Marine Ecology-An Evolutionary Perspective最新文献

Identifying the core microbiome structure of a metaorganism can be used to monitor the impact of a perturbation against it and the changes in its stability (i.e., dysbiosis), resistance, and resilience. The core-microbiome interaction regulates holobiont health and homeostasis and is an indicator of the resilience of the whole community. This study determined the exclusive and shared core microbiome taxa of two reef-building coral species (Pocillopora damicornis and P. verrucosa), as well as the surrounding seawater and sediment, in six coral communities along the Northeastern tropical Pacific region. We also analysed the putative metabolic functions of the most abundant OTUs of these core microbiomes and evaluated the influence of anthropogenic stressors (i.e., tourism, fishery, eutrophication, among others) on core microbiome composition. Bacterial diversity was assessed by sequencing the V4 region of the 16S rRNA. The bacterial families Planctomycetaceae, Oceanospirillaceae, and Moraxellaceae presented the highest relative abundances in corals samples, while Flavobacteriaceae and Rhodobacteraceae dominated in seawater samples. In the sediment samples, Pseudoalteromonadaceae, Oxalobacteraceae, Moraxellaceae, and Pseudonocardiaceae had the highest representation. The core microbiomes of the two coral species, seawater, and sediment, shared 571 OTUs. The P. damicornis core microbiome varied between sites with low and moderately-high anthropogenic stressors. The core microbiomes of both coral species showed an increase in the relative abundance of the families Planctomycetaceae and Pseudomonadaceae in the sites with moderate-high anthropogenic stressors, associated with higher values of ammonium, chlorophyll a, and extinction coefficient. In contrast, the core microbiome of P. verrucosa, seawater, and sediments did not vary between sites with different anthropogenic stress conditions. Aerobic chemoheterotrophy was the metabolic function with the highest occurrence in all substrates' core microbiomes, followed by ureolysis and photoautotrophy.

Research on the feeding habits of batoids provides information of intra and interspecific interactions of this taxon in marine ecosystems. We analyzed 832 stomachs of nine ray species collected from the artisanal fishery on the Northwest coast of Baja California Sur (NBCS). We identified 79 prey items assembled in five trophic groups (crustaceans, fish, mollusks, polychaetes, and sipunculidae). Results indicated that the red crab Pleuroncodes planipes was the most important prey in the diet of the seven batoid species. A low dietary similarity of the rays was observed, which evidenced different feeding strategies. In this regard, we identified four well-separated trophic guilds. Each guild was characterized by the consumption of specific prey: (1) Hypanus dipterurus and Narcine entemedor that fed mostly on polychaetes; (2) Rostroraja velezi and Gymnura marmorata fed mostly on fishes (Clupeidae and Batrachoididae); (3) Hypanus longus, Myliobatis californica, and Platyrhinoidis triseriata fed on crustaceans (Munnidae) and Sipunculus worms; and (4) Pseudobatos productus and Zapteryx exasperata fed on crustaceans (Portunidae) and fishes (Synodontidae and Batrachoididae). We concluded that batoids off the NBCS show prey sharing between the different species.

The sea urchin, Diadema setosum, is a poisonous species that originates in the Indo-Pacific and the Red Sea. Although this species has been recorded in several areas in the Mediterranean Sea, its habitat selection, density, distribution and ecological impacts have not been comprehensively documented to date. This study combined the diving observations (n = 53 sites) and local ecological knowledge (LEK) of SCUBA divers (n = 100) to provide information on the distribution and density of this invasive sea urchin on the Aegean and Levantine coasts of Turkey between September and October 2020. The results indicated that D. setosum was more prevalent along the southern coast of Turkey compared with the western coast, where it is colder. The highest densities of D. setosum were observed in rocky habitats at a depth range of 0–5 m. Moreover, the densities increased with increasing bottom temperatures (up to 150 ind./100 m²). Recent reports from the Levantine and south Aegean coasts highlighted that the densities of D. setosum increased dramatically during the past year. The results of the present study suggested that D. setosum provides shelter for a total of four fish species, including Chromis chromis, Gobius sp., Cheilodipterus novemstriatus and Thalassoma pavo. This species of urchin poses a threat due to its potential grazing and bioerosion effects in the Mediterranean. Thus, future studies should focus on the feeding ecology of D. setosum and the competition with native species that share the same habitat to obtain an improved understanding of the ecological impacts of this invasive species. Although the present study provides the first comprehensive dataset on the density and distribution of this invasive sea urchin for Turkey in the eastern Mediterranean region, we suggest that its population should be monitored for long periods using direct observations, LEK and citizen science.

Water depth can affect the size spectra (SS) and biomass of free-living nematodes, but these relationships are largely unknown for the Gulf of Mexico (GoM). Here, we examined the SS and biomass of meiofaunal nematode assemblages at 27 sites along a water-depth gradient from 44 to 3466 m in the Perdido belt, northwestern GoM. Nematodes were identified to species level, measured (length and width), and assigned to shape morphotypes and trophic groups. Nematode SS were defined by a median length of 951 μm (range: 223–4289 μm) and a median width of 33 μm (range: 12–109 μm). SS revealed a dominant long/slender morphotype (e.g., Paramicrolaimus sp., Filoncholaimus sp., and Ledovitia sp.), better adapted to the very fine sediments of the deep sea, whereas stout/short nematodes (mostly Desmoscolex sp., Greeffiella sp., and Quadricoma sp.) were less abundant. Water-depth gradient significantly influenced mean individual (IB) and total biomasses likely because reduced availability of organic carbon with depth. The two deepest sites had particularly high mean IB suggesting local sources of organic carbon in the abyssal region related to the Perdido belt oil field. The most abundant trophic group was microbial feeder sucker (56%), followed by microbial feeder scraper (23%), and predator ingester (20%). The mean IB of predator nematodes was significantly larger than that of nematode preys. However, the logarithm of ratio IB_predator/IB_prey was rather low (0.34) and in agreement with the empiric consumer-resource body-size relationship calculated for marine invertebrates. Our study provides novel insights about the structure of benthic nematode assemblages in the western Gulf of Mexico across a wide depth gradient.

