After the Fall: The Demographic Destiny of a Gorgonian Population Stricken by Catastrophic Mortality

In recent years, the frequency of mass mortality events in marine ecosystems has increased, and several populations of benthic organism have been affected, reducing their density and changing their size and age structure. Few details are known about the dynamics of these populations over long time intervals. In late summer of both 1999 and 2003 two drastic mass mortality events, co-occurring with anomalous temperature increases, affected the northwestern Mediterranean rocky coastal communities. Due to these events the Paramuricea clavata population living at the western edge of La Spezia Gulf (Italy) was stricken, and 78% of the colonies died. This population was monitored from 1998 (pre-mortality) until 2013. This paper deals with the photographic sampling of permanent plots carried out in 2013. The findings were compared with those from the previous sampling series. This long-term, non-destructive sampling highlights the demographic trajectory of the octocoral population there after two anomalous mortality events, indicating that some new drop-point between local extinction and complete recovery may be have been reached. Long-term monitoring (including pre-mortality data) could allow evaluating the effects of global climate change on the conservation of impacted populations.

Impact of industrial effluent on macrobenthic diversity: A case study of Thannirbhavi and Chitrapur coastal area of Mangalore

In view of understanding the impact of effluents and on the occurrence and distribution of macrobenthic organisms, an investigation has been carried out for a period of 8 months from October 2006 to May 2007 in the nearshore water of Thannirbhavi and Chitrapur receiving treated industrial effluents and Bengre coast having estuarine influences. The quality composition of benthic organism revealed the presence of hydroids such as Obeliasp,Cordylophorasp and companularia sp. Polychaetes belonging to 15 diferent families have been identified and their distribution revealed variation with respect to the type of the effluents. 24 different types of molluscss have been identified and their occurrence and distribution was found to be related to type of sediment and the quality of the effluents. Bulks of crustaceans were formed mainly due to species of Gammarus, Caprellids and Tanaidaceans. The great abundance and diversity of benthic organisms was observed in the Thannirbhavi receiving effluents from a fertilizer industry, when compare to the Chitrapur receiving treated effluents from a dye industry and an oil refinery industry. Silty-clayey sediment harbored higher density of polychaetes where as sandy-silty sediment supported greater abundance of molluscs.

Composition of coral species and benthic organism at Tiaka Oilfield, Tolo Bay, Central Sulawesi

This research aims to find out the composition of the coral and benthic organisms at Tiaka Oilfield. This study was conducted in July 2015. Monitoring of coral and benthic organisms used line intercept transect and visual census method. The research results indicated that 16 coral species were consisting of 6 genera. Coral species dominated by the genus Acropora. Benthic organisms that live in symbiosis with coral reef ecosystems in the Tiaka Oil Field were found 11 benthic species consisting of 54 species

The effects of organic matter concentration on sediment reworking of Perinereis aibuhitensis : a mesocosm study

<p>The organic matter (OM) concentration is one of the most important factors influencing benthic organism sediment reworking during bioturbation. This study was designed to evaluate differences in sediment reworking rate of Perinereis aibuhitensis based on quantification of its pellet production (PP) and OM transport rate from ambient sediment to the surface due to its feeding. The mesocosm experiment was conducted in acrylic container (15×1×20 cm) with two treatments (high OM treatment and low OM treatment) and each treatment had ten replicates. The pellets in each container were removed 2h before the beginning of the pellet collection, and then newly produced pellets were collected every 2 h during 24 h at each treatment. The mean grain size of pellets (5.1 ∅) was smaller than that of ambient sediment particles (5.9 ∅), and the mean OM concentration was much higher in pellet (0.69% for C and 0.06% for N) than in ambient sediment (0.46% for C and 0.05% for N). Since an organism cannot produce more organic matter than it ingests, production of organically enriched pellets by this species indicates selective ingestion. The overall OM transport rate was 0.7 g C m<sup>-2</sup> day<sup>-1</sup> in carbon and 0.06 g N m<sup>-2</sup> day<sup>-1 </sup>in nitrogen, respectively. The daily PP was much higher in high OM treatment than that of low OM treatment with mean values of 0.007 and 0.002 g ind.<sup>-1</sup> h<sup>-1</sup>, respectively. It is expected that Perinereis feeding activity strongly depended on OM concentrations. The overall sediment reworking rate based on the pellet production was much higher in high OM concentration (0.005 mm day<sup>-1</sup>) than in low OM (0.001 mm day<sup>-1</sup>) concentration.</p>

HYDRODYNAMIC MODELLING IN INSHORE REEF AREA WITHIN KUANTAN COASTAL REGION

Current circulation provides major transport mechanism especially for benthic organism in the ocean. The present study described current circulation in inshore reef area within Kuantan coastal region by applying a numerical modelling of MIKE 21 Flow Model FM software. Model simulation produced good outcomes when compared with field data measurement with root mean square error (RMSE) for surface elevation, current speed and direction were below 20. Results also clearly indicated that current speed in inshore reef area was highly correlated with local tidal pattern in which higher flow speed were observed during high tides compared to low tide. Contrary to previous belief, our results clearly show the prevalence of tidal forcing in shaping current flow pattern in the study area since the impact of wind forcing was minimal during different monsoon seasons. This study gave new insight into how local tidal properties can regulate hydrodynamic pattern especially in fine-scale inshore reef area.

