Effects of Climate Change and Anthropogenic Activities on Algivorous Cichlid Fish in Lake Tanganyika

Over the last century, water temperatures in Lake Tanganyika have risen due to climate change, which increased thermal stratification and reduced the magnitude of nutrient availability. A rise in temperature increases the C:N:P ratio resulting in a poor algal diet. In addition, lake littoral habitat is experiencing increased sediment load due to deforestation of the watershed caused by anthropogenic activities. Sediments cover benthic algae and reduce its nutritional value, consequently affecting the foraging behavior, distribution, and growth performance of algivorous fish. Algae and algivorous fish are an important link in the lake food chain; therefore, if the rise in temperature will continue as predicted, then this may have a cascading effect for the rest of the community in the food chain including human being. This, in turn, may contribute to food insecurity at local and regional levels. To counteract this adaptation and mitigation measures such as environmental monitoring systems and creating new opportunities should be considered.

Comparison of three sampling methods for small-bodied fish in lentic nearshore and open water habitats

We performed a preliminary evaluation of a mobile sampling platform with adjustable push net and live box (Platform) against two common methods for sampling small-bodied fish (i.e., 10–100 mm) in two distinct lentic habitats. Nearshore (NS) littoral habitat was sampled by Platform and beach seine, and open water (OW) pelagic habitat by Platform and Kodiak trawl. Our goal was to evaluate the Platform’s ability to describe fish assemblage structure across habitat types in contrast to common techniques restricted to single habitat types that are less comparable due to gear-specific bias. Platform sample speed had a significant positive effect on recapture efficiency of both nearly neutrally buoyant objects and marked fish. Marked fish recapture efficiencies were similar for Platform in NS and OW, indicating similar efficiency across habitat types. Platform capture efficiency was similar to beach seine and greater than Kodiak trawl. With similar sampling time, the Platform collected more individuals and taxa in NS relative to beach seine and in OW relative to Kodiak trawl. Greater taxa detection by the Platform suggests that it may be effective at detecting species that are numerically rare in specific habitats when compared to these methods. Fish CPUE was significantly greater NS regardless of technique. However, by using the Platform, there is greater confidence that this difference was reliable and not a gear selectivity artifact. Overall, this preliminary study demonstrates the Platform’s potential to collect standardized data across NS and OW habitats, track ontogenetic habitat shifts, and detect differences in small-bodied fish taxa richness, relative abundance, and density between NS and OW habitats. Continued experimentation beyond a single reservoir and fish size range is required before consensus can be established regarding the utility of this new push net design.

The comparative lake ecology of two allopatric Arctic Charr, Salvelinus alpinus,populations with differing life histories in Cumberland Sound, Nunavut.

The lake ecology of high-latitude fishes is strongly influenced by seasonal feeding opportunities and environmental stochasticity in Arctic environments. Arctic Charr (Salvelinus alpinus) populations are prevalent throughout the Arctic and show multiple life history strategies across their range. Unlike Old World populations the lake ecology of Arctic Charr populations on south Baffin Island remain poorly defined. We examined the comparative seasonal lake ecology of two differing Arctic Charr populations (anadromous and landlocked) in Cumberland Sound, Nunavut. Anadromous charr showed no evidence of feeding occurring within freshwater once they began seaward migrations. Anadromous charr achieve sexual maturation at a larger size and younger age than landlocked charr. Landlocked charr used more lake habitats than anadromous charr with feeding opportunities as an apparent influence on habitat selection. Landlocked charr fed year round. They adopted a cannibalistic feeding strategy in the winter but consumed a variety of prey items in the fall. Littoral habitat was found to be important to all sizes of charr in both seasons. Smaller anadromous charr (<350mm) did not use the benthic habitat. The variable ecology and form demonstrated further emphasizes the phenotypic adaptability of Arctic Charr that allows its widespread distribution in the Arctic.

Effects of Climate Change and Anthropogenic Activities on Algivorous Cichlid Fish in Lake Tanganyika

Over the last century, water temperatures in Lake Tanganyika have risen due to climate change, which increased thermal stratification and reduced the magnitude of nutrient availability. A rise in temperature increases the C:N:P ratio resulting in a poor algal diet. In addition, lake littoral habitat is experiencing increased sediment load due to deforestation of the watershed caused by anthropogenic activities. Sediments cover benthic algae and reduce its nutritional value, consequently affecting the foraging behavior, distribution, and growth performance of algivorous fish. Algae and algivorous fish are an important link in the lake food chain; therefore, if the rise in temperature will continue as predicted, then this may have a cascading effect for the rest of the community in the food chain including human being. This, in turn, may contribute to food insecurity at local and regional levels. To counteract this adaptation and mitigation measures such as environmental monitoring systems and creating new opportunities should be considered.

