Posts Tagged 'fisheries'

Economic impacts of ocean acidification: a meta-analysis

This paper presents the first comprehensive review and synthesis of studies that forecast economic impacts of ocean acidification. The changes in seawater chemistry resulting from increased carbon dioxide emissions, collectively known as ocean acidification, will have detrimental impacts to marine ecosystem services. Those services include wild capture fisheries, aquaculture, recreation, shoreline protection, and others. The current literature valuing expected impacts to those services is rather thin and tends to focus on mollusk harvesting and aquaculture. Despite the paucity of studies, we divide all relevant estimates into seven additively separable economic sectors to provide the first aggregate estimate of economic damages from ocean acidification at the end of this century. We perform non-parametric bootstrap to characterize the distribution of estimates within each sector and the aggregation across sectors. We also perform meta-regressions to explore whether estimates provided by these studies are generally consistent with expectations based on ocean chemistry and economic theory. We find a global average of per capita annual losses in the year 2100 between $47 and $58 and we find strong evidence that estimates are consistent with expectations given future emissions and socio-economic scenarios that underlie the original studies.

Continue reading ‘Economic impacts of ocean acidification: a meta-analysis’

The regulations of varied carbon-nitrogen supplies to physiology and amino acid contents in Gracilariopsis lemaneiformis (Gracilariales, Rhodophyta)

Highlights

  • Growth, photosynthesis, and amino acid accumulation of G. lemaneiformis increases with higher nitrogen application.

  • Application of nitrogen fertiliser maybe an effective way to increase G. lemaneiformis yield with improved nutrient quality.

  • Seawater nitrogen enrichment may alleviate the physiological stress caused by high CO2 on G. lemaneiformis in the future.

Abstract

Gracilariopsis lemaneiformis (Gracilariales, Rhodophyta) is an important economic alga in Southern China. In the present study, G. lemaneiformis thalli collected from Nan’ao Island, China, were cultured in six different treatments with three carbon supply levels (20, 400 and 1000 μatm) and two nitrogen supply levels (15 and 300 μmol L1). The thalli were used in the examination of the effects of altered carbon supply and high nitrogen content in seawater on the growth, photosynthetic characteristics and amino acid (AA) content of this farmed algal species. Regardless of nitrogen levels, the relative growth rate of G. lemaneiformis increased with CO2 supply. Decrease and increase in the carbon supply of the culture both decreased the maximum quantum yield of photosystem PS II (Fv/Fm), initial slope of the rapid light curves (ɑ), non-photochemical quenching, maximum relative electron transport rate and AA content of G. lemaneiformis thalli. Moreover, under low and high CO2 supply conditions, the growth rates, Fv/Fm, antioxidant activities (SOD, CAT and POD) and AAs of G. lemaneiformis increases with higher nitrogen application (300 μmol L1). Our results indicated that the inhibition of growth, photosynthesis, and AA accumulation of G. lemaneiformis can be alleviated by appropriately increasing the concentration of nitrogen in seawater. We suggest that during G. lemaneiformis mariculture, the appropriate application of nitrogen fertiliser may be an effective way to increase algal yield with improved nutrient quality, and seawater nitrogen enrichment may alleviate the physiological stress caused by high CO2 on G. lemaneiformis in the future.

Continue reading ‘The regulations of varied carbon-nitrogen supplies to physiology and amino acid contents in Gracilariopsis lemaneiformis (Gracilariales, Rhodophyta)’

Combining mesocosms with models to unravel the effects of global warming and ocean acidification on temperate marine ecosystems

Ocean warming and species exploitation have already caused large-scale reorganization of biological communities across the world. Accurate projections of future biodiversity change require a comprehensive understanding of how entire communities respond to global change. We combined a time-dynamic integrated food web modelling approach (Ecosim) with a community-level mesocosm experiment to determine the independent and combined effects of ocean warming and acidification, and fisheries exploitation, on a temperate coastal ecosystem. The mesocosm enabled important physiological and behavioural responses to climate stressors to be projected for trophic levels ranging from primary producers to top predators, including sharks. We show that under current-day rates of exploitation, warming and ocean acidification will benefit most species in higher trophic levels (e.g. mammals, birds, demersal finfish) in their current climate ranges, with the exception of small pelagic fish, but these benefits will be reduced or lost when these physical stressors co-occur. We show that increases in exploitation will, in most instances, suppress any positive effects of human-driven climate change, causing individual species biomass to decrease at high-trophic levels. Species diversity at the trailing edges of species distributions is likely to decline in the face of ocean warming, acidification and exploitation. We showcase how multi-level mesocosm food web experiments can be used to directly inform dynamic food web models, enabling the ecological processes that drive the responses of marine ecosystems to scenarios of global change to be captured in model projections and their individual and combined effects to be teased apart. Our approach for blending theoretical and empirical results from mesocosm experiments with computational models will provide resource managers and conservation biologists with improved tools for forecasting biodiversity change and altered ecosystem processes due to climate change.

