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93-547: The park is noted for abundant sea life , tropical bird breeding grounds, colorful coral reefs, and shipwrecks and sunken treasures. The park's centerpiece is Fort Jefferson, a massive but unfinished coastal fortress . Fort Jefferson is the largest brick masonry structure in the Western Hemisphere, composed of more than 16 million bricks. Dry Tortugas is unique in its combination of a largely undisturbed tropical ecosystem with significant historic artifacts. The park

186-437: A Cessna airplane crashed into the water near the islands, killing cinematographer Neal Fredericks while he was filming scenery for the feature film CrossBones . In September 2022, the islands were again directly struck by Hurricane Ian . The Dry Tortugas archipelago is classified as a borderline subtropical—tropical ecosystem, hosting species that do not normally breed in, and are not commonly found anywhere else within,

279-858: A and b ) and also include siphonoxanthin and siphonein. Currently, Halimeda does not appear to be cultivated for aquaculture purposes. Methanol and dimethyformamide extracts of Halimeda opuntia have been observed to have antibacterial properties against some species of microorganisms, including Saccharomyces cerevisiae , Escherichia coli , Bacillus subtilis , and most significantly, Staphylococcus aureus. Halimeda opuntia ethanol extract exhibited activity against hepatitis C virus (HCV) due to polymerase inhibitory (HCV-796) binding sites based on molecular docking simulation. Methanolic extracts of Halimeda macroloba have recently been found to exhibit cytotoxicity towards MCF-7 and HT 29 cells, which are derived from human breast cancer cell lines and colon cancer lines, respectively. These results therefore suggest

372-844: A backbone, make up a huge portion of all life in the sea. Invertebrate sea life includes Cnidaria such as jellyfish and sea anemones ; Ctenophora ; sea worms including the phyla Platyhelminthes , Nemertea , Annelida , Sipuncula , Echiura , Chaetognatha , and Phoronida ; Mollusca including shellfish , squid , octopus ; Arthropoda including Chelicerata and Crustacea ; Porifera ; Bryozoa ; Echinodermata including starfish ; and Urochordata including sea squirts or tunicates . Over 10,000 species of fungi are known from marine environments. These are parasitic on marine algae or animals, or are saprobes on algae, corals, protozoan cysts, sea grasses, wood and other substrata, and can also be found in sea foam . Spores of many species have special appendages which facilitate attachment to

465-452: A calcareous alga, Halimeda has been found to have good potential as a carbon sink and can play an important role in regulating the ocean's carbon budget. Some species such as H. opuntia have been found to produce up to 54.37 g CaCO 3 m yr . The genus also contributes to reef building, as it is large producer of carbon sediments on reefs, generating a wide range of sediment sizes from coarse particles to silt and clay. Although it

558-552: A huge community of life, including the corals themselves, their symbiotic zooxanthellae , tropical fish and many other organisms. Much attention in marine biology is focused on coral reefs and the El Niño weather phenomenon. In 1998, coral reefs experienced the most severe mass bleaching events on record, when vast expanses of reefs across the world died because sea surface temperatures rose well above normal. Some reefs are recovering, but scientists say that between 50% and 70% of

651-566: A regulated manner. During the United States federal government shutdowns of 1995–1996 , Dry Tortugas was closed along with all other national parks. Seeing this as having a damaging effect on their tourism-dependent economy, the residents of Key West , Florida , raised money to keep Dry Tortugas open. The effort was inspired by the Smithsonian Institution , which raised private donations to keep its museums open during

744-418: A rock surface. The last type is the "sand-grower", where the filaments hold on to fine sand particles, forming a root-like structure. Halimeda is coenocytic and siphonous, meaning its cells are not divided by cross walls, and is instead a continuous filament of cells. This differentiates the genus from Acetabularia , which is another genus of green seaweed that is calcified. Halimeda is highly abundant in

837-540: A satellite-based voice-over-IP system, which is prone to garbling and delays, and by a radio relay system using an abandoned Air Force tower between Key West and the Dry Tortugas. Visitation steadily rose for several decades, reaching a peak of 83,704 in 2000. Since then visitation has slowly declined, with an average of about 63,000 per year in the period from 2007 to 2016. In August 2004, the Dry Tortugas were directly struck by Hurricane Charley . The following day,