Marine urbanization promotes the addition of hard substrata that barely resembles natural substrate nearby. We manipulated habitat topography in five marinas across one of the most populated regions from the Southwestern Atlantic Ocean to describe the effect of habitat complexity on the diversity of benthic communities across sites with distinct conditions and biotas. The highest biomass was found in the two marinas under high pollution and freshwater disturbances, regardless of habitat complexity. Habitat topography did not affect species richness but determined the structure of sessile communities in all marinas. The structure of mobile communities was affected only in the most diverse site, increasing the abundance of isopods. In general, fragile ascidians, hydrozoans, and non-calcified polychaetes dominated complex habitats, while structurally defended animals such as barnacles, serpulids, and encrusting bryozoans dominated simple habitats, suggesting that dominant species are selected by habitat complexity based on their morphological traits. However, the final community structure was also determined by differences across marinas, suggesting that the effect of increasing habitat topography is mostly site-specific. Therefore, strategies to minimize the disparity between natural and artificial habitats must consider historic local community and a multiple stressors scenario.

The distribution of species depends on the relationship with other species and the influence of abiotic factors, modulated by long-term evolutionary and biogeographic processes. Polychaetes and fish are important components of the biota that inhabit estuarine systems, coexisting in various habitats, although the relationship between these groups and their responses to environmental variables is poorly understood. This study aimed to assess the concordance between fish and polychaete communities in three zones (inner, middle, and outer) of a tropical bay and to determine environmental influences on these communities. The raised hypothesis is that benthic fish is associated with polychaetes and that these taxonomic groups respond differently to environmental conditions. Environmental characteristics were the main drivers determining the occurrence of fish species and polychaetes families; however, no consistent relationship was observed between fish and polychaetes. Sediment granulometry seems to be an essential driver in determining polychaetes and fish distribution while turbidity and phosphorus were also important for fish. The three zones differed in both water physicochemical and sediment (nutrients and granulometry) variables, which determined their uses by different fish and polychaetes species. Only one fish species, the gerreid Eucinostomus argenteus showed a weak but significant association with the Goniadidae and Spionidae polychaetes, which may be associated with similar environmental preferences of both taxa. The lack of a consistent relationship between benthic fish and their likely invertebrate prey may be associated with the small spatial scale of this study and the early fish life stages. Most fish in shallow coastal areas are still in their early life, feeding mainly on polychaetes and other benthic macroinvertebrates, and as the area is shallow, planktonic organisms may be included in their diet, thus relieving predation pressure on benthic organisms. These findings are important to unveil relationships among different taxonomical groups and their environment.

Animal populations can present different mating tactics according to the number of mates males or females obtain. The limiting factors for copulation in symbiont crustaceans are the size, structural complexity, and density of refuge, in addition to predation risk outside their shelters. In this study, we aimed to investigate, comparatively, if the occupation of the same refuge leads to the same reproductive tactic in two symbiont species of alpheid shrimps. For this purpose, we described the population distribution of Alpheus estuariensis, a burrowing shrimp, and Salmoneus carvachoi, a tenant species, in an intertidal mudflat in Pernambuco, northeastern Brazil. Alpheus estuariensis experiences sexual dimorphism relative to body and cheliped size, where males present larger body sizes and allocate more resources to cheliped growth than females. However, both males and females presented positive allometric growth in chelipeds. In S. carvachoi, male-phase individuals reach smaller body sizes than hermaphrodites. Male-phase shrimps experience positive allometry in cheliped size, while hermaphrodites do not. Both species were found inhabiting burrows as sexual pairs more frequently than expected by chance. Paired females of A. estuariensis were found carrying embryos more frequently than solitary ones. We did not find a statistical difference between the frequency of single and paired ovigerous hermaphrodites in S. carvachoi. Our results indicate that A. estuariensis is social monogamous, while S. carvachoi is promiscuous. We argue that different biological and ecological aspects of these species could explain the distinct tactics adopted by them. Alpheus estuariensis digs its own refuge and is a much larger species, bearing a more robust cheliped than S. carvachoi. Thus, we argue that the burrowing species (A. estuariensis) should monopolize and defend their refuge, and S. carvachoi only takes advantage of this resource.

Eutrophication results in macroalgal blooms with usually negative effects on the marine communities; nevertheless, positive and neutral effects have also been reported. We hypothesized that the macroalgal canopy plays an important role in secondary consumers like the scavenger snail Buccinastrum deforme through amelioration of physical stress and through carrion retention below the canopy. We evaluated if the canopy provided by Ulva spp. affected the habitat conditions and population traits of B. deforme in a macrotidal coastal system of North Patagonia. Our results indicated that the Ulva canopy was associated with lower desiccation, a higher abundance of crab carrions, and with larger and heavier snails. We did not, however, find differences in the sex ratio, the juvenile, and total density of B. deforme between microhabitats with and without an Ulva canopy. These results suggest that macroalgal canopy of Ulva has a modest ecological effect on B. deforme.