Continue reading ‘Combining mesocosms with models to unravel the effects of global warming and ocean acidification on temperate marine ecosystems’

Evolved differences in energy metabolism and growth dictate the impacts of ocean acidification on abalone aquaculture

Ocean acidification (OA) poses a major threat to marine ecosystems and shellfish aquaculture. A promising mitigation strategy is the identification and breeding of shellfish varieties exhibiting resilience to acidification stress. We experimentally compared the effects of OA on two populations of red abalone (Haliotis rufescens), a marine mollusc important to fisheries and global aquaculture. Results from our experiments simulating captive aquaculture conditions demonstrated that abalone sourced from a strong upwelling region were tolerant of ongoing OA, whereas a captive-raised population sourced from a region of weaker upwelling exhibited significant mortality and vulnerability to OA. This difference was linked to population-specific variation in the maternal provisioning of lipids to offspring, with a positive correlation between lipid concentrations and survival under OA. This relationship also persisted in experiments on second-generation animals, and larval lipid consumption rates varied among paternal crosses, which is consistent with the presence of genetic variation for physiological traits relevant for OA survival. Across experimental trials, growth rates differed among family lineages, and the highest mortality under OA occurred in the fastest growing crosses. Identifying traits that convey resilience to OA is critical to the continued success of abalone and other shellfish production, and these mitigation efforts should be incorporated into breeding programs for commercial and restoration aquaculture.

Continue reading ‘Evolved differences in energy metabolism and growth dictate the impacts of ocean acidification on abalone aquaculture’

Resilience of cold water aquaculture: a review of likely scenarios as climate changes in the Gulf of Maine

Climate change is one of the biggest challenges facing development and continuation of sustainable aquaculture in temperate regions. We primarily consider the ecological and physical resilience of aquaculture in the Gulf of Maine (GoM), where a thriving industry includes marine algae, extensive and intensive shellfish aquaculture, and a well‐established Atlantic salmon industry, as well as the infrastructure required to support these economically important ventures. The historical record of sea surface temperature in the GoM, estimated from gridded, interpolated in situ measurements, shows considerable interannual and decade‐scale variability superimposed on an overall warming trend. Climate model projections of sea surface temperature indicate that the surface waters in the GoM could warm 0.5–3.5°C beyond recent values by the year 2100. This suggests that, while variability will continue, anomalous warmth of marine heatwaves that have been observed in the past decade could become the norm in the GoM ca. 2050, but with the most significant impacts to existing aquaculture along the southernmost region of the coast. We consider adaptations leading to aquacultural resilience despite the effects of warming, larger numbers of harmful nonindigenous species (including pathogens and parasites), acidification, sea‐level rise, and more frequent storms and storm surges. Some new species will be needed, but immediate attention to adapt existing species (e.g. preserve/define wild biodiversity, breed for temperature tolerance and incorporate greater husbandry) and aquaculture infrastructure can be successful. We predict that these measures and continued collaboration between industry, stakeholders, government and researchers will lead to sustaining a vibrant working waterfront in the GoM.

Continue reading ‘Resilience of cold water aquaculture: a review of likely scenarios as climate changes in the Gulf of Maine’

Carbonate chemistry dynamics in shellfish farming areas along the Chilean coast: natural ranges and biological implications

The increasing shellfish aquaculture requires knowledge about nearshore environmental variability to manage sustainably and create climate change adaptation strategies. We used data from mooring time series and in situ sampling to characterize oceanographic and carbonate system variability in three bivalve aquaculture areas located along a latitudinal gradient off the Humboldt Current System. Our results showed pHT <8 in most coastal sites and occasionally below 7.5 during austral spring–summer in the lower (−30°S) and central (−37°S) latitudes, related to upwelling. Farmed mussels were exposed to undersaturated (Ωarag < 1) and hypoxic (<2 ml l−1) waters during warm seasons at −37°S, while in the higher latitude (43°S) undersaturated waters were only detected during colder seasons, associated with freshwater runoff. We suggest that both Argopecten purpuratus farmed at −30°S and Mytilus chilensis farmed at −43°S may enhance their growth during summer due to higher temperatures, lower pCO2, and oversaturated waters. In contrast, Mytilus galloprovincialis farmed at 37°S grows better during spring–summer, following higher temperatures and high pCO2. This knowledge is relevant for aquaculture, but it must be improved using high-resolution time series and in situ experimentation with farmed species to aid their adaptation to climate change and ocean acidification.