930-552: A shipwreck believed to be part of the 1622 Spanish treasure fleet . The wreck located in 1,332 ft (406 m) of water, yielded olive jars, copper, gold, silver, glass and other cultural artifacts. On September 6, 1622, the Nuestra Señora de Atocha was driven by a severe hurricane onto a coral reef near the Dry Tortugas , about 35 mi (56 km) west of Key West . Mel Fisher and his company discovered

1023-475: A small freshwater fountain existed beneath several seaside mahoe and buttonwood trees, and was the only freshwater source for many miles. Maintenance issues necessitated its removal, but a replacement water barrel is scheduled for installation in the fall of 2013. Each year several bird guides offer tours of Dry Tortugas National Park during April and early May when daily bird lists can often reach 100 or more species. An active eradication program has resulted in

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1116-409: A transition zone between freshwater river environments and saltwater maritime environments. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The shifting flows of both sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among

1209-409: A year. Information on the phases of Halimeda 's life cycle are limited. It is thought that there is a haploid gametophyte phase, which might be followed by a sporophyte phase, since it not yet known when meiosis occurs. Asexual reproduction occurs via vegetative "cloning" through fragmentation and dispersal. The genus' photosynthetic pigments are those typical of class Chlorophyta (chlorophyll

1302-464: Is accessible only by seaplane or boat and has averaged about 63,000 visitors annually in the period from 2008 to 2017. Activities include snorkeling , picnicking, birdwatching , camping, scuba diving , saltwater fishing and kayaking. Overnight camping is limited to eight primitive campsites at the Garden Key campground, located just south of Fort Jefferson. Dry Tortugas National Park is part of

1395-452: Is also becoming understood that the well-being of marine organisms and other organisms are linked in fundamental ways. The human body of knowledge regarding the relationship between life in the sea and important cycles is rapidly growing, with new discoveries being made nearly every day. These cycles include those of matter (such as the carbon cycle ) and of air (such as Earth's respiration , and movement of energy through ecosystems including

1488-471: Is closely linked to oceanography , especially biological oceanography , and may be regarded as a sub-field of marine science . It also encompasses many ideas from ecology . Fisheries science and marine conservation can be considered partial offshoots of marine biology (as well as environmental studies ). Marine chemistry , physical oceanography and atmospheric sciences are also closely related to this field. An active research topic in marine biology

1581-450: Is distinctly segmented and calcified. Calcium carbonate is deposited as aragonite and calcification begins as early as 36 hours. Their segments are composed of 60-80% aragonite and are separated by nodes which are non-calcified. The thalli are composed of siphons which are ramified into medullary filaments surrounded by a cortex. The medullary filaments branch out trichotomously to form peripheral utricles which stick to each other to enclose

1674-461: Is extreme and there is no sunlight, but some life still exists. A white flatfish , a shrimp and a jellyfish were seen by the American crew of the bathyscaphe Trieste when it dove to the bottom in 1960. In general, the deep sea is considered to start at the aphotic zone , the point where sunlight loses its power of transference through the water. Many life forms that live at these depths have

1767-413: Is more than 99 percent water. The northern and western portions of the park, including the central island group, were designated a 46-square-mile (120 km) research natural area in 2007, in which no marine life may be taken, nor may vessels anchor. Vessels wishing to moor in this area must use designated mooring buoys or docks. About 54 percent of the park remains open for fishing. The park is bordered on

1860-426: Is still much more to learn about the deeper parts of the ocean . In biology, many phyla, families and genera have some species that live in the sea and others that live on land. Marine biology classifies species based on their environment rather than their taxonomy. For this reason, marine biology encompasses not only organisms that live only in a marine environment, but also other organisms whose lives revolve around

1953-797: Is to discover and map the life cycles of various species and where they spend their time. Technologies that aid in this discovery include pop-up satellite archival tags , acoustic tags , and a variety of other data loggers . Marine biologists study how the ocean currents , tides and many other oceanic factors affect ocean life forms, including their growth, distribution and well-being. This has only recently become technically feasible with advances in GPS and newer underwater visual devices. Most ocean life breeds in specific places, nests in others, spends time as juveniles in still others, and in maturity in yet others. Scientists know little about where many species spend different parts of their life cycles especially in

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2046-426: Is widespread and very diverse under the ocean. Microscopic photosynthetic algae contribute a larger proportion of the world's photosynthetic output than all the terrestrial forests combined. Most of the niche occupied by sub plants on land is actually occupied by macroscopic algae in the ocean, such as Sargassum and kelp , which are commonly known as seaweeds that create kelp forests . Plants that survive in

