Deep-Water Japanese Blunthorn Lobster Palinustus waguensis Kubo, 1963: First Estimates of Life History Parameters From the Southwest Coast of India

Palinustus waguensis Kubo, 1963, is the deep-sea Japanese blunthorn lobster belonging to the Family Palinuridae. It is a species that has been rarely reported, living in rocky habitats on deep-reef slopes at a depth of 100–250 m. An estimated catch of 100 kg of P. waguensis consisting of 113 males, 54 females, and 23 berried lobsters were collected during the first fortnight of January 2019 from the multi-day shrimp trawls operating off Sakthikulangara, Kerala, India. The mean total length was recorded as 112.3 mm in males, 102.6 mm in females. The parameters of the length-weight relationship were estimated as, a = 0.041, b = 2.84 for males and a = 0.05, b = 2.86 for females, which were not significantly different (P > 0.05, r2 > 0.90) between the males and females. The relative condition factor (K) in the males and females of P. waguensis ranged from 2.07–4.96 and 1.87–3.86, respectively, attributing to the better feeding efficiency in males. Food and feeding analysis revealed the dietary content as fish (53 %), crab (23.5 %), shrimp (7.8 %), digested matter (11.6 %), and foraminifera (4 %). Feeding intensity analysis about the fullness of the stomach showed the specimens bearing full stomachs (11.3 %), three-fourth full (9.9 %). Length at 50 % maturity (Lm50) was 96.9 mm. Gonado-somatic index (GSI) ranged from 3.39 to 8.13. The present study forms the first report on the biology of the deep-water Japanese blunthorn lobster, P. waguensis from India.

Community similarity and species overlap between habitats provide insight into the deep reef refuge hypothesis

The deep reef refuge hypothesis (DRRH) postulates that mesophotic coral ecosystems (MCEs) may provide a refuge for shallow coral reefs (SCRs). Understanding this process is an important conservation tool given increasing threats to coral reefs. To establish a better framework to analyze the DRRH, we analyzed stony coral communities in American Sāmoa across MCEs and SCRs to describe the community similarity and species overlap to test the foundational assumption of the DRRH. We suggest a different approach to determine species as depth specialists or generalists that changes the conceptual role of MCEs and emphasizes their importance in conservation planning regardless of their role as a refuge or not. This further encourages a reconsideration of a broader framework for the DRRH. We found 12 species of corals exclusively on MCEs and 183 exclusively on SCRs with another 63 species overlapping between depth zones. Of these, 19 appear to have the greatest potential to serve as reseeding species. Two additional species are listed under the U.S. Endangered Species Act, Acropora speciosa and Fimbriaphyllia paradivisa categorized as an occasional deep specialist and a deep exclusive species, respectively. Based on the community distinctiveness and minimal species overlap of SCR and MCE communities, we propose a broader framework by evaluating species overlap across coral reef habitats. This provides an opportunity to consider the opposite of the DRRH where SCRs support MCEs.

Gorgonian Responses to Environmental Change on Coral Reefs in SE Sulawesi, Indonesia