Continue reading ‘Carbonate chemistry dynamics in shellfish farming areas along the Chilean coast: natural ranges and biological implications’

First-hand knowledge of BC ocean change: oyster farmers’ experiences of environmental change and oyster die-off events

Recent studies call for transdisciplinary research to address the consequences of anthropogenic change on human-environment systems, like the impact of ocean acidification (OA) on oyster aquaculture. I surveyed oyster farmers in coastal British Columbia, Canada, about their first-hand experiences of ocean change. Farmers reported that oyster mortality (die-off events) is one of many challenges they face and is likely related to several interacting environmental factors, including water temperature and oyster food, particularly in 2016. I examined temperature, productivity, and carbonate chemistry conditions from 2013 to 2017 using available observations and the Salish Sea model, to understand poor oyster growing conditions in 2016. While temperatures were relatively high and chlorophyll relatively low during the 2016 spring bloom, carbonate conditions were relatively good, suggesting OA was not a key driver of difficult oyster growing conditions. This work provides a novel example of using local knowledge to better inform scientific investigation and adaptation to environmental change.

Continue reading ‘First-hand knowledge of BC ocean change: oyster farmers’ experiences of environmental change and oyster die-off events’

Climate change increases the risk of fisheries conflict

The effects of climate change on the ocean environment – especially ocean warming, acidification, and sea level rise – will impact fish stocks and fishers in important ways. Likely impacts include changes in fish stocks’ productivity and distribution, human migration to and away from coastal areas, stresses on coastal fisheries infrastructure, and challenges to prevailing maritime boundaries. In this paper, we explore these and other related phenomena, in order to assess whether and how the impacts of climate change on fisheries will contribute to the risk of fisheries conflict. We argue that climate change will entail an increase in the conditions that may precipitate fisheries conflict, and thereby create new challenges for existing fisheries management institutions. Several potential changes in fisheries management policy are recommended to avert the growing risk of fisheries-related conflicts.

Continue reading ‘Climate change increases the risk of fisheries conflict’

Ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100

The Arctic Ocean is an early warning system for indicators and effects of climate change. We use a novel combination of experimental and time-series data on effects of ocean warming and acidification on the commercially important Northeast Arctic cod (Gadus morhua) to incorporate these physiological processes into the recruitment model of the fish population. By running an ecological-economic optimization model, we investigate how the interaction of ocean warming, acidification and fishing pressure affects the sustainability of the fishery in terms of ecological, economic, social and consumer-related indicators, ranging from present day conditions up to future climate change scenarios. We find that near-term climate change will benefit the fishery, but under likely future warming and acidification this large fishery is at risk of collapse by the end of the century, even with the best adaptation effort in terms of reduced fishing pressure.

Continue reading ‘Ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100’

Effects of climate change and fishing on the Pearl River Estuary ecosystem and fisheries

Climate change poses a challenge to the management of marine ecosystems and fisheries. Estuarine ecosystems in particular are exposed to a broad range of environmental changes caused by the effects of climate change both on land and in the ocean, and such ecosystems have also had a long history of human disturbance from over-exploitation and habitat changes. In this study, we examine the effects of climate change and fishing on the Pearl River Estuary (PRE) ecosystem using Ecopath with Ecosim. Our results show that changes in net primary production and ocean warming are the dominant climatic factors impacting biomass and fisheries productivity in the PRE. Additionally, physiological changes of fishes and invertebrates that are induced by climate change were projected to be modified by trophic interactions. Overall, our study suggests that the combined effects of climate change and fishing will reduce the potential fisheries catches in the PRE. Reducing fishing efforts can reduce the impacts of climate change on selected functional groups; however, some prey fishes are expected to experience higher predation mortality and consequently decreases in biomass under low fishing intensity scenarios. Thus, our study highlights the non-linearity of the responses of estuarine ecosystems when climate change interacts with other human stressors.

Continue reading ‘Effects of climate change and fishing on the Pearl River Estuary ecosystem and fisheries’


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