Rodger Dawson

The effects of macrobenthic deposit-feeding on the degradation of chloropigments in sandy sediments

Microcosms with sediments containing either the bivalve Macoma balthica (surface deposit-feeder), the polychaete Leitoscoloplos fragilis (subsurface deposit-feeder), or both animals were maintained in a flow-through seawater system. Two different plant-derived food sources (Ulva rotundata or Zostera marina) were added (weekly) to the microcosms. The conversion of chlorophyll a to phaeophorbide a was significantly higher in microcosms containing macrofauna than in the controls with no macrofauna. Microbenthos in the controls were only capable of converting chlorophylls a and b to phaeophytins. The highest production of phaeophorbide a was in isolated deposit-feeder treatments with U. rotundata as the food source. Even though the total macrofaunal biomass was greater in the treatments with the two deposit-feeders together, more phaeophorbide was produced in the isolated treatments. Because M. balthica has a different feeding mode than L. fragilis, feeding interference between surface and subsurface deposit-feeding activities may have occurred in the combined treatments, thus producing less phaeophorbides. Phaeophorbides may represent good feeding markers for macrobenthic deposit-feeding processes. The amount of ingested chlorophyll that is converted to phaeopigments is dependent upon the quality of plant source materials and the interactions between coexisting species.

Products of photosynthesis by marine phytoplankton: Chitin in TCA “protein” precipitates☆

Abstract Evidence is presented which documents probable errors in previous estimates of 14 CO 2 incorporation and cellular distribution in estuarine and marine phytoplankton. Extension of the standard extraction procedure for phytoplankton photosynthetic carbon pools shows the presence of chitin (poly N- acetyl- d -glucosamine ) in the previously considered protein pool. Trichloracetic acid (TCA) precipitates were processed in several ways including alkali extraction (protein solubilization), 4 and 6 N HC1 hydrolysis, hydrolysis with purified chitinase coupled with HPLC and colorimetric analysis of amino sugars. Data for Thalassiosira pseudonana cultures and natural photoplankton populations are presented. The results show the presence of diatom chitin (chitan) in the TCA precipitate which has been previously characterized solely as the “protei” fraction.

Dissolved/dispersed Hydrocarbons, Tarballs and the Surface Microlayer: Experiences from an IOC/UNEP Workshop in Bermuda, December, 1984

Abstract An intercomparison exercise was conducted at the Bermuda Biological Station for Research, Inc, Bermuda on 1–15 December 1984. It primarily involved the testing of the IOC Manual for monitoring oil and dissolved/dispersed petroleum hydrocarbons (DDPH) in marine waters and on beaches (IOC, Manuals and Guides, No. 13). An additional exercise sought to intercompare methodologies for the collection of sea surface microlayer samples. DDPH measurements in the inshore waters of Bermuda resulted in a mean concentration of 0.057 μg l−1 of (n = 30) chrysene equivalents with a 60% relative standard deviation (RSD). Open ocean samples yielded a mean concentration of 0.011 μg l−1 (n = 44) with a 65% RSD. These concentrations are extremely low and the results indicate that the method described in the Manual is sufficiently sensitive for the detection of ‘hot spots’ The collection of beach tar using the method outlined in the Manual indicated that the data, when expresed as per metre of linear beach length, are an extremely good measure of oil contamination. The mean of 42 collections was 23.1 ± 14.4 g m−1 in the first sampling period and the mean of 39 transects was 40.6 ± 17.7 g m−1 on the second sampling period. Although 14 individuals took part in the sampling the results of individuals were consistent enough to demonstrate that beach tar collections are indeed valuable tools for monitoring contamination by petroleum in the marine environment. The operational manual for the sampling of the sea surface microlayer (IOC Manuals and Guides, No. 15), was also tested. The results indicated that this method collects reproduceable volumes of elevated concentrations of materials from the sea surface suitable at least for qualitative analyses. However, the spatial distribution and stability of surface films may render quantitative analyses less meaningful.

Shipboard trials of an ozone-based ballast water treatment system

Legislation introduced by the United Nations International Maritime Organization (IMO) has focused primarily on standards defining successful treatments designed to remove invasive species entrained in ballast water. An earlier shipboard study found that ozone introduced into salt water ballast resulted in the formation of bromine compounds, measured as total residual oxidants (TRO) that were toxic to both bacteria and plankton. However, the diffuser system employed to deliver ozone to the ballast water tanks resulted in patchiness in TRO distribution and toxicity to entrained organisms. In this follow-up study, the shipboard diffuser system was replaced by a single Venturi-type injection system designed to deliver a more homogeneous biocide distribution. Within-tank variability in TRO levels and associated toxicity to zooplankton, phytoplankton and marine bacteria was measured via a matrix of tubes deployed to sample different locations in treated and untreated (control) tanks. Three trials were conducted aboard the oil tanker S/T Prince William Sound in the Strait of Juan de Fuca off Port Angeles, Washington State, USA, between June and December 2007. Mortalities of plankton and bacteria and oxidant concentrations were recorded for treated and untreated ballast water up to 3days following treatment, and residual toxicity beyond this period was measured by bioassay of standard test organisms. Results indicated uniform compliance with current IMO standards, but only partial compliance with other existing and pending ballast water legislation.

