The Puerto Velero Marina, located on the central Caribbean coast of Colombia, is an example of an artificial structure that serves as a substrate for a vulnerable community such as cnidarians (Hydrozoa and Anthozoa). This study provides the first assessment of corals and other cnidarians inhabiting artificial marine habitats in a marginal environment of the Caribbean of Colombia. The Puerto Velero Marina was built into a 7 km² sand spit generated by sedimentation at the mouth of the Magdalena River. In this study were recorded 14 cnidarian species, among which were found 48 small colonies of scleractinian corals such as Porites, Siderastrea, Phyllangia, and Astrangia. This initial biodiversity assessment of the artificial structure provides a baseline that highlights the importance of further monitoring programs to identify non-native species that could reach this kind of hard structures.

Sandstone reefs may be considered a unique geomorphologic feature within the subtropical Southwestern Atlantic Ocean region; however, biodiversity on these reefs has received little to no attention. Herein, we recorded the fish assemblage and benthic cover of sandstone reefs between 23 and 29 m depth in Southern Brazil and evidenced potential threats to habitat health. Video analysis and underwater censuses recorded 30 fish species. The unexpected high biomass of Epinephelus marginatus indicated that sandstone reefs may contain suitable habitats for the recovery of this endangered species. A rich benthic coverage including bryozoans, algae, hydrozoans, sponges, and octocorals increased local habitat structural complexity. However, a wide diversity of tangled fishing gear and broken sandstone slabs suggested that a valuable feature from Southern Brazil seascape is being lost by cumulative fishing impacts. An extensive mapping of sandstone reefs is urgently needed for better delineation of marine protected areas network in Southeast and Southern Brazil.

The aim of the present study was to risk screen 45 jellyfish species (30 hydromedusae, 14 scyphomedusae, one cubomedusa) for their potential invasiveness in the Mediterranean Sea to aid managers in making informed decisions on targeting appropriate species for management. Using the Aquatic Species Invasiveness Screening Kit (AS-ISK), calibrated basic and climate-change threshold assessment scores of 6.5 and 12.5, respectively, were identified for distinguishing reliably between species that pose ‘low-to-medium’ and ‘high’ risk of becoming invasive in the risk assessment area. Using these thresholds, 16 species were classified as high risk, 23 as medium risk and six as low risk under current climate conditions. Whereas, under future climate conditions, 13, 30 and two species, respectively, were classified as high, medium and low risk, respectively. Upside-down jellyfish Cassiopea andromeda, Australian spotted jellyfish Phyllorhiza punctata, sea nettle Chrysaora quinquecirrha and Rhopilema nomadica were the highest-scoring species, with the maximum increase in risk score under predicted climate change conditions being achieved by C. andromeda.

Zooplankton were studied in the largest scale investigation in the South Yellow Sea in spring 2007 by using large plankton net when the green tide hasn't yet occurred. Ninety-six zooplankton species were identified. Copepods, pelagic larvae and hydromedusae were comprised of the largest number of species; Calanus sinicus, Paracalanus parvus, Aidanosagitta crassa, Euphausiidae larvae, Oithona plumifera and Corycaeus affinis were dominant species and their abundance comprised 81.65% of total abundance. Three high abundance areas contained with an average of 224.31 ± 247.93 individual/m³, with an average total biomass of 674.33 ± 1696.92 mg/m³; The average of Shannon-Wiener diversity, Pielou evenness and Margalef richness was 1.96 ± 0.61, 0.50 ± 0.14 and 2.31 ± 0.95, respectively. The Shannon-Wiener diversity and Pielou evenness showed positive correlation with bottom temperature, while Shannon-Wiener diversity and Margalef richness were positively correlated with bottom salinity. Additionally, Pielou evenness and Margalef richness showed negative correlation with total abundance which indicated that sampling efforts might affect the findings.

A survey of the epiphytic leaves of Posidonia oceanica was conducted along a depth transect at both the control station Attaya in the Kerkennah Islands and the disturbed Mahres station on the Sfax coast (Tunisia). Samples were collected by scuba divers at depths of 5, 10, 15, and 20 m in July 2008. We evaluated whether the pattern of spatial variability of the macroepiphyte assemblages of leaves of Posidonia oceanica differed in relation to anthropogenic interference. The results indicate that the decrease in shoot density and leaf length according to depth was low at Mahres. The biomass of epiphytic leaves and the percentage cover of epiphytic assemblages decreased with depth for both stations and heavily at Mahres, this decline being related to anthropogenic disturbance. This study shows that the highest values of epifauna and epiflora were detected at the disturbed station Mahres. Macroalgae assemblages decreased with depth at both stations and were dominated by Rhodophyta, whereas the percentage cover of the epifauna leaf that decreases according to depth was dominated by Hydrozoa and Bryozoa. Changes in epiphyte assemblages, epiphytic biomass, percentage cover, and species richness in proportion to Heterokontophyta, Rhodophyta, Cyanobacteria, Hydrozoa, Porifera, and Tunicata between the two stations constitute promising tools for detecting environmental disturbance.