Posts Tagged 'field'

Exploring the interactions and implications between ocean acidification and eutrophication in Budd inlet

Ocean Acidification is one of the greatest symptoms that climate change has inflicted on marine environments. Oceans naturally absorb carbon dioxide, however anthropogenic CO2 has manifested greater adverse influences on marine life, which is stressing our ability to use these resources. Ocean pH has dropped 30% to 8.1 since the industrial age, however the pH reduction along coastlines and within estuaries has deteriorated even more, having a greater need to be monitored. Acidification is worse, especially around the Puget Sound because of high nutrient loads flowing into the Puget Sound from coastal communities, and other human industrial scale activities like agriculture. Nutrients, primarily in the form of nitrogen, increase algae and microbe primary productivity, eventually outputting new CO2 through biological processes, resulting in amplification of the effect greenhouse gases are already exerting on marine ecosystems. This thesis project explored this relationship by looking at water samples collected from five locations in Budd inlet, and were tested for pH, nitrate, alkalinity. These variables were collected with the goal of determining if there was a noticeable difference between sample locations, and if there was a correlation between these variables all in context to the city of Olympia and Capitol Lake having some influence on findings. Results found no clear statistically significant differences between each variables and sample sites, however pH and nitrate concentrations had the greatest correlation. This suggests nutrients are indeed contributing significantly towards furthering acidification, more so than can be determined by CO2 emissions levels alone. More research is warranted on establishing causal relationships between nutrient loads and acidification levels in all Puget Sound inlets.

Continue reading ‘Exploring the interactions and implications between ocean acidification and eutrophication in Budd inlet’

Trends of ocean acidification and pCO2 in the northern North Sea, 2003‐2015

For continental shelf regions, the long‐term trend in sea surface carbon dioxide (CO2) partial pressure (pCO2) and rates of ocean acidification are not accurately known. Here, we investigate the decadal trend of observed wintertime pCO2 as well as computed wintertime pH and aragonite saturation state (Ωar) in the northern North Sea, using the first decade long monthly underway data from a Voluntary Observing Ship (VOS) covering the period 2004‐2015. We also evaluate how seawater CO2 chemistry, in response to physical and biological processes, drives variations in the above parameters on seasonal and interannual timescales. In the northern North Sea, pCO2, pH, and Ωar are subject to strong seasonal variations with mean wintertime values of 375±11 μatm, 8.17±0.01, and 1.96±0.05. Dissolved Inorganic Carbon (DIC) is found to be the primary driver of both seasonal and interannual changes while total alkalinity (TA) and sea surface temperature (SST) have secondary effects that reduce the changes produced by DIC. Average interannual variations during winter are around 3%, 0.1% and 2% for pCO2, pH, and Ωar, respectively, and slightly larger in the eastern part of the study area (Skagerrak region) than in the western part (North Atlantic Water (NAW) region). Statistically significant long‐term trends were found only in the NAW region with mean annual rates of 2.39±0.58 μatm yr‐1, ‐0.0024±0.001 yr‐1, and ‐0.010±0.003 yr‐1for pCO2, pH and Ωar, respectively. The drivers of the observed trends as well as reasons for the lack of statistically significant trends in the Skagerrak region are discussed.

Continue reading ‘Trends of ocean acidification and pCO2 in the northern North Sea, 2003‐2015’

Influence of water quality parameters on the prevalence of Livoneca redmanii (Isopoda; Cymothoidae) infestation of Mediterranean Sea fishes, Egypt