2139-636: The Atocha's sister galleon the Santa Margarita , lost in the same year, and the remains of a slave ship known as the Henrietta Marie , lost in 1700. Fort Jefferson is a massive but unfinished coastal fortress . It is the largest masonry structure in the Western Hemisphere, and is composed of more than 16 million bricks. Planning for a fortification began almost immediately after American acquisition, and construction started in 1847. Work

2232-669: The Everglades & Dry Tortugas Biosphere Reserve , established by UNESCO in 1976 under its Man and the Biosphere Programme . The Dry Tortugas are a small archipelago of coral islands about 70 miles (110 km) west of Key West, Florida . They represent the westernmost extent of the Florida Keys , though several reefs and submarine banks continue westward outside the park, beyond the Tortugas. The park area

2325-602: The Navy established a base in the Dry Tortugas, and it subsequently set up a coaling (refueling) and a wireless (radio) station there as well. During World War I , a seaplane base was established in the islands, but it was abandoned soon thereafter. From 1903 until 1939 the Carnegie Institution of Washington operated the Marine Biology Laboratory on Loggerhead Key which "...quickly became

2418-534: The United States Army Corps of Engineers hired enslaved laborers. Between 1847 and 1860, approximately 17% of Key West's enslaved people were leased to the Corp as laborers. The majority of the enslaved people working at Fort Jefferson were men, who were the base of the hard, unskilled workers. Some were also employed as domestic servants, boatmen and cooks. Enslaved women were also present. They did

2511-558: The Woods Hole Oceanographic Institution . An account of a visit to the fort at the Dry Tortugas by President Franklin D. Roosevelt and Justice-to-be Robert H. Jackson can be found in Jackson's book That Man: An Insider's Portrait of Franklin D. Roosevelt . Fort Jefferson was home to African Americans not only as enslaved persons but also as Union Soldiers, freedmen and prisoners. Starting in 1847,

2604-655: The epipelagic , mesopelagic , bathypelagic , abyssopelagic , and hadopelagic zones. Zones which vary by the amount of light they receive include the photic and aphotic zones . Much of the aphotic zone's energy is supplied by the open ocean in the form of detritus . The deepest recorded oceanic trench measured to date is the Mariana Trench , near the Philippines , in the Pacific Ocean at 10,924 m (35,840 ft). At such depths, water pressure

2697-405: The marine environment are often called seabirds . Examples include albatross , penguins , gannets , and auks . Although they spend most of their lives in the ocean, species such as gulls can often be found thousands of miles inland. There are five main types of marine mammals: cetaceans ( toothed whales and baleen whales ); sirenians such as manatees ; pinnipeds including seals and

2790-456: The microorganisms within the ocean; looking at how they are affected by their environment and how that affects larger marine creatures and their ecosystem. Biological oceanography is similar to marine biology, but it studies ocean life from a different perspective. Biological oceanography takes a bottom up approach in terms of the food web, while marine biology studies the ocean from a top down perspective. Biological oceanography mainly focuses on

2883-588: The saltwater crocodile . Most extant marine reptiles, except for some sea snakes, are oviparous and need to return to land to lay their eggs. Thus most species, excluding sea turtles, spend most of their lives on or near land rather than in the ocean. Despite their marine adaptations, most sea snakes prefer shallow waters nearby land, around islands, especially waters that are somewhat sheltered, as well as near estuaries. Some extinct marine reptiles, such as ichthyosaurs , evolved to be viviparous and had no requirement to return to land. Birds adapted to living in

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2976-441: The walrus ; sea otters ; and the polar bear . All are air-breathing, meaning that while some such as the sperm whale can dive for prolonged periods, all must return to the surface to breathe. The marine ecosystem is large, and thus there are many sub-fields of marine biology. Most involve studying specializations of particular animal groups, such as phycology , invertebrate zoology and ichthyology . Other subfields study

3069-469: The Dry Tortugas include the Yankee Freedom III catamaran , private vessel chartering and seaplane services. Other methods of visiting the Dry Tortugas include chartering of authorized and approved private vessels. There are no road connections to Dry Tortugas, and cars cannot access the islands. Inside Dry Tortugas National Park the goods and services are limited. Visitors are required to bring

3162-538: The Dry Tortugas is the driest place in Florida with an annual precipitation of about 38 in (970 mm). There is no large jungle or forest canopy area on the islands, and the sandy soil (which drains quickly) and intense sun only enhance the drought-like conditions often found on the islands. Seasonally there is little temperature variation, with high temperatures in summer around 91 °F (33 °C) and low temperatures in winter around 65 °F (18 °C). Like

