George D. Grice

Large-Scale Enclosed Water-Column Ecosystems an Overview of Foodweb I, the Final CEPEX Experiment

Enclosures of various sizes and configurations have been employed to maintain natural planktonic communities and to examine their responses to pollutants (e.g. Menzel & Steele, 1978; Steele, 1979). Studies on feeding, growth, and mortality of larval fishes, at times conducted in conjunction with pollution experiments, have also been successfully conducted in large enclosures (Koeller & Parsons, 1977). Implicit in these and other comparable studies has been the expectation (or hope) that a balance could be achieved between the advantages and difficulties inherent in more traditional field and laboratory studies. Field studies offer the realism of working with the natural assemblage with its many interacting components and links, but also suffer the disadvantage associated with a turbulent and advective system, which generally makes the repetitive sampling of the same populations impossible. Laboratory studies reverse the balance; control and definition of the components are gained at the expense of realism. The use of large containers represents a hybrid approach characterized by a partial control over a moderately realistic ecosystem. In the ideal case, the use of large containers allows sufficient control to permit experimental manipulation of (and the testing of hypotheses concerning) planktonic assemblages which are sufficiently realistic to permit extension of the experimental results to the ‘real world’.

Acid-iron waste as a factor affecting the distribution and abundance of zooplankton in the New York Bight: I. Laboratory studies on the effects of acid waste on copepods

Laboratory experiments were conducted using three species of copepods to study the effects acid-iron wastes might have on zooplankton. Individuals of Calanus finmarchicus, Temora longicornis and Pseudocalanus sp. were maintained in bottles containing varying dilutions of acid wastes in sea water or control sea water solutions for 24 to 48 hours to examine survival of adults exposed to high concentrations of waste. They were also maintained for time periods up to 18 days to ascertain effects on reproduction and survival of young. In addition, individuals of C. finmarchicus were transferred through a series of increasing dilutions of acid wastes and into filtered sea water to simulate the short-term effects of acid waste concentrations in the wake of a discharging barge. Substantial mortality of adults of the above three copepods occurred at concentrations of acid waste producing pHs of approximately 6·5 and lower. However, this mortality is not indicative of mortality in the field as these concentrations and pH values exist for only a short time (less than 3 min) due to rapid mixing of the acid waste with sea water. Individuals maintained in buffered acid wastes of comparable dilutions showed no mortality, while individuals maintained in test media using sulfuric acid in place of acid waste showed high mortalities at pHs of 5·5 or less. Thus, acidity of test solutions may be a principal cause of copepod mortality rather than some toxic component of the waste material. Inhibition of reproduction and deleterious effects on survival of young were observed in experiments of 18 days duration at concentrations of acid wastes which do not in fact persist for such periods on the acid grounds. No mortality was observed when C. finmarchicus was transferred through acid waste dilutions with pH values and time periods comparable to those they would encounter on the acid grounds during discharge of acid wastes. Acid waste discharges, therefore, did not appear to be responsible for the large variations in zooplankton biomass previously observed in the survey area since mortality of species due to short term exposure to high concentrations of waste appears small and little effect on adults or larval forms at great dilutions could be demonstrated. Although the average biomass from the acid grounds was 30% less than that from the adjacent control area, this difference could not be directly linked to the toxicity of acid-iron waste. The spatial pattern of biomass variations and the results from the initial laboratory toxicity studies suggested the difference was probably due to a transitory large scale patchiness of zooplankton. We have conducted further laboratory studies on the effects of acid wastes on copepod species that occur in the area where acid waste is discharged. The results of these experiments are reported here. We have also counted the zooplankton samples collected at the time of our synoptic field sampling survey of the acid waste dumping site and a nearby control area. The analysis of these data and the implications to the observed distribution of zooplankton biomass and to monitoring studies are presented in the succeeding paper (Wiebe et al., 1973).

Trophic Interactions and Production Processes in Natural Zooplankton Communities in Enclosed Water Columns

A major advantage of large volume in situ enclosures over small-scale laboratory cultures is that the large enclosures enable study of interactions at higher trophic levels while maintaining environmental concentrations of organisms typical of the natural environment. Small-volume cultures have been used successfully to investigate the dynamics of natural assemblages of phytoplankton species--

Acid-iron waste disposal and the summer distribution of standing crops in the New York bight

