scholarly journals The challenges of a small population exposed to multiple anthropogenic stressors and a changing climate: the St. Lawrence Estuary beluga

2021 ◽  
Vol 40 ◽  
Author(s):  
Véronique Lesage
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Extinction Risk ◽  
Small Population ◽  
Ecosystem Structure ◽  
Toxic Substances ◽  
Natal Philopatry ◽  
Lawrence Estuary ◽  
Fat Reserves ◽  
St Lawrence Estuary

Until 2012, the St. Lawrence Estuary beluga population was considered stable with about 1100 individuals. An abnormally high number of calves reported dead that year triggered a population status reassessment. This review article summarizes the findings from this reassessment and various studies subsequent to it and provides an updated analysis of carcass recovery rates up to 2019. The 2013 review indicated a decreased incidence of cancer in adults, suggesting positive impacts from the regulation of toxic substances (e.g., PCBs and PAHs). However, the review also revealed that the population initiated a decline of ca. 1% per year in the early 2000s and had reached a size of ca. 900 individuals by 2012. This decline was accompanied by high inter-annual variability in calf survival and pregnancy rates and by more frequent peripartum complications among dead females. The change in population dynamics coincided with a shift in the St. Lawrence ecosystem structure and warmer environmental conditions, suggesting a link through effects on reproductive success and adult female body condition. This was supported by the continued high calf mortality after 2012 and a documented decline of fat reserves in beluga blubber from 1998 to 2016. Other factors, such as the exposure to chronic vessel noise, increasing whale-watching activities, high contaminant levels and episodic harmful algal blooms, may also be contributing to the long-term non-recovery and current decline of the population. The strong natal philopatry and complex social system of the beluga likely increase its vulnerability to extinction risk by limiting dispersal.

scholarly journals Agricultural Conservation Practices and Aquatic Ecological Responses

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1687
Author(s):  
Richard E. Lizotte ◽  
Peter C. Smiley ◽  
Robert B. Gillespie ◽  
Scott S. Knight
Keyword(s):  
Aquatic Ecosystems ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Soil Health ◽  
Conservation Agriculture ◽  
Agricultural Runoff ◽  
The United States ◽  
Ecosystem Structure ◽  
Ecological Responses ◽  
And Function

Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function.

Dynamics in a Plankton Model with Toxic Substances and Phytoplankton Harvesting

2020 ◽  
Vol 30 (02) ◽  
pp. 2050035 ◽  
Author(s):  
Hua Zhang ◽  
Ben Niu
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Initial Population ◽  
Toxic Substances ◽  
Environmental Capacity ◽  
Existence And Stability ◽  
Small Phytoplankton ◽  
Normal Form Method ◽  
Bautin Bifurcation ◽  
Plankton Model

In this paper, a phytoplankton–zooplankton model incorporating toxic substances and nonlinear phytoplankton harvesting is established. The existence and stability of the equilibrium of this model are first investigated. The occurrence of transcritical, saddle-node, Hopf and Bautin bifurcations at different equilibria is then verified. In addition, the properties of Hopf bifurcation and Bautin bifurcation are discussed by using normal form method. These results demonstrate that phytoplankton and zooplankton populations will oscillate periodically when the harvesting level is high. More interestingly, it is found that the oscillations are always unstable for small phytoplankton carrying capacity, while the dynamics have close relations with the initial population densities for a large environmental capacity. The existence of Bautin bifurcation theoretically indicates that toxic phytoplankton can cause extinction once there exist harmful algal blooms for some time. These results are numerically illustrated for the model with spatial diffusion, which shows that local phytoplankton blooms will lead to global populations extinction.

scholarly journals Tumors in St. Lawrence Beluga Whales (Delphinapterus leucas)

1994 ◽  
Vol 31 (4) ◽  
pp. 444-449 ◽  
Author(s):  
S. De Guise ◽  
A. Lagacé ◽  
P. Béland
Keyword(s):  
Small Population ◽  
Delphinapterus Leucas ◽  
Carcinogenic Effect ◽  
Lawrence Estuary ◽  
Beluga Whales ◽  
High Prevalence ◽  
Endangered Population ◽  
High Concentrations ◽  
St Lawrence Estuary ◽  
St Lawrence River

A population of 450–500 belugas ( Delphinapterus leucas) resides in the polluted estuary of the St. Lawrence River. Stranded carcasses of this endangered population were recovered and necropsied. High concentrations of organochlorines, heavy metals, and benzo-a-pyrene exposure were demonstrated in tissues of these whales. Between 1988 and 1990, 21 tumors were found in 12 out of 24 carcasses. Among these tumors, six were malignant and 15 were benign. The animals were between 1.5 and >29 years of age, and the ages of animals with and without tumors did not differ when two juvenile animals (1.5 and 3.5 years of age) were excluded. Seven other neoplasms had been reported previously in six out of 21 well-preserved carcasses examined in the same laboratory between 1982 and 1987. Overall, 28 of the 75 confirmed tumors reported so far in cetaceans (37%) were from this small population of beluga whales in the St. Lawrence Estuary. Such a high prevalence of tumors would suggest an influence of contaminants through a direct carcinogenic effect and/or a decreased resistance to the development of tumors in this population.

