Although algal blooms, including those considered toxic or harmful, can be natural phenomena, the nature of the global problem of harmful algal blooms (HABs) has expanded both in extent and its public perception over the last several decades. Of concern, especially for resource managers, is the potential relationship between HABs and the accelerated eutrophication of coastal waters from human activities. We address current insights into the relationships between HABs and eutrophication, focusing on sources of nutrients, known effects of nutrient loading and reduction, new understanding of pathways of nutrient acquisition among HAB species, and relationships between nutrients and toxic algae. Through specific, regional, and global examples of these various relationships, we offer both an assessment of the state of understanding, and the uncertainties that require future research efforts. The sources of nutrients poten- tially stimulating algal blooms include sewage, atmospheric deposition, groundwater flow, as well as agricultural and aquaculture runoff and discharge. On a global basis, strong correlations have been demonstrated between total phos- phorus inputs and phytoplankton production in freshwaters, and between total nitrogen input and phytoplankton pro- duction in estuarine and marine waters. There are also numerous examples in geographic regions ranging from the largest and second largest U.S. mainland estuaries (Chesapeake Bay and the Albemarle-Pamlico Estuarine System), to the Inland Sea of Japan, the Black Sea, and Chinese coastal waters, where increases in nutrient loading have been linked with the development of large biomass blooms, leading to anoxia and even toxic or harmful impacts on fisheries re- sources, ecosystems, and human health or recreation. Many of these regions have witnessed reductions in phytoplankton biomass (as chlorophyll a) or HAB incidence when nutrient controls were put in place. Shifts in species composition have often been attributed to changes in nutrient supply ratios, primarily N:P or N:Si. Recently this concept has been extended to include organic forms of nutrients, and an elevation in the ratio of dissolved organic carbon to dissolved organic nitrogen (DOC:DON) has been observed during several recent blooms. The physiological strategies by which different groups of species acquire their nutrients have become better understood, and alternate modes of nutrition such as heterotrophy and mixotrophy are now recognized as common among HAB species. Despite our increased un- derstanding of the pathways by which nutrients are delivered to ecosystems and the pathways by which they are assimilated differentially by different groups of species, the relationships between nutrient delivery and the development of blooms and their potential toxicity or harmfulness remain poorly understood. Many factors such as algal species presence/ abundance, degree of flushing or water exchange, weather conditions, and presence and abundance of grazers contribute to the success of a given species at a given point in time. Similar nutrient loads do not have the same impact in different environments or in the same environment at different points in time. Eutrophication is one of several mechanisms by which harmful algae appear to be increasing in extent and duration in many locations. Although important, it is not the only explanation for blooms or toxic outbreaks. Nutrient enrichment has been strongly linked to stimulation of some harmful species, but for others it has not been an apparent contributing factor. The overall effect of nutrient over- enrichment on harmful algal species is clearly species specific.

/pdf/harmful-algal-blooms-and-eutrophication-nutrient-sources-4ujytujxjq.pdf

Harmful Algal Blooms and Eutrophication: Nutrient Sources, Composition, and Consequences

(2002). The Effects of Harmful Algal Blooms on Aquatic Organisms. Reviews in Fisheries Science: Vol. 10, No. 2, pp. 113-390.

The Effects of Harmful Algal Blooms on Aquatic Organisms

Ongoing climate change is predicted to affect individual organisms during all life stages, thereby affecting populations of a species, communities and the functioning of ecosystems. These effects of climate change can be direct, through changing water temperatures and associated phenologies, the lengths and frequency of hypoxia events, through ongoing ocean acidification trends or through shifts in hydrodynamics and in sea level. In some cases, climate interactions with a species will also, or mostly, be indirect and mediated through direct effects on key prey species which change the composition and dynamic coupling of food webs. Thus, the implications of climate change for marine fish populations can be seen to result from phenomena at four interlinked levels of biological organization: (1) organismal-level physiological changes will occur in response to changing environmental variables such as temperature, dissolved oxygen and ocean carbon dioxide levels. An integrated view of relevant effects, adaptation processes and tolerance limits is provided by the concept of oxygen and capacity-limited thermal tolerance (OCLT). (2) Individual-level behavioural changes may occur such as the avoidance of unfavourable conditions and, if possible, movement into suitable areas. (3) Population-level changes may be observed via changes in the balance between rates of mortality, growth and reproduction. This includes changes in the retention or dispersion of early life stages by ocean currents, which lead to the establishment of new populations in new areas or abandonment of traditional habitats. (4) Ecosystem-level changes in productivity and food web interactions will result from differing physiological responses by organisms at different levels of the food web. The shifts in biogeography and warming-induced biodiversity will affect species productivity and may, thus, explain changes in fisheries economies. This paper tries to establish links between various levels of biological organization by means of addressing the effective physiological principles at the cellular, tissue and whole organism levels.

