Marine Ecology-An Evolutionary Perspective最新文献

The current rapid climate warming is expected to cause an ocean temperature increase of 3°C–5°C by 2100, leading to deoxygenated and acidified tropical seas. Without mitigation measures, the total loss of tropical corals is inevitable. Already, one-third of tropical reefs are considered permanently lost. Coral bleaching initiated by the loss of symbionts, the photosynthetic zooxanthellae, is the main process whereby corals respond to thermal stress, followed by recovery. However, increased thermal stress and frequency of bleaching have caused widespread coral recovery failure. Zooxantheallae of the genus Symbiodinium are considered the thermally vulnerable part of the coral symbiosis. In recent decades, warming has displaced genotypes of lower thermal resilience to subtropical latitudes; few genotypes of higher temperature tolerance remain abundant in tropical seas, but these will not withstand warming predictions either. Interestingly, high temperatures in the Red Sea have selected for exceptionally heat-resistant coral genotypes and for the highest known thermal resilience in endemic zooxanthellae at the same time. Actions to overcome the coral bleaching crisis have been proposed by combining coral ecophysiology and mass culturing of thermally resilient Red Sea symbionts for naturalisation to the global tropical ocean, including restoration of collapsed reefs using corals with thermally resilient symbiont genotypes.

Ostreobium comprises endolithic algae commonly seen in conjunction with scleractinian corals. In the past, it was solely recognized as a coral skeleton bioeroder. Their relationship with corals is critical because they give photosynthetic byproducts and help the coral when it loses its primary symbionts due to stress. The variety of these algae in coral species of the genus Porites in the Tropical Eastern Pacific and western Atlantic was investigated. Ostreobium samples from seven Porites species including two from the Tropical Eastern Pacific (TEP) (P. panamensis and P. lobata) and five from the Caribbean (P. furcata, P. porites, P. colonensis, P. branneri, and P. astreoides) were extracted. Published rbcL sequences from algae found within various coral species from other parts of the world were also compared. A biogeographic analysis and two methodologies, PTP (Poisson tree process) and GMYC (general mixed Yule-coalescent), were used to delineate the different species. The findings revealed a significant degree of genetic diversity within Ostreobium, with more than 15 groups of not more than three individuals and 40 individual lineages. Its origins date back to the Ordovician, 500 Ma, and it does not appear to preserve host specificity. The sampled locations still have a wide variety of Ostreobium. Biogeographically patterns were also confirmed, making it impossible to pinpoint the precise origins of most clades. The ancestry analyses revealed convergent events for not only the emergence of Ostreobium in a few genera of local corals, but also the phenomenon occurred in genera from far-off places.

Most artificial reefs (ARs) in the Gulf of Mexico are considered intermediate to high vertical relief structures which have recruited large predatory species indicating a lack of juvenile habitat. Small, inexpensive ARs, standard monitoring units for the recruitment of reef fishes (SMURFs), were deployed at eight treatment stations at −20 m as habitat for juvenile fishes to understand and determine the effects of substrate type on the recruitment of juvenile fishes. Each treatment station contained four SMURFs with four treatments: small and large concrete rubble (~10 and ~20 cm), oyster shells, and bare. Surveys conducted from July 2017 to July 2019 yielded 39 different juvenile species, including one of the most economically important species, Lutjanus campechanus, present across all replicates. There were 5238 individual fishes collected, and the family Lutjanidae accounted for ~49% of these. The highest species richness and diversity occurred in SMURFs containing oysters or small concrete rubble while bare treatment had the lowest. Both concrete rubble and oyster shells might offer shelter to numerous body shapes and sizes of juvenile fishes as a result from a variety of crevice sizes. This study suggests that the deployment of low-relief structures with different substrate materials might affect recruitment of select species and provide further information useful to designing ARs, aiding fisheries production. Because enhancing fisheries is one of the goals of the Texas Parks and Wildlife Department Artificial Reef Program it is here recommended to continue developing other designs of low-relief to be allocated in between existing high-relief ARs that should serve as stepping stones for the survival of species of fisheries interest (e.g., L. campechanus).

Coastal algal reef ecosystems, which are formed by the skeletal carbonate of crustose coralline algae (CCA), provide vital habitats for a diverse range of marine organisms and serve as valuable archives of long-term environmental data. Despite the importance of these reef ecosystems, there is currently a lack of available information regarding the accretion rates of CCA in subtropical intertidal zones in the Taoyuan algal reef. We measured the vertical accretion and horizontal growth of CCA cultured in two aquaculture tanks over a 9-month period. The vertical accretion and horizontal growth rate of CCA was approximately 0.29–0.43 and 5.5 μm·day⁻¹ (the extrapolated annual value is equivalent to 0.11–0.16 and 2.0 mm·year⁻¹, respectively). Newly colonized CCA had faster horizontal growth of approximately 110 μm·day⁻¹ (equivalent to 40.2 mm·year⁻¹). These results highlight the slow and gradual process of algal reef ecosystem formation in the subtropical intertidal zones. The CCA had a faster lateral growth rate as seen in the newly settled CCA. These findings contribute to our understanding of the overall growth dynamics of CCA.

