Kelimpahan Dinoflagellata Bentik Berbahaya di Habitat Lamun dan Makroalga di Pulau Pari, Kepulauan Seribu, Indonesia

<p class="Papertext"><strong>The Abundance of the Harmful Benthic Dinoflagellate in the Seagrass and Macroalgae Habitats on Pari Island, Thousand Islands, Indonesia. </strong>Benthic dinoflagellates are an important part of benthic ecosystems and part of their ecological functions. However, ciguatoxin (CTX) producer dinoflagellates, which could cause Ciguatera Fish Poisoning (CFP) disease, is a known threat to marine biota and the island’s coastal communities, such as in Pari Island. Thus, this research aimed is to study the population of five harmful and toxin producer benthic dinoflagellate genera, namely <span style="text-decoration: underline;">Amphidinium</span>, <span style="text-decoration: underline;">Coolia</span>, <span style="text-decoration: underline;">Gambierdiscus</span>, <span style="text-decoration: underline;">Ostreopsis</span>, and <span style="text-decoration: underline;">Prorocentrum</span>, in macroalgae and seagrass habitats of Pari Island. Benthic dinoflagellate samples were collected in Juni 2019 using artificial substrates in the form of a 10×15 cm nylon screen. Environmental variables, such as nutrient concentration (nitrogen and phosphorus) and water temperature were also measured. The results showed that the average benthic dinoflagellate density in seagrass habitats was four times higher compared to the macroalgae habitats. <em>Gambierdiscus</em> were found as the most abundant benthic dinoflagellate in seagrass habitats, while <em>Prorocentrum</em> were more abundant in macroalgae habitats. Principal Component Analysis (PCA) showed that the N:P ratio was the most important regulating parameter for most benthic dinoflagellate genera in this study, except <em>Ostreopsis</em>, which was found to be more abundant in phosphorus-rich macroalga habitats. The data also shows an increase of benthic dinoflagellate cell density up to seven times compared to the previous research data in 2012 and 2013. That trend indicates an increase in the disturbance and pressure on the macroalgae and seagrass habitats of Pari Island, which require special attention to prevent the occurrence of toxic Benthic Harmful Algal Blooms (bHABs) and CFP cases in the island.</p>

EVIDENCE OF MASS MORTALITY OF THE LONG-LIVED BIVALVE MERCENARIA STIMPSONI CAUSED BY A CATASTROPHIC TSUNAMI

ABSTRACT Tsunamis are huge disasters that can significantly damage benthic organisms and the sea-bottom environment in coastal areas. It is of great ecological importance to understand how benthic ecosystems respond to such destructive forces and how individual species are affected. Investigating the effect of such disasters on animals that are seldom caught alive is particularly difficult. Bivalve mollusks are especially suitable for investigating how a tsunami affects coastal benthic species because they preserve an environmental record in their shells that can be extended back in time by crossdating the records of multiple individuals. Here we studied dead shells of Mercenaria stimpsoni, a long-lived clam, and precisely determined the time of death by using nuclear bomb–induced radiocarbon (bomb-14C) and by counting annual growth increments. First, a quasi-continuous, regional bomb-14C record was created by analyzing the shells of 6 live-caught M. stimpsoni individuals. Then 27 dead shells collected from the seafloor of Funakoshi Bay were 14C-dated and analyzed. The results showed that the huge tsunami that struck northeastern Japan on 11 March 2011 caused mass mortality of this bivalve in Funakoshi Bay. Nine of the 27 clams died during the March 2011 tsunami, probably by starvation after burial by tsunami deposits or exposure above the seafloor as a result of sediment liquefaction during the earthquake. The dating method used in this study can help us understand how long-lived marine organisms with low population density are affected by huge natural disasters such as a tsunami.

Metagenomics of Antarctic Marine Sediment Reveals Potential for Diverse Chemolithoautotrophy

The impacts of climate change in polar regions, like Antarctica, have the potential to alter numerous ecosystems and biogeochemical cycles. Increasing temperature and freshwater runoff from melting ice can have profound impacts on the cycling of organic and inorganic nutrients between the pelagic and benthic ecosystems.