<p>Gorgonian corals (Cnidaria: Anthozoa: Octocorallia) are conspicuous, diverse and often dominant components of benthic marine environments. Intra- & interspecific morphological variability in gorgonians are influenced by environmental factors such as light, sedimentation and flow rates. Yet, little is known about the responses of gorgonian taxa to environmental parameters particularly in Indonesia, despite their high regional abundance and diversity. With a burgeoning human population and subsequent marine resource exploitation, reefs throughout the Indonesian archipelago are under rapid decline and often destroyed. Conservation surveys are however, underway with a tendency to overlook gorgonian taxa primarily due to unresolved taxonomic assignment leading to difficulties in field identification. The aims of this study were to: 1) characterise gorgonian diversity and ecology across a gradient of habitat quality within the Wakatobi Marine National Park (WMNP), SE Sulawesi, Indonesia, 2) assess morphological and genetic variability between morphotypes of the ubiquitous zooxanthellate isidid Isis hippuris Linnaeus 1758 from healthy and degraded reefs, 3) determine if I. hippuris morphotypes are environmentally induced (plastic) or genetically derived through reciprocal transplant experiments (RTEs) between contrasting reefs and thus, 4) identify mechanisms of plasticity capacity or divergence through phenotypic trait integration in response to environmental change. Ecological surveys revealed considerable gorgonian diversity with a total of 197 species and morphotypes from 42 genera, and 12 families within the suborders Calcaxonia and Holaxonia and the group Scleraxonia, with current estimates of over 21 new species and 28 new species records for the region. Gorgonian abundance and diversity increased with reef health and bathymetry. However, a clear loss of gorgonian diversity existed with increased sedimentation and reduced light due to anthropogenic disturbance. In particular, two distinct I. hippuris morphotypes were highly abundant between environmental clines: short-branched multi/planar colonies on healthy reefs, and long-branched bushy colonies on degraded reefs. Comparative morphological and molecular analyses using ITS2 sequence and predicted secondary structure, further corroborated haplotype differences relative to morphotypes between environments. However, unsatisfactory assignment of I. hippuris morphotypes to previously described alternatives (Isis reticulata Nutting 1910, Isis minorbrachyblasta Zou, Huang & Wang 1991) questions the validity to such taxonomic assignments. Phylogenetic analyses also confirm that the polyphyletic nature of the Isididae lies in its type species I. hippuris, being unrelated to the rest of its family members. A one-year RTE revealed three key results, that: 1) reduced survivorship of healthy reef morphotypes on degraded reefs implied the onset of lineage segregation through immigrant inviability, 2) prominent phenotypic traits were at the morphological and bio-optical levels revealing high phenotypic plasticity in healthy clones, and relative insensitivity to environmental change in degraded reef morphotypes, indicative of local adaptation leading to incipient ecological divergence, and 3) photoacclimation at the bio-optical level was not attributed to endosymbiont diversity or shuffling, with all test colonies possessing a novel clade D1a Symbiodinium. While it is clear that gorgonian taxa within the WMNP are of exceptional diversity and abundance, responses to environmental perturbation highlight three pertinent, testable ideas. Firstly, increased species richness specifically with depth in azooxanthellate taxa, invite tests of deep-reef refugia previously established through geological change. Secondly, ecological assessment targets research on informative taxa for focused systematics and mechanisms of phenotypic divergence. Thirdly, exploring intrinsic and extrinsic interactions that define the host-symbiont relationship and differential biological success using physiological and next generation sequencing approaches. These objectives would provide considerable insight into the evolutionary processes to environmental change, accelerated by anthropogenic encroachment. Taken together, this work signifies that gorgonian corals within the WMNP are of foremost diversity and concern, exhibiting informative ecological and mechanistic responses to environmental perturbation. This evidence elicits tests of deep-reef refugia, priority systematics, mechanisms of ecological divergence and physiological assessment. Such tests inevitably expand our understanding of the intrinsic and extrinsic associations of gorgonian taxa to environmental change from an historical and predictive perspective yielding benefits to conservation assessment and management.</p>

Gorgonian Responses to Environmental Change on Coral Reefs in SE Sulawesi, Indonesia