/pdf/climate-change-effects-on-fishes-and-fisheries-towards-a-1sfdj8i5bb.pdf

Climate change effects on fishes and fisheries: towards a cause-and-effect understanding

http://www.dulvy.com/uploads/2/1/0/4/21048414/sheppard_et_al_mpb10.pdf

The Gulf: a young sea in decline.

This paper develops a framework for the study of climate on fish populations based on first principles of physiology, ecology, and available observations. Environmental variables and oceanographic features that are relevant to fish and that are likely to be affected by climate change are reviewed. Working hypotheses are derived from the differences in the expected response of different species groups. A review of published data on Northeast Atlantic fish species representing different biogeographic affinities, habitats, and body size lends support to the hypothesis that global warming results in a shift in abundance and distribution (in patterns of occurrence with latitude and depth) of fish species. Pelagic species exhibit clear changes in seasonal migration patterns related to climateinduced changes in zooplankton productivity. Lusitanian species have increased in recent decades (sprat, anchovy, and horse mackerel), especially at the northern limit of their distribution areas, while Boreal species decreased at the southern limit of their distribution range (cod and plaice), but increased at the northern limit (cod). Although the underlying mechanisms remain uncertain, available evidence suggests climate-related changes in recruitment success to be the key process, stemming from either higher production or survival in the pelagic egg or larval stage, or owing to changes in the quality/quantity of nursery habitats.

Resolving the effect of climate change on fish populations

A fish kill of massive proportion in Kuwait Bay, Arabian Gulf, 2001: the roles of bacterial disease, harmful algae, and eutrophication.

Significant natural and aquaculture fish deaths in Kuwait Bay occurred from September to October of 1999 and were attributed to a bloom of the dinoflagellate Gymnodinium sp. A chronology of the bloom event suggests that a period of low winds and stable water-column structure preceded the bloom. Maximum cell concentrations of Gymnodinium sp. (>6 × 10 6 cells l -1 ) were also immediately preceded by a more than 20-fold increase in mean inorganic nitrogen concentrations (up to 60 µM) and elevated inorganic phosphate concentrations. This, combined with elevated inorganic and or- ganic nutrient concentrations within the bloom, suggests that coastal nutrient eutrophication was likely to have contributed significantly to bloom development and support. Termination of the Gymno- dinium sp. bloom coincided with a bloom of the non-toxic ciliate Mesodinium rubrum, which appeared as large red patches in Kuwait Bay. While no adverse human health effects were associated with the bloom, closure of shellfish and selected finfish (largely mullet Liza macrolepis) markets resulted in sig- nificant economic losses to the region. The occurrence of this toxic algal bloom event, the first within the Arabian Sea, highlights the need for monitoring and research programs in the Arabian Sea and Kuwait Bay that focus on nutrients and eutrophication, in addition to oil related pollution issues.

https://www.int-res.com/articles/meps/214/m214p015.pdf

First record of a fish-killing Gymnodinium sp. bloom in Kuwait Bay, Arabian Sea: chronology and potential causes

In Iraq, the majority of rock slope instability issues along highways result in road deterioration or collapse. Among these is located along Bazian-Basara main road on the southwestern limb of the Bazian anticline fold. For the study of this problem, stations along the road within Sinjar and Pila Spi formations are selected. The study included an investigation of the slopeʾs stability and the occurrence and potential failures. The stability of the slopes was evaluated using the SMRTool-v205 software, which is used to classify the condition and degree of the slopeʾs stability. The stability analysis results demonstrate the possibility of wedge sliding and direct toppling occurrence in the stations 4,8, and 10, thus, described as unstable slopes and need important intervention. Whereas the dominant failure modes in stations 3,4,6,7,9, and 10 and stations 1 and 5 in the slope with a dip of 90̊ are direct toppling, flexure toppling, and wedge sliding, therefore, described as normal and partially stable slopes and need to systematic monitoring. As well as, direct toppling is the dominant failure mode in stations 1 with a slope of dip 20̊ and stations 2,5, and 7 which are classified as good and stable slopes but need to be monitored occasionally.

https://igj-iraq.org/igj/index.php/igj/article/download/651/969

Assessment of Rock Slope Stability along Bazian-Basara Main Road, Sulaimani, NE Iraq

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A fish kill of massive proportion in Kuwait Bay, Arabian Gulf, 2001: the roles of bacterial disease, harmful algae, and eutrophication.

First record of a fish-killing Gymnodinium sp. bloom in Kuwait Bay, Arabian Sea: chronology and potential causes

Assessment of Rock Slope Stability along Bazian-Basara Main Road, Sulaimani, NE Iraq