Antarctic macroalgal-associated amphipod assemblages exhibit long-term resistance to ocean acidification.

The pH of the world's oceans has decreased since the Industrial Revolution due to the oceanic uptake of increased atmospheric CO in a process called ocean acidification. Low pH has been linked to negative impacts on the calcification, growth, and survival of calcifying invertebrates. Along the Western Antarctic Peninsula, dominant brown macroalgae often shelter large numbers of diverse invertebrate mesograzers, many of which are calcified.

Linking phenotypic variation to patterns of genetic isolation along a speciation continuum.

Investigating taxa at varying stages of divergence can shed light on the evolutionary forces that lead to reproductive isolation and eventual speciation. The forces promoting isolation vary in space and time, which makes it difficult to reconstruct the trajectory that resulted in the divergence observed among species today. The red macroalgal genus Plocamium is known worldwide for its cryptic genetic and chemical diversity.

Nutritional consistency of macroalgae across a sea ice cover gradient along the Western Antarctic Peninsula.

Sea ice can profoundly influence photosynthetic organisms by altering subsurface irradiance, but it is susceptible to changes in the climate. The patterns and timing of sea ice cover can vary on a monthly to annual timescale in small sub-regions of the Western Antarctic Peninsula (WAP). During the latter part of the 20th century, sea ice coverage significantly decreased in the WAP, a trend that aligns with warming in this area.

New Sesterterpenes from the Antarctic Sponge sp.

Chemical investigation of the Antarctic sponge sp. has previously led to the identification of new suberitane derivatives, some of which show bioactivity toward respiratory syncytial virus (RSV). Our ongoing NMR-guided investigation of new specimens of the sponge resulted in the isolation of five new analogs (-), previously reported suberitenones A-D (-), and oxaspirosuberitenone ().

Tetrasporophytic bias coupled with heterozygote deficiency in Antarctic Plocamium sp. (Florideophyceae, Rhodophyta).

Meiosis and syngamy generate an alternation between two ploidy stages, but the timing of these two processes varies widely across taxa, thereby generating life cycle diversity. One hypothesis suggests that life cycles with long-lived haploid stages are correlated with selfing, asexual reproduction, or both. Though mostly studied in angiosperms, selfing and asexual reproduction are often associated with marginal habitats.

Genetic Evidence Supports Species Delimitation of in the Northern Gulf of Mexico.

AbstractAccurate species delimitation is crucial to understanding biodiversity. In the northern Gulf of Mexico, recent genetic evidence has suggested that the tricolor is not a species distinct from the gray . We collected specimens from Apalachee Bay, Florida, and morphologically identified 11 as and 16 as .

Tongalides, Halogenated Butenolides from an Antarctic sp. Rhodophyte.

Six new halogenated butenolides, tongalides A-C (-) and their acetylated congeners (-), were isolated from an extract of the Antarctic rhodophyte sp. that displayed significant antibiotic activity. The structures of the compounds were determined by analysis of data acquired by spectroscopic and spectrometric techniques including NMR, HRESIMS, optical rotation, and X-ray diffraction studies.

Who Cares More about Chemical Defenses - the Macroalgal Producer or Its Main Grazer?

The consequences of defensive secondary metabolite concentrations and interspecific metabolite diversity on grazers have been extensively investigated. Grazers which prefer certain food sources are often found in high abundance on their host and as a result, understanding the interaction between the two is important to understand community structure. The effects of intraspecific diversity, however, on the grazer are not well understood.

Hidden Diversity in an Antarctic Algal Forest: Metabolomic Profiling Linked to Patterns of Genetic Diversification in the Antarctic Red Alga sp.

The common Antarctic red alga sp. is rich in halogenated monoterpenes with known anticancer and antimicrobial properties and extracts of sp. have strong ecological activity in deterring feeding by sympatric herbivores.

Bioactivity of Spongian Diterpenoid Scaffolds from the Antarctic Sponge .

The Antarctic sponge is rich in defensive terpenoids with promising antimicrobial potential. Investigation of this demosponge has resulted in the generation of a small chemical library containing diterpenoid secondary metabolites with bioactivity in an infectious disease screening campaign focused on , , and methicillin-resistant (MRSA) biofilm. In total, eleven natural products were isolated, including three new compounds designated dendrillins B-D (-).

Every Rule Has an Exception: a Cheater in the Community-Wide Mutualism in Antarctic Seaweed Forests.

