Crust Biometry of Hydrolithon Boreale (Rhodophyta: Hydrolithaceae) on Leave of Posidonia Oceanica Along a Mediterranean Coast Fed by Siliciclastic-Carbonate

A study was conducted to estimate biometry of an epiphytic micro-calcareous red algae, Hydrolithon boreale found on leaves of a Mediterranean meadow, Posidonia oceanica along the entire Turkish coast of the Mediterranean Sea in time (winter and summer 2019) and space (regions, and bottom type and depth). Percent occurrence of the epiphyte was lower in winter (25%), particularly found in a small bay in the west than summer (44%), entirely along the coast. The epiphyte grew up to 5 mm in diameter, 0.35 mm in thickness of the crust size, and was populated up to 1006 ind/m2 in summer owing to the increased utilization of the carbonate by the epiphyte with the increased water temperature. The size was contrasted to the density (abundance and biomass) in space. The biometry was significantly dependent on the siliciclastic-carbonate deposition as inferred from SiO2 of the water in relation the leaf area index (LAI) of P. oceanica. Therefore, this deposition induced specimens growing in size, followed by the reduced density in relation to N-based nutrient of the water. Further major environmental parameters which negatively affected the biometry were pH and total suspended matter of the water, analogous to the turbidity. Of the trace elements, Ni was negatively correlated with the biometry whereas the LAI was however positively correlated with all the anthropogenic-sourced trace elements (V, Cu, Zn, As, Cd, and Pb) in the leaves. Of the bottom types, the calcite rock had higher density than the other soft bottoms in contrast to the size of the epiphyte.

Comparison of Four Foraminiferal Biotic Indices Assessing the Environmental Quality of Coastal Mediterranean Soft Bottoms

Coastal environments are exposed to numerous pressures that potentially affect marine soft bottom faunas. Among these pressures, organic matter enrichment is very frequent. Several indices based on living (Rose Bengal-stained) foraminiferal communities have recently been developed to assess the induced impact and determine the environmental quality of these environments. Here, we use an open waters Mediterranean Sea data set to test the benefits and drawbacks of four foraminiferal indices: (1) the effective number of species (exp(H’bc)), (2) the Tolerant Species Index for the Mediterranean (TSI-Med), (3) the Foraminifera AMBI (Foram-AMBI), and (4) the Foram Stress Index (FSI). These indices all intend to measure the response of the foraminiferal communities to organic matter enrichment, and therefore, their results should be very similar. We found that the diversity-based index, exp(H’bc), was not suitable to evaluate the environmental quality of our Mediterranean coastal settings, as it had a non-monotonic relationship with the organic matter enrichment gradient. The three indices based on groups of indicator species (TSI-Med, Foram-AMBI, and FSI) yielded fairly similar results. For Foram-AMBI, using only assigned species to calculate proportions of indicator species partly avoided to misinterpret the results. In TSI-Med, a correction based on sediment grain size is applied to distinguish between natural and anthropogenic organic enrichment. Such a correction could also be added to Foram-AMBI and FSI. The limits between the Ecological Quality Status (EQS) classes used for macrofauna were not adapted for Foram-AMBI. Here, we propose new EQS class limits for the Foram-AMBI as follows: very good: 0 ≤ x < 1.4; good: 1.4 ≤ x < 2.4; moderate: 2.4 ≤ x < 3.4; poor: 3.4 ≤ x < 4.4; bad: 4.4 ≤ x ≤ 6. These limits could evolve in the future as new data become available, especially with a poor and bad environmental quality.

Nondestructive Monitoring of Soft Bottom Fish and Habitats Using a Standardized, Remote and Unbaited 360° Video Sampling Method

Lagoon soft-bottoms are key habitats within coral reef seascapes. Coral reef fish use these habitats as nurseries, feeding grounds and transit areas. At present, most soft-bottom sampling methods are destructive (trawling, longlining, hook and line). We developed a remote, unbaited 360° video sampling method (RUV360) to monitor fish species assemblages in soft bottoms. A low-cost, high-definition camera enclosed in a waterproof housing and fixed on a tripod was set on the sea floor in New Caledonia from a boat. Then, 534 videos were recorded to assess the efficiency of the RUV360. The technique was successful in sampling bare soft-bottoms, seagrass beds, macroalgae meadows and mixed soft-bottoms. It is easy to use and particularly efficient, i.e., 88% of the stations were sampled successfully. We observed 10,007 fish belonging to 172 species, including 45 species targeted by fishermen in New Caledonia, as well as many key species. The results are consistent with the known characteristics of the lagoon soft bottom fish assemblages of New Caledonia. We provide future users with general recommendations and reference plots to estimate the proportion of the theoretical total species richness sampled, according to the number of stations or the duration of the footage.

