Shallow Coastal Reefs Research Articles

Changes in sea floor productivity are crucial to understanding the impact of climate change in temperate coastal ecosystems according to a new size-based model

The multifaceted effects of climate change on physical and biogeochemical processes are rapidly altering marine ecosystems but often are considered in isolation, leaving our understanding of interactions between these drivers of ecosystem change relatively poor. This is particularly true for shallow coastal ecosystems, which are fuelled by a combination of distinct pelagic and benthic energy pathways that may respond to climate change in fundamentally distinct ways. The fish production supported by these systems is likely to be impacted by climate change differently to those of offshore and shelf ecosystems, which have relatively simpler food webs and mostly lack benthic primary production sources. We developed a novel, multispecies size spectrum model for shallow coastal reefs, specifically designed to simulate potential interactive outcomes of changing benthic and pelagic energy inputs and temperatures and calculate the relative importance of these variables for the fish community. Our model, calibrated using field data from an extensive temperate reef monitoring program, predicts that changes in resource levels will have much stronger impacts on fish biomass and yields than changes driven by physiological responses to temperature. Under increased plankton abundance, species in all fish trophic groups were predicted to increase in biomass, average size, and yields. By contrast, changes in benthic resources produced variable responses across fish trophic groups. Increased benthic resources led to increasing benthivorous and piscivorous fish biomasses, yields, and mean body sizes, but biomass decreases among herbivore and planktivore species. When resource changes were combined with warming seas, physiological responses generally decreased species’ biomass and yields. Our results suggest that understanding changes in benthic production and its implications for coastal fisheries should be a priority research area. Our modified size spectrum model provides a framework for further study of benthic and pelagic energy pathways that can be easily adapted to other ecosystems.

Sea Slugs—“Rare in Space and Time”—But Not Always

The term “rare in space and time” is often used to typify the spatial and temporal patterns of occurrence of heterobranch sea slugs. However, “rare” in this context has not been clearly defined. In an attempt to provide more insight into the concept of rarity in sea slug assemblages, we analysed abundance data from 209 individual surveys conducted over a 5-year period in a subtropical estuary and a 7-year period on a shallow coastal reef, on the Sunshine Coast, Qld, Australia. Using an ‘intuitive’ method (<10 individuals recorded over the study), and the ‘quartile’ method we assessed numerical rarity (number of individuals of a species seen over the study period) and temporal rarity (frequency of observation). We also assessed numerical rarity using octaves based on log2 abundance bins. The quartile method did not effectively capture either measure of rarity. The octave method, however, fitted closely to subjective classifications of abundance and defined a similar number of species as rare when compared to the intuitive method. Using the octave method, 66% of species in both the estuary and on the reef, were considered as rare. Consequently, we recommend the octave method to allocate abundance classifications. To address the poor fit for temporal classifications based on quartiles, we propose the following as a working model for wider testing: rare ≤25% of surveys; uncommon 26−50%, common 51−75%; and abundant >75%.

Biphasic allometric growth in juvenile green turtles Chelonia mydas

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 37:301-308 (2018) - DOI: https://doi.org/10.3354/esr00930 Biphasic allometric growth in juvenile green turtles Chelonia mydas Michael Salmon1,*, Cody R. Mott2, Michael J. Bresette2 1Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, 33431, USA 2Inwater Research Group, Jensen Beach, Florida 34957, USA *Corresponding author: salmon@fau.edu ABSTRACT: Green turtles raised in the laboratory widen faster than they lengthen, thus changing in shape from the proportions they show as hatchlings. By doing so, young turtles may sooner achieve a size refuge from their gape-limited predators. In this study, we document that wild juveniles captured at open-water weed lines in the Gulf of Mexico show similarly wider proportions, demonstrating for the first time that this growth pattern occurs in nature. We additionally quantified the shell dimensions of older juveniles that had abandoned weed lines and returned to occupy shallow coastal reefs. Those turtles exhibited a narrower ’hatchling like’ body shape. We conclude that juvenile green turtles show a biphasic pattern of initial widening, followed later by a secondary narrowing once they achieve a size that exceeds 25-30 cm in straight-line carapace length. We hypothesize that secondary narrowing may be advantageous for reducing lethal interactions with a different subset of larger predators, those that typically dismember their prey rather than swallow them whole. Finally, we categorize this complex growth pattern as one of several vulnerability traits that promote juvenile turtle survival, and document that they are expressed in different combinations among other marine turtle species. KEY WORDS: Allometric growth · Evolution · Predator-prey · Sea turtle · Vulnerability traits Full text in pdf format PreviousCite this article as: Salmon M, Mott CR, Bresette MJ (2018) Biphasic allometric growth in juvenile green turtles Chelonia mydas. Endang Species Res 37:301-308. https://doi.org/10.3354/esr00930 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 37. Online publication date: December 13, 2018 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2018 Inter-Research.

