Deep sea

Abstract

Two new species of deepwater cardinalfish, Epigonus gemma [7 specimens, 37.7–76.7 mm in standard length (SL)] and Epigonus hexacanthus (22 specimens, 32.2–57.0 mm SL) are described based on specimens from deep reefs off Curaçao, southern Caribbean Sea. Epigonus gemma is distinguished from other congeners by a combination of the following characters: dorsal-fin rays VII-I, 9–10; pectoral-fin rays 16; total gill rakers 25–27; vertebrae 10 + 15; pyloric caeca 8–9; pored lateral-line scales 43–44 + 5–6; opercular spine absent; maxillary mustache-like processes absent; ribs on last abdominal vertebra absent; tongue toothless; endopterygoid teeth absent; and enlarged conical teeth on symphysis of lower jaw present. Epigonus hexacanthus is distinguished from other congeners by a combination of the following characters: dorsal-fin rays VI-I, 10; pectoral-fin rays 16–17; total gill rakers 25–27; vertebrae 10 + 15; pyloric caeca 6–7; pored lateral-line scales 32–35 + 3–5; opercular spine absent; maxillary mustache-like processes absent; ribs on last abdominal vertebra absent; lingual teeth present; endopterygoid teeth present; and enlarged conical teeth on symphysis of lower jaw absent. Eight specimens (37.6–54.4 mm SL) of E. hexacanthus are female with mature gonads, rendering the species the smallest in size at sexual maturity among its congeners. A key to the species of Epigonus currently known from the Caribbean Sea is provided.

Available here: https://link.springer.com/article/10.1007/s10228-024-00948-2#citeas

MSc thesis report

The coral reefs of Bonaire, providing resources and environmental services, are often ranked among the richest, most resilient and least degraded in the Caribbean, but they are not escaping the global degrading trend in coral reefs. Identifying and combatting local stressors, increases the resilience to global stressors. Research has shown that even the deeper, relatively unexplored reefs, mesophotic coral ecosystems (MCE), ranging from 30 to 150m in depth, are being impacted by anthropogenic disturbances. As the MCEs start where Scuba diving stops, and submersibles are often too costly, this study deployed an ROV to explore and monitor the shallow (5-20m) and the upper-mesophotic (40- 60m) reefs at eight sites along the leeward coast of Bonaire. These sites were subdivided into different zones, showing a gradient in human impact and water quality. The imagery obtained by the ROV is of adequate quality, allowing for identification to genus level if not species level, and showed comparable results in estimated percentage coral cover with other recent studies. The benthic community composition changed along the vertical (depth) and horizontal (human impact and water quality) gradient. Benthic cyanobacterial mats were found around 40-60m depth, covering large parts of the ocean floor. Hard and soft corals, sponges, macroalgae and crustose coralline algae occurred at 40m depth at six of the eight monitored sites, indicating the presence of MCEs, and only at one site (Karpata), hard corals were present at 60m depth. Coral cover showed a clear increasing trend with decreasing human impact, addressing the need for a better understanding of heterogeneity among sites and local conservation measures. Developments in underwater robotics and machine learning enable more research on these hidden coral reefs and identification of the effect of local stressors on MCEs.

Hexactinellid sponges are important members of deep-sea benthic ecosystems because they provide available hard substrate habitats for filter-feeding invertebrates. However, symbioses between hexactinellid sponges and their symbionts are poorly known. Zoantharians associated with hexactinellid sponges have been reported widely from deep-sea marine ecosystems, either on the bodies or stalks of hexactinellid sponges. Despite these records, there has been a lack of research on their diversity and phylogenetic relationships. In this study, 20 specimens associated with amphidiscophoran and hexasterophoran sponges were collected from the waters of Australia and Japan in the Pacific, and from Curaçao in the southern Caribbean, and these were examined in addition to museum specimens. Based on molecular phylogenetic analyses and morphological observations, we formally describe two new genera and three new species of Zoantharia and report several previously described species. The results suggest at least two independent origins for the symbioses between hexactinellid sponges and zoantharians. Our results demonstrate that the diversity of hexactinellid sponge-associated zoantharians is much higher than has been previously thought. The new taxa described in this work further reconfirm that the deep-sea harbours high levels of undescribed zoantharian diversity.