<p>Gorgonian corals (Cnidaria: Anthozoa: Octocorallia) are conspicuous, diverse and often dominant components of benthic marine environments. Intra- & interspecific morphological variability in gorgonians are influenced by environmental factors such as light, sedimentation and flow rates. Yet, little is known about the responses of gorgonian taxa to environmental parameters particularly in Indonesia, despite their high regional abundance and diversity. With a burgeoning human population and subsequent marine resource exploitation, reefs throughout the Indonesian archipelago are under rapid decline and often destroyed. Conservation surveys are however, underway with a tendency to overlook gorgonian taxa primarily due to unresolved taxonomic assignment leading to difficulties in field identification. The aims of this study were to: 1) characterise gorgonian diversity and ecology across a gradient of habitat quality within the Wakatobi Marine National Park (WMNP), SE Sulawesi, Indonesia, 2) assess morphological and genetic variability between morphotypes of the ubiquitous zooxanthellate isidid Isis hippuris Linnaeus 1758 from healthy and degraded reefs, 3) determine if I. hippuris morphotypes are environmentally induced (plastic) or genetically derived through reciprocal transplant experiments (RTEs) between contrasting reefs and thus, 4) identify mechanisms of plasticity capacity or divergence through phenotypic trait integration in response to environmental change. Ecological surveys revealed considerable gorgonian diversity with a total of 197 species and morphotypes from 42 genera, and 12 families within the suborders Calcaxonia and Holaxonia and the group Scleraxonia, with current estimates of over 21 new species and 28 new species records for the region. Gorgonian abundance and diversity increased with reef health and bathymetry. However, a clear loss of gorgonian diversity existed with increased sedimentation and reduced light due to anthropogenic disturbance. In particular, two distinct I. hippuris morphotypes were highly abundant between environmental clines: short-branched multi/planar colonies on healthy reefs, and long-branched bushy colonies on degraded reefs. Comparative morphological and molecular analyses using ITS2 sequence and predicted secondary structure, further corroborated haplotype differences relative to morphotypes between environments. However, unsatisfactory assignment of I. hippuris morphotypes to previously described alternatives (Isis reticulata Nutting 1910, Isis minorbrachyblasta Zou, Huang & Wang 1991) questions the validity to such taxonomic assignments. Phylogenetic analyses also confirm that the polyphyletic nature of the Isididae lies in its type species I. hippuris, being unrelated to the rest of its family members. A one-year RTE revealed three key results, that: 1) reduced survivorship of healthy reef morphotypes on degraded reefs implied the onset of lineage segregation through immigrant inviability, 2) prominent phenotypic traits were at the morphological and bio-optical levels revealing high phenotypic plasticity in healthy clones, and relative insensitivity to environmental change in degraded reef morphotypes, indicative of local adaptation leading to incipient ecological divergence, and 3) photoacclimation at the bio-optical level was not attributed to endosymbiont diversity or shuffling, with all test colonies possessing a novel clade D1a Symbiodinium. While it is clear that gorgonian taxa within the WMNP are of exceptional diversity and abundance, responses to environmental perturbation highlight three pertinent, testable ideas. Firstly, increased species richness specifically with depth in azooxanthellate taxa, invite tests of deep-reef refugia previously established through geological change. Secondly, ecological assessment targets research on informative taxa for focused systematics and mechanisms of phenotypic divergence. Thirdly, exploring intrinsic and extrinsic interactions that define the host-symbiont relationship and differential biological success using physiological and next generation sequencing approaches. These objectives would provide considerable insight into the evolutionary processes to environmental change, accelerated by anthropogenic encroachment. Taken together, this work signifies that gorgonian corals within the WMNP are of foremost diversity and concern, exhibiting informative ecological and mechanistic responses to environmental perturbation. This evidence elicits tests of deep-reef refugia, priority systematics, mechanisms of ecological divergence and physiological assessment. Such tests inevitably expand our understanding of the intrinsic and extrinsic associations of gorgonian taxa to environmental change from an historical and predictive perspective yielding benefits to conservation assessment and management.</p>

Deep Heat: A Comparison of Water Temperature, Anemone Bleaching, Anemonefish Density and Reproduction between Shallow and Mesophotic Reefs