Fat reserves and condition indices in greater snow geese

1985 ◽  
Vol 63 (2) ◽  
pp. 331-333 ◽  
Author(s):  
G. Gauthier ◽  
J. Bédard
Keyword(s):  
Subcutaneous Fat ◽  
Dry Weight ◽  
Condition Index ◽  
Lawrence Estuary ◽  
Fat Reserves ◽  
Snow Geese ◽  
Ether Extraction ◽  
Total Fat ◽  
Condition Indices ◽  
St Lawrence Estuary

We evaluate several external condition indices as predictors of total fat reserves (TFR) in greater snow geese. In 1979 and 1980, we collected 373 adult geese during their spring staging halt along the St. Lawrence estuary, Québec, and determined their fat content by ether extraction. Body weight (BW) alone and BW divided by various morphometric measurements are relatively poor predictors of TFR (maximum r2 = 0.56). The thickness of subcutaneous fat (measured externally with an adiposimeter) combined with BW is the best predictor of TFR (R2 = 0.65). This condition index can be useful in predicting the average condition of living geese, provided a reasonable sample size is available. We also examined some internal condition indices. Of these, the dry weight of abdominal fat is the easiest to apply and one of the most reliable (r2 = 0.86).

scholarly journals Potential Harmful Algal Blooms (HABs) in Segara Anakan Lagoon, Central Java, Indonesia

2018 ◽  
Vol 47 ◽  
pp. 04010 ◽  
Author(s):  
Rose Dewi ◽  
Muhammad Zainuri ◽  
Sutrisno Anggoro ◽  
Tjahjo Winanto ◽  
Hadi Endrawati
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Anthropogenic Activities ◽  
Harmful Effect ◽  
Nursery Ground ◽  
Toxic Substances ◽  
Anthropogenic Pressures ◽  
Central Java ◽  
Spatial Approach ◽  
Segara Anakan Lagoon

Segara Anakan Lagoon (SAL), located along side of soutern coast on western part of Central Java 108°46'–109 ° 05'E; 7 ° 34'–7 ° 48'S. SAL is necessasrily ecosistem as nursery ground. This has been becoming important research relating to primary productivity. The existance of antropogenical activities around the area, is changing inrush input into lagoon. This is going to be worried about giving influences in physical, chemistry, and biological factors of the water and causing deflation in rate value of primer productivity. Rainy and dry season's variability with important impacts on the phytoplankton community structure, abundance and dynamics. Furthermore, the number of coastal ecosystems with identified eutrophication symptoms is increasing worldwide due to the increasing anthropogenic pressures. One of 1the first symptoms of eutrophication is enhanced phytoplankton biomass. Generally, Fitoplanton is important biological indicators in the process. However, high abundance of biomass phytoplankton could give harmful effect toward lagoon, they could produce toxic substances that will be accumulated, it can be endangering .The aim of the research is to determine and calculate potential species of Harmful Algal Blooms (HABs) in SAL with spastial and temporal approach. The spatial approach is done at seven different stations of ecological characteristics SAL, with representations: natural factors and the presence of anthropogenic activities. On the temporal approach (time series) for a year, it refers to the monsoon wind pattern, which are called season (western, the transitional season 1, eastern, and the transitional season 2).The results of laboratory tests are discussed descriptively. Phytoplankton sample were taken vertically using plankton nets, meshsize 25 μm. The result showed that SAL have been found and consisted of 82 species from 5 division phytoplankton: Chrysophyta, Chlorophyta, Cyanophyta, Pyrophyta, and Euglenophyta. 20 species from 9 genus were identified potential as HABs, with four genus of them were known having toxin and endangering for human (Nitzschia, Oscillatoria, Anabaena dan Protoperidinium).Whether, five genus do not produce toxins but giving deflation Oxygen of waters with anoxia condition (Chaetoceros, Coscinodiscus, Rhizosolenia, Thalassiosira, Thalassiotrix).The highest of HABS abundance is dominated during the transitional season II. On the spatial approach, antropoegenic characteristics station contribute to the whole height of HABs. Influence of rainfall, spatially, antropogenical pressure, and hydrodinamical watres causing enhancement of HABs potency.

scholarly journals Auxotrophic interactions: a stabilizing attribute of aquatic microbial communities?