Hexactinellid sponges are important members of deep-sea benthic ecosystems because they provide available hard substrate habitats for filter-feeding invertebrates. However, symbioses between hexactinellid sponges and their symbionts are poorly known. Zoantharians associated with hexactinellid sponges have been reported widely from deep-sea marine ecosystems, either on the bodies or stalks of hexactinellid sponges. Despite these records, there has been a lack of research on their diversity and phylogenetic relationships. In this study, 20 specimens associated with amphidiscophoran and hexasterophoran sponges were collected from the waters of Australia and Japan in the Pacific, and from Curaçao in the southern Caribbean, and these were examined in addition to museum specimens. Based on molecular phylogenetic analyses and morphological observations, we formally describe two new genera and three new species of Zoantharia and report several previously described species. The results suggest at least two independent origins for the symbioses between hexactinellid sponges and zoantharians. Our results demonstrate that the diversity of hexactinellid sponge-associated zoantharians is much higher than has been previously thought. The new taxa described in this work further reconfirm that the deep-sea harbours high levels of undescribed zoantharian diversity.

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In 2015 an Expert group assessed the ten Dutch World Heritage candidate sites and advised the Ministry of Education, Culture and Science with regards to the potential nomination of Bonaire National Marine Park. The conclusion was that further research is needed to demonstrate its Outstanding Universal Value (OUV). According to the Expert group, the current size and boundaries of BNMP do not contain features which qualify the property as unique, hence extension of the BNMP boundaries was recommended. Possibilities for extension are the island Curaçao, the islands off the coast of Venezuela and the 12 miles zone.

In collaboration with the Ministry of Economic Affairs it was decided to start by studying the nature values of the 12 miles zone of Bonaire, because this is the most feasible boundary extension. The 12 miles zone of Bonaire has a total area of almost 360,000 ha, which is a 74-fold enlargement compared to the 4,860 ha of the current boundaries of BNMP.

The objective was to determine the existence of potential nature values per zone based on the following criteria: rare, threatened or characteristic species; rare, untouched or undisturbed geomorphological features; important physical oceanographic features; potential ecosystem services. An inventory of previous studies by IMARES and available data from two deep sea expeditions in 2000 and 2013 were incorporated in this study.

Our review updates the current state of knowledge on the deep sea of the Caribbean Sea, focussing on the 12 miles zone of Bonaire. It provides a general framework for the decision making process on the boundary extension of the potential World Heritage Site and how to strengthen the potential OUV.

The available information shows that the 12 miles zone contains some attributes that will strengthen the OUV to some extent, such as the discovery of 16 species new to science at the deeper reef of Bonaire and the presence of some species endemic to the Southern Caribbean Ecoregion. Convincing documentation is still lacking, however evidence from past deep sea expeditions indicates that further studies of deep water biodiversity will likely easily yield a wealth of new species. Also potential offshore sea mounts within the 12 miles zone of Bonaire may be worthwhile investigating, by mapping the seafloor through a bathymetric survey. These potential habitats, structures and new species in the 12 miles zone of Bonaire could greatly add to the OUV of the BNMP.

Abstract:

Here we establish a neotype for Alatina alata (Reynaud, 1830) from the Dutch Caribbean island of Bonaire. The species was originally described one hundred and eighty three years ago as Carybdea alata in La Centurie Zoologique—a monograph published by René Primevère Lesson during the age of worldwide scientific exploration. While monitoring monthly reproductive swarms of A. alata medusae in Bonaire, we documented the ecology and sexual reproduction of this cubozoan species. Examination of forty six A. alata specimens and additional archived multimedia material in the collections of the National Museum of Natural History, Washington, DC revealed that A. alata is found at depths ranging from surface waters to 675 m. Additional studies have reported it at depths of up to 1607 m in the tropical and subtropical Atlantic Ocean. Herein, we resolve the taxonomic confusion long associated with A. alata due to a lack of detail in the original description and conflicting statements in the scientific literature. A new cubozoan character, the velarial lappet, is described for this taxon. The complete description provided here serves to stabilize the taxonomy of the second oldest box jellyfish species, and provide a thorough redescription of the species.