French Polynesia is experiencing increasing coral bleaching events in shallow waters triggered by thermal anomalies and marine heatwaves linked to climate change, a trend that is replicated worldwide. As sea surface thermal anomalies are assumed to lessen with depth, mesophotic deep reefs have been hypothesized to act as refuges from anthropogenic and natural disturbances, the ‘deep reef refugia hypothesis’ (DRRH). However, evidence supporting the DRRH is either inconclusive or conflicting. We address this by investigating four assumptions of the DRRH focusing on the symbiotic association between anemones and anemonefish. First, we compare long-term temperature conditions between shallow (8 m) and mesophotic sites (50 m) on the island of Moorea from 2011–2020. Second, we compare the densities of the orange-fin anemonefish, Amphiprion chrysopterus between shallow and mesophotic (down to 60 m) reefs across three archipelagos in French Polynesia. Finally, we compare the percentage of anemone bleaching, as well as anemonefish reproduction, between shallow and mesophotic reefs. We found that the water column was well mixed in the cooler austral winter months with only a 0.19 °C difference in temperature between depths, but in the warmer summer months mixing was reduced resulting in a 0.71–1.03 °C temperature difference. However, during thermal anomalies, despite a time lag in warm surface waters reaching mesophotic reefs, there was ultimately a 1.0 °C increase in water temperature at both 8 and 50 m, pushing temperatures over bleaching thresholds at both depths. As such, anemone bleaching was observed in mesophotic reefs during these thermal anomalies, but was buffered compared to the percentage of bleaching in shallower waters, which was nearly five times greater. Our large-scale sampling across French Polynesia found orange-fin anemonefish, A. chrysopterus, in mesophotic zones in two high islands and one atoll across two archipelagos, extending its bathymetric limit to 60 m; however, orange-fin anemonefish densities were either similar to, or 25–92 times lower than in shallower zones. Three spawning events were observed at 50 m, which occurred at a similar frequency to spawning on shallower reefs at the same date. Our findings of thermal anomalies and bleaching in mesophotic reefs, coupled with mainly lower densities of anemonefish in mesophotic populations, suggest that mesophotic reefs show only a limited ability to provide refugia from anthropogenic and natural disturbances.

Plasticity of Porites astreoides Early Life History Stages Suggests Mesophotic Coral Ecosystems Act as Refugia in Bermuda

As the devastating impacts of global climate change and local anthropogenic stressors on shallow-water coral reefs are expected to rise, mesophotic coral ecosystems have increasingly been regarded as potential lifeboats for coral survival, providing a source of propagules to replenish shallower reefs. Yet, there is still limited knowledge of the capacity for coral larvae to adjust to light intensities that change with depth. This study elucidates the mechanisms underlying plasticity during early life stages of the coral Porites astreoides that enable survival across broad depth gradients. We examined physiological and morphological variations in larvae from shallow (8–10 m) and mesophotic (45 m) reefs in Bermuda, and evaluated differences in survival, settlement patterns and size among recruits depending on light conditions using a reciprocal ex situ transplantation experiment. Larvae released from mesophotic adults were found to have significantly lower respiration rates and were significantly larger than those derived from shallow adults, indicating higher content of energetic resources and suggesting a greater dispersal potential for mesophotic larvae compared to their shallow counterparts. Additionally, larvae released from mesophotic adults experienced higher settlement success and larger initial spat size compared to larvae from shallow adults, demonstrating a potential connection between parental origin, offspring quality, and recruitment success. Although both shallow and mesophotic larvae exhibited the capacity to survive and settle under reciprocal light conditions, all larvae had higher survival under mesophotic light conditions regardless of parental origin, suggesting that conditions experienced under low light may enable longer larval life, further extending the dispersal period. These results indicate that larvae from mesophotic Porites astreoides colonies are likely capable of reseeding shallow reefs in Bermuda, thereby supporting the Deep Reef Refugia Hypothesis.

