Freshwater Diversity and Ecology

Vocabulary flashcards covering limnology, aquatic taxonomic groups, speciation dynamics, ecosystem values, and aquatic microorganisms based on the lecture.

Epilimnion

The warm, well-lit surface layer of a stratified lake.

Metalimnion

The middle layer of a stratified lake, providing an optimal balance of cooler temperatures and aquatic plant presence for oxygen retention.

Hypolimnion

The bottom layer of a deep reservoir or lake, characterized by very cold temperatures and typically low oxygen levels dominated by anoxic bacteria.

Phosphorus

The chemical element identified as relatively the scarcest nutrient required by organisms in freshwater ecosystems relative to their nutritional demand.

Family Sialidae

A family of insects in the order Megaloptera, known as alderflies, whose larvae lose identification colors and patterns rapidly when stored in ethanol.

Keystone Species

An organism that exerts an overwhelming and disproportionate influence on its ecological niche or wider ecosystem integrity relative to its abundance.

Indirect Value

The ecological and economic benefit provided by natural ecosystem services, such as pest suppression by predators or nutrient cycling by soil microbes.

Direct Value

The tangible economic value derived from marketable biological resources, such as harvested fish or livestock.

Viruses

Non-living biological entities that lack independent metabolic machinery and reproduce by injecting their genetic material into host cells.

Archaea

A domain of single-celled prokaryotic extremophiles that lack typical cell organelles and thrive in extreme conditions like hot springs or hypersaline lakes.

Cyanobacteria

Photosynthetic prokaryotes in the domain Bacteria, commonly referred to as blue-green algae, that proliferate in nutrient-dense eutrophic waters.

Green Algae

The most diverse group of photosynthetic algae, commonly found across all aquatic habitats as slimy or filamentous growth.

Golden Algae

A group of algae typically restricted to low-nutrient oligotrophic lakes, rarely forming dense accumulations.

Phytoplankton

Photosynthetic plant or algal organisms that float freely within open water columns.

Zooplankton

Microscopic animal organisms that drift within open aquatic water columns.

Benthic Organisms

Organisms that live attached to, on, or within the bottom substrate of a body of water.

Protozoa

An artificial, paraphyletic group of single-celled or simple eukaryotic organisms that cannot be classified into plants, animals, or fungi.

Naegleria fowleri

A pathogenic protozoan amoeba that inhabits warm lake sediments and causes fatal brain infections if forced up human nasal passages.

Aquatic Fungi

Eukaryotic decomposers essential for breaking down organic carbon sources, such as submerged leaf litter, in freshwater ecosystems.

Surface Liquid Freshwater Coverage

The proportion of the Earth's surface covered by liquid surface fresh water, estimated at approximately $0.8\%\text{ to }0.9\%$.

Primary Driver of Freshwater Speciation

The dynamic fragmentation, re-routing, and geological isolation of land-locked aquatic networks, which rapidly separates populations.

Reason for Lack of Freshwater-Exclusive Higher Taxa

The dynamic, geological reconnecting of river basins over time, which prevents isolations from lasting long enough to evolve unique phyla or classes.

Family Simuliidae

A family of blood-sucking black flies whose aquatic larvae host protozoan parasites that cause sleeping sickness in human populations.

Chytrid Fungus

A major fungal pathogen affecting global amphibian populations, varying in impact across different elevations and latitudes.

Diatoms

Single-celled photosynthetic algae featuring silica-based, ornate cell walls that are distributed widely across diverse aquatic habitats.

Planktonic Sampling

The standardized technique of collecting free-floating organisms in the open water column, favored for its scientific repeatability.