Abstract Ecological consequences arising from the disposal of 50 million tons of acid-iron industrial waste in the coastal waters off New York over the past 22 yr were assessed. Most of the data were obtained at two identical grids of stations which enabled comparisons of hydrographic, chemical and biological conditions within the acid-iron disposal area with similar parameters in a nearby control area. Supplementary information on benthos and sediment was obtained at other locations peripheral to the two station grids and in Hudson Gorge, and these were used to construct a synoptic picture of the physio—chemical conditions and standing crops in the New York Bight. At each grid station the hydrographic measurements made were temperature, salinity and light penetration; chemical observations consisted of dissolved oxygen, dissolved and suspended iron, total inorganic nitrogen and phosphate; while chlorophyll α, zooplankton and benthos biomass provided a measure of the abundance of standing crops. Trace metal spectra (Fe, Zn, Co, Cu, Pb, Cr, Ni and Cd) were determined on selected zooplankton, benthos and sediment samples. Laboratory toxicity studies were conducted on phytoplankton and zooplankton species at several concentrations of acid-iron waste in seawater. The maximum concentration of iron in the water column (832 μg 1−1) occurred as suspended material within a restricted area of the acid grid. In terms of raw acid-iron effluent this suggests a maximum in situ concentration of 1 part waste in 39,000 parts of seawater thereby providing a useful guide for the design of laboratory toxicity studies. Despite the abundance of suspended iron in the overlying water of the acid-grid the average concentrations of iron in the sediments of both the acid and control grids were remarkably similar, while sediments from the nearby Hudson Gorge were notably richer in iron. However, a comparison of previous measurements in the study area dating back to 1948 indicates that there has been no accumulation of iron within the sediments below the disposal area or Hudson Gorge over the past 22 yr. The phytoplankton toxicity experiment conducted with an acid-iron waste concentration four times greater than that observed in the field showed no adverse effect on phytoplankton growth or diversity. Similar experiments with copepods caused either failure of these organisms to reproduce or a delay in the time required to transform eggs into adults. Although the average zooplankton abundance within the control grid exceeded that of the acid grid by about 30 per cent, the range of values describing zooplankton abundance in the two areas was similar. This difference was attributed to a transitory large scale patchiness in the area and not to toxicity of acid-iron waste. A positive correlation was found between Fe:C in zooplankton and the amount of particulate iron present in the seawater. The average number of benthic animals on the bottom of the acid grid area was significantly less than in the sediment of the control grid but there was no difference in biomass or species diversity between the two areas. As was the case with zooplankton the higher Fe:C in the benthos corresponded to the higher iron in the sediment of Hudson Gorge and acid-grid. The heavy metal content of zooplankton, benthos and sediment showed that samples from the acid grid were significantly richer in these elements than the comparable control area samples. However, a broader comparison showed that samples from Hudson Gorge contained the maximum amounts of lead and chromium in benthos as well as the maximum concentrations of all eight metals in the sediment. These data are consistent with the possibility that entrapment in the gorge sediments may be the ultimate fate of the heavy metal enrichment in the New York Bight area and that sources of heavy metals other than acid-iron waste may be substantial. The remaining data reviewed in this study did not demonstrate any adverse in situ effects of acid-iron waste on the distribution of such parameters as dissolved oxygen, chlorophyll α and plant nutrients. Present indications are that the disposal of acid-iron waste in the New York Bight appears to influence standing crops in minor ways considering the magnitude and nature of the waste material involved.

Acid-iron waste as a factor affecting the distribution and abundance of zooplankton in the New York Bight: II. Spatial variations in the field and implications for monitoring studies

Abstract A study was undertaken in the New York Bight in an effort to understand small scale variations of single species populations and coastal zooplankton communities as they relate to the disposal of acid wastes. Two grids of eight locations each, one day and one night station per location, were placed so that one covered the acid grounds and the other a similar area functioning as a control 9 km to the northeast. Thirty-nine taxonomic categories of zooplankton were counted from oblique net tow samples collected at the 32 stations. Biomass was determined from length measurements of individuals of 24 taxa. Species composition of the samples was typical of neritic waters of the north-east Atlantic coast. The spatial distribution of the majority of the species was markedly aggregated, but no trend was observed which would suggest that the acid wastes were an important factor in shaping the distributions. Species did not show collective agreement as to the area in which a higher average abundance for each occurred; and no significant trends in percent similarity or diversity (Simpsons D and the information theory H ′) were evident. Although Vaccaro et al. (1972) found zooplankton biomass to be approximately 30% higher from the control area than from the acid grounds, comparison of the biomass difference between the two areas on a species by species basis showed that 95% of the overall difference was accounted for by only three species, Pseudocalanus sp. and its copepodids, Calanus finmarchicus copepodids and Temora longicornis . The acid-iron wastes appeared to be a minor factor affecting the distribution and abundance of zooplankton species during the time of this investigation. The laboratory data reported in the preceding paper (Grice et al ., (1973)) support this conclusion. Empirical measures of the variability of single species populations and community indices presented in the text may be useful guides for future surveys or monitoring studies.