A comparison of food sources of nudibranch mollusks at different depths off the Kuril Islands using fatty acid trophic markers

Gastropod molluscs such as nudibranchs are important members of deep-sea benthic ecosystems. However, data on the trophic ecology and feeding specialization of these animals are limited to date. The method of fatty acid trophic markers (FATM) was applied to determine the dietary preferences of nudibranchs off the Kuril Islands. Fatty acid (FA) compositions of Dendronotus sp., Tritonia tetraquetra, and Colga pacifica collected from deep waters were analyzed and compared with those of Aeolidia papillosa and Coryphella verrucosa from the offshore zone. The high level of FATM such as 22:5n-6 and C20 monounsaturated FAs indicated that Dendronotus sp. preys on sea anemones and/or anthoathecates hydroids similarly to that of shallow-water species A. papillosa and C. verrucosa. The high percentage of tetracosapolyenoic acids and the ratio 24:6n-3/24:5n-6 indicated that T. tetraquetra preys on soft corals such as Gersemia and/or Acanella at a depth of 250 m, but soft corals of the family Primnoidae may be the main item in the diet of T. tetraquetra at a depth of 500 m. The high content of Δ 7,13-22:2 and 22:6n-3 shows that C. pacifica can feed on bryozoans. In C. pacifica, 22:5n-6 may be synthesized intrinsically by the mollusks, whereas odd-chain and branched saturated FAs originate from associated bacteria.

Environmental DNA metabarcoding for monitoring metazoan biodiversity in Antarctic nearshore ecosystems

Antarctic benthic ecosystems support high biodiversity but their characterization is limited to a few well-studied areas, due to the extreme environment and remoteness making access and sampling difficult. Our aim was to compare water and sediment as sources of environmental DNA (eDNA) to better characterise Antarctic benthic communities and further develop practical approaches for DNA-based biodiversity assessment in remote environments. We used a cytochrome c oxidase subunit I (COI) metabarcoding approach to characterise metazoan communities in 26 nearshore sites across 12 locations in the Vestfold Hills (East Antarctica) based on DNA extracted from either sediment cores or filtered seawater. We detected a total of 99 metazoan species from 12 phyla across 26 sites, with similar numbers of species detected in sediment and water eDNA samples. However, significantly different communities were detected in the two sample types at sites where both were collected (i.e., where paired samples were available). For example, nematodes and echinoderms were more likely to be detected exclusively in sediment and water eDNA samples, respectively. eDNA from water and sediment core samples are complementary sample types, with epifauna more likely to be detected in water column samples and infauna in sediment. More reference DNA sequences are needed for infauna/meiofauna to increase the proportion of sequences and number of taxa that can be identified. Developing a better understanding of the temporal and spatial dynamics of eDNA at low temperatures would also aid interpretation of eDNA signals from polar environments. Our results provide a preliminary scan of benthic metazoan communities in the Vestfold Hills, with additional markers required to provide a comprehensive biodiversity survey. However, our study demonstrates the choice of sample type for eDNA studies of benthic ecosystems (sediment, water or both) needs to be carefully considered in light of the research or monitoring question of interest.

Oxygen Consumption Rates of Sponges and the Effect of UV-B Radiation and Sediment

<p>Sponges are an important part of many benthic ecosystems, but little is known of their physiology and ecology, which is alarming given the predicted rise in global environmental stress and observed increases in mortality and disease of these organisms. The overall aim of this study was to further understand the physiological processes of sponges and the influence of environmental stress on these organisms. Oxygen consumption rates were investigated, as this is an important measure of the energy required for all physiological activities. The impact of ultraviolet-B(UV-B) radiation and sedimentation on sponges were selected because their input into the marine environment has been predicted to increase in the future, yet little is known about their affect on these organisms. Oxygen consumption rates were measured from a number of temperate and tropical sponges in New Zealand and Indonesia. Variability in oxygen consumption rates was found within and between species from their respective habitats. Interestingly, oxygen consumption rates in the temperate sponges appeared to increase with the proportion of inorganic material (spicule load). Ultraviolet-B radiation, at 60microWcm-2, was found to have no affect on the oxygen consumption of model temperate and tropical sponges. Sponge oxygen consumption, however, increased with repetitive exposure to 2.5 g L-1of sediment, while rates decreased in specimens under higher levels at 8.5 and 16.5 g L-1. Explanations for differences in oxygen consumption rates were constrained by the low level of information on sponges at a species-specific level, and highlighted the needed for future bioenergetic research. The results from the UV-B and sedimentation work suggest that some sponge species may be able to tolerate increasing environmental stress with the onset of global climate change, although interactions between factors could have the potential to negatively affect these organisms.</p>