The invasive Diadema setosum (Leske, 1778) long-spined sea urchin has been in the Mediterranean Sea since 2006, and then, it has been known that its population density has reached high values on the southern Aegean coasts of Türkiye. This study aimed to report the mass mortality event of D. setosum with the determined agent on the Aegean coast of Türkiye. In addition, it was targeted to provide information on the current status of its density based on seasonal SCUBA diving observations for the period between January 2023 and November 2023. The results showed that the mass mortality of D. setosum was determined in Muğla, Aegean Sea, in August 2023. Spine loss, the mucoid layer at the bottom of the appendages, and the outer body surface were observed as the clinical symptoms of the diseased samples. Bacterial growth was detected on Vibrio-selected TCBS agar plates, while no other parasitic agents were determined in the coelomic fluid of sea urchins. The results of the biochemical (API 20E) and molecular tests confirmed the isolated bacteria as Vibrio spp. The density of D. setosum showed statistically significant temporal changes, and the highest and lowest mean density values were recorded in autumn and spring, respectively. Environmental stressors, such as increasing sea temperature levels, affect the marine ecosystem and lead to opportunistic pathogens. Long-term monitoring of disease outbreaks is necessary to understand the interactions between species and the ecosystem.

The conservation of species, especially those with high levels of exploitation and economic interest, relies on the knowledge of their biology and geographical distribution. In the marine realm, similar morphology between species is a common difficulty in identifying sympatric species, especially in early stages of development. Therefore, genetic identification of crustacean species has been shown to be the only way to identify the species. We used a 451-bp fragment of the 16S rDNA gene to differentiate nine species of decapod crustaceans, five of which are sympatric and heavily exploited in the Mediterranean Sea: Aristeus antennatus (blue and red shrimp), A. virilis (stout red shrimp), A. varidens (striped red shrimp), Aristaeomorpha foliacea (giant red shrimp), Aristaeopsis edwardsiana (scarlet shrimp), Gennadas elegans (graceful blunt-tail prawn), Gennadas valens (valuable blunt-tail prawn), Parapenaeus longirostris (deep-water rose shrimp) and Penaeus kerathurus (camarote prawn). Analysis of the 16S rDNA gene provides clear evidence of genetic differentiation to be used as an easy method to identify these species.

The gastropod Parvaplustrum wareni (Parvaplustridae) is an important faunal component in the ecosystem of deep-sea hydrothermal vents of the Piip submarine volcano, Bering Sea. To highlight trophic relationships in this ecosystem, the fatty acid (FA) composition of the hydrothermal gastropod P. wareni has been studied. This is one of the few studies analyzing FA compositions of gastropods in a hydrothermal vent ecosystem. The major polyunsaturated FAs of this mollusk are represented by n-3 and n-6 FAs: arachidonic acid (20:4n-6), eicosapentaenoic acid (20:5n-3), docosatetraenoic acid (22:4n-6), and docosapentaenoic acid (22:5n-3). The low level of FA markers of phytoplankton suggests an insignificant role of organic matter created by photosynthesis in the nutrition of P. wareni. A high level of monounsaturated FAs (more than 70% of total FAs) dominated by palmitoleic (16:1n-7) and cis-vaccenic (18:1n-7) FAs indicates the bacterial nutrition of the mollusk. In general, the analysis of the P. wareni FA composition has allowed a conclusion that the organic matter created by chemosynthesis provides a favorable basis for the P. wareni population to thrive in the hydrothermal vents of the Piip volcano.

Hurricanes are natural periodic events that disrupt marine ecosystems along their path, altering the distribution and abundance of organisms. In October 2016, Hurricane Matthew struck the Santa Marta region (Colombia) and impacted its coastal zone, yet there have been insufficient studies to measure its effects. The aim of this study was to assess the impact of Hurricane Matthew on the meiofaunal community in the region. To achieve this, sediment samples were collected from the intertidal zone of three beaches 5 days after the hurricane had passed. The results were compared with previous data collected in October 2014, on the abundance and diversity of taxonomic groups of intertidal meiofauna, as well as physicochemical variables such as granulometry, organic matter in sediments, salinity, and water temperature. Following Hurricane Matthew, the physicochemical variables showed changes due to the effect of the cyclonic surge in the coastal zone. The average organism abundance not only experienced a decline in both abundance and richness but also underwent changes in composition. Nematoda, originally the fourth most abundant group in 2014, became the most dominant taxon post-hurricane. Conversely, the relative abundance of Copepoda decreased. The total number of recorded taxa was 13, which is close to the 15 previously reported. The ANOSIM and PERMANOVA tests confirmed differences in the meiofaunal community before and after Hurricane Matthew, with Tardigrada, Cnidaria, Ostracoda and Mollusca, being the main groups that contributed the most to the dissimilarity between periods. The environmental variables of organic matter and temperature best explained the structure of the meiofaunal community after the natural phenomenon. This study highlights the importance of meiofauna as a monitoring tool for beaches and the effects of environmental disturbances such as hurricanes, which are expected to become more common in coastal areas due to climate change.