Temporal variation in total phosphorus concentrations revealed from a multidecadal monitoring program on Big Platte Lake,Michigan

Effective water quality management depends on enactment of appropriately designed monitoring programs to reveal current and forecasted conditions. Because water quality conditions are influenced by numerous factors, commonly measured attributes such as total phosphorus (TP) can be highly temporally varying. For highly varying processes, monitoring programs should be long-term and periodic quantitative analyses are needed so that temporal trends can be distinguished from stochastic variation, which can yield insights into potential modifications to the program. Using generalized additive mixed modeling, we assessed temporal (yearly and monthly) trends and quantified other sources of variation (daily and subsampling) in TP concentrations from a multidecadal depth-specific monitoring program on Big Platte Lake, Michigan. Yearly TP concentrations decreased from the late 1980s to late 1990s before rebounding through the early 2000s. At depths of 2.29 to 13.72 m, TP concentrations have cycled around stationary points since the early 2000s, while at the surface and depths ≥?18.29 concentrations have continued declining. Summer and fall peaks in TP concentrations were observed at most depths, with the fall peak at deeper depths occurring 1 month earlier than shallower depths. Daily sampling variation (i.e., variation within a given month and year) was greatest at shallowest and deepest depths. Variation in subsamples collected from depth-specific water samples constituted a small fraction of total variation. Based on model results, cost-saving measures to consider for the monitoring program include reducing subsampling of depth-specific concentrations and reducing the number of sampling depths given observed consistencies across the program period.     

Scaling relationships,individual variation and the influence of temperature on maximum swimming speed in early settled stages of the turbot Scophthalmus maximus

Escape-swimming speeds (U _max) were studied in settled turbot (Scophthalmus maximus L.) reared at 18°C. Metamorphosis was complete at 4.0 cm total length (TL). U _max scaled in proportion to TL^0.74 in fish of 0.88 5o 8.00 cm TL at 18C. The scaling relationship for U _max was similar for temperatures between 13 and 23°C and could be fitted by the model: . U _max temperature-dependent, with a Q₁₀ of 1.77 over the temperature range studied. Analysis of covariance showed that U _max for farmed turbot was 14% lower than for wild fish filmed within 2 wk of capture; 3 mo after capture the average differences in escape performance were no longer significant, which suggests that the lower escape speeds of farmed fish are due to acclimation effects and not genetic stock differences. In order to assess the individual variability of U _max, 18 wild juvenile turbot [TL=6.2±0.4 cm (Week 1) to 7.5±0.5 cm (Week 17); means±SD] were maintained in individual containers at 18°C. U _max was determined weekly for 6 wk, standardised for fish length using the scaling relationship U _max=1.46 TL ^0.74, and individuals were ranked in order of performance. Temperature was reduced after 6 wk to 13°C, resulting in a significant decline in U _max from 104.0±14.4 to 87.8±12.5 cm s^-1 (means±SD). After 3 wk at 13°C U _max had increased to a level not significantly different from that at 18°C. Kendall's coefficient of concordance showed that repeatability of ranking of the experimental U _max of individuals was maintained over a 13 wk period and through temperature change. The results demonstrate that escape-swimming speeds in juvenile turbot are repeatable, individually variable, and can be modified in response to temperature acclination.     

Temperature and development in larvae of the turbot Scophthalmus maximus

Turbot (Scophthalmus maximus L.) were reared at 12 and 16°C until 26 d after hatching. At both temperatures, starting at the neural plate stage, somites were initially formed every 75 min. Expressed as a percentage of development time (DT, fertilisation to 90% larvae hatching) somite formation occurred relatively earlier during embryogenesis at 12°C (45% DT) than at 16°C (55% DT). At 12°C, after the 32-somite stage the rate of somite formation decreased to one every 300 min. The larvae hatched after 6 d at 12°C and 3 d at 16°C at a relatively primitive stage of development, prior to the opening of the mouth and anus, with unpigmented eyes, and a straight gut. Temperature altered the relative timing of organogenesis in the larval stages. At 12°C, the following characters appeared (in this order): swimbladder>loop in the gut (at the time of yolk exhaustion)>caudal fin. In contrast, at 16°C, the caudal fin appeared at the same time as the loop in the gut. At 16°C, spines formed on the head in the region of the otic capsule at the time the swimbladder formed and the yolk was exhausted, but were absent in 12°C larvae. At both temperatures, in 1 d-old larvae the myotomes just behind the yolk-sac contained 200 inner muscle fibres (presumptive white muscle). The initial growth of inner muscle was largely due to hypertrophy, but by 26 d at 12°C and 11 d at 16°C hyperplastic growth became important, as evidenced by a significant increase in the number of small fibres (<10 m²). By 26 d the average number of inner muscle fibres had increased to 341 at 12°C and 988 at 16°C. New muscle fibres were added in distinct germinal zones at the dorsal and ventral apices of the myotomes. Metamorphosis was associated with a thickening of the superficial (presumptive red) muscle layer and the appearance of tonic muscle fibres.     