On the Tethyida (Porifera, Demospongiae) from Bahia State, northeast Brazil, with descriptions of two new species, taxonomic appointments and new records.

The recently proposed order Tethyida is characterized by the presence of megasclere styles, tylostyles or oxeas arranged in tracts ending as bouquets at or near the surface, and microsclere euasters. Two new species are described from the shallow coastal reefs (0-10 m) of Bahia, Brazil. Timea kamasary sp. nov. is represented by thin sciaphylous specimens with three categories of spicules: tylostyles, spined spheroxyasters and spined/smooth oxyasters in varied sizes. This species differs from Timea unistellata (Topsent, 1892) by having a different category of oxyasters. Tethya bitylastra sp. nov. is characterized by having strongyloxeas I and II, spherasters, oxyasters I and II, strongylasters and two categories of tylasters. This new species differs from Tethya maza Selenka, 1879 by having a second category of tylaster. Furthermore, we present taxonomic appointment for Timea berlincki (Leite, Fonseca, Leal Hajdu, 2015) and Tethya maza and the first record of Timea stenosclera (Hechtel, 1969) for the Southwest Atlantic.

The Devil in the Deep: Expanding the Known Habitat of a Rare and Protected Fish

Abstract The accepted geographic range of a species is related to both opportunity and effort in sampling that range. In deepwater ecosystems where human access is limited, the geographic ranges of many marine species are likely to be underestimated. A chance recording from baited cameras deployed on deep uncharted reef revealed an eastern blue devil fish (Paraplesiops bleekeri) at a depth of 51 m and more than 2 km further down the continental shelf slope than previously observed. This is the first verifiable observation of eastern blue devil fish, a protected and endemic southeastern Australian temperate reef species, at depths greater than the typically accepted depth range of 30 m. Knowledge on the ecology of this and many other reef species is indeed often limited to shallow coastal reefs, which are easily accessible by divers and researchers. Suitable habitat for many reef species appears to exist on deeper offshore reefs but is likely being overlooked due to the logistics of conducting research on these often uncharted habitats. On the basis of our observation at a depth of 51 m and observations by recreational fishers catching eastern blue devil fishes on deep offshore reefs, we suggest that the current depth range of eastern blue devil fish is being underestimated at 30 m. We also observed several common reef species well outside of their accepted depth range. Notably, immaculate damsel (Mecaenichthys immaculatus), red morwong (Cheilodactylus fuscus), mado (Atypichthys strigatus), white-ear (Parma microlepis) and silver sweep (Scorpis lineolata) were abundant and recorded in a number of locations at up to a depth of at least 55 m. This underestimation of depth potentially represents a large area of deep offshore reefs and micro-habitats out on the continental shelf that could contribute to the resilience of eastern blue devil fish to extinction risk and contribute to the resilience of many reef species to climate change

The Ongoing Study of the Chemistry of the Marine Inhabitants of The Ramsar Site of Port Royal, Jamaica

Research efforts to examine the chemistry of marine organisms collected from the Ramsar site of Port Royal, Jamaica, has led to the isolation of a range of compounds as diverse as the species from which they were derived. Six sponges, two algal species, one ascidian and one soft coral collected from the mangrove area and the shallow coastal reefs were studied to yield compounds including steroids, aromatic compounds and terpenoids.

Depth, bay position and habitat structure as determinants of coral reef fish distributions: Are deep reefs a potential refuge?