2020 ◽  
Vol 96 (11) ◽  
Author(s):  
Winifred M Johnson ◽  
Harriet Alexander ◽  
Raven L Bier ◽  
Dan R Miller ◽  
Mario E Muscarella ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Theoretical Work ◽  
Microbial Interactions ◽  
Ecosystem Structure ◽  
Community Members ◽  
Aquatic Microorganisms ◽  
The Stability

ABSTRACT Auxotrophy, or an organism's requirement for an exogenous source of an organic molecule, is widespread throughout species and ecosystems. Auxotrophy can result in obligate interactions between organisms, influencing ecosystem structure and community composition. We explore how auxotrophy-induced interactions between aquatic microorganisms affect microbial community structure and stability. While some studies have documented auxotrophy in aquatic microorganisms, these studies are not widespread, and we therefore do not know the full extent of auxotrophic interactions in aquatic environments. Current theoretical and experimental work suggests that auxotrophy links microbial community members through a complex web of metabolic dependencies. We discuss the proposed ways in which auxotrophy may enhance or undermine the stability of aquatic microbial communities, highlighting areas where our limited understanding of these interactions prevents us from being able to predict the ecological implications of auxotrophy. Finally, we examine an example of auxotrophy in harmful algal blooms to place this often theoretical discussion in a field context where auxotrophy may have implications for the development and robustness of algal bloom communities. We seek to draw attention to the relationship between auxotrophy and community stability in an effort to encourage further field and theoretical work that explores the underlying principles of microbial interactions.

scholarly journals A novel random forest approach to revealing interactions and controls on chlorophyll concentration and bacterial communities during coastal phytoplankton blooms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yiwei Cheng ◽  
Ved N. Bhoot ◽  
Karl Kumbier ◽  
Marilou P. Sison-Mangus ◽  
James B. Brown ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Chlorophyll Concentration ◽  
Ecosystem Structure ◽  
Monterey Bay ◽  
Phytoplankton Abundance ◽  
Abundance Patterns ◽  
Machine Learning Model ◽  
Marine Algal ◽  
Coastal Phytoplankton

AbstractIncreasing occurrence of harmful algal blooms across the land–water interface poses significant risks to coastal ecosystem structure and human health. Defining significant drivers and their interactive impacts on blooms allows for more effective analysis and identification of specific conditions supporting phytoplankton growth. A novel iterative Random Forests (iRF) machine-learning model was developed and applied to two example cases along the California coast to identify key stable interactions: (1) phytoplankton abundance in response to various drivers due to coastal conditions and land-sea nutrient fluxes, (2) microbial community structure during algal blooms. In Example 1, watershed derived nutrients were identified as the least significant interacting variable associated with Monterey Bay phytoplankton abundance. In Example 2, through iRF analysis of field-based 16S OTU bacterial community and algae datasets, we independently found stable interactions of prokaryote abundance patterns associated with phytoplankton abundance that have been previously identified in laboratory-based studies. Our study represents the first iRF application to marine algal blooms that helps to identify ocean, microbial, and terrestrial conditions that are considered dominant causal factors on bloom dynamics.

scholarly journals Harmful Algal in Banyuasin Coastal Waters, South Sumatera

2016 ◽  
Vol 8 (2) ◽  
pp. 232 ◽  
Author(s):  
Riris Aryawati ◽  
Dietriech Geoffrey Bengen ◽  
Tri Prartono ◽  
Hilda Zulkifli
Keyword(s):  
Food Chain ◽  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Biology Education ◽  
Mesh Size ◽  
Toxic Substances ◽  
Water Ecosystem ◽  
Monitoring Result ◽  
Harmful Effects

<p>Phytoplankton have important as food-chain major component and primary production of marine environment. However, high abundance of phytoplankton could give harmful effects toward water ecosystem. Moreover, they could produce toxic substances that will be accumulated within their consumer. This accumulation could be dangerous for human or animals.This research were aimed to determine and calculatespecies of harmful algae in Banyuasin coastal waters. The study was conducted on April, June, August, October and December of 2013, and in February 2014, at ten stations. Phytoplankton samples were taken vertically using plankton nets. In the form of cone-shaped with a diameter of 30 cm, length 100 cm and mesh size 30 μm.The result showed that there are 35 genera of phytoplankton. That have been found and consisted of four groups; Bacillariophyceae, Dinophyceae, Cyanophyceae and Chlorophyceae. 13 species were identified as Harmful Algal (Chaetoceros, Coscinodiscus, Nitzschia, Skeletonema, Thalassiosira, Alexandrium, Ceratium, Dinophysis, Noctiluca, Protoperidinium, Prorocentrum, Anabaena dan Oscillatoria), with seven of them were known for having toxin (Nitzschia, Alexandrium, Dinophysis, Protoperidinium Prorocentrum, Anabaena and Oscillatoria). Monitoring result showed that the highest number of species of potential harmful algal blooms (HABs) occured in June and the highest abundance occured in August, especially Chaetoceros and Skeletonema.</p><p><strong>How to Cite</strong></p><p>Aryawati, R., Bengen, D. G., Prartono, T., &amp; Zulkifli, H. (2016). Harmful Algal in Banyuasin Coastal Waters, South Sumatera. <em>Biosaintifika: Journal of Biology &amp; Biology Education</em>, 8(2), 231-239.</p>

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