Differential tolerance to metals among populations of the introduced bryozoan Bugula neritina

Resistance to heavy metals is a potentially important trait for introduced marine organisms, facilitating their successful invasion into disturbed natural communities. We conducted laboratory and field experiments to examine differential resistance to copper (Cu) between two source populations of the introduced bryozoan Bugula neritina, originating from a polluted (Port Kembla Harbour, NSW, Australia) and an unpolluted (Botany Bay, NSW, Australia) environment. A laboratory toxicity test was conducted to test the relative resistance of B. neritina recruits from the two sources, by measuring the attachment success, survival and growth of individuals exposed to a range of Cu concentrations (0, 25, 50 and 100 μg l⁻¹ Cu). Upon completion, reciprocal transplantation of the colonies to the original polluted and unpolluted locations was carried out to assess ongoing survival and growth of colonies in the field. B. neritina colonies originating from the polluted Port Kembla Harbour had increased resistance to Cu relative to populations from an unpolluted part of Botany Bay. There appeared to be a cost associated with increased metal tolerance. In the laboratory, Botany Bay recruits displayed significantly higher growth in control treatments and significantly poorer growth at 100 μg l⁻¹ Cu with respect to Port Kembla Harbour individuals, which showed unusually uniform and low growth irrespective of Cu concentration. No difference in attachment success or post-metamorphic survival was observed between populations. Field transplantation showed copper resistance in Port Kembla Harbour colonies constituted an advantage in polluted but not benign environments. The findings of this study provide evidence of the benefits to invasive species of pollution tolerance and suggest that human disturbance can facilitate the establishment and spread of invasive species in marine systems.     

Non-compliance and the quota price in an ITQ fishery

This paper examines the effects of non-compliance on quota demands and the equilibrium quota price in an ITQ fishery. I show that whereas lower quota prices are implied unambiguously by expected penalties which are a function of the absolute violation size, the expectation of penalties based upon relative violations of quota demands can, under certain conditions, produce higher quota prices than in a compliant quota market. If there are both compliant and non-compliant firms in the fishery, the result would then be a shift in quota demand from compliant to non-compliant firms, rather than the reverse. The findings are generally applicable to quota markets in other industries, including pollution permit markets.     

Metabolic constraints on burst-swimming in the Antarctic teleost Notothenia neglecta

Immediate-energy-supply pathways were analysed during burst-swimming in white muscle of the Antarctic fish Notothenia neglecta, (collected during Austral summer 1984 near Signy Island, South Orkneys). Selected enzyme activities were determined, and tissue metabolites were measured, before and after 3 min of burst-work. The activity of glycolytic enzymes is very low compared to that in other fish, while the activities of creatine phosphokinase, adenylate kinase and AMPdeaminase are relatively high. Concentrations of metabolites associated with cellular energy status declined with exercise. At the same time, there was no change in the concentrations of most of the glycolytic metabolites measured (including glycogen, glucose and lactate), while [creatine phosphate] declined and [inosine monophosphate] increased. These observations were used to propose that the potential for ATP generation via creatine-phosphate hydrolysis is enhanced in N. neglecta, while glycolytic capacity is relatively reduced. This is an unusual pattern of ATP production and places severe constraints upon the behavior of the fish. While the capacity for very short-term, high-power-output swimming is increased, the capacity for medium-duration swimming is reduced. Ecological repercussions are discussed.     

Tiger shark (Galeocerdo cuvier) abundance and growth in a subtropical embayment: evidence from 7 years of standardized fishing effort

