Pollution, Eutrophication

EXAM QUESTION → Eutrophication: Increase of organic matter in a system. That’s it. Nixon, 1995.

Human Effects on Marine Environments

  • Complex - long term (chronic) and short term (acute) pollution

  • Pollutants may have synergistic or antagonistic effects

  • May come from point sources (a sewage pipe, single point of pollution) and non-point sources (variety of non-discrete locations)

  • Chesapeake Bay pollution breakdown: 23% point sources, 34% fertilizers, 25% atmospheric nitrate, 14% atmospheric ammonium, 4% animal waste

Assessing impacts on marine life

  • Baseline is critical - need to know what “normal” looks like

  • Single species vs community: Indicator species are chosen as bio-assays of pollution effects, direct studies can be made on uptake of substances and effects on mortality/population growth

  • Note: LD50 - Lethal Dose 50. Half of population dies at this dose

Toxic Substances

  • Noncumulative: do not increase in concentration in body over time

  • Cumulative: increase in concentration; ex. Metals

  • Food chain magnification: occurs when concentration of substance increases as passed from trophic level to trophic level ex. algal toxins

Toxic Metals

  • Mercury - from fossil fuel and waste combustion, mining, etc. Causes birth defects. Bio-magnifies

  • Cadmium - Batteries, sewage, electroplating factories. Kidney function and bone deformities

  • Lead - Batteries, paints, urban runoff, sewage, etc. Neurotoxin, mental development of children

Pesticides and Herbicides

  • Designed to kill pests and plants

  • Targets are often nonspecific, marine species also killed off

  • Pesticide toxicity often affects human health

Carbon-Based

  • DDT - chlorinated hydrocarbons. Used to kill mosquito. Banned in many countries… strong effect on reproductive function and eggshell thickness in birds of prey in the 70’s.

  • PCBs - Polychlorinated Biphenyls. Used as lubricants in industrial machinery. Highly toxic, implicated in reproductive failures in humans and marine mammals. Release in Northeast USA resulted in area closures to fishing and health advisories.

  • PAHs - Polycyclic aromatic hydrocarbons - Derivatives of fossil fuels, can be present in sewage and asphalt. Toxic effect on benthic invertebrates and fishes, effects on hormonal cycles and reproductive effects of fishes. Lot of interest

  • TBT - paint. Population declines and gender change in Dog whelk (mollusk)

Plastic Pollution

  • Organic polymers (silica, cellulose are also organic polymers)

  • Microplastics are in everything.

Oil Pollution

  • Oil sources: Leaks in terminals, loading pippes in harbords, offshore drilling, wrecks of oil tankers, washout of oil into storm drains and direct washout to the shoreline, etc

  • Aromatic compounds (compounds with benzene rings) are more toxic; percent aromatics is a good indicator

  • Refined oil has more aromatics than crude oil. Crude oil is generally less toxic

  • Impair cell membrane function, neurotoxic, behavioral effects

  • Deep Water Horizon Oil Spill: 2010, off Louisiana, 62,000 barrels of oil per DAY escaped. Caused mutant fish and crabs. Mortality rate doubled for marine mammals, food web contaminated for years to come. 1/3 oil is still in gulf.

  • Effects on seabirds: Loss of insulation, soaked to skin and often die of hypothermia. Ingest toxic oil while preening.

Nutrient Pollution

  • Not the same as eutrophication…

  • Inputs: River runoff, Ag runoff, sewage effluent, Urbanization, Tourism activities, Atmospheric Input → Large hypoxic or anoxic dead zones in coastal areas throughout the world. Dead matter on the bottom will generate a lot of bacteria.

  • Fish Kills: bunch of suffocated and dead fish.

Treatment of Sewage and Wastewater to combat eutrophication

  • Primary treatment: Solids intercepted by screens

  • Secondary treatment: More toxic nitrogenous organic compounds and colloids are stirred in aerobic tanks. Only phosphates, nitrates, and ammonia will be released into coastal waters… solid residue is then disposed.

  • Tertiary treatment: Even dissolved phosphates, nitrates, and ammonia are removed by means of anaerobic decomposition processes.

Microbial Pollution

  • Fecal coliforms after sewage spills

  • Indicators for water quality

  • Correlated with pathogens and disease-inducing microbes

Invasive Species

Vector: Means of Transport

Invasion Frequency: Most arrivals do not result in invasion success. Frequency of arrival is important

Ecological suitability of target habitat

Survival of initial population

  1. Definition. Marine species invasion: The establishment of marine species in regions where they were previously absent

  2. Invasion rate. Rate of invasion of marine coastal waters of North America, increasing since 1790. Invasions are common - facilitated via ship ballast water. Canals are important for invaders.

  3. Types of Invasions: Natural range expansions, Breakdown of biogeographic barriers (ballast water and canals, ex. zebra mussels, green crab, sea walnut), accidental and intentional introductions (fisheries, aquariums)

  4. Ecological consequences: Loss of genetic diversity. Parasites, diseases, impact on economy.

Aquarium dumping

  • Ex. Lion Fish, Killer Algae