scholarly journals Increases in Picocyanobacteria Abundance in Agriculturally Eutrophic Pampean Lakes Inferred from Historical Records of Secchi Depth and Chlorophyll-a

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 159
Author(s):  
Horacio Ernesto Zagarese ◽  
Nadia R. Diovisalvi ◽  
María de los Ángeles González Sagrario ◽  
Irina Izaguirre ◽  
Paulina Fermani ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Size Structure ◽  
Generalized Additive Models ◽  
Secchi Depth ◽  
Additive Models ◽  
Validation Dataset ◽  
Secchi Disc ◽  
Secchi Disc Depth ◽  
Before And After ◽  
Pampa Region

Phytoplankton size structure has profound consequences on food-web organization and energy transfer. Presently, picocyanobacteria (size < 2 µm) represent a major fraction of the autotrophic plankton of Pampean lakes. Glyphosate is known to stimulate the development of picocyanobacteria capable of degrading the herbicide. Due to the worldwide adoption of glyphosate-resistant crops, herbicide usage has increased sharply since the mid-1990s. Unfortunately, there are very few studies (none for the Pampa region) reporting picocyanobacteria abundance before 2000. The proliferation of µm sized particles should decrease Secchi disc depth (ZSD). Therefore ZSD, conditional to chlorophyll-a, may serve as an indicator of picocyanobacteria abundance. We use generalized additive models (GAMs) to analyze a “validation” dataset consisting of 82 records of ZSD, chlorophyll-a, and picocyanobacteria abundance from two Pampean lakes surveys (2009 and 2015). In support of the hypothesis, ZSD was negatively related to picocyanobacteria after accounting for the effect of chlorophyll-a. We then fitted a “historical” dataset using hierarchical GAMs to compare ZSD conditional to chlorophyll-a, before and after 2000. We estimated that ZSD levels during 2000–2021 were, on average, only about half as deep as those during 1980–1999. We conclude that the adoption of glyphosate-resistant crops has stimulated outbreaks of picocyanobacteria populations, resulting in lower water transparency.

Dependance of phytoplankton chlorophyll on bottom resuspension in Cleveland Bay, northern Queensland

1981 ◽  
Vol 32 (6) ◽  
pp. 981 ◽  
Author(s):  
TA Walker
Keyword(s):  
Great Barrier Reef ◽  
Bottom Sediment ◽  
Chlorophyll A ◽  
Water Depth ◽  
Inverse Correlation ◽  
Barrier Reef ◽  
Secchi Disc ◽  
Secchi Disc Depth ◽  
The Mean ◽  
Strong Inverse Correlation

In relatively shallow regions of the lagoon of the central Great Barrier Reef. phytoplankton chlorophyll a concentrations are dependent on intermittent resuspension of bottom sediment by wind-generated waves. This results in a strong inverse correlation between chlorophyll a levels and transparency over a period of time. Bottom resuspension and resettling cause a mide transparency range to occur at any given station. but the mean Secchi disc depth increases linearly with water depth across the lagoon.

scholarly journals Sardine potential habitat and environmental forcing off western Portugal

2010 ◽  
Vol 67 (8) ◽  
pp. 1553-1564 ◽  
Author(s):  
Juan P. Zwolinski ◽  
Paulo B. Oliveira ◽  
Victor Quintino ◽  
Yorgos Stratoudakis
Keyword(s):  
Chlorophyll A ◽  
Seasonal Pattern ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Seasonal Effect ◽  
Oceanic Circulation ◽  
Environmental Forcing ◽  
Potential Habitat ◽  
The North ◽  
Spatio Temporal

Abstract Zwolinski, J. P., Oliveira, P. B., Quintino, V., and Stratoudakis, Y. 2010. Sardine potential habitat and environmental forcing off western Portugal. – ICES Journal of Marine Science, 67: 1553–1564. Relationships between sardine (Sardina pilchardus) distribution and the environment off western Portugal were explored using data from seven acoustic surveys (spring and autumn of 2000, 2001, 2005, and spring 2006). Four environmental variables (salinity, temperature, chlorophyll a, and acoustic epipelagic backscatter other than fish) were related to the acoustic presence and density of sardine. Univariate quotient analysis revealed sardine preferences for waters with high chlorophyll a content, low temperature and salinity, and low acoustic epipelagic backscatter. Generalized additive models depicted significant relationships between the environment and sardine presence but not with sardine density. Maps of sardine potential habitat (SPH) built upon the presence/absence models revealed a clear seasonal effect in the across-bathymetry and alongshelf extension of SPH off western Portugal. During autumn, SPH covered a large part of the northern Portuguese continental shelf but was almost absent from the southern region, whereas in spring SPH extended farther south but was reduced to a narrow band of shallow coastal waters in the north. This seasonal pattern agrees with the spatio-temporal variation of primary production and oceanic circulation described for the western Iberian shelf.