Abstract:

To protect deep-sea biodiversity, the United Nations have adopted a number of resolutions that should protect vulnerable marine ecosystems (VMEs), such as cold water corals and sponges, by the regulation of deep-sea fisheries on the high seas. In a parallel process, the Convention on Biological Diversity (CBD) calls upon states to identify Ecological and Biological Significant Areas (EBSAs) that serve as focal areas, without any special legal status, and establish a network of marine protected areas by 2012. In addition, at the tenth meeting of the Conference to the Parties of the CBD in Nagoya, in 2010, it was agreed that by 2020, 10% of coastal and marine areas should be protected.

The Netherlands is involved in both processes since our country has ratified the CBD and therefore is bound to contribute to the protection of biodiversity, both in its national waters and in the high seas. In this report we provide a worldwide overview on the protection of VMEs and of the status of the EBSA selection processes as per March 2012. Next, we zoom in on three areas that are of interest to the Dutch government (Caribbean, West Africa, Antarctica) and we summarize the spatial protection measures, list the closed VME areas and EBSA selection processes and we provide information on the regional seas conventions and their mandates.

The Sargasso Sea is a fundamentally important part of the world’s ocean, located within the North Atlantic sub-tropical gyre with its boundaries defined by the surrounding currents. It is the only sea without land boundaries with water depths ranging from the surface coral reefs of Bermuda to abyssal plains at 4500 m. The Sargasso Sea’s importance derives from the interdependent mix of its physical structure and properties, its ecosystems, its role in global scale ocean and earth system processes, its socio-economic and cultural values, and its role in global scientific research. Despite this, the Sargasso Sea is threatened by a range of human activities that either directly adversely impact it or have the potential to do so. Being open ocean, the Sargasso Sea is part of the High Seas, the area of ocean that covers nearly 50% of the earth’s surface but which is beyond the jurisdiction and responsibility of any national government, and as such it enjoys little protection. To promote the importance of the Sargasso Sea, the Sargasso Sea Alliance was created under the leadership of the Government of Bermuda in 2010. This report provides a summary of the scientific and other supporting evidence for the importance of the Sargasso Sea and is intended to develop international recognition of this; to start the process of establishing appropriate management and precautionary regimes within existing agreements; and to stimulate a wider debate on appropriate management and protection for the High Seas.

Nine reasons why the Sargasso Sea is important are described and discussed. It is a place of legend with a rich history of great importance to Bermuda; it has an iconic ecosystem based upon floating Sargassum, the world’s only holopelagic seaweed, hosting a rich and diverse community including ten endemic species; it provides essential habitat for nurturing a wide diversity of species many of which are endangered or threatened; it is the only breeding location for the threatened European and American eels; it lies within a large ocean gyre which concentrates pollutants and which has a variety of oceanographic processes that impact its productivity and species diversity; it plays a disproportionately large role in global ocean processes of carbon sequestration; it is of major importance for global scientific research and monitoring and is home to the world’s longest ocean time series of measurements; it has significant values to local and world-wide economies; and it is threatened by activities including over-fishing, pollution, shipping, and Sargassum harvesting.

Apart from over-fishing many of the threats are potential, with few direct causal relationships between specific activities and adverse impacts. But there is accumulative evidence that the Sargasso Sea is being adversely impacted by human activities, and with the possibility of new uses for Sargassum in the future, the lack of direct scientific evidence does not preclude international action through the established precautionary approach. The opportunity to recognise the importance of the Sargasso Sea and to develop and implement procedures to protect this iconic region and the wider High Seas should be taken before it is too late.