Increasing disturbance frequency and severity on coral reefs has caused declines in the abundance of structurally complex corals and many fish species that depend on them. However, most studies have focused on the shallowest 10 m, despite coral habitat extending to > 30 m in many regions. Reefs in deeper water and offshore locations are less exposed to many stressors associated with coral decline, and may offer a refuge for coral-associated fishes. Understanding how distributions and species-specific fish-habitat relationships vary along depth and distance-from- shore gradients is critical for assessing refuge potential. Here we examined the community structure, distributions and coral habitat associations of 123 reef fish species along a depth gradient from = 20 m. Our results suggest that while many species are restricted to vulnerable shallow depths, deep offshore reefs provide a potential refuge for a substantial proportion of coral-associated fishes threatened by degradation of shallow coastal reefs, and deep reefs should be afforded greater consideration in conservation planning for coral reef fishes.

Pseudopataecus carnatobarbatus, a new species of velvetfish (Teleostei: Scorpaeniformes: Aploactinidae) from the Kimberley coast of Western Australia

Pseudopataecus carnatobarbatus, new species, is described from 12 specimens collected on shallow coastal reefs of northernWestern Australia, between the Monte Bello Islands and Adele Island. It is distinguished from its sole congener, P. taenianotusJohnson 2004, by branched (versus simple) tips to most fin rays, last soft dorsal-fin ray joined by membrane more fully toupper caudal-fin ray, spinous dorsal fin more distinctly notched, pelvic fins more robust, anterior face of lower lip smooth (ver-sus profusely covered with cirri), and a narrow quadrangular pit on the forehead, bounded by frontal, supraorbital, ocular andpreocular ridges (versus pit and preocular ridge absent). It also has modally fewer anal-fin rays and modally greater numbers ofgill rakers. Pseudopataecus carnatobarbatus is found in an extremely high tidal range area of Australia, where movement of upto 11 m occurs during spring tides. Specimens were collected in rocky tide pools with coral rubble and thick stands of brownmacroalgae, especially Padina species. The new species has been found in intertidal areas up to only 13 m deep, whereas P. taenianotus has been collected by trawling soft bottom habitats in depths of 20 to 63 m.

Geographic range determinants of two commercially important marine molluscs

Aim We modelled the spatial abundance patterns of two abalone species (Haliotis rubra Donovan 1808 and H. laevigata Leach 1814) inhabiting inshore rocky reefs to better understand the importance of current sea surface temperature (SST) (among other predictors) and, ultimately, the effect of future climate change, on marine molluscs. Location Southern Australia. Methods We used an ensemble species distribution modelling approach that combined likelihood-based generalized linear models and boosted regression trees. For each modelling technique, a two-step procedure was used to predict: (1) the current probability of presence, followed by (2) current abundance conditional on presence. The resulting models were validated using an independent, spatially explicit dataset of abalone abundance patterns in Victoria. Results For both species, the presence of reef was the main driver of abalone occurrence, while SST was the main driver of spatial abundance patterns. Predictive maps at c. 1-km resolution showed maximal abundance on shallow coastal reefs characterized by mild winter SSTs for both species. Main conclusions Sea surface temperature was a major driver of abundance patterns for both abalone species, and the resulting ensemble models were used to build fine-resolution predictive range maps (c. 1 km) that incorporate measures of habitat suitability and quality in support of resource management. By integrating this output with structured spatial population models, a more robust understanding of the potential impacts of threatening human processes such as climate change can be established.

Nocturnally active western rock lobsters Panulirus cygnus forage close to shallow coastal reefs

The western rock lobster Panulirus cygnus is an abundant consumer along the lower west coast of Australia, sheltering in reef during the day and foraging in surrounding habitat at night. We used acoustic telemetry to determine the distances from high-relief reef where nocturnally active P. cygnus forage at 3 sites representing 3 common shallow-water habitats: meadows of the seagrasses Amphibolis spp. and Posidonia sinuosa and macroalga-dominated pavement. We focussed on among-site variation in core and total nocturnal activity area, distance of foraging from high-relief reef and total distance between position estimates. We found that P. cygnus moved over an extensive area at all sites and that 90% of lobster activity occurred within 60 m of the nearest high-relief reef at all 3 sites regardless of habitat type. Foraging activity by P. cygnus is therefore likely to be greatest within this zone around coastal reefs. Core (50% utilisation distribution (UD)) and total (95% UD) nocturnal activity areas did not differ significantly between sites and averaged 2556 ± 482 m 2 and 10 437 ± 2221 m 2 , respectively. Total distance between position estimates and average distance from reef did not differ between sites either.

