermister was floated across a reef flat. Using equations associated with the alkalinity anomaly technique, and by making certain assumptions, the productivity and calcification rates of the reef flat were calculated. At an average light intensity of 800 μE · m −2 · s −1, the average net oxygen production was 21.5 mmol O 2 · m −2 · h −1 and the average rate of calcification was 11.0 mmol CaCO 3 · m −2 · h −1. Results showed three metabolic zones within the transect which corresponded to zonation seen in an aerial photograph and confirmed by benthic surveys.

Multiple discriminant analysis of macrobenthic infaunal assemblages

Multiple discriminant analysis is applied, in a general benthic survey, to correlate the animal associations with some measurements of physical and chemical variables. Four major macrobenthic assemblages are identified in the study area. In addition, species characterizing the various faunal groups are defined. The delineation of such animal assemblages is mainly due to the relative organic carbon content and the fine silt-clay fraction (positive graphic skewness) of the sediment, which is largely deposited in the sampling area by a river drainage. The application of multiple discriminant analysis to demonstrate such correlative relationships between biotic and abiotic variables in benthic studies is discussed.

The family Paraonidae (Polychaeta) in british waters: a new species and new records with a key to species

Aricidea laubieri sp.nov. and six other species of the Paraonidae new to the British Isles were found during benthic surveys in the Celtic and North Seas. These increase the number of British representatives of the family to 15. New records of a further seven species are given, which in several cases extend the known geographical or bathymetric range. The identity of some previous records attributed to Aricidea Jeffreysii (McIntosh, 1879) and to Aricidea suecica Eliason, 1920, is discussed. A dichotomous key to British species is presented.

Five species of polychaete new to British waters

In the course of benthic surveys carried out around the U.K. by the Oil Pollution Research Unit, a number of species of polychaete not previously recorded from British waters were found. A new species of Aricidea and six other species of the Paraonidae new for Britain have been described by Hartley (1981), and this note records a further five species taken either in the Firth of Forth (56° 19′ N, 3° 34.8′ W, 2–5–5 m depth, fine sand) or in the Forties oilfield (57° 44.0′ N, o° 54°0′ E, 100–130 m depth, fine to muddy sand) with 0.1 m2 Van Veen/Day grabs in September 1979 and June 1978 respectively. The sieve mesh used was 0.1 mm diameter.

A Physico-Chemical Method for the Extraction of Marine and Estuarine Benthos from Clays and Resistant Muds

In making benthic surveys it is often difficult to extract all the animals from the various sediments in good condition. Even the IBP Handbook (Holme & Mclntyre, 1971) does not give comprehensive details of methods for extracting animals from the complete range of sediment types. The greatest difficulty is presented by clays and compacted silt. In recent work we have had very satisfactory results by using the following procedure. Core and grab samples taken in the field are stored in seal-tight buckets for processing in the laboratory. In the case of grab samples taken from boats, preliminary sieving is performed on site and only the resistant sediments returned to the laboratory. The samples are broken into pieces of approximately 100 cm3 or less and stored in 5 % formaldehyde solution using a volume about three times that of the sediment. This serves to fix and preserve the fauna and also helps in the breakdown of clays. At this stage samples may be stored for a long time. Wherever layers of soft mud are found among the resistant material they are washed off, sieved and the fauna preserved separately. The resistant samples are then frozen in a domestic freezer and left for 24 h before thawing. The freezing is very effective in breaking down resistant sediments into small particles, thus releasing the animals, which can readily be removed by elutriation. Normally, most animals seem to be adversely affected by freezing in much the same way as some vegetables lose their consistency when frozen (an exception to this are members of the polychaete family Phyllodocidae). However, the prior treatment with formalin seems to protect the tissues from damage by freezing.

Does improved waste treatment have demonstrable biological benefits?