scholarly journals Biochemical Composition of Seston Reflecting the Physiological Status and Community Composition of Phytoplankton in a Temperate Coastal Embayment of Korea

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3221
Author(s):  
Riaz Bibi ◽  
Hee Yoon Kang ◽  
Dongyoung Kim ◽  
Jaebin Jang ◽  
Changseong Kim ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Size Structure ◽  
Salinity Gradient ◽  
Generalized Additive Models ◽  
Taxonomic Composition ◽  
Additive Models ◽  
Physiological Status ◽  
Bay Area ◽  
Close Relationship ◽  
Gwangyang Bay

The biochemical composition of seston along a salinity gradient were examined in the low-turbidity, temperate, estuarine embayment, Gwangyang Bay in Korea. Seasonal variations in sestonic protein (PRT), carbohydrate (CHO), and lipid (LIP) concentrations were analyzed to assess the effects of physiological status and taxonomic composition of phytoplankton. The concentrations of biochemical compounds displayed a close relationship with chlorophyll a (Chla). PRT:CHO ratios were high (>1.0) in the estuarine channel in warmer months and in whole bay in February, indicating a N-replete condition for phytoplankton growth. High CHO:LIP ratios (>2.5) in the saline deep-bay area during the warmer months (>2.0) emphasized the importance of temperature and photoperiod over nutritional conditions. The low POC:Chla (<200), molar C:N (~7) ratios, and biopolymeric carbon concentrations coupled with high primary productivity indicated a low detrital contribution to the particulate organic matter pool. Diatom dominance throughout the year contributed to consistently high carbohydrate concentrations. Furthermore, generalized additive models highlighted that phytoplankton community (i.e., size) structure may serve as an important descriptor of sestonic biochemical composition. Collectively, our results suggest that physiological and taxonomic features of phytoplankton play prominent roles in determining the biochemical composition of seston, supporting the fact that the ecosystem processes in Gwangyang Bay are largely based on phytoplankton dynamics.

scholarly journals Changes in Planktivory and Herbivory Regimes in a Shallow South American Lake (Lake Blanca Chica, Argentina) Over the Last 250 Years

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 597
Author(s):  
David Carrozzo ◽  
Simona Musazzi ◽  
Andrea Lami ◽  
Francisco E. Córdoba ◽  
María de los Ángeles González Sagrario
Keyword(s):  
Size Structure ◽  
Generalized Additive Models ◽  
Management Strategies ◽  
Zooplankton Community ◽  
Fish Predation ◽  
Additive Models ◽  
Fish Scales ◽  
Pheophorbide A ◽  
Food Web Structure ◽  
Species Dominance

Shallow lakes are vulnerable ecosystems impacted by human activities and climate change. The Cladocera occupy a central role in food webs and are an excellent paleoecological indicator of food web structure and trophic status. We conducted a paleolimnological study in Lake Blanca Chica (Argentina) to detect changes on the planktivory and herbivory regimes over the last 250 years. Generalized additive models were fitted to the time series of fish predation indicators (ephippial abundance and size, mucrone size, fish scales, and the planktivory index) and pheophorbide a concentration. The cladoceran assemblage changed from littoral-benthic to pelagic species dominance and zooplankton switched from large-bodied (Daphnia) to small-bodied grazers (Bosmina) ca. 1900 due to increased predation. The shift in planktivory regime (ca. 1920–1930), indicated by fish scales and the planktivory index, as well as herbivory (ca. 1920–1950), was triggered by eutrophication. Changes in planktivory affected the size structure of Bosmina, reducing its body size. This study describes the baseline for the lake as well as the profound changes in the composition and size structure of the zooplankton community due to increased predation and the shift in the planktivory regime. These findings will provide a reference status for future management strategies of this ecosystem.

scholarly journals Effect of Phosphorous Loadings on Macrophytes Structure and Trophic State of Dam Reservoir on a Small Lowland River (Eastern Poland)

2013 ◽  
Vol 39 (3) ◽  
pp. 33-46 ◽  
Author(s):  
Monika Tarkowska-Kukuryk
Keyword(s):  
Chlorophyll A ◽  
Trophic State ◽  
Water Current ◽  
Trophic State Index ◽  
Lowland River ◽  
Dam Reservoir ◽  
Secchi Disc ◽  
Eutrophic Lakes ◽  
Secchi Disc Depth ◽  
Dam Site