3255-510: The Dry Tortugas, consisting mainly of disarticulated Halimeda plates. Between the Dry Tortugas and Key West is a 39 ft (12 m) thick example of these sand deposits, known as "the quicksands ". Dry Tortugas has a tropical savanna climate ( Aw ), with a rainy season coinciding with the Atlantic hurricane season from May to October and a dry season extending from November through April. Despite occasional exposure to tropical systems,

3348-446: The ability to create their own light known as bio-luminescence . Marine life also flourishes around seamounts that rise from the depths, where fish and other sea life congregate to spawn and feed. Hydrothermal vents along the mid-ocean ridge spreading centers act as oases , as do their opposites, cold seeps . Such places support unique biomes and many new microbes and other lifeforms have been discovered at these locations.There

3441-500: The absence of surface fresh water on the island. The name is the second oldest surviving European place-name in the US. The archipelago includes a high concentration of historically significant shipwrecks dating from the 17th century to the present. In 1742 HMS Tyger wrecked in the Dry Tortugas. The stranded crew lived on Garden Key for 56 days, and fought a battle with a Spanish sloop, before sailing to Jamaica in several boats. Florida

3534-417: The area that extends from the shoreline to the edge of the continental shelf . Most marine life is found in coastal habitats, even though the shelf area occupies only seven percent of the total ocean area. Open ocean habitats are found in the deep ocean beyond the edge of the continental shelf. Alternatively, marine habitats can be divided into pelagic and demersal habitats. Pelagic habitats are found near

3627-400: The areas that are close to the shore, are constantly being exposed and covered by the ocean's tides . A huge array of life can be found within this zone. Shore habitats span from the upper intertidal zones to the area where land vegetation takes prominence. It can be underwater anywhere from daily to very infrequently. Many species here are scavengers, living off of sea life that is washed up on

3720-571: The best-equipped marine biological station in the tropical world." Through the years, over 150 researchers used the facilities to perform a wide range of research. In June 1911 the laboratory built a vessel in Miami, Anton Dohrn , for use by researchers as well as logistics between the station and Key West. The vessel, excepting a period of World War I service with the Navy, supported the laboratory's work until closure in 1939 and donation of Anton Dohrn to

3813-451: The canopy of Acropora colonies were larger than those in open areas exposed to herbivory. Halimeda reproduces both sexually and asexually. Sexual reproduction is rarely observed because it is completed in 36 hours. The process begins with gametangia forming on the edges of the segments of the thalli. By the next day, the cells of the thallus will have been entirely converted to gametangia. These will mature overnight and release gametes in

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3906-424: The continental United States or the islands and waters surrounding it. When the cold wave of January 1977 wiped out 96 percent of branching coral, once extensive branching coral formations became rubble fields. The Dry Tortugas National Park now consists of patch reef and branching coral rubble. Dry Tortugas National Park has an official bird list of 299 species. Of these, only eight species frequently nest within

3999-418: The development of marine protected areas . This data is important to both scientists and fishermen because they are discovering that, by restricting commercial fishing in one small area, they can have a large impact in maintaining a healthy fish population in a much larger area. The study of marine biology dates to Aristotle (384–322 BC), who made many observations of life in the sea around Lesbos , laying

4092-607: The distinction between plants and animals often breaks down in very small organisms. Other zooplankton include cnidarians , ctenophores , chaetognaths , molluscs , arthropods , urochordates , and annelids such as polychaetes . Many larger animals begin their life as zooplankton before they become large enough to take their familiar forms. Two examples are fish larvae and sea stars (also called starfish ). Microscopic algae and plants provide important habitats for life, sometimes acting as hiding places for larval forms of larger fish and foraging places for invertebrates. Algal life

4185-455: The doctor who treated John Wilkes Booth in the wake of the Lincoln assassination, was imprisoned here for conspiracy with three others until early 1869, when he was pardoned in 1869 after averting a viral outbreak. Also imprisoned was a leader of the "Chicago Conspiracy", Englishman George St. Leger Grenfell , who is supposed to have drowned having escaped in a small boat. During the 1880s,

4278-639: The east, south and west by the Florida Keys National Marine Sanctuary , and on the northwest by the Tortugas Ecological Reserve. The keys are low and irregular. Some have thin growths of mangroves , and various other vegetation, while the smallest have only small patches of grass, or no plant life. There are nominally seven islands, but there have been up to eleven during the past two centuries. The islands are continually changing in size and shape, and