The quality of water in the aquatic ecosystem is a very sensitive issue and is controlled by many physical and chemical factors. The deterioration of water quality has variable effect on parasitic population and their rate of infestation and consequently the negative impact can impede fish viability and productivity. The current study aimed to: i) Surveying the parasitic isopod infesting some of the edible fish species inhabit the Egyptian Mediterranean Sea water ii) Assess the seasonal variations in water quality parameters of Mediterranean coastal water of Egypt. iii) Investigating the effect of water quality parameters on the rate of parasitic isopod infestation among the examined fishes. Water samples during each season were analyzed for physico-chemical parameters using standard methods. The selected parameters namely: temperature, pH, salinity, oxidizable organic matter (OOM), ammonia, nitrite, nitrate and some heavy metals (Lead, Copper, Arsenic and Mercury). A total of 400 Mediterranean Sea fish of Tilapia zilli, Solea spp, Mugil capito and Sardinella species were examined for isopod parasites. Parasites were preserved and identified. The results revealed isolation of the isopod species Livoneca redmanii, with an infestation rate of 19% among the examined fish species with the highest rate among Mugil capito (36%) and reached its total maximum value during summer (32%). Correlation analysis revealed that infestation rates were highly correlated (positively) with certain water quality parameters, such as temperature, oxidzable organic matter (OOM) and nitrite. High water temperatures during summer and spring seasons, and high nitrite concentrations were significantly associated with high infestation rates in Tilapia zilli (R2=0.91, P=0.046 and R2 = 0.97, P=0.015). The findings suggested that deterioration of water quality with varying seasons was stressful to fish, and consequently increased the incidences of the parasitic Isopod (Livoneca redmanii) so considered as a predisposing agent to parasitism. The study recommended
periodical monitoring of water quality parameters in fish water resources and the need to take all measures by the responsible authorities to prevent pollution of these resources to minimized and control the prevalence of parasite
infestations particularly of isopods.

Continue reading ‘Influence of water quality parameters on the prevalence of Livoneca redmanii (Isopoda; Cymothoidae) infestation of Mediterranean Sea fishes, Egypt’

Abiotic drivers of interannual phytoplankton variability and a 1999–2000 regime shift in the North Sea examined by multivariate statistics

The Dutch coastal zone is a region of the North Sea with a marked interannual and long‐term abiotic and phytoplankton variability. To investigate the relationship between abiotic variability and phytoplankton composition, two routine water monitoring data sets (1991–2005) were examined. Multivariate statistics revealed two significant partitions in the data. The first consisted of interannual abiotic fluctuations that were correlated to Rhine discharge that affected the abundance of summer and autumn diatom species. The second partition was caused by a shift in the abiotic data from 1998 to 1999 that was followed by a shift in phytoplankton composition from 1999 to 2000. Important factors in the abiotic shift were decreases in suspended matter (SPM) and phosphate (DIP) concentrations, as well as in pH. The decrease in SPM was caused by a reduction in wind speed. The increase in water column daily irradiance from the decrease in SPM led to increases in the abundance of winter–spring species, notably the prymnesiophyte Phaeocystis globosa. Because wind speed is related to the North Atlantic Oscillation (NAO) index it was possible to correlate NAO index and P. globosa abundance. Only five abiotic variables representing interannual and long‐term variability, including Rhine discharge and NAO index, were needed to model the observed partitions in phytoplankton composition. It was concluded that interannual variability in the coastal phytoplankton composition was related to year‐to‐year changes in river discharge while the long‐term shift was caused by an alternating large‐scale meteorological phenomenon.

Continue reading ‘Abiotic drivers of interannual phytoplankton variability and a 1999–2000 regime shift in the North Sea examined by multivariate statistics’

Carbonate characteristics of the Gulf of Anadyr waters

The first field data describing the dynamics of the carbonate system, the aragonite saturation state, and CO2 fluxes between the ocean and the atmosphere in the Gulf of Anadyr in the late autumn season are presented. It was established that during this period the gulf waters absorbed carbon dioxide from the atmosphere at a rate of –22.5 mmol m–2 day–1, which determined the “classical” mechanism of seawater acidification due to uptake of excess atmospheric CO2. In general, surface waters of the gulf were supersaturated with respect to aragonite. The exception was the highly dynamic region of Anadyr Strait, where the vertical distribution of the investigated parameters was homogeneous, the surface waters were close to equilibrium with respect to aragonite, and the CO2 flux was directed to the atmosphere. The bottom waters of the gulf, in contrast, were characterized by significant seasonal corrosivity due to remineralization of organic matter. It was shown that, during the late fall, relatively salty and acidic, quasi-equilibrium with respect to aragonite, and oxygen-depleted waters with high concentrations of nutrients and CO2 enter into the Chirikov Basin and further to the Arctic Ocean with Navarin Current.