Shipboard testing of the efficacy of SeaKleen® as a ballast water treatment to eliminate non‐indigenous species aboard a working tanker in Pacific waters

Trials were conducted aboard the tanker Seabulk Mariner to test a natural product, SeaKleen®, as a biocide controlling non‐indigenous populations of plankton and bacteria in ballast water. SeaKleen® was dosed into matched ballast tanks at two different concentrations, 0.8 mg L−1 active ingredient (a.i.) and 1.6 mg L−1 a.i. during ballasting off the Oregon coast during a three‐day passage to Prince William Sound, Alaska. Live organism counts from treated ballast water were compared with those from untreated (control tank) water collected from the same source location. Shipboard chemical analyses were made to verify dose and quantify chemical degradation and residuals following dilution. Results indicated that both SeaKleen® doses resulted in complete zooplankton and phytoplankton mortality and that the higher dose (1.6 mg L−1 a.i.) caused a two‐log removal of culturable bacteria over a 92 h grow‐out period. Spectrophotometry confirmed initial dosing to within 5% of nominal values. Shipboard bioassays were conducted using larval fish (Cyprinodon variegatus), brine shrimp (Artemia salina) and the bioluminescent dinoflagellate Pyrocystis lunula. Exposure of the test organisms to water drawn from treated ballast tanks 48 h after SeaKleen® was added to the tanks resulted in 100% mortalities in Cyprinodon and Pyrocystis at both doses. Corresponding mortalities for Artemia larvae were 100% and 60% for high and low SeaKleen® doses, respectively. Toxicity testing of treated water, subjected to varying dilutions, indicated that residual toxicity to even the most sensitive organisms would be eliminated once the discharge had dispersed beyond 100 feet from the vessel.

GC/MS based analyses of individual organic constituents of chao phraya river water and estimated discharge rates into the upper gulf of Thailand

Abstract Detailed GC/MS based chemical analyses of organic concentrates from the Chao Phraya River obtained from a water sample collected in the Bangkok metropolitan area indicated that hydrocarbons of petroleum or combustion sources may be minor constituents of the dissolved lipophilic fraction relative to biogenic hydrocarbons and industrial chemicals. Using published data on river discharge and the concentrations measured in an integrated sample, tentative input rates into the Upper Gulf of Thailand for characterized chemicals are calculated.

The Influence of Water Quality on the Toxicity and Degradation of Juglone (5-Hydroxy 1,4-Naphthoquinone)

This study was part of a broader investigation of low molecular weight quinones under consideration as biocides for the control of aquatic nuisance species (ANS). Preliminary investigations identified the 2-ring naphthoquinones as broad spectrum biocides controlling a wide range of aquatic organisms. All biocides were relatively short-lived in saline waters, with half-lives between 5 and 30h. Juglone (5-hydroxy 1,4-naphthoquinone) and plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) showed the greatest toxicity against most aquatic organisms. These qualities formed the basis for a patent focusing on these two compounds as biocides for ANS control, with juglone identified as the more cost-effective of the two. Although juglone has been extensively studied as a plant toxin and reducing agent, remarkably little information exists on its use as an aquatic biocide. We describe the toxicity of juglone over the range of water quality parameters likely to be encountered in ballast water, a major vector for ANS. Tests indicated that its molecular stability was enhanced in freshwater and particularly under neutral to acid conditions. This was supported by results of bioassays on the freshwater cladoceran Daphnia magna that indicated enhanced juglone toxicity at pHs of ≤6.7. A low octanol:water partition coefficient for juglone indicated little capacity for these compounds to be adsorbed by suspended particulates and for bioaccumulation. These properties together with their relatively rapid degradation (t½ ≤30h), particularly in the marine environment, indicated a low the risk of residual toxicity associated with the release of juglone-treated water.

Global strategies for the assessment of pollution in marine environments and progress achieved in the IOC-GIPME programme☆

Abstract The aims and objectives of the Intergovernmental Oceanographic Commissions Programme for the Global Investigation of the Pollution of the Marine Environment (GIPME) are described and the major achievements in developing international capabilities for a worldwide monitoring system are highlighted. A great deal of emphasis has been placed on developing, testing and calibrating methodologies to ensure the quality of data for the major classes of contaminants measured in a variety of marine phases and to attempt to determine fluxes in the marine environment. The availability of suitable certified and uncompromised reference and standard materials is seen as an important aspect in ensuring the quality of data in this monitoring effort. The translation of a contamination assessment to a pollution assessment via a knowledge of biological effects at the cellular, organism and community levels is a major ongoing effort of the IOC and an evaluation of the relevance of a variety of biological procedures is currently being addressed by a group of experts.