4371-625: The eastern limit in the vicinity of Miami. These Florida Keys are the surface expression of the 3.7 mi (6.0 km) thick southern Florida carbonate platform , which has been accumulating sediments since the Early Cretaceous . Two stratigraphic units are exposed at the surface, the Key Largo Limestone and the Miami Limestone. The Key Largo Limestone are reefs up to 200 ft (61 m) thick, parallel to

4464-500: The ecosystem of the ocean with an emphasis on plankton : their diversity (morphology, nutritional sources, motility, and metabolism); their productivity and how that plays a role in the global carbon cycle; and their distribution (predation and life cycle). Biological oceanography also investigates the role of microbes in food webs, and how humans impact the ecosystems in the oceans. Marine habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in

4557-466: The family Halimedaceae. It has five monophyletic sections - Halimeda J.V. Lamouroux , Micronesicae Hillis-Col , Opuntia J. Agardh ex De Toni , Pseudo-opuntia J. Agardh ex De Toni , and Rhipsalis J. Agardh ex De Toni - which were based on the differences in the fusions of medullary siphons. Halimeda tuna serves as the holotype for the genus. There are 71 species and 67 infraspecific names listed on Algaebase as of 2015. The thalli of Halimeda

4650-501: The food, water and supplies they might need during their time in the park. The closest restaurants and hotels are located in Key West. However, primitive camping sites are available within Dry Tortugas on Garden Key. Marine biology Marine biology is the scientific study of the biology of marine life , organisms that inhabit the sea . Given that in biology many phyla , families and genera have some species that live in

4743-484: The foundation for many future discoveries. In 1768, Samuel Gottlieb Gmelin (1744–1774) published the Historia Fucorum , the first work dedicated to marine algae and the first book on marine biology to use the new binomial nomenclature of Linnaeus . It included elaborate illustrations of seaweed and marine algae on folded leaves. The British naturalist Edward Forbes (1815–1854) is generally regarded as

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4836-513: The founder of the science of marine biology. The pace of oceanographic and marine biology studies quickly accelerated during the course of the 19th century. The observations made in the first studies of marine biology fueled the Age of Discovery and exploration that followed. During this time, a vast amount of knowledge was gained about the life that exists in the oceans of the world. Many voyages contributed significantly to this pool of knowledge. Among

4929-423: The home to many exotic biological materials that may inspire biomimetic materials . Through constant monitoring of the ocean, there have been discoveries of marine life which could be used to create remedies for certain diseases such as cancer and leukemia. In addition, Ziconotide, an approved drug used to treat pain, was created from a snail which resides in the ocean. Marine biology is a branch of biology . It

5022-411: The infant and juvenile years. For example, it is still largely unknown where juvenile sea turtles and some sharks in the first year of their life travel. Recent advances in underwater tracking devices are illuminating what we know about marine organisms that live at great ocean depths. The information that pop-up satellite archival tags gives aids in fishing closures for certain times of the year and

5115-402: The intersiphonal spaces of each segment. It is in these spaces that aragonite is precipitated. Halimeda has three types of holdfasts which serve as attachment points to the substrate. The "sprawler" type has a few loose filaments growing at the ends or in between the segments (Fig. 1). In the "rock-grower" type, the matted holdfast is composed of branched filaments which secure the thallus to

5208-414: The morning of the next day, after which the thallus is left white and dies in a process known as holocarpy. Some species of Halimeda have been found to reproduce synchronously in mass spawning events similar to that of corals, albeit occurring over several months, with small portions of the population spawning each day. Therefore it is likely that the life span of the genus is limited to a few months to

5301-516: The most productive natural habitats in the world. Reefs comprise some of the densest and most diverse habitats in the world. The best-known types of reefs are tropical coral reefs which exist in most tropical waters; however, reefs can also exist in cold water. Reefs are built up by corals and other calcium -depositing animals, usually on top of a rocky outcrop on the ocean floor. Reefs can also grow on other surfaces, which has made it possible to create artificial reefs . Coral reefs also support

5394-422: The most significant were the voyages of HMS  Beagle where Charles Darwin came up with his theories of evolution and on the formation of coral reefs . Another important expedition was undertaken by HMS Challenger , where findings were made of unexpectedly high species diversity among fauna stimulating much theorizing by population ecologists on how such varieties of life could be maintained in what

