Influence of the water-accommodated fraction of no. 2 fuel oil on energetics of Cancer irroratus larvae

The influence of the water-accommodated fraction of No. 2 fuel oil on aspects of larval development of Cancer irroratus (Say) has been investigated. Rates of survival, respiration, ingestion and growth were estimated for both oil-treated and untreated larvae. Larvae reared in oil-treated water exhibited lower survival to megalopa than did larvae reared in untreated water. The presence of oil also altered several aspects of larval energetics. Reductions were seen in food consumption and growth rate while the metabolic cost of maintenance increased. One overall effect that may occur as a result of lowered larval survival and growth rate would be the reduction in larval recruitment in oil-polluted areas.     

Influence of predation on infaunal abundance in Upper Chesapeake Bay,USA

The importance of predators in controlling the densities of infaunal (>0.5 mm) organisms was investigated in the mesohaline region of the Upper Chesapeake Bay (USA) using field experiments. The role of predators in controlling infaunal density and community characteristics varied with habitat type, season (i.e., predator abundance) and developmental or successional stage of the community. Few infaunal species were adversely affected by predator exclusion. Species that increased greatly in abundance in the absence of predators (e.g. Eteone heteropoda, Streblospio benedicti, Nereis succinea, and juvenile Macoma balthica and Mya arenaria) lived near the sediment-water interface and had major population pulses from fall through spring. Species whose abundances increased moderately or were not affected by predator exclusion were deeper burrowing organisms (e.g. Heteromastus filiformis and adult Mya arenaria), or were relatively small organisms (e.g. Paraprionospio pinnata, Scolecolepides viridis and Peloscolex gabriellae) whose principal predators could be other members of the infauna. Competition did not appear to be an important factor controlling infaunal density in these experiments.This work is Contribution No. 973 of the Center for Environmental and Estuarine Studies of the University of Maryland     

Plankton of the fladen ground during FLEX 76 II. Population dynamics and production of Thysanoessa inermis (Crustacea: Euphausiacea)

Samples taken in the northern North Sea with the Continuous Plankton Recorder (CPR), the Undulating Oceanographic Recorder (UOR) and the Longhurst-Hardy Plankton Recorder (LHPR) during the Fladen Ground Experiment in 1976 (FLEX 76) are used to describe the vertical distribution and population dynamics of Thysanoessa inermis (Krøyer) and to provide estimates of the production and carbon budget of the population from 19th March to 3 June 1976. Spawning occurred in late April and early May, in near synchronisation with the start of the spring bloom of phytoplankton. Eggs, nauplii and calyptopes reached maximum abundance in succession, and furciliae were numerous when sampling ceased in early June. Adults increased in length from a mean of 12.1 mm in mid-March to 17.5 mm in early June and the estimated production was 2.40 mg m^-3 over the 74 d period. Total carbon ingested by the population of T. inermis was estimated to be 10 mg C m^-2 d^-1 in the upper 100m which was only 1.5% of the daily primary production of 0.68 gC m^-2 measured over the FLEX period 26 March to 4 June 1976. The grazing by T. inermis on the phytoplankton population was assumed to have little effect on the control and depletion of the spring phytoplankton bloom during FLEX 77.JOSDAP Contribution No. 50     

Territorial behavior of the black and yellow rockfish and gopher rockfish (Scorpaenidae,Sebastes)

Tagged black-and-yellow rockfish Sebastes chrysomelas and gopher rockfish S. carnatus were observed in situ for 1 yr at 3 study sites off California, USA in order to determine the nature of their home ranges and territories. Three basic patterns of space use were identified: (1) a shelter hole located within a larger area of activity (in which the fish presumably fed, since its size increased with size of fish and decreased with prey density); (2) discontinuous home ranges, in which the shelter holes and feeding areas were separte; and (3) dispersed home ranges with little or no exclusive area. Fish in the first category were regarded as territorial, since their home ranges were defended and relatively exclusive. Because individuals did not patrol borders, however, territories often overlapped at their peripheries. In addition, some territory holders appeared to tolerate the sheltering of other fish within their territories, as long as these intruders left the territory during periods of activity. Some fish with discontinuous home ranges (commuters) may have been territorial, but others may have been forced to occupy suboptimal feeding areas. Fish in the third category (floaters) were regarded as nonterritorial; their activities were apparently limited to areas where they could escape the aggression of territory holders. The varying patterns appeared to develop through defense and accommodation during the turnover of individuals, with each fish securing shelter and feeding areas as these became available.     

A flume study of drift in marine infaunal amphipods (Haustoriidae)

Amphipods of the infaunal family Haustoriidae are characteristic of high-energy marine sands and occur both in the sediment and the overlying water column. Sediments in this habitat are subject to constant reworking by tidal currents, suggesting that resident amphipod populations are affected by this disturbance in a phenomenon similar to freshwater invertebrate drift. A controlled-velocity laboratory flume was used to examine the effect of haustoriid density, current velocity, illumination, and food availability on drift rates to determine a causal basis for drift. Drift is densityindependent and greatest at night and during high current flow; it is also greater at night from sterile sediment than from untreated sand. Flume transport was usually less than 10% of amphipods present in the sediment. Haustoriids captured downstream were mostly adults occurring in a 1:1 sex ratio, suggesting no obvious function of drift in reproduction. Current-induced displacement of haustoriids may produce the patchiness in distribution observed in nature. Disturbance of the bed could also function to keep amphipod densities below the carrying capacity of the local environment. In certain cases, food limitation may cause amphipods to actively leave the substrate. Under all conditions, greater drift rates in darkness are probably adaptive in avoidance of predators. Despite the nature of sediment movement in a high-energy environment, haustoriid drift may have an active as well as passive component.     

