Meiobenthology

The aim of this work is to present a view on eukaryotic life under oxic and permanent anoxic conditions associated with hydrogen sulfide in bottom sediments of the Black Sea with emphasis on unicellular eukaryotes (protists). It was shown that benthic Ciliophora, Gromiida and Foraminifera are present at all studied depths. Thus, obtained results showed that benthic protists are the constant and integral components of the meiobenthic communities under varying conditions of the Black Sea. Unevenness has been detected in spatial and bathymetric distribution of the protozoans and metazoans. The contribution of benthic protists to meiobenthos at different parts of the Black Sea under conditions ranging from normoxia to anoxia enriched with hydrogen sulfide (to the 300 m water depth) was investigated in the present study.

O presente trabalho teve como objetivo estudar a meiofauna da Praia Rasa (Búzios-RJ), descrevendo sua distribuição espaço-temporal e sua composição faunística em grupos taxonômicos superiores. Em razão da dominância do Filo Nematoda nesta praia, o presente trabalho também estudou sua distribuição espaço-temporal e de seus tipos tróficos. As amostragens da meiofauna e das variáveis ambientais foram realizadas mensalmente de novembro de 2006 a outubro de 2007, em duas zonas do perfil praial: ressurgência e saturação. Os resultados obtidos revelaram que a meiofauna da Praia Rasa foi composta por sete grandes grupos faunísticos (Nematoda, Turbellaria, Copepoda, Tardigrada, Polychaeta, Oligochaeta e Halacaroidea). A densidade média da meiofauna total esteve entre 8 e 4747,33 ind.10 cm-2, sendo que as menores densidades ocorreram nos meses de verão. Os Nematoda representaram, em média, mais de 90% da meiofauna encontrada na camada dos 10 cm superiores do sedimento de ambas as zonas estudadas. A densidade média dos Nematoda variou de 4,33 a 4669 ind.10 cm-2 durante o período estudado. Os tipos tróficos dos Nematoda foram estudados nos períodos úmido e seco, determinados a partir de dados meteorológicos locais. Os quatro tipos tróficos dos Nematoda foram encontrados na Praia Rasa: Comedores de Epistrato (Herbívoros), Detritívoros Não Seletivos, Detritívoros Seletivos e os Predadores/Onívoros. No período úmido, os Comedores de Epistrato (Herbívoros), foram mais abundantes, enquanto que no periodo seco, os Detritívoros Não Seletivos dominaram. A distribuição dos grupos tróficos foi diferenciada entre as zonas do perfil praial, sendo os Herbívoros mais abundantes na Zona de Ressurgência, os Detritívoros Não Seletivos e os Predadores/Onívoros em geral foram mais abundantes na Zona de Saturação. A diferença entre as zonas de Ressurgência e Saturação foi evidenciada pela temperatura do sedimento e pelo percentual de MOT no sedimento. A densidade dos Nematoda no sedimento esteve significativamente associada ao percentual de areia muito fina. As interações entre a meiofauna e as variáveis ambientais foram melhor explicadas pela granulometria, MOT, concentração em Clorofila a e a temperatura do sedimento.