5487-478: The north-east coast of Queensland , Australia . Halimeda beds form in the western or lee side of outer shield reefs where flow of nutrient-rich water from the open sea allows them to flourish, and are the most extensive, actively accumulating Halimeda beds in the world. The genus is one of the best studied examples of cryptic species pairs due to morphological convergence within the marine macroalgae. Some species grow so vigorously in tropical lagoons that

5580-446: The number of distinct landmasses varies, as changing water levels expose and cover the lower islands and sandy land bridges between some of the islands. Some of the smaller islands have disappeared and reappeared multiple times as a result of hurricane impact. The major islands within the park are, roughly from west to east, Loggerhead Key , Garden Key, Bush Key, Long Key, Hospital Key, Middle Key, and East Key. The total land area within

5673-440: The ocean). Large areas beneath the ocean surface still remain effectively unexplored. Marine biology can be contrasted with biological oceanography . Marine life is a field of study both in marine biology and in biological oceanography . Biological oceanography is the study of how organisms affect and are affected by the physics , chemistry , and geology of the oceanographic system . Biological oceanography mostly focuses on

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5766-515: The open ocean ( pelagic ) zone, where solid objects are rare and the surface of the water is the only visible boundary. The organisms studied range from microscopic phytoplankton and zooplankton to huge cetaceans (whales) 25–32 meters (82–105 feet) in length. Marine ecology is the study of how marine organisms interact with each other and the environment. Marine life is a vast resource, providing food, medicine, and raw materials, in addition to helping to support recreation and tourism all over

5859-599: The park in a single day. Many birds land inside the parade grounds of Fort Jefferson where they are often observed at close range. Common migratory warblers include the northern parula , American redstart , prairie warbler , hooded warbler , palm warbler , black-and-white warbler , common yellowthroat , yellow-rumped warbler , ovenbird , northern waterthrush , black-throated blue warbler , blackpoll warbler , and Cape May warbler , with more than 20 additional warbler species having shown up at least once. Several raptor species are often seen hunting songbirds. Until early 2013

5952-437: The park varies with water level. The total land area is about 144 acres (58 hectares). The three westernmost keys, which are also the three largest keys (Loggerhead Key, Garden Key, and Bush Key), make up about 93 percent of the total land area of the group. Formerly existing keys were (from west to east): The Dry Tortugas are the western extension of an arcuate chain of Pleistocene reef and oolitic limestone islands, with

6045-412: The park: sooty tern , brown noddy , brown pelican , magnificent frigatebird , masked booby , roseate tern , bridled tern and mourning dove . The park features the only nesting colonies of sooty tern, brown noddy, magnificent frigatebird, and masked booby in the contiguous United States . Birdwatching activity peaks each spring (usually April) when dozens of migratory bird species can pass through

6138-531: The physical effects of continual immersion in sea water and the ocean in general, adaptation to a salty environment, and the effects of changing various oceanic properties on marine life. A subfield of marine biology studies the relationships between oceans and ocean life, and global warming and environmental issues (such as carbon dioxide displacement). Recent marine biotechnology has focused largely on marine biomolecules , especially proteins , that may have uses in medicine or engineering. Marine environments are

6231-714: The removal of invasive Casuarina trees and agave from Loggerhead Key, by cutting and herbicide treatment. Pterois , commonly known as lionfish, have also been found in the park's waters and the National Park Service was reviewing (in 2015) the lionfish management plan to determine what actions to take to manage the spread of this invasive species in Dry Tortugas National Park and Everglades National Park . Most visitors arrive in Dry Tortugas National Park by either boat or seaplane from Key West. Official ferry and transportation services to

6324-418: The rest of the lower keys, there has never been a recorded frost or freeze. The hardiness zone is 12a, with an annual mean minimum temperature of 52 °F (11 °C). The first European to see the Dry Tortugas was Juan Ponce de León , who visited on June 21, 1513. Ponce de León caught 160 sea turtles there and subsequently referred to the islands as the "Tortugas" (turtles). They are called Dry owing to

6417-449: The resultant case, The United States of America v. Peter Anderson , was quickly dropped. The park is a landing location for immigrants arriving from Cuba in homebuilt boats called "chugs". Receiving and housing the migrants is a particular problem for Dry Tortugas, which has limited resources for such arrivals and which is several hours from the nearest Coast Guard or Border Patrol units. Communications with Key West are accomplished using