Since 1972, 10 benthic surveys and 9 static fish bioassays have been conducted to assess the impact of AVTEX Fibers, Inc. effluent on the lower South Fork of the Shenandoah River. AVTEX (formerly FMC Corp.) is a rayon and polyester fibers plant located in Front Royal, Virginia. Benthic samples were taken at four stations, one above and three below the plant discharges. Single surveys in 1972 and 1973 indicated a severe impact on the benthic community along the right side of the river, below the plant, as a result of the channelized effluent. Diversity values (¯d) were low (0–2.42) and numbers of taxa and organisms were reduced. A fish bioassay in 1973 indicated the effluent to be acutely toxic at the 34.5% level (mixture of effluent and river water). In early 1974, FMC Corp. constructed an activated sludge treatment system to reduce BOD and supplement the neutralization and chemical precipitation (zinc hydroxide and liquid-solid separation) facilities that had been used to treat waste waters since 1948. After the new equipment was placed in operation, the previously stressed area became more stable. In 1975 and 1976 the stressed area exhibited greater ¯d values (1.19–3.39) and an increased number of taxa and organisms. Bioassays showed the effluent to be acutely toxic to fish only once since 1973. The major improvements in the effluent were a 70% reduction in BOD5 and a 60% reduction in the amount of zinc entering the river. Community conditions in 1977 indicated a partial remission of improvement, probably due to drought conditions. The rehabilitation of damaged ecosystems is a process important to all biologists. An important factor in encouraging industry to participate in this activity is evidence that improved waste treatment will often have demonstrable biological benefits rather soon. As data accumulate on the recovery process it may be possible to predict the degree of rehabilitation and time required more precisely.

Canonical correlation analysis of marine macrobenthos survey data

Canonical correlation analysis is applied to measurements of environmental variables and species distributions made during a survey of macrobenthos around a sewage-treatment farm drain. The implications of data reduction, necessary to enable the method to proceed, are discussed. The amount of data was reduced by discarding the rarest species, discarding species occurring at fewest stations, and including only those species and environmental variables which correlated highly with the greatest number of other variables. Only the third data-reduction scheme gave ecologically sensible results. Use of station scores on the first two canonical variates (CV1 and CV2) enabled the sampling grid to be divided into a group of nearshore stations, a group of intermediate depth, and a group of deep offshore stations. Loadings of environmental variables on the canonical variates were found to be unstable but correlations between these variables and canonical variates enabled the variates to be interpreted: CV1 as a gradient of depth and associated changes in sediment characteristics, CV2 with depth- and nutrient-related components, and CV3 as patchiness in sediment characteristics different from that normally expected with depth. Use of correlations between species and canonical variates enables definition of two major species groups, one confined to nearshore environments and a second offshore. These groups (and their sub-groups) related well to groups defined previously by hierarchical classification. It is concluded that, with careful attention to the method of data reduction, canonical correlation analysis can be an effective tool in the analysis of marine benthic survey data.

An attempted pollution abatement in the Gulf of La Napoule (Cannes, France)

A benthic survey was carried out in 1973 at the servicing of a 1285 m long submarine pipe designed to achieve pollution abatement in the Gulf of La Napoule (Cannes, French Mediterranean coast) and repeated 4 years later (1977). This last survey points to a good recovery of benthic communities in the eastern part of the Gulf (off Cannes) but a severe change in the western part of the Gulf with the appearance, in a deposition area, of the species Scolelepis fuliginosa and Capitella capitata which are highly characteristic of polluted areas and which had not been sampled during the first survey.

Two new species of Ctenostomata (Bryozoa) from the Norwegian Sea

Abstract A small collection of bryozoan material from the deep waters of the Norwegian Sea yielded a total of six taxa, including Aethozoon pellucida gen. and sp. nov., and Flustrellidra inarmata sp. nov. The potential value of deep-water benthic surveys is discussed briefly. The bryozoan fauna comprises a high proportion of new or little known species and interesting bathymetric distributions are emerging.

