Archive for August, 2020



Comparison of physical-chemical conditions for seaweed cultivation in the Spermonde Archipelago, Indonesia

Seaweed cultivation is one of the alternative livelihoods that could support the economy of the small island communities. However, the good growth of seaweed is intrinsically linked to the physicalchemical conditions of the seaweed cultivation area. Therefore, the objectives of this study were to assess and compare the physical-chemical conditions of seaweed farming areas and their relationship with seaweed growth in the Spermonde Archipelago, one of the major seaweed cultivation areas in South Sulawesi, Indonesia. The physical-chemical parameters measured in the field or through laboratory analysis included temperature, salinity, pH, dissolved oxygen (DO), phosphate (PO4), nitrate (NO3), and carbon dioxide (CO2). Data were collected from June to September 2019 from the waters around the islands of Balang Caddi (BC), Polewali (Pw), and Laiya (Ly), and in the coastal areas of Bonto Pannu (BP) and Punaga (Pg) villages. Data on seaweed growth was collected from seaweed (Kappaphycus alvarezii) farming trials using different culture methods (longlines, polyethylene nets, and baskets) at two sites (BC and Ly Islands) starting in June with further monthly planting from July to September. The physicalchemical parameters were similar for all sites and in general, met the acceptance criteria for K. alvarezii growth; however, seaweed growth was affected by the cultivation method applied. The growth of seaweed cultivated with the longline method was constrained by the presence of epiphytes attached to the thallus. However, with the polyethylene net and basket methods, the epiphytes were much reduced, resulting in improved growth and bright green seaweed thalli.

Continue reading ‘Comparison of physical-chemical conditions for seaweed cultivation in the Spermonde Archipelago, Indonesia’

Understanding the metabolic capacity of Antarctic fishes to acclimate to future ocean conditions

Antarctic fishes have evolved under stable, extreme cold temperatures for millions of years. Adapted to thrive in the cold environment, their specialized phenotypes will likely render them particularly susceptible to future ocean warming and acidification as a result of climate change. Moving from a period of stability to one of environmental change, species persistence will depend on maintaining energetic equilibrium, or sustaining the increased energy demand without compromising important biological functions such as growth and reproduction. Metabolic capacity to acclimate, marked by a return to metabolic equilibrium through physiological compensation of resting metabolic rate (RMR), will likely determine which species will be better poised to cope with shifts in environmental conditions. Focusing on the suborder Notothenioidei, a dominant group of Antarctic fishes, and in particular 4 well-studied species, Trematomus bernacchii, Pagothenia borchgrevinki, Notothenia rossii and N. coriiceps, we discuss metabolic acclimation potential to warming and CO2-acidification using an integrative and comparative framework. There are species-specific differences in the physiological compensation of RMR during warming and the duration of acclimation time required to achieve compensation; for some species RMR fully recovered within 3.5 weeks of exposure, such as P. borchgrevinki, while for other species, such as N. coriiceps, RMR remained significantly elevated past 9 weeks of exposure. In all instances, added exposure to increased PCO2, further compromised the ability of species to return RMR to pre-exposure levels. The period of metabolic imbalance, marked by elevated RMR, was underlined by energetic disturbance and elevated energetic costs, which shifted energy away from fitness-related functions, such as growth. In T. bernacchii and N. coriiceps, long duration of elevated RMR impacted condition factor and/or growth rate. Low growth rate can affect development and ultimately the timing of reproduction, severely compromising the species’ survival potential and the biodiversity of the notothenioid lineage. Therefore, the ability to achieve full compensation of RMR, and in a short-time frame, in order to avoid long term consequences of metabolic imbalance, will likely be an important determinant in a species’ capacity to persist in a changing environment. Much work is still required to develop our understanding of the bioenergetics of Antarctic fishes in the face of environmental change, and a targeted approach of nesting a mechanistic focus in an ecological and comparative framework will better aid our predictions on the effect of global climate change on species persistence in the polar regions.

Continue reading ‘Understanding the metabolic capacity of Antarctic fishes to acclimate to future ocean conditions’

Effects of climate change on coastal ecosystem food webs: implications for aquaculture

Highlights

• Food web models and scenarios were used to forecast effects of climate change.

• Modeled bays were vulnerable to the effects of climate change.

• In two of three study bays the ability to support bivalve aquaculture disappeared.

Abstract

Coastal ecosystems provide important ecosystem services for millions of people. Climate change is modifying coastal ecosystem food web structure and function and threatens these essential ecosystem services. We used a combination of two new and one existing ecosystem food web models and altered scenarios that are possible with climate change to quantify the impacts of climate change on ecosystem stability in three coastal bays in Maine, United States. We also examined the impact of climate change on bivalve fisheries and aquaculture. Our modeled scenarios explicitly considered the predicted effects of future climatic change and human intervention and included: 1) the influence of increased terrestrial dissolved organic carbon loading on phytoplankton biomass; 2) benthic community change driven by synergisms between climate change, historical overfishing, and increased species invasion; and 3) altered trophic level energy transfer driven by ocean warming and acidification. The effects of climate change strongly negatively influenced ecosystem energy flow and ecosystem stability and negatively affected modeled bivalve carrying capacity in each of our models along the Maine coast of the eastern United States. Our results suggest that the interconnected nature of ecosystem food webs make them extremely vulnerable to synergistic effects of climate change. To better inform fisheries and aquaculture management, the effects of climate change must be explicitly incorporated.