A lattice-automaton bioturbation simulator with coupled physics, chemistry, and biology in marine sediments (eLABS v0.2)

Seawater–sediment interaction is a crucial factor in carbon and nutrient cycling on a wide range of spatial and temporal scales. This interaction is mediated not just through geochemistry but also via biology. Infauna vigorously mix sediment particles, enhance porewater–seawater exchange, and consequently, facilitate chemical reactions. In turn, the ecology and activity of benthic fauna are impacted by their environment, amplifying the sensitivity of seawater–sediment interaction to environmental change. However, numerical representation of the bioturbation of sediment has often been treated simply as an enhanced diffusion of solutes and solids. Whilst reasonably successful in representing the mixing of bulk and predominantly oxic marine sediments, the diffusional approach to bioturbation is limited by a lack of environmental sensitivity. To better capture the mechanics and effects of sediment bioturbation, we extend a published bioturbation model (Lattice-Automaton Bioturbation Simulator; LABS) by adopting a novel method to simulate realistic infaunal behavior that drives sediment mixing. In this new model (extended LABS – eLABS), simulated benthic organism action is combined with a deterministic calculation of water flow and oxygen and organic matter concentration fields to better reflect the physicochemical evolution of sediment in response to bioturbation. The predicted burrow geometry and mixing intensity thus attain a dependence on physicochemical sedimentary conditions. This interplay between biology, chemistry, and physics is important to mechanistically explain empirical observations of bioturbation and to account for the impact of environmental changes. As an illustrative example, we show how higher organic rain can drive more intense sediment mixing by “luring” benthic organisms deeper into sediments, while lower ambient dissolved oxygen restricts the oxic habitat depth and hence tends to reduce bulk mixing rates. Our model, with its oxygen and food availability controls, is a new tool to interpret the trace fossil record, e.g., burrows, as well as to explore biological engineering of past marine environments.

Abundance of Meiofauna and Physical-Chemical Parameters as Water Quality Indicator

The zone of Losari Coast is an icon of Makassar city, however increase activity of surrounding communities causes a decrease in the water quality. Meiofauna is an effective benthic organism used as an indicator of water quality. This study assessed the meiofauna abundance and physical-chemical parameters as water quality indicator in the Losari Coast, Makassar. The sampling method in this study was purposive sampling. The resuts showed that total meiofauna abundance identified was 66791 indv.m-2, composed of 12 phylum and 91 species or genera. Stations at the estuary of the Jeneberang and Tallo River are two sites with high level of abundance, this condition allows presence of organic contaminants triggers the high growth of meiofauna in these locations. Dissolved Oxygen is below its supposed level in waters. Acidity, phosphate and nitrate content at some of research stations exceed the threshold of their allowed presence in waters set by Indonesia government. Ostracoda, oligochaeta, polychaeta, tunicata and ciliophora are phylums with a high level of abundance, because the phylum has high adaptability to pollutant. Good water quality is indicated by a variety of biota living in the waters, the range of diversity and uniformity indices shows that meiofauna species are categorized highly diverse and evenly distributed. The dominance index shows that there is no species was dominant, except stations around Losari reclamation project. Temperature, current velocity, depth, brightness, salinity, pH, DO, nitrate-seawater, and phosphate-seawater correlate with meiofauna abundance. The results as a consideration for the management or monitoring of coastal environments.

A lattice-automaton bioturbation simulator for the coupled physics, chemistry, and biology of marine sediments (eLABS v0.1)

Seawater-sediment interaction is a crucial factor in the dynamics of carbon and nutrient cycling on a wide range of spatial and temporal scales. This interaction is mediated not just through geochemistry, but also via biology. Infauna vigorously mix sediment particles, enhance porewater-seawater exchange and consequently facilitate chemical reactions. In turn, the ecology and activity of benthic fauna are impacted by their environment, amplifying the sensitivity of seawater-sediment interaction to environmental change. However, numerical representation of the bioturbation of sediment has often been treated simply as an enhanced diffusion of solutes and solids. Whilst reasonably successful in representing the mixing of bulk and predominantly oxic marine sediments, the diffusional approach to bioturbation is limited by lacking an environmental sensitivity. To better capture the mechanics and effects of sediment bioturbation, we summarize and extend a published bioturbation model (acronym: LABS) that adopts a novel lattice automaton method to simulate the behaviors of infauna that drive sediment mixing. In this new model (eLABS), simulated benthic organism behavior is combined with a deterministic calculation of water flow and oxygen and organic matter concentration fields to better reflect the physicochemical evolution of sediment. The predicted burrow geometry and mixing intensity thus attain a dependence on physicochemical sedimentary conditions. Such an interplay between biology, chemistry and physics can be important to mechanistically explain empirical observations of bioturbation and to account for the impact of environmental changes. As an illustrative example, we show how higher organic rain can drive more intense sediment mixing by luring benthic organisms deeper into sediments, while lower ambient dissolved oxygen restricts the oxic habitat depth and hence tends to reduce bulk mixing rates. Finally, our model, with its oxygen and food availability controls, represents a new tool to interpret the geological record of trace fossils, e.g., burrows, as well as to mechanistically explore biological engineering of early marine environments.

Long-term sediment exposure to ZnO nanoparticles induces oxidative stress in Caenorhabditis elegans

Long-term sediment exposure to ZnO-NPs induces oxidative stress in benthic organism C. elegans which is mediated by the transcription factor DAF-16/FOXO triggering stress-responsive gene activation.