Abstrak Praktikum kali ini adalah menganalisis keberadaan meiobenthos pada sedimen di pesisir dan sedimen yang menempel pada lamun di Pulau Tunda. Tujuan praktikum ini adalah menentukan klasifikasi sedimen dan komunitas meiobentos daerah pesisi di Pulau Tunda, serta menemukan hubungan antara sedimen dan meiobentos. Metode yang digunakan pada praktikum ini adalah analisis Grainsize, meiobenthos. Hasilnya adalah ditemukan berbagai macam meiobentos pada sedimen maupun lamun di beberpa titik tempat pengambilan sampel di Pulau Tunda yang menunjukan keanekaragaman meiobentos di beragam sedimen di daerah tersebut. Abstract This practice is to analyze the presence of meiobenthos in coastal sediments and sediments attached to seagrasses on Tunda Island. The purpose of this practicum is to determine the classification of sediments and the meiobentos community in the pesisi area on Tunda Island, and to find out the relationship between sediment and meiobentos. The method used in this lab is the analysis of Grainsize, meiobenthos. The result was that various meiobentos in sediments and seagrasses were found in several sampling points on Tunda Island which showed meiobentos diversity in various sediments in the area. PENDAHULUAN Daerah pesisir merupakan daerah yang sangat peka terhadap degradasi lingkungan, utamanya dipengaruhi proses atau aktivitas di daratan. Intensifnya tingkat dan eksploitasi manusia dalam memanfaatkan sumber daya di darat maupun laut menjadi penyebab utama terjadinya degradasi lingkungan pesisir. Salah satu gangguan terhadap ekosistem daerah perairan pesisir dapat disebabkan oleh adanya kegiatan industri yang membuang limbah cemaranya ke sungai yang bermuara di perairan pantai (Sidqi, Tandjung, & Nitimulyo, 2003). Ekosistem padang lamun merupakan suatu ekosistem yang kompleks dan mempunyai fungsi dan manfaat yang sangat penting bagi perairan wilayah pesisir. Secara taksonomi lamun (seagrass) termasuk dalam kelompok Angiospermae yang hidupnya terbatas di lingkungan laut yang umumnya hidup di perairan dangkal wilayah pesisir.Pertumbuhan dan kepadatan lamun sangat dipengaruhi oleh pola pasang surut, turbiditas, salinitas dan temperatur perairan. Kegiatan manusia di wilayah pesisir seperti perikanan,

A Termodinâmica Ambiental é o ramo da Física e das ciências da engenharia que estuda as variações de energia e a relação destas com o ambiente. Nos ecossistemas, esta energia geralmente é convertida em calor que é libertado para o ambiente causando graves impactos ambientais.

Marine nematodes belonging to two genera Prooncholaimus and Acanthonchus are described from
Tanjung Tajam on the westernmost end of Pulau Ubin in the East Johor Strait. Prooncholaimus tani new species
is characterised by having short cervical setae, a large buccal cavity, pocket-shaped amphid, thin gubernaculum
and curved, L-shaped spicules. Acanthonchus singaporensis new species has a cuticle striated with transverse rows
of minute punctations but is irregular laterally at the posterior region; cervical setae are present posterior to the
amphid, the latter being multispiral with a total of 5.5 turns. Spicules are paired, cuticulatised. The gubernaculum
is also paired and almost equal length to the spicules. Six tubular supplements are present with the most anterior
large and heavily cuticularised with a hook near the posterior end of the supplement.

Meiobenthos is a sediment-dwelling community with various taxonomic groups ranging in size from 63 to 500 µm. As a matter and energy link between primary producers and macrofauna, they have other functions in the ecosystem. Since this group has been scarcely studied in Venezuela, it was proposed to analyze the spatial and temporal variations in the composition and abundance of subtidal meiobenthos in the country's central coast. Samplings were conducted monthly from June 2014 to March 2015. In each sampling campaign, 12 random stations were established, and three samples were taken at each using a cylindrical sampler of 5.0 cm internal diameter. Organisms were identified and counted using microscopes, and data was processed using hypothesis tests (ANOSIM) and multivariate analyzes (SIMPER, nMDS). Meiobenthos showed a richness of 164 morphotypes and 14 phyla, with a dominance of planktonic copepods and foraminifers, followed by cnidarians and mollusks. Out of the total species reported, 84 are strictly benthic. Regarding abundance, there was a greater representation of foraminifera, followed by nematodes and mollusks, with values higher than those reported for tropical areas. Spatially, no differences were found in the composition and abundance of this community. However, two maximums were found throughout the study period, one starting in June until reaching maximum densities between August and October and the second one in February.

The environmental status of the Falerno-Domitio littoral, a sector of the Italian south coast (Campania region) locally affected by an extensive anthropic pressure and pollution, was assessed by a multi-disciplinary approach, consisting of geological vs. biological studies. Geochemical abundance of potentially hazardous trace metals in beach sands is mainly constrained by the nature of the source rocks. Geochemical data of marine sediment quality with regards to possible heavy metal pollution and the enrichment factors of selected potentially toxic metals show that Cr and V values are higher in marine samples than in natural sources, suggesting that they are, at least in part, of anthropic derivation. A relationship between meiobenthos and heavy metals (Cr, Co, and V) has been also observed, providing a valuable biological marker to human-deriving chemical pollution. Ecotoxicological analyses confirm a relationship between enrichment in selected metals and moderate toxicity of some sea-bottom sediments closer to the coastline.