Reef benthos of Seychelles - A field guide

During the 2019 First Descent: Seychelles Expedition, shallow and deep reef ecosystems of the Seychelles Outer Islands were studied by deploying a variety of underwater technologies to survey their benthic flora and fauna. Submersibles, remotely operated vehicles (ROVs) and SCUBA diving teams used stereo-video camera systems to record benthic communities during transect surveys conducted at 10 m, 30 m, 60 m, 120 m, 250 m and 350 m depths. In total, ~ 45 h of video footage was collected during benthic transect surveys, which was subsequently processed using annotation software in order to assess reef biodiversity and community composition. Here, we present a photographic guide for the visual identification of the marine macrophytes, corals, sponges and other common invertebrates that inhabit Seychelles’ reefs. It is hoped that the resulting guide will aid marine biologists, conservationists, managers, divers and naturalists with the coarse identification of organisms as seen in underwater footage or live in the field. A total of 184 morphotypes (= morphologically similar individuals) were identified belonging to Octocorallia (47), Porifera (35), Scleractinia (32), Asteroidea (19), Echinoidea (10), Actiniaria (9), Chlorophyta (8), Antipatharia (6), Hydrozoa (6), Holothuroidea (5), Mollusca (2), Rhodophyta (2), Tracheophyta (2), Annelida (1), Crinoidea (1), Ctenophora (1), Ochrophyta (1) and Zoantharia (1). Out of these, we identified one to phylum level, eight to class, 14 to order, 27 to family, 110 to genus and 24 to species. This represents the first attempt to catalogue the benthic diversity from shallow reefs and up to 350 m depth in Seychelles.

Co-development, co-production and co-dissemination of scientific research: a case study to demonstrate mutual benefits

Inadequate and inequitable distribution of research capacity and resources limits both the opportunity for leadership and participation in science. It also results in biases of effort, poor and misinterpretation of global patterns and the availability of limited usable knowledge for current challenges. Increased participation in ocean research and decision-making is needed to account for many stressors and challenges. The current intergovernmental attention on the ocean (e.g. UN Decade of Ocean Science for Sustainable Development) and the development of technologies that permit exploration and accelerate exploitation suggest that it is timely to focus on the ocean and its stewardship. Employing the principles of co-development, co-production and co-dissemination, this paper uses a case study of a deep reef project in Seychelles to illustrate some activities that can be employed to magnify research outcomes and legacy. We provide examples that range from ministerial briefings and planning meetings to joint fieldwork, grant allocation and co-authoring outputs. These activities helped us to align priorities, promote authentic interactions and focus on equitable science. Finally, reflecting on our experiences, we acknowledge the benefits brought by respectful and long-term partnerships, the variety of activities needed to develop these and challenges of maintaining them. In the future, we also want to include more opportunities for regional peer-to-peer learning and technology transfer.

Mesophotic Coral Ecosystems of the Great Barrier Reef Are Understudied and Underexplored

Mesophotic coral ecosystems (MCEs) are characterized by the presence of photosynthetically active organisms such as corals and algae, and associated communities at depths ranging from 30 to 150 m in tropical and subtropical regions. Due to the increased awareness of the potential importance of these reefs as an integral part of coral reef ecosystems (i.e., deep reef refuge, specialized biodiversity, transition zone between shallow and deep-sea environments, and recreational and intrinsic values), interest from the scientific community has grown around the world over the last two decades. Several nations have already made management declarations and started to extend marine protected areas and fishery management to MCEs. The estimated area of Australian MCEs is likely equivalent to that of shallow reef ecosystems down to 30 m; however, Australian MCEs attract limited research effort compared to other major coral reef regions around the world. In this perspective, we briefly explore the reasons for this scarcity of research on mesophotic ecosystems of the Great Barrier Reef (GBR) of Australia (e.g., strict diving regulations, new researchers’ involvement, and logistics and cost). At present, research efforts on the mesophotic ecosystems of the GBR are in decline and if this trajectory is maintained, the global disparity in knowledge between MCEs near Australia and those from the other main coral reef regions worldwide will sharpen deeply. We call for action from the research community, grant agencies, and decision-makers toward a wider understanding of these important ecosystems in Australia.