Oxygen Consumption Rates of Sponges and the Effect of UV-B Radiation and Sediment

<p>Sponges are an important part of many benthic ecosystems, but little is known of their physiology and ecology, which is alarming given the predicted rise in global environmental stress and observed increases in mortality and disease of these organisms. The overall aim of this study was to further understand the physiological processes of sponges and the influence of environmental stress on these organisms. Oxygen consumption rates were investigated, as this is an important measure of the energy required for all physiological activities. The impact of ultraviolet-B(UV-B) radiation and sedimentation on sponges were selected because their input into the marine environment has been predicted to increase in the future, yet little is known about their affect on these organisms. Oxygen consumption rates were measured from a number of temperate and tropical sponges in New Zealand and Indonesia. Variability in oxygen consumption rates was found within and between species from their respective habitats. Interestingly, oxygen consumption rates in the temperate sponges appeared to increase with the proportion of inorganic material (spicule load). Ultraviolet-B radiation, at 60microWcm-2, was found to have no affect on the oxygen consumption of model temperate and tropical sponges. Sponge oxygen consumption, however, increased with repetitive exposure to 2.5 g L-1of sediment, while rates decreased in specimens under higher levels at 8.5 and 16.5 g L-1. Explanations for differences in oxygen consumption rates were constrained by the low level of information on sponges at a species-specific level, and highlighted the needed for future bioenergetic research. The results from the UV-B and sedimentation work suggest that some sponge species may be able to tolerate increasing environmental stress with the onset of global climate change, although interactions between factors could have the potential to negatively affect these organisms.</p>

Arrival and proliferation of the invasive seaweed Rugulopteryx okamurae in NE Atlantic islands

The present study reports the recent occurrence and expansion of Rugulopteryx okamurae in the Azores archipelago (NE Atlantic). Morphological and molecular characters confirmed the species identification. Quick surveys around the island of São Miguel showed that it has successfully colonized the island and is quickly expanding. In some locations, R. okamurae is currently the dominant organism smothering all other benthic biota and posing a serious threat to the benthic ecosystems across the region. The species first record dates from 2019 near the main harbour of the island, suggesting that its introduction was driven by human-assisted transport, via boat ballast waters or adhered to ship hulls and likely originating from the Mediterranean populations that have been proliferating in recent years across the Strait of Gibraltar.

Lobster Distribution and Biodiversity on the Continental Shelf of Brazil: A Review

The continental shelf of Brazil is home to a wide range of lobster species, with varying body size, color, habitat preference, and geographic and bathymetric distribution. Spiny lobsters (Panulirus) and slipper lobsters (Scyllaridae) are exploited for export and for the domestic market. Deep sea lobsters (Nephropidae and Polychelidae) have no commercial potential, and little is known about their biology. In this review, we identified 24 lobster species from benthic ecosystems off Brazil (Palinuridae 25%, Scyllaridae 29%, Nephropidae 25%, Polychelidae 17%, Enoplometopidae 4%). We designed a simplified theoretical scheme to understand the role of lobsters in the ecosystem, based on available evidence of distribution, biodiversity, life cycle, connectivity, and abundance. Finally, we propose a theoretical scheme of trophic top-down control, with interactions between a large decapod (spiny lobster), a demersal predator (red snapper), an apex predator (small tuna), benthic invertebrates and fishing exploitation.

Glacial lake outburst floods enhance benthic microbial productivity in perennially ice-covered Lake Untersee (East Antarctica)

Benthic ecosystems of perennially ice-covered lakes in Antarctica are highly sensitive to climate-driven changes. Lake Untersee has been in hydrological steady-state for several hundred years with a high pH water column and extremely low levels of dissolved inorganic carbon. Here, we show that glacial lake outburst floods can replenish carbon dioxide-depleted lakes with carbon, enhancing phototrophic activity of the benthic ecosystem. In 2019, a glacial lake outburst flood brought 17.5 million m3 of water to Lake Untersee, the most substantial reported increase for any surface lake in Antarctica. High-resolution grain-size and carbon isotope analyses of microbial mats suggest that glacial lake outburst floods have occurred periodically over the Holocene and help explain the complex patterns of carbon cycling and sequestration observed in the lake. Our findings suggest that periodic flooding events may provide biological stimuli to other carbon dioxide-depleted Antarctic ecosystems and perhaps even icy lakes on early Mars.