Intertidal ecology and potential power impacts, Bay of Fundy, Canada

A large-scale tidal power project in the upper reaches of the Bay of Fundy would cause major changes in the tidal elevations of the headpond which would have a pronounced effect on intertidal ecology. The new mean low water level would be, on average, slightly above the present mean sea level whilst the new mean high water level would drop about 0.7 m. This would result in a much compressed intertidal zone. Mud and sand flats, below the present mean sea level, would be converted to sub-tidal habitat, whilst the high saltmarsh, flooded at present only on the highest spring tides, would become colonized by terrestrial vegetation. There would be major shifts in the relative importance of primary production by saltmarshes, intertidal microalgae and phytopiankton, but overall, it is likely that production would increase. Changes in both primary food sources and habitat area would affect the abundance of intertidal invertebrate organisms and the fish and migratory shorebirds that feed upon them.     

Bimodal size distributions in wild juvenile Atlantic salmon populations and their relationship with age at smolt migration

A bimodal length distribution developed in an Atlantic salmon population planted as start-fed fry in a Norwegian stream. The earliest fish to smolt were from the upper modal group.     

Alternative developmental pathways and the propensity to migrate: a case study in the Atlantic salmon

Migratory behaviour with its associated phenotypic changes is generally viewed as an adaptive strategy because it incurs survival or reproductive advantages to migrants. The development of a migrant phenotype is believed to be controlled by threshold mechanisms, where individuals emigrate only after surpassing a particular body size but delay migration if below. For such a strategy to respond to natural selection, part of the phenotypic variance in the propensity to migrate must be explained by variation in additive genetic effects. Here, we use data gathered in the field and from a common rearing experiment to test for a genetic basis associated with seaward migration in Atlantic salmon (Salmo salar L.). We document a high heritability of the liability trait underlying the propensity to emigrate in juvenile salmon, and significant differences between offspring grouped according to their sires in body-size threshold values above which emigration takes place. The presence of additive genetic variance in both the liability and thresholds makes the onset of migration a process sensitive to selection and may therefore constitute an important explanatory mechanism for the interpopulation differences in the size at seaward migration observed in this species.     

The Anna Karenina Principle Applied to Ecological Risk Assessments of Multiple Stressors

Successful ecological risk assessments are all alike; every unsuccessful ecological risk assessment fails in its own way. Tolstoy posited a similar analogy in his novel Anna Karenina: “Happy families are all alike; every unhappy family is unhappy in its own way.” By that, Tolstoy meant that for a marriage to be happy, it had to succeed in several key aspects. Failure on even one of these aspects, and the marriage is doomed. In this paper, I argue that the Anna Karenina principle also applies to ecological risk assessments involving multiple stressors. In particular, I argue that multiple stressors assessments and environmental decision making will not have a happy marriage unless the following can be achieved: (1) there must be societal and political buy-in to the assessment and decision-making process; (2) the assessment must have the latitude to consider a wide range of stressors and potential risk management options; (3) there must be a commitment to following a rigorous focusing of the assessment and to expending resources for model development and data collection; and (4) an adaptive management strategy must be adopted wherein risk management actions are undertaken, system response intensively observed and assessed, and revised management actions taken as appropriate. Failure to meet any of the above criteria for success will doom a multiple stressors assessment and prevent its use in effective decision-making.     

Rocky shore zonation in the Ranee tidal power basin

Data from a series of rocky shore transects, within the enclosed basin of the Ranee estuary and immediately outside the barrage, describe the distribution and zonation patterns of the intertidal biota, after more than a decade of its regular operation as a tidal power station. In the absence of quantitative pre-barrage information, the distribution of species has been compared with published information on their former extent of penetration into the estuary.     

Net ground speed of downstream migrating radio-tagged Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) smolts in relation to environmental factors

The downstream migration of Atlantic salmon (Salmo salarL.) and sea trout smolt (S. trutta L.) was investigated using radio telemetry in the spring of 1999 and 2000. Forty wild sea trout smolts, 20 F1 sea trout smolts, 20 hatchery salmon smolts and 20 salmon smolts from river stockings were radio tagged and released in the Danish River Lilleaa. The downstream migration of the different groups of fish was monitored by manual tracking and by three automatic listening stations. The downstream migration of radio tagged smolts of both species occurred concurrently with their untagged counterparts. The diel migration pattern of the radio tagged smolts was predominantly nocturnal in both species. Wild sea trout smolt migrated significantly faster than both the F1 trout and the introduced salmon. There was no correlation between net ground speed, gill Na⁺,K⁺-ATPase activity or fish length in any of the different groups. The migration speed of wild sea trout smolts was positively correlated with water discharge in both years. In F1 sea trout smolts, migration speed was positively correlated with temperature in 1999. The migration speed of salmon smolts did not correlate to any of the investigated parameters.     

No Matter – How?: Dealing with Matter‐less Stressors in LCA of Wind Energy Systems

The portfolio of impacts that are quantified in life cycle assessment (LCA) has grown to include rather different stressors than those that were the focus of early LCAs. Some of the newest life cycle impact assessment (LCIA) models are still in an early phase of development and have not yet been included in any LCA study. This is the case for sound emissions and noise impacts, which have been only recently modeled. Sound emissions are matter‐less, time dependent, and bound to the physical properties of waves. The way sound emissions and the relative noise impacts are modeled in LCA can show how new or existing matter‐less impacts can be addressed. In this study, we analyze, through the example of sound emissions, the specific features of a matter‐less impact that does not stem from the use of a kilogram of matter, nor is related to the emission of a kilogram of matter. We take as a case study the production of energy by means of wind turbines, contradicting the commonly held assumption that windmills have no emissions during use. We show how to account for sound emissions in the life cycle inventory phase of the life cycle of a wind turbine and then calculate the relative impacts using a noise LCIA model.     