6510-808: The role of viruses in marine ecosystems is barely being explored even in the beginning of the 21st century. The role of phytoplankton is better understood due to their critical position as the most numerous primary producers on Earth. Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae (red, green, brown, and yellow-green), diatoms , dinoflagellates , euglenoids , coccolithophorids , cryptomonads , chrysophytes , chlorophytes , prasinophytes , and silicoflagellates . Zooplankton tend to be somewhat larger, and not all are microscopic. Many Protozoa are zooplankton, including dinoflagellates, zooflagellates , foraminiferans , and radiolarians . Some of these (such as dinoflagellates) are also phytoplankton;

6603-511: The sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy . A large proportion of all life on Earth lives in the ocean. The exact size of this "large proportion" is unknown, since many ocean species are still to be discovered. The ocean is a complex three-dimensional world, covering approximately 71% of the Earth's surface. The habitats studied in marine biology include everything from

6696-408: The sea are often found in shallow waters, such as the seagrasses (examples of which are eelgrass, Zostera , and turtle grass, Thalassia ). These plants have adapted to the high salinity of the ocean environment. The intertidal zone is also a good place to find plant life in the sea, where mangroves or cordgrass or beach grass might grow. As on land, invertebrates , or animals that lack

6789-407: The sea. As inhabitants of the largest environment on Earth, microbial marine systems drive changes in every global system. Microbes are responsible for virtually all photosynthesis that occurs in the ocean, as well as the cycling of carbon , nitrogen , phosphorus and other nutrients and trace elements. Microscopic life undersea is incredibly diverse and still poorly understood. For example,

6882-412: The sediment is composed solely of the remains of their tissues, forming a calcareous " Halimeda sand ". In fact some tropical reef systems, such as atolls , consist largely of Halimeda sand accumulated over the aeons. Overall, Halimeda represents the most common green algea large grains in the sediment of the lower latitudes. The genus Halimeda J.V. Lamouroux belongs to the order Bryopsidales under

6975-495: The shelf edge, consisting of hermatypic corals and calcarenites . The Miami Limestone is less than 49 ft (15 m) thick, and in general is found behind the Key Largo Limestone reef, but overlies it in the western extent of the keys. It consists of a bryozoan facies and an oolitic facies and represents a subtidal shoal . Additionally, excellent examples of Holocene carbonate-sand deposits are found in

7068-424: The shore. Many land animals also make much use of the shore and intertidal habitats. A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion . Estuaries are also near shore and influenced by the tides . An estuary is a partially enclosed coastal body of water with one or more rivers or streams flowing into it and with a free connection to the open sea. Estuaries form

7161-404: The shutdown. Failing to find anybody to accept the money to reopen the park, Key West residents, under the auspices of the satirical micronation Conch Republic , sent a flotilla of civilian boats and fire department boats to Fort Jefferson in order to reopen the national park. When officials attempted to enter the fort, they were cited. The citation was contested in court the following year, and

7254-423: The substratum. A very diverse range of unusual secondary metabolites is produced by marine fungi. A reported 33,400 species of fish , including bony and cartilaginous fish , had been described by 2016, more than all other vertebrates combined. About 60% of fish species live in saltwater. Reptiles which inhabit or frequent the sea include sea turtles , sea snakes , terrapins , the marine iguana , and

7347-426: The surface or in the open water column , away from the bottom of the ocean and affected by ocean currents , while demersal habitats are near or on the bottom. Marine habitats can be modified by their inhabitants. Some marine organisms, like corals, kelp and sea grasses, are ecosystem engineers which reshape the marine environment to the point where they create further habitat for other organisms. Intertidal zones ,

7440-435: The tiny layers of surface water in which organisms and abiotic items may be trapped in surface tension between the ocean and atmosphere, to the depths of the oceanic trenches , sometimes 10,000 meters or more beneath the surface of the ocean. Specific habitats include estuaries , coral reefs , kelp forests , seagrass meadows , the surrounds of seamounts and thermal vents , tidepools , muddy, sandy and rocky bottoms, and

7533-662: The tropics including the Thai-Malay Peninsula and the Florida Keys. Some species (e.g. H. copiosa, discoidea, gracilis, opuntia, simulans, and tuna ) have a global distribution. Halimeda tuna is found solely in the Mediterranean. Species of Halimeda with sand-grower type holdfasts grow on sandy or muddy substrates, and are thus common in lagoons and backreefs. Those with the "sprawler" type are abundant in forereefs and on coral pinnacles. Being