Movements of the western rock lobster (Panulirus cygnus) within shallow coastal waters using acoustic telemetry

Understanding the residency and movement patterns of major consumers, such as lobsters, in coastal waters is important for the management of coastal habitats and their fisheries. In the present study, we tagged 34 Panulirus cygnus with acoustic transmitters on a shallow coastal reef in south-western Australia and monitored their movements using fixed and manual receivers between November and May 2005–2006 and 2006–2007. We determined the proportion of ‘white’ (migratory-phase) lobsters emigrating from the reef between November and January and also characterised the large-scale movements of ‘red’ (residential-phase) and white lobsters. We undertook tank experiments to determine the effect of tagging and handling on P. cygnus behaviour. Counter to our expectation, 50% of white lobsters were detected on the reef after the migration period, whereas only a small proportion (13.6%) of white lobsters were tracked leaving the reef and only one individual displayed directional offshore movement. This limited movement indicates that coastal no-take zones may build up legal-sized 4–5+ year old lobsters because many of these are likely to remain resident over the migration season. Laboratory experiments and field observations suggest that tagging and handling affect lobster behaviour and movement for a few days post tagging, potentially confounding conclusions on dispersal and movement patterns in some studies.

Effects of the declaration of marine reserves on Tasmanian reef fishes, invertebrates and plants

Abstract The reef biota in four Tasmanian marine reserves and at associated unprotected reference sites was investigated over a 6-year period following protection from fishing. The largest reserve at Maria Island (7 km coastline length) proved the most effective at achieving species conservation and resource enhancement. The number of fish, invertebrate and algal species, the densities of large fishes (>325 mm length), bastard trumpeter (Latridopsis forsteri) and rock lobsters (Jasus edwardsii), and the mean size of blue-throated wrasse (Notolabrus tetricus) and abalone (Haliotis rubra), all increased significantly within the Maria Island reserve relative to external reference sites. Increases of an order of magnitude in the biomass of rock lobsters and two orders of magnitude in the abundance of trumpeter were particularly noticeable. Small abalone declined in density within the reserve, while large abalone became more numerous. The effectiveness of marine reserves corresponded with reserve size. Changes in species richness of fishes, invertebrates or plants were not detected in any of the three smaller reserves, other than an increase in number of fish species greater than 325 mm size within the Tinderbox marine reserve (2 km reserve length). Although patterns were partly obscured by the low power of statistical tests, trends were generally evident at the Tinderbox reserve for increasing densities of large fishes and rock lobsters, and for increases in the mean size of rock lobsters, abalone and blue-throated wrasse. Most of these trends were not apparent in the reserves with small reef areas at Governor Island (1 km reserve length) and Ninepin Point (1 km length). Rock lobsters above the legal size limit nevertheless became abundant in all reserves by the end of the study while remaining rare outside. Indirect changes to reef assemblages were also detected following the declaration of the Maria Island marine reserve. Accompanying the increase in macroalgal species richness was a change in predominant plant species from Cystophora retroflexa to Ecklonia radiata. Results of this study provide the first clear evidence that shallow Tasmanian reef ecosystems are overfished, and that unfished coastal ecosystems differ substantially from those where fishing occurs. The most noticeable changes caused by fishing were the virtual elimination of net-susceptible and heavily targeted species, which may otherwise be common, plus indirect changes to algal communities. We suggest that ecosystem change associated with fishing of shallow coastal reefs may be a widespread phenomenon worldwide.

An electromagnetic tracking system for studying the movements of rock (spiny) lobsters

A simple and inexpensive method for examining the movements of rock (spiny) lobsters is described. Electromagnetic tags emitting a pulsed signal were detected in loop antennae placed on the bottom in a grid pattern within a shallow coastal reef area. Signals were received in a tuned receiver and then interpreted using an oscilloscope. Results showing examples of the nocturnal movements of Panulirus cygnus George the western rock lobster in Western Australia are presented.