Continue reading ‘Carbonate characteristics of the Gulf of Anadyr waters’

Multi-decadal change in reef-scale production and calcification associated with recent disturbances on a Lizard Island reef flat

Climate change is threatening the persistence of coral reef ecosystems resulting in both chronic and acute impacts which include higher frequency and severity of cyclones, warming sea surface temperatures, and ocean acidification. This study measured net ecosystem primary production (NEP) and net ecosystem calcification (NEC) on a reef flat after the most severe El Nino-driven mass bleaching event on Australia’s Great Barrier Reef (GBR) in 2016 and again in 2018 after another consecutive bleaching event in 2017. Our results indicate temporal changes in reef metabolism likely as result of both the continuing press disturbance of ocean acidification and severe pulse disturbances (cyclones and bleaching events). In 2016, NEP was within the range of values reported in past studies, however, it declined in 2018. NEC over a 12-h period was lower in 2016 than 2018; but when compared with past studies there was a severe decline in daytime net calcification from 2008–2009, to 2016 followed by an increase in 2018 (but still NEC remained lower than values reported in 2008–2009). Conversely, nighttime net calcification was similar to that reported in 2009 indicating nighttime dissolution did not increase over the past decade. Overall coral cover remained stable following recent disturbances, however, algal turf was the dominant benthic component on the reef flat, while calcifiers (corals and calcified algae) were minor components (<20% of total benthic cover). This study documented temporal changes in community function following major pulse disturbances (bleaching events and cyclones) within the context of ongoing OA at the same location over the last decade. Repeated pulse disturbances could jeopardize the persistence of the reef flat as a net calcifying entity, with the potential for cascading effects on other ecosystem services.

Continue reading ‘Multi-decadal change in reef-scale production and calcification associated with recent disturbances on a Lizard Island reef flat’

The role of river runoff in the Kara Sea surface layer acidification and carbonate system changes

This study aims to perform the results of the investigation of the Kara Sea carbonate system changes and the factors that determine it. The important feature of the Kara Sea water structure is strong stratification caused mainly by the Ob’ and Yenisey rivers discharge which is estimated as 81% of the total continental runoff to the sea. Occurring climate changes, as an increase in the total volume of the Arctic Ocean water (due to melting of glaciers, sea ice decline and river runoff increase), air temperature and CO2 concentration growth should affect greatly the Kara Sea carbonate system. However, riverine water influence seems to be the main driver of future acidification of the Kara Sea water due to permafrost thawing as it stores a great amount of buried carbon. An increase of carbon (mainly inorganic) flow to the sea will lead to carbonate equilibrium shift, oxidation of organic matter and release of CO2 that ultimately leads to a decrease in pH and therefore acidification. The area of the riverine plume depends on the amount of freshwater flowing into the sea and the conditions of the wind forcing. According to the data from Shirshov Institute cruises within the plume area aragonite saturation is below 1 that shows its state as acidified. Prevalence of pCO2 values in the freshened surface layer over the atmospheric shows that atmospheric carbon dioxide, apparently, cannot serve as the main driver for the acidification of the surface waters of the Kara Sea. At the shallow shelf to the north of the Ob’ Inlet mouth we observe acidification of the whole water column from surface to the bottom layer due to elevated riverine discharge and increase of flowing terrestrial carbon.

Continue reading ‘The role of river runoff in the Kara Sea surface layer acidification and carbonate system changes’

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Ocean acidification in the IPCC AR5 WG II

OUP book