Benthic and epibenthic macroinvertebrates of the Hudson River: I. Distribution, natural history and community structure

A 1972 benthic survey of the invertebrate fauna represented the first spatial and temporal investigation over a large portion of the Hudson River estuary. The benthic investigation was one segment of a team effort which included phytoplankton, zooplankton, ichthyoplankton and rooted aquatic plants. The 55 stations that spanned an 80-mile area from New York Harbor to Poughkeepsie were sampled four times with a modified Petersen dredge. One hundred and five taxa were identified. Ten groups accounted for 95% of the organisms found. These included 19 species of polychaetes, 13 genera of chironomids, 10 species each of bivalves and gastropods, 8 species each of amphipods and decapods and 6 species of isopods. Salinity was one of the most important measurable factors controlling species range and community boundaries. The number of species was highest in the polymesohaline zones and lowest in fresh water. Stations with the highest numbers of animals were located south of the Tappan Zee Bridge. Many of these stations contained an average of 10 000 organisms/m 2 or a peak total of 60 000/m 2. In stations south of Haverstraw Bay, the populations of benthic fauna equalled or exceeded those populations found in other estuaries throughout the world. The highest densities reflected the presence of 4 species, e.g. 2 polychaetes, Streblospio benedicti and Scolecolepides viridis, the isopod, Cyathura polita, and the bivalve, Mya arenaria. Faunal homogeneity analysis by Sanders' affinity index system indicates the presence of broad communities within the 80-mile sampling area. This conclusion may be obscured, however, by the presence of two large complexes, the oligochaetes and the chironomids, which were not identified to species.

A DISTANCE-MEASURING WHEEL FOR ESTIMATING SUBSTRATE SURFACE AREA

Summary A submersible distance-measuring wheel for determining surface area enclosed by benthic survey quadrats is described. The instrument permits the accurate determination of actual substrate surface area on an uneven sea bottom. The device is inexpensive, hand held and battery operated. An example to demonstrate its use is included in the text.

A new towed underwater camera system for wide-range benthic surveys

Following a short review of previous underwater camera systems, a new combined underwater camera system, consisting of a remote controlled TV- and photocamera mounted on a ship-towed steel-tubing sled, is described. The method of using this apparatus for wide-range surveys of the marine littoral benthos, and the techniques used to evaluate and quantify the observations are presented. On the basis of first results obtained in the North Adriatic Sea, the efficiency of the new system is compared with various other instruments and techniques. Advantages and disadvantages, possible improvements, and future prospects are discussed.

The classification and ordination of shallow-water benthic samples from Prince Edward Island, Canada

This paper gives an account of a benthic survey of the Bideford River estuary in north-west Prince Edward Island. Four transects, from M.L.W. and running perpendicular to the shore, were sampled every 5 m by a diver-operated suction dredge. Plants were recorded as dry weight and animals as both numbers and dry weight. Major trends in the data have been isolated by the multivariate statistical techniques of cluster analysis (classification) and principal components analysis (ordination). Classification produced hierarchical groupings of individuals (stations or species depending on the type of analysis) which are displayed as dendrograms. The structure shown in the dendrograms focusses attention on individuals which are important indicators of the ecological factors giving rise to the observed distribution of the benthos. After a mathematical transformation of the original data, principal components analysis gave 3–5 new coordinates which together accounted for over 50 % of the total variance. Individuals were given loadings on each of the new coordinates. The first few coordinates represented important ecological factors affecting the distribution of the benthos. Individuals with high loadings on the coordinates were used as indicators to identify these factors. Both classification and ordination led to the same conclusions. In all four transects the littoral stations were divided into upper and lower zones influenced by a gradient of tidal emersion. Sublittoral stations were influenced by several factors correlated with the distance from shore. Probably the extent of sea-ice in winter and the influx of fresh water during the spring thaw are important. A Yoldia-Tellina community was associated with finer sediments in all transects, but the rest of the benthos was not clearly associated with substratum-type.

The Occurrence of the Brackish Water Clam, Rangia cuneata, in the Potomac River, Maryland

The brackish water clam,Rangia cuneata, previously reported to occur from Virginia to the Gulf of Mexico, has been found in the Potomac River, Maryland, where they have been consumed for food. Current sampling of the population, compared with previous benthic surveys, indicates that the species has been established in the Potomac River only since about 1960. Introduction is believed to have been made along with seed oysters transplanted from the James River, Virginia.