Callogorgia spp. and Their Brittle Stars: Recording Unknown Relationships in the Pacific Ocean and the Caribbean Sea

The habitat formed by the Callogorgia species, with their abundance and colony sizes, provides an important refuge for a variety of brittle stars which are recognized as the epibionts of octocorals in both shallow and deep environments. In such a relationship, ophiurans benefit directly from being elevated because they facilitate their feeding by suspension, while octocorals do not seem to benefit or be harmed. During three different expeditions developed in the Colombian Pacific from 2012 to 2013 and in the Caribbean Sea during 1998 and 2012 by the INVEMAR - Marine and Coastal Research institute, different samplings were carried out on soft bottoms through trawls with an epibenthic net. For the Pacific Ocean, 33 fragments of the octocoral Callogorgia cf. galapagensis Cairns, 2018 with 178 specimens of the ophiuroid Astrodia cf. excavata (Lütken and Mortensen, 1899) were found in two stations at depths 530 and 668 m. Considering the abundance of A. cf excavata, other biological characters such as size, presence of mature gonads, and evidence of arm regeneration were also detailed. In contrast, in the Caribbean Sea, Callogorgia gracilis (Milne Edwards and Haime, 1857) was found with ophiuroids belonging to the genera Asteroschema and Ophiomitra. The octocoral Callogorgia americana (Cairns and Bayer, 2002) was also found, but without associated brittle stars. These findings constituted the first specific association reported in the Eastern Tropical Pacific, and new relationships for the Caribbean Sea. This further reflected a possible specific association between the Callogorgia and Astrodia species that needed to be further explored. Thus, the Callogorgia species and the brittle star A. cf. excavata represented new records for the Colombian Pacific Ocean and the southern Caribbean Sea.

First record of Eualus drachi Noël, 1978 (Decapoda: Caridea) in the Adriatic Sea

Three specimens of decapod shrimp Eualus drachi Noël, 1978, were found in the red coral rem-nant collected for commercial purposes near the island Sveti Andrija, Croatia. It is the first record of this species in the Adriatic Sea. The decapod biodiversity of deeper coralligenous habitats, such as the red coral colonies, is poorly investigated in contrast to coastal areas and soft bottoms of traditional trawling grounds. This paper highlights the usefulness of examining the remnants of a commercial coral extraction originating from previously less investigated marine habitats in order to improve the knowledge on the biodiversity of such habitats.

First record of Marphysa chirigota (Annelida: Eunicidae) in the Mediterranean Sea (Gulf of Tunis)

To date, the genus Marphysa is represented by only three species, Marphysa sanguinea, Marphysa aegypti and Marphysa birgeri in the Mediterranean Sea. Combining morphological, molecular data (16S rRNA and cytochrome c oxidase subunit I mitochondrial loci) and environmental information, we are here presenting the first Mediterranean report of Marphysa chirigota, based on the specimens collected at Radès Station (Gulf of Tunis, western Mediterranean). The current information on the distribution of of the Marphysa species strongly supports that M. sanguinea inhabits hard bottoms and has a restricted distribution close to its type location (south English coast and nearby NE European Atlantic). The specimens from Radès Station, as well as all those reported as M. sanguinea along the Tunisian coast, were found in the shallow water soft bottoms. Therefore, we suggest that the presence of M. sanguinea in Tunisia seems is doubtful, and all Marphysa species reports from Tunisia might correspond to M. chirigota.

Space-time variations of megazoobenthos subject to natural and anthropogenic impacts in two Cuban bays: evidence of recovery?

The spatiotemporal variations of megazoobenthos on soft bottoms in Buena Vista (BV) and San Juan de Los Remedios (SJR) bays, Cuba, were assessed to infer the effects of the elimination of bottom trawl fisheries and the creation of protected areas. Data were collected at 11 sites in 2010-2013 (six routines and five exploratories) and 11 sites in 2014-2017 (four routines and seven exploratories). Samples were obtained by dredging. Mollusks were the most frequent and diverse group, followed by echinoderms and crustaceans. Total density (7.60 ind m-2) and biomass (15.82 g m-2) of the benthic community were highest in SJR in 2015. Although total biomass was lower at BV (t = 2.21; P = 0.032), there were no significant differences in density between bays (t = 0.77; P = 0.444). The site with a lower total density and biomass was located at BV. There were no differences between years except at one site, where density increased between 2010 and 2017. Total density and biomass were not significantly different inside and outside of the Zone Under Special Regime of Use and Protection (ZUSRUP) at the beginning of the sampled period. However, both density and biomass were significantly higher within the ZUSRUP at the end (2017), which suggests this protected area’s effectivity. The progressive increase in density at one site and greater density and biomass values at SJR, where bottom trawl fisheries were more intensive, suggest eliminating bottom trawl nets may have contributed to the benthic fauna recovery.