Continue reading ‘Effects of climate change on coastal ecosystem food webs: implications for aquaculture’

Inorganic carbon uptake strategies in coralline algae: plasticity across evolutionary lineages under ocean acidification and warming

Highlights

• Ambient diffusive CO2 use of reef-building crustose coralline algae ranges from 35 to 65%.

• Algae largely maintain or increase bicarbonate use under ocean acidification and warming.

• Maintained or increased bicarbonate use is associated with sustained metabolic performance.

• Lineage predicts inorganic carbon uptake strategy.

• Proposed initial framework for inorganic carbon uptake strategies in crustose coralline algae.

Abstract

Dissolved inorganic carbon (DIC) assimilation is essential to the reef-building capacity of crustose coralline algae (CCA). Little is known, however, about the DIC uptake strategies and their potential plasticity under ongoing ocean acidification (OA) and warming. The persistence of CCA lineages throughout historical oscillations of pCO2 and temperature suggests that evolutionary history may play a role in selecting for adaptive traits. We evaluated the effects of pCO2 and temperature on the plasticity of DIC uptake strategies and associated energetic consequences in reef-building CCA from different evolutionary lineages. We simulated past, present, moderate (IPCC RCP 6.0) and high pCO2 (RCP 8.5) and present and high (RCP 8.5) temperature conditions and quantified stable carbon isotope fractionation (13ε), organic carbon content, growth and photochemical efficiency. All investigated CCA species possess CO2-concentrating mechanisms (CCMs) and assimilate CO2 via diffusion to varying degrees. Under OA and warming, CCA either increased or maintained CCM capacity, which was associated with overall neutral effects on metabolic performance. More basal taxa, Sporolithales and Hapalidiales, had greater capacity for diffusive CO2 use than Corallinales. We suggest that CCMs are an adaptation that supports a robust carbon physiology and are likely responsible for the endurance of CCA in historically changing oceans.

Continue reading ‘Inorganic carbon uptake strategies in coralline algae: plasticity across evolutionary lineages under ocean acidification and warming’

Webinar: consistent ocean acidification messaging: the key to consistent understanding

Date: Wed, Sep 2, 2020 11:00 AM – 12:00 PM PDT

Description: Communicating ocean acidification is a challenge for scientists, researchers, educators, and professionals alike. Arguably one of the greatest obstacles to productive conversations about ocean acidification is the absence of clear, concise, and consistent messaging of complicated processes. Successful messaging can be established by utilizing language that is digestible and constant across educational landscapes. The National Network for Ocean and Climate Change Interpretation (NNOCCI) supported by the National Science Foundation established a framework for communicating climate science, and specifically ocean acidification, to the general public. During this presentation, the process and lessons learned in creating visual aids with specific examples of how ocean acidification impacts ecosystems in various geographic regions will be discussed. Each infographic has the same general layout and consistent messaging, tailored to each ocean region. The visual aids simplify current climate and ocean change research to articulate why ocean acidification is occurring, how it is impacting our ocean, and also provide actionable solutions for viewers.

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A regional vulnerability assessment for the Dungeness crab (Metacarcinus magister) to changing ocean conditions: insights from model projections and empirical experiments

Among global coastal regions, the Northern California Current System (N-CCS) is already experiencing effects from ocean acidification and hypoxia during the summer, primarily due to the region’s seasonal upwelling, current systems, and high productivity. Oxygen, pH, and temperature conditions are expected to become more stressful with continued fossil fuel emissions under global climate change, posing a serious threat to the region’s fisheries. N-CCS fishing communities rely heavily on the economically and culturally important Dungeness crab (Metacarcinus magister). The fishery is currently sustainably managed, but potential negative impacts from changing ocean conditions on Dungeness crab life stages and populations could have adverse effects for the fishery and the communities that rely on it. To quantify the vulnerability of Dungeness crab life stages and populations to predicted future conditions, both model projections and empirical experiments need to be employed. A semi-quantitative, life stage-specific framework was adapted here to assess the vulnerability of Dungeness crab to low pH, low dissolved oxygen, and high temperature under present and future projected conditions in the seasonally dynamic N-CCS. This was achieved using a combination of regional ocean models, species distribution maps, larval transport models, a population matrix model, and a literature review. This multi-faceted approach revealed that crab vulnerability to the three climate stressors will increase in the future (year 2100) under the most intense emissions scenario, with vulnerability to low oxygen being the most severe to the N-CCS population overall. Increases in vulnerability were largely driven by the adult life stage, which contributes the most to population growth. Empirical experiments demonstrated that adult crab respiration rates increase exponentially with temperature, potentially making this life stage more susceptible to hypoxia in the future. Together, this work provides novel insights into the effects of changing ocean conditions on Dungeness crab populations, which may help inform fishery management strategies.