The megabenthic fauna in the deep sea south of New England,USA

Data from 105 benthic trawls made in an area south of New England, USA between 40 and 5000 m show the fauna to be zoned with depth, areas of rapid faunal change separating regions of relative faunal homogeneity. Distinct faunal assemblages with characteristic catch rates, diversity, and dominant species are found on the shelf (40 to 264 m), upper continental slope (283 to 650 m), middle continental slope (653 to 1290 m), lower continental slope (1380 to 1947 m), the transitional region from slope to rise (2116 to 2481 m), the upper continental (2504 to 3113 m), the middle continental rise (3244 to 3470 m), and lower continental rise to abyssal plain (3879 to 4986 m). Catch rates and diversity are greatest on the lower continental slope and transition to the upper rise, and are lowest at the greatest depths. Dominance, particularly by echinoderms, is an important aspect of community structure. The 3 major taxa represented (decapod crustaccean, echinoderms, and fishes) do not always display the same patterns within and between assemblages. Generalities derived from study of a single group need not apply to all segments of the deep-ocean community. Overall patterns in the megafauna are similar to those described in other groups and areas, but species assemblages are not the same everywhere and perhaps too much has been made of the horizontal extent of zones. Trophic level is related to degree of zonation, but where predators are generalists their ranges may be wide rather than restricted. Diversity patterns can be understood in terms of the interrelationships of predation, competition, environmental heterogeneity, and trophic level. Faunal zones are of importance as the geographical units within which evolution, community development, and diversification take place.This research was supported by the National Science Foundation under Grant OCE76-21878, the Office of Naval Research under Contract N00014-74-C0262, and, in part, by the United States Department of Energy under Contract No. EY-76-C-02-0016 and the Canadian Natural Sciences and Engineering Research Cancil under Grant A-7230     

Turnover of tracer (14C, 3H labelled) alanine in inshore marine sediments

The turnover rate constants (k) of alanine in coastal marine sediments were measured using ³H-and ¹⁴C-alanine in tracer amounts (less than in situ concentrations of alanine in the porewater). After incubation ¹⁴C-label was recovered in free dissolved alanine, adsorbed alanine, volatile fatty acids and carbon dioxide pools. Alanine left the free dissolved pool by two processes: 1) adsorption (k=0.06 min^-1) and 2) biological uptake (k=0.16 min^-1). Adsorption of alanine was deduced from the persistence of ¹⁴C-alanine, which was slowly metabolized after an initial rapid rate of degradation. Adsorption was confirmed in biologically inactivated sediments. The adsorbed ¹⁴C-alanine was only partially exchanged by the addition of excess non-labelled alanine, indicating the existence of at least 2 different adsorbed pools. The rates of adsorption and desorption were equal, but the k-values were different, indicating that the adsorbed pool was 2500 fold greater than the free pool. From the biological turnover rate constant (0.16 min^-1), the mineralization percentage (80%) and the concentration of alanine (800 nmol l^-1 of porewater) a mineralization rate in the sediment of 75 nmol cm^-3 d^-1 was determined. This was in excess of the measured total NH ₄ ⁺ production. It is concluded that much of the dissolved alanine (800 nm) was biologically unavailable and a more realistic free dissolved pool would be 10 nM.     

Influence du niveau sonore de bruit ambiant sur le métabolisme de Crangon crangon (Decapoda: Natantia) en élevage

The influence of ambient noise on the metabolism of the sand-shrimp Crangon crangon L. was estimated from NH₄ excretion and O₂ consumption rates. Two ambient noise levels were compared: the first (+32 dB bar⁺¹) was that present under usual rearing conditions, the second (+5 to 0 dB bar⁺¹) was the level in a soundproof rearing tank. Over a 24 h period, NH₄ excretion and O₂ consumption rates were higher by 1.4 times and 1.2 to 1.4 times, respectively, under the noisy conditions than in the sound-proof tank. The influence of ambient noise level on the shrimp's metabolic level appears to be long-lasting(>1 month). When the acoustic pressure of the environment was increased abruptly, the excretion rate was strongly enhanced but oxygen consumption was reduced; these stress-effects usually disappeared within 3 h. The influence of ambient noise on the metabolic level of this shrimp should be taken into consideration during physiological studies as well as rearing experiments in the laboratory.     

Theory of equity in pricing for resource conservation

This paper seeks to construct some theoretical tools that can be used to examine formally the equity issues raised in the use of pricing as a means to conserve scarce resources, in particular, the criteria that can be used to judge the equity of such a price change and the special problem raised by differences in elasticity of demand of different customer groups are considered. Toward this end the concept of a “superfair” distribution (a distribution under which each and every participant obtains a share of the total which is equal to or greater than that individuars pro-rata share, in his own estimation) is introduced and discussed.