Migrations of pre-adult western rock lobsters, Panulirus cygnus, in Western Australia

In September 1978, 5 034 juvenile western rock (spiny) lobsters (Panulirus cygnus George) were tagged on a shallow coastal reef near Cliff Head in Western Australia. Of these, 26% were recaptured and removed from the population during the subsequent commercial fishery between 15 November 1978 and 30 June 1979. A resurvey of the tagging site in September 1979 found that size structure of the population was similar to the tagged population in September 1978 but that the 1979 population was composed of almost completely different individuals and only 2% of the rock lobsters tagged in September 1978 were recaught at this time. A wide range of movement was indicated by the recapture positions of 354 rock lobsters caught off the tagging site. Most travelled almost directly offshore but some also travelled offshore in a northwesterly direction. Both trends were shown in the data from the recaptures of 18 rock lobster released farther offshore from Cliff Head in September 1981, and of 19 released at a close inshore site in earlier years. Maximum offshore rates of movement of up to 622 m d-1 were recorded for distances up to 37 nautical miles (ca. 68 km). Growth rates for the tagged individuals which moved off, and those that were caught on, the tagging site were similar and close to growth rate under optimal conditions for this species. Under the present high levels of exploitation few, if any, of the rock lobsters remain to become permanent residents in the coastal reefs. It is believed that the north-westerly movements of some of the pre-adult rock lobsters, on their way to the breeding grounds on the outer edge of the continental shelf, are due to the upstream movement of these rock lobsters in a current from the north. The north-westerly movements allow the rock lobster population increased utilization of the food supplies of the coastal area.

Environmental factors affecting growth and survival of juvenile western rock lobsters Panulirus longipes (Milne-Edwards)

The effects of temperature, photoperiod, oxygen, food supply, crowding, and autotomy of limbs have been measured under controlled conditions in aquaria. Growth rate increased with temperature to a maximum 26� C above which both growth rate and survival declined. Varying the length of photoperiod did not affect growth rate or survival, except that the growth rate was depressed significantly in continuous darkness. A mild deficiency of oxygen (60-67 % saturation) resulted in a smaller size increment at a moult; depression to 47-55 % saturation caused deaths at ecdysis. Daily feeding was necessary to maintain maximum rate of growth. The fist response to decreased food supply was a reduction in frequency of moulting. More severe shortage of food also depressed growth increment per moult. Feeding rates and conversion ratios have been measured. Frequency of moulting (and hence growth rate) was depressed markedly when juveniles were held in isolation. At a moult replacing two lost limbs, the growth rate was not affected; replacement of four limbs reduced that moult increment. Single loss of up to four limbs did not result in an earlier moult, but repetitive loss of two or more limbs at or immediately after each ecdysis led to precocious moulting. The impact of these and other components of the environment (shelter, salinity, turbidity, competitors and predators) upon juveniles during the 4 years spent on shallow coastal reefs is discussed. Food supply is emerging as the dominant factor determining growth and survival in the wild population.

Studies on recruitment in the Western Australian rock lobster Panulirus longipes cygnus George: density and natural mortality of juveniles

Density of juveniles on shallow coastal reefs was measured by a single census mark-recapture method, samples being taken by baited traps. Verification that marked and unmarked individuals were equally vulnerable to trapping was obtained by double marking and direct underwater checking. Very little dispersal or migration of the juveniles occurred from January to October, but in November and December the larger specimens moved to deeper water while smaller juveniles (age group 2+ years) appeared on the reefs by January. In a test area away from the centre of the coastal range of this species, density of juveniles at the beginning of each of the past five years fluctuated greatly from one year to another (ranging from 5385 per ha in January 1967, to 1212 per ha in January 1969). Natural mortality of juveniles varied with density (M = 0.499D0 × 10-3), shelter possibly limiting the carrying capacity of a reef. In aquaria, cannibalism of newly moulted rock lobsters has been shown to increase with crowding, despite surplus feeding. Density-independent factors operating upon planktonic larvae and densitydependent factors limiting survival of juveniles play complementary roles in determining the level of recruitment to the adult stock. In the centre of the population range, the second set of factors is of major importance; towards the periphery of the range, the first set of factors is the more important. Catchability declined with water temperature in autumn and increased in spring. In January of five successive years (temperature 22.2-23.2°C) catch per unit effort was directly proportional to population density (c/g = 5.05D × 10-3. However, catchability rose from 2.5 ? 10-3 in January 1966 to 15.8 × 10-3 in January 1969, possibly due to a decline in the availability of natural food.