Continue reading ‘A regional vulnerability assessment for the Dungeness crab (Metacarcinus magister) to changing ocean conditions: insights from model projections and empirical experiments’

Save the date: Ocean Acidification Week, 8-10 September 2020

Date: 8-10 September 2020

Description: A virtual multi-day forum to highlight different aspects of ocean acidification research and initiatives

The key goals of OA Week are to:

1. Engage the ocean acidification and broader oceanographic communities, raise awareness to the issue of ocean acidification, and bring attention to the global efforts being conducted related to monitoring, research, capacity building, capacity needs, and education.
2. Maintain momentum around the upcoming 5th International Symposium on the Ocean in a High CO2 World, and share progress on GOA-ON’s three High-level Goals.
3. Serve as the “kick off” to a new GOA-ON Webinar Series.

Continue reading ‘Save the date: Ocean Acidification Week, 8-10 September 2020’

Distributions of volatile halocarbons and impacts of ocean acidification on their production in coastal waters of China

Highlights

• Distributions of VHCs were measured in the Changjiang Estuary and its adjacent area.

• The environmental factors that influenced the distributions of VHCs were examined.

• The Changjiang Estuary and its adjacent area were a source of the atmospheric VHCs.

• Mesocosm experiments showed that elevated fCO2 had little impact on the VHCs.

Abstract

The volatile halocarbons (VHCs) CH3I, C2HCl3, C2Cl4, and CH2Br2 were measured in the Changjiang Estuary and adjacent waters during autumn 2018. Results revealed that their concentrations in coastal waters were influenced by anthropogenic activities, biological release, and complex hydrographic features. The vertical distributions of VHCs were determined mostly by the mixing of water masses. By investigating the impacts of temperature, salinity, chlorophyll a, nutrients, and pH on the distributions of these trace gases we revealed that C2HCl3 and C2Cl4 were positively correlated with salinity and nutrient availability. The sea-to-air fluxes of CH3I, C2HCl3, C2Cl4, and CH2Br2 were estimated to be 27.62, 280.3, 221.73, and 142.41 nmol m−2 day−1, respectively, suggesting that the study area was a net source of these trace gases. The impact of elevated fCO2 on the production of the four volatile halocarbons was studied using mesocosms in Wu Yuan Bay, Xiamen. The results showed that elevated fCO2 had little impact on the VHCs. Positive relationships were observed between CH2Br2 and phytoplankton biomass when fCO2 was low, and between CH3I and phytoplankton biomass when fCO2 was high, suggesting that algal release was a significant source of both compounds.

Continue reading ‘Distributions of volatile halocarbons and impacts of ocean acidification on their production in coastal waters of China’

We’re learning about ocean acidification, and ‘SOCAN’ you! (audio)

Photo: Dr. Emily Hall leads the Ocean Acidification Program and Chemical & Physical Ecology Program at Mote Marine Laboratory.

Photo: Dr. Emily Hall leads the Ocean Acidification Program and Chemical & Physical Ecology Program at Mote Marine Laboratory.

Today we welcome back our favorite “ocean chemistry nut,” Dr. Emily Hall, manager of Mote’s Ocean Acidification Research Program and Chemical & Physical Ecology Program. Dr. Hall and her colleagues have been scoping out the challenges of acidification—water chemistry changes partly driven by humans—across ocean environments of the U.S. southeast. Acidification is a concern for shellfish, crabs, corals and other marine species populations that support livelihoods. Dr. Hall updates hosts Hayley and Joe on the possible—and sometimes bizarre—impacts of acidification, and how we can help deal with them. That’s the topic of a new research synthesis that she and her partners authored on behalf of the Southeast Ocean & Coastal Acidification Network (SOCAN).

Continue reading ‘We’re learning about ocean acidification, and ‘SOCAN’ you! (audio)’

Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates

High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. At CO2 levels ≥634 µatm, HNF abundance was reduced, coinciding with increased abundance of picophytoplankton and prokaryotes. This increase in picophytoplankton and prokaryote abundance was likely due to a reduction in top-down control of grazing HNFs. Nanophytoplankton abundance was elevated in the 634 µatm treatment, suggesting that moderate increases in CO2 may stimulate growth. The taxonomic and morphological differences in CO2 tolerance we observed are likely to favour dominance of microbial communities by prokaryotes, nanophytoplankton, and picophytoplankton. Such changes in predator–prey interactions with ocean acidification could have a significant effect on the food web and biogeochemistry in the Southern Ocean, intensifying organic-matter recycling in surface waters; reducing vertical carbon flux; and reducing the quality, quantity, and availability of food for higher trophic levels.

Continue reading ‘Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates’


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