The tiger shark (Galeocerdo cuvier Peron and Lesueur 1822) is a widely distributed predator with a broad diet and the potential to affect marine community structure, yet information on local patterns of abundance for this species is lacking. Tiger shark catch data were gathered over 7 years of tag and release research fishing (1991–2000, 2002–2004) in Shark Bay, Western Australia (25°45′S, 113°44′E). Sharks were caught using drumlines deployed in six permanent zones (~3 km² in area). Fishing effort was standardized across days and months, and catch rates on hooks were expressed as the number of sharks caught h⁻¹. A total of 449 individual tiger sharks was captured; 29 were recaptured. Tiger shark catch rate showed seasonal periodicity, being higher during the warm season (Sep–May) than during the cold season (Jun–Aug), and was marked by inter-annual variability. The most striking feature of the catch data was a consistent pattern of slow, continuous variation within each year from a peak during the height of the warm season (February) to a trough in the cold season (July). Annual growth rates of recaptured individuals were generally consistent with estimates from other regions, but exceeded those for populations elsewhere for sharks >275 cm fork length (FL), perhaps because mature sharks in the study area rely heavily on large prey. The data suggest that (1) the threat of predation faced by animals consumed by tiger sharks fluctuates dramatically within and between years, and (2) efforts to monitor large shark abundance should be extensive enough to detect inter-annual variation and sufficiently intensive to account for intra-annual trends.     

Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTI_SD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTI_SD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTI_SD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming.     

Baselines for land-use change in the tropics: application to avoided deforestation projects

Although forest conservation activities, particularly in the tropics, offer significant potential for mitigating carbon (C) emissions, these types of activities have faced obstacles in the policy arena caused by the difficulty in determining key elements of the project cycle, particularly the baseline. A baseline for forest conservation has two main components: the projected land-use change and the corresponding carbon stocks in applicable pools in vegetation and soil, with land-use change being the most difficult to address analytically. In this paper we focus on developing and comparing three models, ranging from relatively simple extrapolations of past trends in land use based on simple drivers such as population growth to more complex extrapolations of past trends using spatially explicit models of land-use change driven by biophysical and socioeconomic factors. The three models used for making baseline projections of tropical deforestation at the regional scale are: the Forest Area Change (FAC) model, the Land Use and Carbon Sequestration (LUCS) model, and the Geographical Modeling (GEOMOD) model. The models were used to project deforestation in six tropical regions that featured different ecological and socioeconomic conditions, population dynamics, and uses of the land: (1) northern Belize; (2) Santa Cruz State, Bolivia; (3) Paraná State, Brazil; (4) Campeche, Mexico; (5) Chiapas, Mexico; and (6) Michoacán, Mexico. A comparison of all model outputs across all six regions shows that each model produced quite different deforestation baselines. In general, the simplest FAC model, applied at the national administrative-unit scale, projected the highest amount of forest loss (four out of six regions) and the LUCS model the least amount of loss (four out of five regions). Based on simulations of GEOMOD, we found that readily observable physical and biological factors as well as distance to areas of past disturbance were each about twice as important as either sociological/demographic or economic/infrastructure factors (less observable) in explaining empirical land-use patterns. We propose from the lessons learned, a methodology comprised of three main steps and six tasks can be used to begin developing credible baselines. We also propose that the baselines be projected over a 10-year period because, although projections beyond 10 years are feasible, they are likely to be unrealistic for policy purposes. In the first step, an historic land-use change and deforestation estimate is made by determining the analytic domain (size of the region relative to the size of proposed project), obtaining historic data, analyzing candidate baseline drivers, and identifying three to four major drivers. In the second step, a baseline of where deforestation is likely to occur–a potential land-use change (PLUC) map—is produced using a spatial model such as GEOMOD that uses the key drivers from step one. Then rates of deforestation are projected over a 10-year baseline period based on one of the three models. Using the PLUC maps, projected rates of deforestation, and carbon stock estimates, baseline projections are developed that can be used for project GHG accounting and crediting purposes: The final step proposes that, at agreed interval (e.g., about 10 years), the baseline assumptions about baseline drivers be re-assessed. This step reviews the viability of the 10-year baseline in light of changes in one or more key baseline drivers (e.g., new roads, new communities, new protected area, etc.). The potential land-use change map and estimates of rates of deforestation could be re-done at the agreed interval, allowing the deforestation rates and changes in spatial drivers to be incorporated into a defense of the existing baseline, or the derivation of a new baseline projection.     

A comparison of the environmental impact of pesticide multiresidues and their occurrence in river waters surveyed by liquid chromatography coupled in tandem with UV diode array detection and mass spectrometry

Twenty-two pesticides and metabolites selected on the basis of a regional priority list, were surveyed in surface river waters by high performance liquid chromatography coupled in tandem with UV diode array detection and mass spectrometry, after an off-line pre-concentration step. Pesticide concentrations ranged between 0.07 and 4.8 microg/l according to the compound and sampling period. Analytical results were linked to the environmental risk of pesticides, evaluated by their system investigation of risk by integration of score (SIRIS) rank.