HIMB

Globally, introductions of non-indigenous species have caused dramatic economic and ecological damage. Most research on marine invasions has occurred in locations easily accessible by researchers, but much less is known about introductions to remote islands. In the central Pacific, Palmyra Atoll represents one of the last remaining quasi-pristine reef systems left in the world. In the 1940s the Atoll underwent extensive military modifications, potentially making it susceptible to invasive species. Here we describe the presence of five non-indigenous invertebrate and algal introductions at Palmyra, including two sponges, Haliclona (Sigmadocia) caerulea and Gelliodes fibrosa; one bryozoan; Zoobotryon verticillatum; one hydroid, Pennaria disticha and one macroalga, Acanthophora spicifera. The Hawaiian Archipelago is the most likely source of the introductions via shipping or yachting activity to the Atoll. Currently, the impacts of these introductions remain unknown although future monitoring will assess the influence of these non-indigenous species on this remote reef system.(Received September 13 2010)(Accepted December 21 2010)(Online publication April 19 2011)

A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8–30.1 °C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress.

We conducted gross and microscopic characterizations of lesions in Cnidaria from Palmyra Atoll, Central Pacific. We found growth anomalies (GA) to be the most commonly encountered lesion. Cases of discoloration and tissue loss were rare. GAs had a focal or multi-focal distribution and were predominantly nodular, exophytic, and umbonate. In scleractinians, the majority of GAs manifested as hyperplasia of the basal body wall (52% of cases), with an associated absence or reduction of polyp structure (mesenteries and filaments, actinopharynx and tentacles), and depletion of zooxanthellae in the gastrodermis of the upper body wall. In the soft corals Sinularia sp. and Lobophytum sp., GAs exclusively manifested as prominent hyperplasia of the coenenchyme with an increased density of solenia. In contrast to scleractinians, soft coral GAs displayed an inflammatory and necrotizing component with marked edema of the mesoglea, accompanied by infiltrates of variably-sized granular amoebocytes. Fungi, algae, sponges, and Crustacea were present in some scleractinian GAs, but absent in soft coral GAs. Fragmentation of tissues was a common finding in Acropora acuminata and Montipora cf. dilatata colonies with tissue loss, although no obvious causative agents were seen. Discoloration in the zoanthid, Palythoa tuberculosa, was found to be the result of necrosis, while in Lobophytum sp. discoloration was the result of zooxanthellar depletion (bleaching). Soft corals with discoloration or tissue loss showed a marked inflammatory response, however no obvious causative organisms were seen. Lesions that appeared similar at the gross level were revealed to be distinct by microscopy, emphasizing the importance of histopathology.► Palmyra Atoll is a functionally intact oceanic reef environment. ► Growth anomalies (GAs) were the most commonly encountered lesion in Cnidaria. ► In scleractinians, 52% of GAs manifested as hyperplasia of the basal body wall. ► In soft corals, GAs manifested as prominent hyperplasia of the coenenchyme. ► GAs negatively impact scleractinian and soft corals at Palmyra.

A management proposal aims to partly remove a WWII military causeway at Palmyra Atoll to improve lagoon water circulation and alleviate sedimentation stress on the southeast backreef, an area of high coral cover and diversity. This action could result in a shift in sedimentation across reef sites. To provide management advice, we quantified the proximate environmental factors driving scleractinian coral cover and community patterns at Palmyra. The proportion of fine sedimentation was the optimal predictor of coral cover and changes in community structure, explaining 23.7% and 24.7% of the variation between sites, respectively. Scleractinian coral cover was negatively correlated with increases in fine sedimentation. Removing the causeway could negatively affect the Montipora corals that dominate the western reef terrace, as this genus was negatively correlated with levels of fine sedimentation. The tolerance limits of corals, and sediment re-distribution patterns, should be determined prior to complete removal of the causeway.► We modeled scleractinian coral cover and community structure with environment at Palmyra Atoll. ► Coral cover showed a negative relationship with levels of fine sediment influx. ► Fine sediment influx was the optimal predictor of coral community structure. ► Removing an existing WWII military causeway could increase sedimentation on the reefs. ► We predict negative impacts to the reefs if sedimentation were to increase as a result.

Coral species are difficult to identify
due to few distinct morphological features and high levels
of phenotypic variation; furthermore, hybridization is
thought to play an important role in coral evolution. The
genus Pocillopora is one of the most abundant reef-building
corals in the Pacific, yet species boundaries within this
important group remain enigmatic, with conflicting
interpretations of molecular data. To further examine the
relationship between morphology and genetic variation, we
examined in situ photographs, microscopic images, and
molecular markers (ORF, CR, ITS-2) from 59 Pocillopora
colonies representing a range of atypical morphologies
thought to be rare or endemic to remote locations (the
Hawaiian Archipelago, Johnston Atoll, Palmyra Atoll, and
Howland Island). Additionally, we combined our data with
previously published genetic data from the western Indian
Ocean, Taiwan, the Great Barrier Reef, and the tropical east
Pacific (n = 298) to examine phylogeographic relationships
more broadly. Mitochondrial markers revealed six distinct
clades, while nuclear data (ITS-2) resolved no clear groups
due in part to intragenomic variation. Although colony-level
morphology is highly variable within each mitochondrial
clade, microscopic corallite-level morphology showed less
variation and stronger concordance with mitochondrial
groups, and one clade was found only in the Hawaiian
Archipelago. These findings will assist with efforts to
delineate species boundaries in the genus Pocillopora and
contribute to understanding the scale of species-level
variation in reef building corals. Accurate determination
of species boundaries will improve conservation efforts and
further our understanding of the evolution and biodiversity
of reef building corals.

Widespread geographic distribution of sponges should be rare, mainly because of the low dispersal capacity of their larvae and asexual products. Here we investigate the potential wide-scale distribution range in one marine sponge, Gelliodes wilsoni, that has been spread widely around the Pacific Rim by shipping. The species was originally described from the Philippines (western Pacific Ocean) by Wilson in 1925 as Gelliodes fibrosa. Recently, similar specimens have been collected from Guam (western Pacific Ocean), Hawaii, Palmyra Atoll (central Pacific Ocean), Acapulco Bay and Baja Peninsula (eastern Pacific Ocean). This species now appears to be widely distributed across the Pacific Ocean, and this distribution seems unlikely to have resulted from an extremely high dispersal capability; it is most likely the result of centuries of trans-Pacific shipping. We also propose the new name G. wilsoni for the species G. fibrosa originally described by Wilson because the same name was previously used by Dendy in 1905 to describe a species from Sri Lanka, which is morphologically different from the species described by Wilson. The case of G. wilsoni is not unique because several sponges (discussed here) have similar distribution patterns across the Pacific (at locations more than 10,000 km apart). This suggests an east–west connectivity and that widespread distribution in sponges is indeed possible, albeit the result of human activities. In an increasingly connected world our research highlights the importance of understanding connectivity across oceanic scales in order to predict where invasive species are likely to occur.

This paper describes a new method developed to directly measure size and temperature specific growth rates of individual wild squid. Our tag and recapture method is complimentary to previously employed statolith aging methods but provides finer scale ...