Abstract The main objective of the study was to evaluate if macrophytes structure and trophic status of dam reservoir Kraśnik on a small lowland river Wyżnica are determined by phosphorous loadings. Studies were conducted seasonally in May, July and October during the years 2008-2009. Samples were taken at four sites: Site 1 - inflow of the Wyżnica River to pre-dam, Site 2 − pre-dam, Site 3 − dam reservoir and Site 4 - outflow of the Wyżnica River from dam reservoir. Physical and chemical parameters (temperature, Secchi disc depth, dissolved oxygen, pH, conductivity, total suspension, chlorophyll-a, TP and P-PO4) were measured in water samples. Together with water parameters there were estimated biomass of phytoplankton and species composition and biomass of emergent, floating-leaved and submerged macrophytes. Concentrations of TP, chlorophyll-a and Secchi disc depth were used to calculate trophic state index of Carlsson for dam reservoir and its pre-dam. Based on mean water current, mean residence time of water in dam reservoir and concentrations of TP and P-PO4 loadings (g m-2) flowing into dam reservoir with the Wyżnica River were calculated. The results showed visible negative effect of phosphorous loadings on both macrophytes composition and trophic state of the reservoir. The marked changes concerned soft vegetation. High P loadings (7.74 g m-2 of TP and 6.03 g m-2 P-PO4) during the spring of 2008 caused the disappearance of characeans meadows. In 2009, the presence of rigid hornwort (Ceratophyllum demersum L.), the species typical for eutrophic lakes was noted. This unrooted submerged plant uptakes dissolved orthophosphates directly from the water column. Values of Carlsson index (51.4 ≤ TSI ≤ 68.2) indicate the eutrophic state of dam reservoir Kraśnik. During summer season in dam reservoir there were observed algal blooms (biomass of phytoplankton exceed 10 mg WW dm-3) and low water transparency (Secchi disc depth ranged from 0.4 to 0.65 m). During the two-year studies in dam reservoir Kraśnik a high reduction of P loadings, mostly dissolved orthophosphates was observed. Dependently on season, reduction of P-PO4 loadings ranged from 52% (July 2008) up to 91% (May 2009). The reduction of TP was lower and reached values from 15% (May 2008) to 48% (July 2009).

scholarly journals Model of Habitat Characteristics of Sardinella lemuru in the Bali Strait, Indonesia

2021 ◽  
Vol 56 (3) ◽  
pp. 229-240
Author(s):  
Adi Wijaya ◽  
Abu Bakar Sambah ◽  
Daduk Setyohadi ◽  
Umi Zakiyah
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Environmental Conditions ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Sea Surface ◽  
Model Parameters ◽  
Photosynthetically Available Radiation ◽  
Chlorophyll A Concentration

This article describes a new approach to the study of the environmental conditions that relate to the Sardinella lemuru habitat in the Bali Strait, through remote sensing data and fish catch data using the generalized additive model. Data that are acquired daily and then compiled into monthly data for sea surface temperature, sea surface chlorophyll-a concentration, photosynthetically available radiation, and sea surface depth (SSD) were used for the years 2008–2010. The objectives of the study are to describe the variability of the environmental conditions in the Bali Strait, to analyze a combination model of environmental factors in estimating the Sardinella lemuru habitat, and to map potential Sardinella lemuru fishing areas. We illustrate the proposed method by constructing seven generalized additive models with catches of Sardinella lemuru as a variable response and use sea surface temperature, sea surface chlorophyll-a concentration, photosynthetically available radiation, and SSD as covariant models for assessing the environmental characteristics of the abundance of Sardinella lemuru. Predicted values were validated using a linear model. Based on the three model parameters, habitat selection for Sardinella lemuru was significantly (P < 0.0001) influenced by photosynthetically available radiation (50–55 Einstein m-2 d-1), sea surface chlorophyll-a concentration (0.2–2.0 mgm-3), sea surface temperature (28.95–29.64 °C), and SSD (60–150 m). Catch predictions show a consistent trend toward environmental conditions and water depth. Our method allows for improvement with the validation of catch predictions that were observed and collected monthly, and the result was significant (P < 0.001, r2 = 0.816). Photosynthetically available radiation explains the highest deviation in continued generalized additive models; therefore, it was considered to be the best predictor of habitat, followed by sea surface chlorophyll-a concentration, sea surface temperature, and then SSD. New research results supplement several previous studies that relate to the analysis of environmental parameters in estimating the fish habitat and can be used in mapping the distribution of potential Sardinella lemuru fishing areas in spatial and temporal scales.

