Marine Population Dynamics Flashcards

Vocabulary and key concepts from the Marine Population Dynamics lecture including growth models, recruitment, mortality, and trophic cascades.

Population

A group of individuals of the same species occupying a specific area and sharing a gene pool over a certain period of time.

Population Dynamics

The study of how populations of a species change over time, seeking to understand abundance fluctuations and resilience.

John Muir

Known as the "Father" of the US National Park System, quoted saying, "When one tugs at a single thing in nature, he finds it attached to the rest of the world."

Management of populations

A key reason to care about population dynamics, involving the understanding of changes in size for endangered species, pests, or invasive species.

Maximum Sustained Yield (MSY)

The goal in fisheries management to maintain and maximize the amount of harvest that can be taken from a stock over an infinite period.

Per capita population growth rate

The rate at which the population size changes, determined by birth, death, emigration, and immigration rates.

Minimum Viable Population (MVP)

The lower bound on the population of a species such that it can survive in the wild.

Carrying Capacity (K)

The maximum sustainable population size of a species in a given area, determined by available resources such as food, habitat, and water.

Intra-specific competition

Competition between individuals of the same species for limited resources as population density increases.

Inter-specific competition

Competition between different species for limited resources.

John Damuth (1981)

Researcher who produced the first clear demonstration of the relationship between body size and population density, showing density declines as organism size increases.

Microbial population density

Bacterial populations in soils or water can exceed $10^9$ per cubic centimeter.

Phytoplankton density

Densities often exceed $10^6$ per cubic meter.

Peters and Wassenberg (1983)

Researchers whose data showed that mammals tend to live at higher population densities than birds, and many aquatic invertebrates live at higher densities than other animals of comparable size.

Random distribution

A distribution pattern where an individual has an equal probability of occurring anywhere in an area, resulting from neutral interactions.

Regular distribution

A distribution pattern where individuals are uniformly spaced, often due to antagonistic interactions or local depletion of resources.

Clumped (Aggregated) distribution

A distribution pattern where individuals live in areas of high local abundance separated by low abundance, due to mutual attraction or common resources.

Closed population model

A simple population model where immigration and emigration are zero, expressed as $N_{t+1} = N_t + B - M$.

Marine Microbes Biomass

Microorganisms account for $> 98\%$ of total ocean biomass.

Log phase

The time of exponential growth in a closed system such as marine microbes in a petri dish.

Stationary phase

A phase in a closed system where growth reaches a plateau because the number of dying cells equals the number of dividing cells.

Death phase

A phase in a closed system characterized by an exponential decrease in the number of living cells.

Oligotrophic region

A nutrient-limited region of the ocean, such as parts of the Atlantic, where nutrients like iron are scarce.

Westrich et al (2018)

Study found that Vibrio bacteria populations in the Atlantic correlated with aerosol particles from Sahara dust storms.

Hillborn and Walters (1992)

Authors who stated that to understand how populations respond to exploitation, we must appreciate how they behave when unexploited.

Biomass model for fish

A non-fishing model expressed as $B_{t+1} = B_t + R + G - M$.

Recruitment (R)

The appearance of new, young organisms in a population following a reproductive event, or the maturing of individuals into adult age classes.

Endogenous factors

Factors affecting recruitment, growth, and mortality that relate to the fish's genetics, physiology, and behavior.

Exogenous factors

External factors determined by the environment that affect population processes.

Asymptotic growth

The typical growth pattern for fish where young fish grow rapidly, growth slows at the onset of maturity, and is reduced in adults.

Natural Mortality Rate

The process of death due to natural causes like predation and disease, typically decreasing as fish "out-grow" predators but potentially increasing with reproductive stress in old age.

Metapopulation

A "population of populations" where semi-isolated sub-populations are periodically connected by dispersal.

Hydrothermal vents

Cited as the best example of a metapopulation structure in the marine environment.

Steller’s Sea Cow (Hydrodamalis gigas)

A giant relative of the Manatee and Dugong, discovered in 1741 and extinct by 1768 due to intense hunting by fur traders.

Neoextinctions

A term for historical extinctions across human history, reviewed by Carlton et al. (1999), suggesting many marine extinctions are unrecorded.

Blitzkrieg hunting

A description of the hunting intensity (7x sustainable limit) that led to the rapid extinction of the Steller's Sea Cow.

Trophic Cascades

Powerful indirect interactions occurring when a trophic level in a food web is suppressed, controlling entire ecosystems.

Top-down cascade

Occurs when predators reduce the abundance or change the behavior of prey, releasing the next lower trophic level from predation or herbivory.

Wilmers et al (2012)

Study analyzing how sea otters, by suppressing urchins, allow kelp forests to increase carbon storage.

Net Primary Productivity (NPP) of kelp with otters

Measured as $313\text{--}900\,g\,C\,m^{-2}\,yr^{-1}$.

Kelp Biomass density with otters

Measured as $101\text{--}180\,g\,C\,m^{-2}$.

Global sea otter carbon value (2012)

Estimated at $US\$205\text{--}408$ million on the European Carbon Exchange based on $US\$47$ per ton of carbon.

Gregr et al (2020)

Study showing that sea otter presence yields $37\%$ more total ecosystem biomass annually and increases value of finfish and ecotourism.

Humphead parrotfish

A critical herbivore for coral reefs; their removal by fishing leads to reefs being smothered by seaweed/algae.

Rarity and Extinction Risk

Species with restricted geographic ranges, narrow habitat tolerances, and small local populations are most vulnerable to extinction.

Vibrio

A common genus of marine bacteria used as a case study for resource limitation in open systems.

Barnacles

An example of dispersal where adults are attached to rocks but larvae travel on far-ranging ocean currents.

Shark vs. Tuna life history

Tuna produce high numbers of eggs ($10^7$) with high early mortality, while sharks have a different strategy impacting their resilience to fishing.