Environmental impact assessment: the growing importance of science in government decision making

The broad acceptance of the conclusions and recommendations contained in the Brundtland Report with its emphasis on environmentally sustainable development is a good indication that this concept is gaining world-wide recognition. Science and the ensuing technology must be credited for creating and sustaining our modern society and we must now apply our expertise to minimize the adverse impacts of industrial growth and preserve our environment.Real progress towards the reconciliation of economic and environmental goals will require effective incorporation of environmental impact assessment (EIA) into the planning process and this paper describes the steps taken to improve the concept and practice of EIA in Canada. Public trust and participation in the process are key ingredients for its success as well as good science and meaningful dialogue between the scientists, the public and the decision makers. The availability of standard and reliable bioassessment techniques, which is the theme of this conference, should be helpful in strengthening the scientific basis for biophysical aspects of EIA.     

Salmon and Complexity: Challenges to Assessment

Salmon in the U.S. Pacific Northwest are in widespread decline despite countless environmental assessment studies and billions of dollars spent. Having been involved in environmental assessment for more than three decades, I am forced to conclude that this decline tells us that our established practices of assessment and management are fundamentally deficient. Rather than studying the salmon, we should examine our own practices. These practices presume that, if individual actions are found to be beneficial through analytical assessments, the cumulative outcomes of many actions will also be beneficial. This “linear” presumption is embedded in institutions, analytical methods, and assessment practices. For a whole class of emerging problems, including declining salmon, this presumption is fundamentally wrong. Declining salmon provide a warning that our own analytical habits of thought and notions of progress are leading to outcomes that are both destructive and contrary to our best intentions. This paper is a response to this warning.     

Assessing researcher impacts from a long-term sampling program of wetland communities in the Everglades National Park, Florida, U.S.A.

1. Long‐term monitoring requires repeated visits to a study site, greatly increasing the potential for cumulative visitation effects. For ecological studies in general, and for monitoring in particular, data must be evaluated for confounding artefacts from researcher presence. We compared aquatic communities at long‐term sampling plots (nine sites, each with three plots, studied continuously from 6 to 22 years) in the Everglades National Park to previously unsampled reference plots adjacent to them to assess the effects of researcher visitation on the flora and fauna. 2. We identified two criteria that are sensitive to local habitat heterogeneity for assessment of visitation impacts. First, the long‐term plots must differ from adjacent reference plots by a magnitude that exceeded variation among plots separated by equal or greater distance (i.e. the difference is greater than expected by scaling of community change proportional with distance); and second, multiple reference plots must consistently differ in direction (e.g. greater abundance or less abundance) from adjacent long‐term plots. We also tested for increased heterogeneity among samples from long‐term plots compared with those not previously visited. 3. We found no evidence of researcher effects on fish or macroinvertebrates, and only weak evidence for alteration of emergent plants and periphyton floating mats. Our failure to document visitor impacts may result from either low visitation rate or the dynamic nature of the wetlands studied.     

Effects of size and early sexual maturity on downstream migration during smolting in Baltic samon (Salmo salar)

The effects of size and previous sexual maturity on downstream migration in two-summer-old Baltic salmon were studied during their normal seaward migratory period in spring. We used an automatic PIT (Passive Integrated Transponder) tag monitoring system for individual recognition of tagged fish. Size affected the probability of migration among both previously immature and previously mature males while there was no such relationship among females. Nearly all females and 63.6% of the previously immature males migrated during the smolting period, while only 24.5% of the previously mature males did. In migrating fish the individual activity level increased from almost zero in May to about 450 antenna passages per day in mid June, coinciding with a pronounced increase in ambient water temperature. During the period of increasing activity in early June the fish changed from night activity to day activity and finally activity all day and night. The fish moved downstream in schools but no specific school size dominated. This paper demonstrates the strong effect of body size and previous sexual maturity on the probability of migration.     

The seaward movement of Atlantic salmon smolts in the Usk estuary, Wales, as inferred from power station catches

The greatest numbers of Atlantic salmon smolts were caught at Uskmouth power station during the day on the flood tide and the least on an ebbing night tide. Catch rates during the day on an ebb tide and at night on a flood tide represented an intermediate state. The results, together with tracking data, suggest that salmon smolts prefer to migrate seaward through the lower Usk estuary during the night Oncc an ebbing tide.     

An evaluation of the quality of fall-fingerling Atlantic salmon (Salmo salar L.) released to natural lacustrine nursery areas in Newfoundland,Canada

Results of experiments on controlled releases of fall-fingerling Atlantic salmon to lacustrine habitats in Newfoundland are reviewed in terms of survival during freshwater residence and smolt yield per unit of standing water habitat. Average survival from parr to smolt in three consecutive annual releases was 12.9% and we conclude that the quality of fall-fingerling salmon, produced from our semi-natural rearing techniques, was satisfactory. Year-class survival decreased progressively with consecutive releases. Rate of increase in juvenile salmon biomass remained stable over the duration of the study, suggesting that the average annual biomass of 1.6 kg ha^–1 of juvenile salmon released did not exceed habitat carrying capacity. Precocity did not appear to represent a significant deterrent to fall-fingerling survival. Annual smolt yield (by year-class) from stocking ranged from 53 to 130 ha^–1 (mean = 77 smolts ha^–1).