scholarly journals Physico-chemical aspects of Chandbill Oxbow lake of Meherpur, Bangladesh

1970 ◽  
Vol 20 (1) ◽  
pp. 31-39
Author(s):  
AKM Nazrul Kabir ◽  
M Niamul Naser
Keyword(s):  
Dissolved Oxygen ◽  
Water Depth ◽  
Secchi Depth ◽  
Ammonia Nitrogen ◽  
Total Alkalinity ◽  
Oxbow Lake ◽  
Total Hardness ◽  
Secchi Disc ◽  
Secchi Disc Depth ◽  
Physico Chemical

Some physico-chemical parameters of Chandbill Baor, a natural oxbow lake of Meherpur district were studied from September 2006 to August 2007. Air temperature of the study area varied from 18.10 to 32.10°C (x-bar± SE : 27.73 ± 1.22°C). The Water temperature (17.10 to 32.10°C; x-bar± SE: 28.24 ± 1.32°C), Secchi disc depth (8.89 to 53.34 cm; x-bar± SE : 26.19 ± 4.29 cm), water depth (132.08 to 307.34 cm; x-bar± SE : 183.93 ± 13.88 cm); total alkalinity (51.3 to 85.5 mg/l; x-bar± SE : 68.4 ± 3.64 mg/l), total hardness (85.5 to 188.10 mg/l; x-bar± SE : 125.81 ± 9.38 mg/l), dissolved oxygen (5.0 to 12.0 mg/l; x-bar± SE: 8.42 ± 0.62 mg/l), free CO2 (5.0 to 30.0 mg/l; x-bar± SE : 14.58 ± 2.64 mg/l), pH (8.0 to 10; x-bar± SE : 8.54 ± 0.19), ammonia-nitrogen (0.3 to 0.7 mg/l; x-bar± SE: 0.46 ± 0.04 mg/l) in the 'Baor' water were found to be suitable for survival of aquatic fauna. Nitrite-nitrogen was absent in the 'em>Baor' throughout the year. Positive correlations were observed in between air and water temperature (r = 0.978); free CO2 and Secchi depth (r = 0.839), free CO2 and water depth (r = 0.714); water depth and Secchi depth (r = 0.903); total hardness and total alkalinity (r = 0.861) and pH with DO (r = 0.661). However, inverse relations were observed among ammonia-nitrogen with water depth (r = −0.727); ammonia-nitrogen with Secchi disc depth (r = −0.840); dissolved oxygen with free CO2 (r = −0.636); pH with Secchi disc depth (r = −0.581) and pH with free CO2 (r = −0.825). The productivity of the lake was found to be medium and could be improved to higher level. Alkaline pH (8.54 ± 0.19) was supposed to be helpful for proper growth and development of fishes and aquatic organisms. This is the first limnological report from a natural ‘Baor’ (Oxbow lake) of Meherpur district, Bangladesh.Key words: Physico-chemical aspects; Oxbow lake; MeherpurDOI: http://dx.doi.org/10.3329/dujbs.v20i1.8835Dhaka Univ. J. Biol. Sci. 20(1): 31-39, 2011 (January)

Oceanographic Conditions on Small Pelagic Fishery in the Gulf of Bone Waters

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Safruddin Safruddin ◽  
Rachmat Hidayat ◽  
Mukti Zainuddin
Keyword(s):  
Chlorophyll A ◽  
Generalized Additive Models ◽  
Pelagic Fish ◽  
Additive Models ◽  
Fish Distribution ◽  
Fishing Ground ◽  
Small Pelagic Fish ◽  
The Relationship ◽  
Pelagic Fishery ◽  
Oceanographic Conditions

This study aimed to investigate the relationship between the dinamic oceanographic condition and fluctuation in the catch of small pelagic fish. Study on the dinamic oceanographic conditions were focused on the sea surface temperature (SST), chlorophyll-a concentration (SSC) and water depth. The study took place in the area of Gulf of Bone located, data collection was started from April to September 2017. The data were collected using experimental fishing metode (large liftnet) and applications of remote sensing in satellite oceanography, which then analysed using Geographic Information System (GIS) dan Generalized Additive Models (GAMs). The result showed that the distribution of small pelagic fish tends to be within the area of temperature ranging from 29.5 to 30.0oC, the chlorophyll-a from 0.7 to 0.9 mg.m-3 and concentrated within the coastal area with in waters depth maximum of 100 m.Keywords: Oceanography, small pelagic fish, distribution, fishing ground, Gulf of Bone

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