Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales.
The American pickerels are two subspecies of Esox americanus, a medium-sized species of North American freshwater predatory fish belonging to the pike family :
Zooplankton are the animal component of the planktonic community. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.
Aurelia aurita is a species of the family Ulmaridae. All species in the genus are very similar, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus.
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs.
The New Zealand bigeye is a species of marine ray-finned fish, a sweeper from the family Pempheridae. It is endemic to the waters around New Zealand. It inhabitants rocky shores with plentiful overhangs and crevices at depths of from near the surface to 70 metres (230 ft).
A lake ecosystem or lacustrine ecosystem includes biotic (living) plants, animals and micro-organisms, as well as abiotic (non-living) physical and chemical interactions. Lake ecosystems are a prime example of lentic ecosystems, which include ponds, lakes and wetlands, and much of this article applies to lentic ecosystems in general. Lentic ecosystems can be compared with lotic ecosystems, which involve flowing terrestrial waters such as rivers and streams. Together, these two ecosystems are examples of freshwater ecosystems.
The emerald shiner is one of hundreds of small, silvery, slender fish species known as shiners. The identifying characteristic of the emerald shiner is the silvery emerald color on its sides. It can grow to 3.5 inches in length and is found across North America from Canada to the Gulf of Mexico, commonly in large, deep lakes and rivers, though sometimes in smaller bodies of water as well. It feeds on small organisms such as zooplankton and insects, congregating in large groups near the surface of the water. It is a quite common fish and is often used as a bait fish.
The limnetic zone is the open and well-lit area of a freestanding body of freshwater, such as a lake or pond. Not included in this area is the littoral zone, which is the shallow, near-shore area of the water body. The key difference between the littoral zone and the limnetic zone is the presence of rooted plant growth. The floor under the limnetic zone cannot sustain plant growth due to a lack of sunlight for photosynthesis. In extremely shallow bodies of water, light may penetrate all the way to floor even in the deepest center parts of the lake. In this situation, there is an absence of a limnetic zone and the littoral zone spans the entire lake. Together, these two zones comprise the photic zone.
The Olympic mudminnow is a fish native to the western lowlands of Washington: the Chehalis River basin, Deschutes River basin, and some Olympic Peninsula basins. It grows to 8 cm in length, and is Washington's only known endemic freshwater fish species. Although they strongly resemble killifish, mudminnows are more closely related to pike and muskellunge.
The brook stickleback is a small freshwater fish that is distributed across the US and Canada. It grows to a length of about 2 inches. It occupies the northern part of the eastern United States, as well as the southern half of Canada. Small populations are scattered throughout the Mississippi-Great Lakes basin extending to Colorado, New Mexico, Kentucky, Tennessee, etc., though some of these areas are not native to the species. This small fish inhabits clear, cool streams and lakes. They eat small invertebrates, algae, insect larvae, and occasionally their own eggs. They are also preyed upon by smallmouth bass and northern pike. Feedin time is usually dawn and sunset. The brook stickleback does have active competition mostly from minnows, but feeding times are different, along with diet. Spawning occurs in midsummer. Males secure a territory, build a nest, and mate with females. Males provide protection for the eggs, ward off predators, and usually die later in the season. This is considered an annual species. The nests are built out of aquatic grasses. Though the brook stickleback is not considered a threatened species, deforesting and changing waters are altering ecosystems of the species. Harvesting of trees around riparian environments is having a large effect of the stream ecosystem where the brook stickleback resides.
Umbridae is a family of fish in the order Esociformes, which contains pike, pickerel, and mudminnows. The single living genus, Umbra, occupies weed-choked freshwater habitats in eastern North America and eastern Europe. While the family traditionally contained the genera Umbra, Novumbra, and Dallia, recent genetic and paleontological research have recovered this grouping as paraphyletic, with Novumbra and Dallia being moved to the family Esocidae.
The eastern mudminnow is a species of freshwater fish belonging to the family Umbridae. It is native to eastern North America, but has been introduced to Europe. It feeds primarily on insect larvae and other small aquatic invertebrates.
Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding. They include particularly fishes of the order Clupeiformes, but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.
The threadfin shad is a small pelagic freshwater forage fish common in lakes, large streams and reservoirs of the Southeastern United States. Like the American gizzard shad, the threadfin shad has an elongated dorsal fin, but unlike the gizzard shad, its mouth is more terminal without a projecting upper jaw. The fins of threadfin shad often have a yellowish color, especially the caudal fin. The back is grey to blue with a dark spot on the shoulder. D. petenense is more often found in moving water, and is rarely found deep in the water column. It occurs in large schools, sometimes with gizzard shad, and can be seen on the surface at dawn and dusk. The threadfin shad may reach lengths of 8 in (200 mm), but only rarely. This fish is very sensitive to changes in temperature and dissolved oxygen, and die-offs are frequent in late summer and fall, especially when water temperature drops to 42 °F. The threadfin shad is a favorite food for many game fishes, including striped bass, largemouth bass, smallmouth bass, and catfish. This fish is widely introduced throughout the United States as a forage for game fish.
The fantail darter is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is widely distributed across streams in North America.
The dollar sunfish is a species of freshwater fish in the sunfish family of order Perciformes. It is categorized as a warm water pan-fish. Early settlers said that this species of sunfish resembled a European species they called bream. Historically it has been found along the Southern Atlantic coastal drainages from North Carolina to Florida, and west to Texas. Lepomis marginatus mainly feeds on detritus and filamentous algae as well as a few terrestrial insects. The juvenile and mature fish do not have many predators, but the eggs in the nest are in danger of predation from a few different species of fish.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