A remarkable new genus and species of Hansenauropodidae (Myriapoda, Pauropoda) from the seashore of Hainan Island, China

Psammopauropus macrospinus gen. et sp. n., a remarkable new genus and species of the pauropod family Hansenauropodidae is described from the marine littoral habitat of Hainan Island, South China. It has one pair of dorsal spines on the pygidium differentiated from seta a1, large globular seta st on pygidium, and globular distal setae on the tarsi by which Psammopauropus can be easily distinguished from all other genera of the family. In addition, the adaptive characters of the littoral pauropods are preliminary discussed. This is the first record of the family Hansenauropodidae from China.

Maritime trap-jaw ants (Hymenoptera, Formicidae, Ponerinae) of the Indo-Australian region – redescription of Odontomachus malignus Smith and description of a related new species from Singapore, including first descriptions of males

The maritime trap-jaw ant Odontomachus malignus Smith, 1859 is thought to be widespread throughout islands in the Indo-Pacific and parts of the Oriental realm. Because of its unique nesting preference for harsh littoral habitat and distinct morphology, O. malignus has usually been assumed to consist of only one species. We, however, describe a new species similar to O. malignus found in the mangroves of Singapore, Southeast Asia – Odontomachus litoralissp. nov. We find strong evidence of both species existing in (near) sympatry, and also distinct morphological differences between O. malignus and the new species. Additional complementary DNA evidence in the form of COI barcodes (313 bp) supporting putative species identification and delimitation is provided. Defining morphological characteristics for the O. malignus species group (nested within the larger O. infandus clade) are given in detail for the first time. The worker and queen castes of the new species are described; a redescription of the worker caste of O. malignus, based on specimens from Singapore and the Philippines in addition to the holotype, is also given. The males of both species are also described for the first time, including male genitalia. A preliminary key to most known species of the O. infandus group based on the worker caste is provided.

Size variation and geographical distribution of the luminous earthworm Pontodrilus litoralis (Grube, 1855) (Clitellata, Megascolecidae) in Southeast Asia and Japan

The luminous earthworm Pontodriluslitoralis (Grube, 1855) occurs in a very wide range of subtropical and tropical coastal areas. Morphometrics on size variation (number of segments, body length and diameter) and genetic analysis using the mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequence were conducted on 14 populations of P.litoralis from Southeast Asia and Japan. Statistical inference on morphometric data revealed significantly different size variations in the body length and diameter among these 14 populations of P.litoralis. However, discordance between the morphometric and mitochondrial COI gene-based phylogenetic analyses was evident, where the size variations in P.litoralis showed a different pattern from the COI genetic differences. The update on the current distribution of P.litoralis is reported and revealed different aspects of the littoral habitat characteristics between Southeast Asia and Japan.

Seasonal and depth variations in diet composition and dietary overlap between three native killifish of an emblematic tropical-mountain lake: Lake Titicaca (Bolivia)

ABSTRACTLake Titicaca (∼3800 m a.s.l.), an emblematic tropical-mountain ecosystem is the major source of fish for people on the Altiplano. The Andean killifish genus Orestias, represent an important resource for local fisheries in Lake Titicaca. It has been suggested that exist an effect of segregation in the Lake Titicaca in order to avoid competition for food resource between native fish species, due most of Orestias species share the littoral habitat, which is now also share with introduced species. Such scenario increases the pressure for food resource. Here I examined the gut content of O. luteus, O. agassizii and O. mulleri (Cuvier & Valenciennes, 1846) from a bay of Lake Titicaca during rainy (April) and dry season (July) with the predominance method, frequency of occurrence and numerical percentage to describe the diet and dietary overlap between these native fish. I also applied a PERMANOVA test in order to determine diet variations related to depth and seasonally, as well as the Levins and Pianka’s index to test diet breadth and dietary overlap respectively. 396 gut contents were evaluated, identifying a high frequency of amphipods and molluscs in the three Orestias native species. Diet breadth revelled a selectivity for a few preys and the composition of the diets was influenced mainly by depth, followed by seasonality (PERMANOVA, P = <0.05). Dietary overlapping between O. luteus and O. agassizii was evidenced in the rainy season. During the dry season, the three species undergone dietary overlapping. This study provided a detail knowledge on the diet variations of native species in Lake Titicaca, especially for Orestias mulleri, a little-known species. Here I also discussed the importance of the amphipods as a food resource in Lake Titicaca not only for fish community, but for the food web in general. The seasonal and depth diet variations here discussed are relevant for fisheries management and conservation and could be used to guide aquaculture development in Lake Titicaca.