Dense macroalgal forests on the Western Antarctic Peninsula serve important ecological roles both in terms of considerable biomass for primary production as well as in being ecosystem engineers. Their function within the Antarctic ecosystem has been described as a crucial member of a community-wide mutualism which benefits macroalgal species and dense assemblages of associated amphipod grazers. However, there is a cheater within the system that can feed on one of the most highly chemically defended macroalgal hosts.

Spongian Diterpenoids Derived from the Antarctic Sponge Are Potent Inhibitors of the Parasite.

From the CHCl extract of the Antarctic sponge we found spongian diterpenes, including previously reported aplysulphurin (), tetrahydroaplysulphurin-1 (), membranolide (), and darwinolide (), utilizing a CHCl/MeOH extraction scheme. However, the extracts also yielded diterpenes bearing one or more methyl acetal functionalities (-), two of which are previously unreported, while others are revised here. Further investigation of diterpene reactivity led to additional new metabolites (-), which identified them as well as the methyl acetals as artifacts from methanolysis of aplysulphurin.

Anverenes B⁻E, New Polyhalogenated Monoterpenes from the Antarctic Red Alga .

The subtidal red alga was collected from the Western Antarctic Peninsula during the 2011 and 2017 austral summers. Bulk collections from specific sites corresponded to chemogroups identified by Young et al. in 2013.

Ocean warming alters predicted microbiome functionality in a common sea urchin.

The microbiome of sea urchins plays a role in maintaining digestive health and innate immunity. Here, we investigated the effects of long-term (90 day) exposure to elevated seawater temperatures on the microbiome of the common, subtropical sea urchin The community composition and diversity of microbes varied according to the type of sample collected from the sea urchin (seawater, feed, intestines, coelomic fluid, digested pellet and faeces), with the lowest microbial diversity (predominately the order Campylobacterales) located in the intestinal tissue. Sea urchins exposed to near-future seawater temperatures maintained the community structure and diversity of microbes associated with their tissues.

Effects of ocean acidification on the shells of four Mediterranean gastropod species near a CO seep.

Marine CO seeps allow the study of the long-term effects of elevated pCO (ocean acidification) on marine invertebrate biomineralization. We investigated the effects of ocean acidification on shell composition and structure in four ecologically important species of Mediterranean gastropods (two limpets, a top-shell snail, and a whelk). Individuals were sampled from three sites near a volcanic CO seep off Vulcano Island, Italy.

Declines in plant palatability from polar to tropical latitudes depend on herbivore and plant identity.

Long-standing theory predicts that the intensity of consumer-prey interactions declines with increasing latitude, yet for plant-herbivore interactions, latitudinal changes in herbivory rates and plant palatability have received variable support. The topic is of growing interest given that lower-latitude species are moving poleward at an accelerating rate due to climate change, and predicting local interactions will depend partly on whether latitudinal gradients occur in these critical biotic interactions. Here, we assayed the palatability of 50 seaweeds collected from polar (Antarctica), temperate (northeastern Pacific; California), and tropical (central Pacific; Fiji) locations to two herbivores native to the tropical and subtropical Atlantic, the generalist crab Mithraculus sculptus and sea urchin Echinometra lucunter.

Darwinolide, a New Diterpene Scaffold That Inhibits Methicillin-Resistant Staphylococcus aureus Biofilm from the Antarctic Sponge Dendrilla membranosa.

A new rearranged spongian diterpene, darwinolide, has been isolated from the Antarctic Dendroceratid sponge Dendrilla membranosa. Characterized on the basis of spectroscopic and crystallographic analysis, the central seven-membered ring is hypothesized to originate from a ring-expansion of a spongian precursor. Darwinolide displays 4-fold selectivity against the biofilm phase of methicillin-resistant Staphylococcus aureus compared to the planktonic phase and may provide a scaffold for the development of therapeutics for this difficult to treat infection.

No barrier to emergence of bathyal king crabs on the Antarctic shelf.

Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope.

Detecting the unexpected: a research framework for ocean acidification.

The threat that ocean acidification (OA) poses to marine ecosystems is now recognized and U.S. funding agencies have designated specific funding for the study of OA.

Reactive oxygen species and the Antarctic macroalgal wound response.

Reactive oxygen species (ROS) are commonly produced by algal, vascular plant, and animal cells involved in the innate immune response as cellular signals promoting defense and healing and/or as a direct defense against invading pathogens. The production of reactive species in macroalgae upon injury, however, is largely uncharacterized. In this study, we surveyed 13 species of macroalgae from the Western Antarctic Peninsula and show that the release of strong oxidants is common after macroalgal wounding.

Site-specific variability in the chemical diversity of the Antarctic red alga Plocamium cartilagineum.

Plocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like "P. cartilagineum" from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators.