An expeditious low-cost method for the acoustic characterization of seabeds in a Mediterranean coastal protected area

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGPosidonia oceanica meadows are ecosystem engineers which, despite their ecological relevance, are experiencing habitat fragmentation and area decrease. Cartography and information on the ecological status of these habitats is key to an effective maritime spatial planning and management for habitat conservation. In this work we apply an acoustic methodology to map benthic habitats (substrate and vegetation) in an archipelago of the Natura 2000 Network close to the coast of Murcia (SE Spain) where dense and sparse areas of P. oceanica, and patches of Cymodocea nodosa appear over a sandy and had bottom. The methodology uses dual frequency information (200 kHz and 38 kHz) acquired with a single-beam echosounder to develop a bathymetry, and performs sea bottom and vegetation supervised classifications, using video and scuba diver observations as groundtruthing data. Sea bottom was classified from acoustic features of the first and second 200 kHz echoes into 5 substrate classes using a random forest classifier: sand, fine sand, coarse sand, hard bottoms and hard bottoms with sandy patches. The vegetation was classified from features extracted from the "above-bottom" part of the echo (height and backscattering intensity) in both frequencies, resulting also in a 5 class classification: C. nodosa meadows, dense P. oceanica meadows, dispersed P. oceanica meadows, dense P. oceanica with sand patches, and no-vegetation; according to the random-forest Gini index, 38 kHz features were the most informational variables for this classification. The validation accuracies of both classifications were 85% (substrates) and 70% (vegetation), close to accuracies reported in the literature when using a similar number of classes. The results of this article (including bathymetric, and substrate and vegetation thematic maps), together with the acoustic methodology described and used, are contributions that can improve the continuous monitoring of Mediterranean seagrasses

New records of introduced species in the Mediterranean Sea (November 2023)

This collective article presents new information about 15 introduced taxa belonging to five phyla: one Rhodophyta, one Chlo-rophyta, one Mollusca, one Annelida, two Arthropoda, and nine Chordata (one Ascidiacea and eight Osteichthyes). The records refer to eight Mediterranean countries and extend from the Alboran Sea to the Levantine Sea as follows: Spain: first record of the African hind Cephalopholis taeniops for the Alboran Sea, and a further record of the Monrovia surgeonfish Acanthurus monrovi-ae, extending its distribution northwards in the Western Mediterranean. Italy: an additional record of the squat lobster Scyllarus subarctus based on its nisto stage, new records of the lionfish Pterois miles in the north-western Ionian Sea, first records of the bivalve Fulvia fragilis for the Italian Adriatic coast, and a record of the amphipod Ptilohyale littoralis in the northern Adriatic Sea, also representing the first report for the Mediterranean Sea. Montenegro: first record of the non-indigenous ascidian Ciona robus- ta. Albania: first record of the red cornetfish Fistularia petimba. Greece: first record of the cryptogenic polychaete Alitta succinea in association with ship fouling, suggesting the possibility of a non-indigenous origin of Mediterranean populations of this species, and first record of the Seychelles dragonet Synchiropus sechellensis for the Saronikos Gulf. Turkiye: first record of the red alga Womersleyella setacea, report of an abundant population of the Indian twospot cardinalfish Cheilodipterus novemstriatus in the Turkish Aegean Sea, and first record of Synodus randalli, also corresponding to the first report for the Mediterranean Sea. Syria: first record of the blenny Istiblennius cf. meleagris. Israel: report of an algal bloom of the green alga Codium parvulum, and first record of Synchiropus sechellensis