7626-600: The wash and some cooking. After the Emancipation Proclamation , some freed African American men enlisted in the Union Army. The 82nd Colored Infantry was stationed at Fort Jefferson near the end of the Civil War . Between 1861 and 1871, there were African Americans held as military prisoners at the fort. Comprising 47,125 acres (73.6 sq mi; 190.7 km), Fort Jefferson National Monument

7719-420: The world's coral reefs are now endangered and predict that global warming could exacerbate this trend. The open ocean is relatively unproductive because of a lack of nutrients, yet because it is so vast, in total it produces the most primary productivity. The open ocean is separated into different zones, and the different zones each have different ecologies. Zones which vary according to their depth include

7812-748: The world, Station biologique de Roscoff , was established in Concarneau, France founded by the College of France in 1859. In the United States, the Scripps Institution of Oceanography dates back to 1903, while the prominent Woods Hole Oceanographic Institute was founded in 1930. The development of technology such as sound navigation and ranging , scuba diving gear, submersibles and remotely operated vehicles allowed marine biologists to discover and explore life in deep oceans that

7905-430: The world. At a fundamental level, marine life helps determine the very nature of our planet. Marine organisms contribute significantly to the oxygen cycle , and are involved in the regulation of the Earth's climate . Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land. Many species are economically important to humans, including both finfish and shellfish. It

7998-481: The wreck July 20, 1985. The estimated $ 450 million cache recovered, known as "The Atocha Motherlode," included 40 tons of gold and silver; there were some 114,000 of the Spanish silver coins known as pieces of eight , gold coins, Colombian emeralds , gold and silver artifacts , and 1,000 silver ingots . In addition to the Atocha , Fisher's company, Salvors Inc., found remains of several nearby shipwrecks, including

8091-626: Was acquired from Spain by the United States in 1819. The Dry Tortugas were seen as a strategic point for the control of the Straits of Florida and the Gulf of Mexico. Work on a lighthouse on Garden Key started in 1825. In 1856 work on a new, more powerful lighthouse on Loggerhead Key was started to replace the Garden Key light. John James Audubon visited the Tortugas in 1832 and so did Louis Agassiz in 1858. The Dry Tortugas are also rich in maritime history. In 1989 Seahawk Deep Ocean Technology explored

8184-469: Was described as pleasant to eat with oil, vinegar, and salt. As in other members of the order Bryopsidales , individual organisms are made up of single multi-nucleate cells. Whole meadows may consist of a single individual alga connected by fine threads running through the substrate. Halimeda is responsible for distinctive circular deposits in various parts of the Great Barrier Reef on

8277-560: Was designated by President Franklin D. Roosevelt under the Antiquities Act on January 4, 1935. The monument was expanded in 1983 and redesignated as Dry Tortugas National Park on October 26, 1992, by an act of Congress. Dry Tortugas is managed by the staff of Everglades National Park . The park was established to protect the island and marine ecosystems of the Dry Tortugas, to preserve Fort Jefferson and submerged cultural resources such as shipwrecks, and to allow for public access in

8370-589: Was half complete in 1860. Workers consisted mostly of enslaved people hired from their owners in Key West and other parts of the State of Florida . Some White laborers, mostly Irish immigrants were also employed. The use of enslaved labor was discontinued in 1863. This bastion remained in Union hands throughout the Civil War . It later was used as a prison until abandoned in 1874. Dr. Samuel Mudd , famous for being

8463-405: Was largely assumed that its abundance on reefs is due to it being unpalatable to herbivores, more recent studies have found that Halimeda is in fact subject to grazing by some herbivores such as Scarus rivulatus, Hipposcarus longiceps, and Chlorurus microrhinos . Hard coral cover can actually play a key role in maintaining Halimeda biomass on reefs, as one study found that thalli growing under

8556-452: Was once thought to not exist. Public interest in the subject continued to develop in the post-war years with the publication of Rachel Carson 's sea trilogy (1941–1955). Halimeda See text Halimeda is a genus of green macroalgae . The algal body ( thallus ) is composed of calcified green segments. Calcium carbonate is deposited in its tissues, making it inedible to most herbivores . However one species, Halimeda tuna ,

8649-465: Was thought to be such a hostile environment. This era was important for the history of marine biology but naturalists were still limited in their studies because they lacked technology that would allow them to adequately examine species that lived in deep parts of the oceans. The creation of marine laboratories was important because it allowed marine biologists to conduct research and process their specimens from expeditions. The oldest marine laboratory in

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