Resting Eggs in the Marine Calanoid Copepod Labidocera Aestiva Wheeler

[Winter- und Sommereier wurden nachgewiesen und beschrieben fur den calanoiden Copepoden Labidocera aestiva. Wintereier, die von im Laboratorium gehaltenen Individuen, welche im November gesammelt worden waren, abgelegt wurden, schlupften im Juni innerhalb von 3 Tagen. Die Produktion der beiden Eitypen erklart die beobachtete saisonale Verbreitung der Art in Kustengewassern entlang der nordostlichen Atlantikkuste zwischen Cap Hatteras und Cap Cod - einem Gebiet mit extremen saisonalen Temperaturschwankungen. L. aestiva verschwindet vom Plankton im Spatherbst und erscheint erneut im Sommer nach dem Schlupfen der Wintereier., Winter- und Sommereier wurden nachgewiesen und beschrieben fur den calanoiden Copepoden Labidocera aestiva. Wintereier, die von im Laboratorium gehaltenen Individuen, welche im November gesammelt worden waren, abgelegt wurden, schlupften im Juni innerhalb von 3 Tagen. Die Produktion der beiden Eitypen erklart die beobachtete saisonale Verbreitung der Art in Kustengewassern entlang der nordostlichen Atlantikkuste zwischen Cap Hatteras und Cap Cod - einem Gebiet mit extremen saisonalen Temperaturschwankungen. L. aestiva verschwindet vom Plankton im Spatherbst und erscheint erneut im Sommer nach dem Schlupfen der Wintereier.]

The Developmental Stages of Paracalanus Crassirostris Dahl, 1894 (Copepoda, Calanoida)1)

[Der Copepode Paracalanus crassirostris Dahl, 1894 wurde im Labor gezuchtet. Alle Entwicklungsstadien werden illustriert. Bei 18°C dauert die vollstandige Entwicklung vom Nauplius I der ersten Generation bis zum Nauplius I der zweiten Generation 14 Tage. Nauplius und Copepodid-Stadien von P. crassirostris werden mit Entwicklungsstadien verwandter Arten verglichen., Der Copepode Paracalanus crassirostris Dahl, 1894 wurde im Labor gezuchtet. Alle Entwicklungsstadien werden illustriert. Bei 18°C dauert die vollstandige Entwicklung vom Nauplius I der ersten Generation bis zum Nauplius I der zweiten Generation 14 Tage. Nauplius und Copepodid-Stadien von P. crassirostris werden mit Entwicklungsstadien verwandter Arten verglichen.]

Introduction and Description of Experimental Ecosystems

The Symposium on Enclosed Marine Experimental Ecosystems took place over 4 days between 13-16 August 1980 at the Institute of Ocean Sciences, which overlooks Saanich Inlet (Sidney, British Columbia, Canada). The location was the site of the CEPEX program (Controlled Ecosystem Pollution, later Populations, Experiment) during its 6 years of operation and had come to be associated with large enclosure work in the minds of many Symposium attendees, either through direct participation, or as visitors over this period. The Symposium was sponsored by the U.S. National Science Foundation as part of its final year of support to the CEPEX program and by the Canadian Research Council. The gathering attracted about 100 participants from 9 countries, and 45 papers were presented.

A Redescription of Pseudodiaptomus Marinus Sato (Copepoda, Calanoida) and Its Occurrence At the Island of Mauritius 1)

Das Vorkommen von Pseudodiaptomus marinus Sato, 1913, ist fur Port Louis auf der Insel Mauritius festgestelt worden. Die Art wird beschrieben und hier zum ersten Mal detailliert abgebildet. Sie steht in Beziehung zu einer orientalischen Gruppe von Arten derselben Gattung. Ihres abnormalen zoogeographischen Verhaltens wegen wird angenommen, dass die Art durch Schiffe von Japan nach Mauritius transportiert worden ist. Intraspezifische Variationen zwischen Exemplaren von verschiedenen Lokalitaten werden beschrieben.

Resting Eggs in Pontella meadi (Copepoda: Calanoida)

Pontella meadi Wheeler produces resting eggs in fall which hatch the following summer. Experiments show that these eggs require 4–8 wk of incubation at 2–3 or 5–6 °C for substantial hatching to occur. Eggs occur in sediment in winter. Resting eggs serve to repopulate temperate inshore areas with this species after its winter disappearance from the plankton. Key words: Copepoda, Calanoida, Pontella, resting eggs, incubation time, distribution